WO2021144395A1

WO2021144395A1 - Carboxylic dithiocarbamic acid anhydride compounds and compositions thereof

Info

Publication number: WO2021144395A1
Application number: PCT/EP2021/050751
Authority: WO
Inventors: Bertrand Schweitzer-Chaput; Paolo Melchiorre; Frank ARROYAVE; Aymeric CHAMPION; Fernando Bravo Lara
Original assignee: Institut Catala dInvestigacio Quimica ICIQ; Institucio Catalana de Recerca i Estudis Avancats ICREA
Current assignee: Institut Catala dInvestigacio Quimica ICIQ; Institucio Catalana de Recerca i Estudis Avancats ICREA
Priority date: 2020-01-15
Filing date: 2021-01-15
Publication date: 2021-07-22
Anticipated expiration: 2022-07-15

Abstract

The present invention relates to certain carboxylic dithiocarbamic acid anhydride compounds compounds and their use as photoinitiators in living free-radical polymerization reactions. The invention also relates to curable or cross-linkable compositions comprising the carboxylic dithiocarbamic acid anhydride compounds of the invention.

Description

CARBOXYLIC DITHIOCARBAMIC ACID ANHYDRIDE COMPOUNDS AND

COMPOSITIONS THEREOF

[1] The present invention relates to certain carboxylic dithiocarbamic acid anhydride compounds and their use as photoinitiators in living free-radical polymerization reactions.

The invention also relates to curable or cross-linkable compositions comprising the carboxylic dithiocarbamic acid anhydride compounds of the invention.

BACKGROUND ART

[2] Photopolymerization is currently used in industry in a broad range of applications such as coating of materials (for example, wood, metal or plastics), decorative paints for outdoor and indoor, binding with adhesives, advanced manufacturing (for example, 3D printing) and medical applications (for example, light-curable dental resins). Most commonly, irradiation with high-intensity UV light is privileged as it enables using non coloured light absorbing initiation systems and allows for the fast release of free radicals within the resin to be cured or cross-linked together with fast curing times. Safety measures however need to be taken when operating with UV light, as exposure of individuals to UV radiation causes health concerns (for example, vision and tissue damage). For main consumer applications, such as dental resins or domestic paints, 3D printing, adhesives and coatings, irradiation with UV light at high intensity must be avoided to exclude the related health hazards, which causes the polymerization reaction to lose in efficiency. For such applications, although irradiation with visible light would be preferred in order to avoid the above-mentioned health concerns, most photoinitiators operating under visible light are coloured systems, which typically results in a poor control over the aspect of the cured or cross-linked product and does not allow for the production of non-coloured products. [3] In addition, the effectiveness of a photoinitiator for polymerization can be measured by several parameters, such as the rate of polymerization, the achievable conversion of monomer, the curing/drying time, the polydispersity index of the formed polymer and the molecular weight of the formed polymer. Different degrees of control over these parameters are desirable depending on the targeted application. Living free-radical polymerization is widely used in industry for the preparation of polymers and polyolefins with a certain control on the degree of polymerization, molecular weight of the polymer and polydispersity index. In particular, reversible addition fragmentation chain transfer (hereinafter, RAFT) polymerization is a useful method to control the length of the polymer while providing a certain degree of homogeneity in polymer chain lengths. RAFT polymerization, as reported in Australian patent application AU2009900271 , is a mechanism where the propagation step involves a chain transfer agent that can reversibly and rapidly add to a certain polymer chain, which means that, when carried out under the control of a RAFT agent, the reaction mixture contains polymer chains with similar lengths, which allows for the formation of polymers with a narrow index of polydispersity and allows for carrying out block polymerization reactions in a reliable way.

[4] The chain transfer agent for the RAFT control typically results from the addition of the RAFT agent to a growing polymer in the free radical form. Such addition is typically triggered by thermal initiators, such as azoisobutyronitrile (hereinafter, AIBN) and other diazo compounds, or photoinitiators (for example, irradiation with gamma rays or light). Consequently, the use of a RAFT agent typically requires the use of an external initiator. Typical RAFT agents are compounds of formula Z-CS2-R wherein the moiety of formula Z-CS2- acts as chain transfer agent. Typical RAFT agents, as reviewed by Rizzardo and co-workers (Rizzardo E., Moad G., Thang S.H. (2008) RAFT Polymerization in Bulk Monomer or in (Organic) Solution in Handbook of RAFT polymerization (ed Christopher Barner-Kowollik) John Wiley & Sons, Inc., ISBN: 978-3-527-31924-4), belong to the family of trithiocarbonates (general formula: Z-S-C(S)-S-R), dithioesters (general formula: Z- C(S)-S-R) or dithiocarbamates (general formula: Z-NR’-C(S)-S-R). Remarkably, RAFT agents are also usually good chain transfer agents for a narrow range of monomers and need to be carefully chosen with account taken of the polymer to be produced. For instance, Zhou and co-workers have reported families of dithiocarbamate compounds useful as RAFT agents when used with AIBN as initiatior (Zhou D. et al. Journal of Polymer Science: Part A: Polymer Chemistry 2005 (43), 4849).

[5] Lalevee and co-workers reported in 2008 the use of certain xanthate derivatives as photoiniferters in controlled free radical polymerization reactions, in particular the compounds of formulae Ph-C(=0)-S-C(=S)-0-C₂H₅ (BEX) and Ph-C(=0)-S-C(=S)-N- (C₂H₅)2 (BEC) (Lalevee, et al. Macromolecules 2008, 41 , 2347). It is particularly shown that the benzoyl free radical (due to the presence of a carbonyl group adjacent to the xanthate functionality in the photoiniferter compound BEX) provides an increased polymerization rate (with respect to the benzyl free radical). While BEX allows reaching a conversion of 1 ,6-hexanediol diacrylate of about 80%, BEC allows reaching a conversion of about 60% in the same conditions. [6] Cabannes-Boue and Poly reported in 2017 a dithiocarbamate compound with a N- carbazole group useful as a photoinitiator under visible light irradiation and capable of undergoing the RAFT polymerization mechanism through reverse photolysis with certain monomers (Cabannes-Boue, B. et al., J. Polymer Chemistry 2017, 8, 1760). According to the authors, the reported compound is able to absorb light in the visible light range and undergo the initiation of a free radical polymerization (through the generation of a free radical) at a wavelength at which the chain transfer agent responsible for the controlled polymerization decomposes very slowly. This subtle balance allows the prepared compound to undergo both photoinitiation and controlled polymerization. The photolysis of the reported compound leads to the formation of two free radicals, one of which can trigger the polymerization and act as an initiator while the second one bearing a N- carbazole unit (which, therefore, strongly absorbs in the visible light range) recombines to act further as a chain transfer agent. This compound cannot provide discoloration of the polymer concomitantly with a controlled polymerization. In addition, it is reported that polymerization was initiated after elapsing of an inhibition period of about one hour, which means that the system needs to be irradiated with light during a certain period for the polymerization to start. Authors also report that said induction period disappears when a pre-formed macroinitiator is used.

[7] International Patent application WO2019123182A1 describes dithiocarbamate compound PI-9 of molecular formula Ph-CO-CH(CH₃)-S-(C=S)-N(C2H₅)2 as an initiator for the solution polymerization of 2-ethylhexylacrylate under UV light irradiation (at 365 nm). It is reported that such initiator allows reaching a monomer conversion of 77% after 45 minutes of irradiation along with a polydispersity index of 2.05.

[8] Dithiocarbamate compounds are well known in the art as well as their use as chain transfer agent in RAFT polymerization reactions. Much fewer carboxylic dithiocarbamic acid anhydride have, however, been reported and have barely been used in the art as photoinitiators for polymerization (except by Lalevee et al as described above for compound BEC). For instance, Ashirbaev and co-workers described a benzoic dithiocarbamic acid anhydride derived from pyrrolidine as a reaction intermediate in the copper-catalysed coupling reaction of benzoyl chloride with difluorinated organozinc reagents (Ashirbaev, S. et al., J. Org. Chem. 2018, 83, 478). The authors report in particular a compound of formula (XII)

The authors are however silent about the suitability of such compounds, including the compound of formula (XII), as photoinitiators, photoiniferters or RAFT agents.

[9] In addition, Hoffmeister and co-workers have reported in the art that the photolysis of a benzene solution of benzoic-pyrrolidine dithiocarbamic acid anhydride yields benzoic acid, N-benzoylpyrrolidine and pyrrolidyl thiuram hexasulphide (Hoffmeister, E. et al., Tetrahedron 1965, 21 , 61 (10), 2857). Thermal decomposition of the same compound is reported to produce carbon disulfide and N-benzoylpyrrolidine.

[10] From what is known in the art, it derives that there is still a need for providing improved carboxylic dithiocarbamic acid anhydride compounds useful as initiators of living free-radical polymerization triggered by irradiation with light, in particular with visible light.

SUMMARY OF THE INVENTION

[11] After extensive and exhaustive investigations, the inventors have surprisingly found new carboxylic dithiocarbamic acid anhydride compounds useful as photoinitiators for living free-radical polymerization reactions of olefins, in particular of acrylate-type olefins. The developed carboxylic dithiocarbamic acid anhydride compounds are compounds of formula (I) which are prompt to be cleaved upon irradiation with light (preferably, with visible light) in the free radicals of formulae (II) and (III) according to reaction (1 ) included below:

In the compounds of the invention, the free radical of formula (II) is suitable for the initiation of a free radical olefin polymerization reaction (by attack of the radical of formula (II) to the double bond of monomer molecule), while the free radical of formula (III) is suitable to act as a chain transfer agent in a controlled living polymerization reaction according to a RAFT mechanism. The specific carboxylic dithiocarbamic acid anhydride group in the compound of formula (I) facilitates that the compounds of formula (I) absorb light in a broad range of the spectrum (300 - 600 nm) and in particular in the visible range of the spectrum, in particular in the 400-500 nm region (blue light), which advantageously allows for the formation of radicals of formulae (II) and (III), even when blue light is used as irradiation system. This advantageously allows avoiding the use of UV light in polymerization applications, hence avoiding the health hazards of UV irradiation. The inventors have also found that the equilibrium of reaction (1) actually competes with a side reaction (2), responsible for deactivation of the initiating system and for the instability upon storage of compounds incorporating a carboxylic dithiocarbamic acid anhydride group by thermal decomposition, see reaction (2) included below:

The formation of free radicals of formulae (II) and (III) by photolysis (see reaction (1) included above) also competes with the reported photolytic degradation of compounds of formula (I) described in the art by Hoffmeister and colleagues (Hoffmeister, E. and Tarbell, D., Tetrahedron 1965, 21 , 61(10), 2857-2864) and as described above. Both thermal and photolytic degradation of the compound of formula (I) would inhibit the photoinitiation mechanism of the compound of formula (I) described in reaction (1).

[12] Hence, the inventors of the present invention have surprisingly found compounds of formula (I) wherein q and the X, Y, Ri , R and R₃ groups were found to provide improved photoinitiator systems for living polymerization induced by light irradiation and in particular, by visible light irradiation such that the compound of the invention is thermally stable (negligible rate of the reaction (2)) and triggers a living controlled free-radical polymerization when irradiated with light and put in presence of an olefin monomer (polymerization is faster than the photolytic degradation of the compound of formula (I) described in the art). [13] Thus, in a first aspect, the present invention refers to a compound of formula (I)

wherein q is 0 or 1 , when q is 0, Ri is a radical selected from the group consisting of a branched (C₃-Ci2)alkyl radical attached to the carbonyl group of the compound of formula (I) through a tertiary or quaternary carbon atom; a ring system attached to the carbonyl group of the compound of formula (I) through a quaternary carbon atom and comprising from one to four rings, wherein each ring is saturated, each ring comprises from 3 to 7 members selected from the group consisting of C, CH, CH₂, NH, O and S, and each ring is optionally substituted at any available position with one or more radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; and a (C₆-C2o)aryl group substituted at one or both carbon atoms adjacent to the carbon atom of the (C₆-C₂o)aryl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci₂)alkyl, and further optionally substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (CrC₆)alkyloxy, halo, (Cr Cejalkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; when q is 1 , X and Y are each independently selected form the group consisting of (Cr C₆)alkyl optionally substituted at any available position with one group selected from (Cr C₆)alkyloxycarbonyl and (CrC₆)alkyloxy; or, alternatively, X and Y together with the carbon atom to which they are attached form a (C3-C₈)cycloalkyl ring; and Ri is a substituent selected from the group consisting of cyano, (CrC₆)alkyloxycarbonyl, (Cr C₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl, an amidine group and a substituent deriving from a hydrocarbon aromatic ring system comprising from one to two fused rings, the rings being further optionally substituted at any available position with one or more substituents selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr C₆)alkylcarbonyl, (CrC₆)alkyloxycarbonyl, (CrC₆)alkylcarbonyloxy, (CrC₆)perfluoroalkyl, halo, nitro, di(Ci-C₆)alkylamino and cyano;

R₂ and R₃ are each a radical independently selected from the group consisting of (Cr Ci₂)alkyl group; (C₅-C2o)heteroaryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr Cejalkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; and (C₆- C₂o)aryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (CrC₆)alkyloxy, halo, (Cr Cejalkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, and nitro, and the ring is further optionally fused with one or two (C₆-C2o)aryl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Cr C₆)alkyl, (CrC₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Cr C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro; with the proviso that the compound of formula (I) is other than a compound of formula (XII)

[14] The inventors have surprisingly found that q and the X, Y and Ri groups in the compound of formula (I) or (XII) of the invention are such that the mechanisms of thermal and photolytic degradations described above no longer prevent the polymerization reaction and allows reaching high degrees of completion of the polymerization reaction. This is attributed to the fact that the polymerization reaction takes place faster than the thermal and photolytic degradation mechanisms. Without being bound to a theory, it is hypothesized that the presence of steric hindrance around the free radical of formula (II) formed according to equation (1) and associated to the X, Y and Ri groups slows down the degradation mechanism in favour of the polymerization process. This has the unexpected advantage of providing higher values of conversion of monomer than with the carboxylic dithiocarbamic acid anhydride initiators known in the state of the art.

[15] In addition, the inventors have surprisingly found that the R₂ and R₃ groups in the compound of formula (I) or (XII) of the invention allow for preparing polymers with narrower distribution of molecular weights than with the carboxylic dithiocarbamic acid anhydride initiators known in the state of the art. In addition, and unexpectedly, while dithiocarbamate RAFT agents described in the state of the art require large induction periods in visible-light triggered polymerization reactions, it was also surprisingly found that the R₂ and R₃ groups in the compound of formula (I) or (XII) allow for a significant reduction of said induction time. It is advantageous as the irradiation period allowing for the formation of the cured product is reduced, which results in a less energetically demanding and faster polymerization process. The formed radical of formula (III) upon photolytic cleavage allows for establishing a controlled living radical polymerization according to a RAFT mechanism and can act as chain transfer agent with no need for long periods of irradiation during the induction period. The compounds of formulae (I) or (XII) were thus advantageously found to provide controlled living radical polymerization in a reduced amount of time with respect to the dithiocarbamate compounds described in the state of the art for visible-light induced photopolymerization together with improved performance in terms of achievable monomer conversion. These compounds are useful photoiniferters of polymerization, even when no solvent is used. [16] In a second aspect, the present invention refers to a process for the preparation of a compound of formula (I) of the present invention.

[17] The present invention, in a third aspect, refers to the use of a compound of formula (I) or of formula (XII) as defined in the first aspect of the invention as a photoinitiator for polymerization. Such polymerization reaction provides polymer materials that incorporate both radicals of formulae (II) and (III) as end groups of the polymer chain.

[18] In a fourth aspect, the present invention refers to a compound of formula (IV) wherein n is an integer of from 1 to 5;

each P is a polymeric block consisting of a polymerized product of a composition comprising a monomer having a polymerizable carbon-carbon double bond and wherein q, X, Y, Ri, R and R are as defined in the first aspect of the invention. The compound of formula (IV) incorporates both radicals of formulae (II) and (III) as end groups of the polymer chain.

[19] The compound of formula (IV) is advantageously functionalizable at the end of the polymer chain, thanks to the presence of a carbonyl group, via chemical modification of the carbonyl group. The compound of formula (IV) may also further act as a macromolecular chain transfer agent in RAFT processes. [20] In a fifth aspect, the present invention refers to a process for the preparation of a compound of formula (IV) of the present invention.

[21] In a sixth aspect, the present invention refers to the use of the compound of formula (IV) of the present invention (and as defined in the fourth aspect of the present invention) as chain transfer agent. [22] In a seventh aspect, the present invention refers to a composition comprising:

(i) at least one compound of formula (I) or of formula (XII) of the present invention, or at least one compound of formula (IV) of the present invention, or a combination of a compound of formula (I) or of formula (XII) and a compound of formula (IV) of the present invention; and (ii) at least one of: a) a monomer comprising in its molecular formula at least one carbon-carbon double bond, and b) an oligomer comprising in its molecular formula at least one carbon-carbon double bond.

[23] In an eighth aspect, the present invention refers to a process for the preparation of a cross-linked material comprising the step of irradiating the composition of the seventh aspect of the present invention with light, preferably with blue light, wherein when the composition does not comprise a compound of formula (I) or of formula (XII) according to the present invention, it further comprises a polymerization initiation system.

[24] In a ninth aspect, the present invention refers to a cross-linked material obtainable by the process of the eighth aspect of the invention.

[25] The research leading to this invention has received funding from “la Caixa” Foundation. The project leading to the present patent application received funding from the European’s Union Horizon 2020 research and innovation programme under grant agreement n^e 899541 .

BRIEF DESCRIPTION OF THE DRAWINGS

[26] Figure 1 shows the evolution of the conversion of monomer into polymer (in %, this is the percentage of monomer polymerized with regard to the total monomer added initially) over time (in minutes) for methyl acrylate when put in presence of 0.5 mol% of a compound of formula (la) (black line with a cross marker), (lb) (black line with a triangular marker), (lc) (black line with a diamond-shaped marker) , (Id) (black line with a square marker), (le) (black line with a circular marker), (G) (black dotted line ·, comparative example) and

BEC (black dotted line - , comparative example) and irradiated with blue light, as measured following the method described in Example 2. The y-axis refers to the % of conversion of monomer into polymer (percentage of monomer polymerized with regard to the total monomer added initially) and the x-axis refers to the time in minutes.

[27] Figure 2 shows the evolution of the conversion of monomer into polymer (in %, this is the percentage of monomer polymerized with regard to the total monomer added initially) over time (in minutes) for methyl acrylate when put in presence of 0.5 mol% of a compound of formula (If) (black plain line), (Ig) ( — line), (Ih) ( line) and BEC ( — — line) and irradiated with blue light, as measured following the method described in Example 2. The y-axis refers to the % of conversion of monomer into polymer (percentage of monomer polymerized with regard to the total monomer added initially) and the x-axis refers to the time in minutes.

[28] Figure 3 shows the absorbance with regard to the wavelength of light (in nm) of a mixture consisting of methyl acrylate and the compound of formula (Id) in 0.5 mol% amount before (plain line) and after (dashed line) irradiation with blue light (400 mW per cm², 460 nm) during 15 minutes. The y-axis refers to the absorbance of the mixture (arbitrary units), and the x-axis refers to the wavelength in nm.

[29] Figure 4 shows the evolution of the conversion of monomer into polymer (in %, this is the percentage of monomer polymerized with regard to the total monomer added initially) over time (in minutes) for methyl acrylate when put in presence of 0.25 mol% of a compound of formula (lb) and irradiated at different intervals of time (from t=0 to 67 seconds, from t = 364 seconds to t = 434 seconds and from t = 734 seconds onwards). The y-axis refers to the % of conversion of monomer into polymer (percentage of monomer polymerized with regard to the total monomer added initially) and the x-axis refers to the time in minutes.

DETAILED DESCRIPTION OF THE INVENTION

[30] All terms as used herein in this application, unless otherwise stated, shall be understood in their ordinary meaning given in the state of the art. Other more specific definitions for certain terms as used in the present application are as set forth below and are intended to apply uniformly throughout the specification and claims unless an otherwise expressly set out definition provides a broader definition.

[31] For the purposes of the present invention, any ranges given include both the lower and the upper end-points of the range. Ranges given, such as temperatures, times, molar ratio and the like, should be considered approximate (this is, with a 5% margin of variation around the indicated points), unless specifically stated.

[32] In the context of the present invention, the term “free radical” and its plural refer to a molecule bearing an atom with an unpaired valence electron.

[33] In the context of the invention, the term “halo” or “halogen” or their plurals refer to a halogen radical or group, they thus refer to fluoro, chloro, bromo or iodo.

[34] In the context of the present invention, the term “alkyl” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims. Examples of alkyl groups include, but are not limited to: methyl, ethyl, propyl, iso-propyl, butyl, iso-butyl, tert-butyl, pentyl, and hexyl. The term “branched alkyl” and its plural refer to a saturated hydrocarbon group having the number of carbon atoms indicated in the description or in the claims wherein at least one of the carbon atoms is tertiary or quaternary. Examples of branched alkyl groups include, but are not limited to, iso-propyl, iso-butyl, tert-butyl, isobutyl, neo-pentyl, 2-methylpentyl and 2-methylhexyl.

[35] In the context of the present invention, the term “alkene” and its plural refer to a saturated linear or branched hydrocarbon compound having the number of carbon atoms indicated in the description or in the claims and at least one carbon-carbon double bond.

[36] In the context of the present invention, the term “tertiary carbon atom” and its plural refer to a carbon atom in a saturated hydrocarbon group having three substituents other than hydrogen. Similarly, the term “quaternary carbon atom” and its plural refer to a carbon atom in a saturated hydrocarbon group having four substituents other than hydrogen.

[37] In the context of the present invention, the term “alkyloxy” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims which is attached to the remainder of the formula through an ether group (-0-).

[38] In the context of the present invention, the term “alkylamino” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims which is attached to the remainder of the formula through an amino group (-NH-).

[39] In the context of the present invention, the term “acylamido” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims, which is attached to the remainder of the formula through a carbonylamino group (that is, a group of formula G-CONH- wherein G is the saturated linear or branched hydrocarbon group).

[40] In the context of the present invention, the term “alkylaminocarbonyl” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims, which is attached to the remainder of the formula through an aminocarbonyl group (that is, a group of formula G-NHCO- where G is the saturated linear or branched hydrocarbon group).

[41] In the context of the present invention, the term “alkyloxycarbonyl” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims, which is attached to the remainder of the formula through an oxycarbonyl group (that is, a group of formula G-OCO- where G is the saturated linear or branched hydrocarbon group).

[42] In the context of the present invention, the term “acyloxy” and its plural refer to a saturated linear or branched hydrocarbon group having the number of carbon atoms indicated in the description or in the claims, which is attached to the remainder of the formula through a carbonyloxy group (that is, a group of formula G-COO- where G is the saturated linear or branched hydrocarbon group).

[43] In the context of the invention, the term “photopolymerization” and its derivatives refer to a process initiated thanks to light irradiation and through which a polymer is formed.

[44] In the context of the present invention, the term “photoinitiator” and its plural refer to a substance which, when submitted to light irradiation, is able to generate reactive species and trigger a chemical transformation, such as a free radical polymerization process.

[45] In the context of the present invention, the term “photoiniferter” and its plural refer to a substance which, when submitted to light irradiation, is able to generate reactive species suitable for the initiation, transfer and termination of a free radical polymerization carried out under the control of chain transfer agent. Dithiocarbamate compounds are known photoiniferters. Thus, in the context of the present invention, a “photoiniferter” is a specific class of “photoinitiators”.

[46] In the context of the present invention, the term “RAFT agent” and its plural refer to a substance or reagent for free radical polymerization processes controlled through the RAFT mechanism.

[47] In the context of the present invention, the term “(C₆-C2o)aryl” and its plural refer to an aromatic hydrocarbon ring system comprising from 1 to 5 6-membered aromatic rings.

[48] In the context of the present invention, the term “(C₅-C2o)heteroaryl” and its plural refer to an aromatic ring system comprising from 1 to 6 aromatic rings comprising each 5 or 6 members independently selected from the group consisting of C, CH, N, NH, O and S.

[49] In the context of the present invention, a cyclic ring A is said to be “fused” with another cyclic ring B when the rings A and B have two adjacent members in common in their cyclic structure. [50] In the context of the present invention, the term “acrylate” and its plural refer to polymerizable compounds comprising in their molecular formula the triradical of formula

[51] In the context of the present invention, the term “methacrylate” and its plural refer to polymerizable compounds comprising in their molecular formula the triradical of formula

[52] In the context of the present invention, the term “acrylamide” and its plural refer to polymerizable compounds comprising in their molecular formula the triradical of formula

(VII):

[53] In the context of the present invention, the term “styrene” and its plural refer to polymerizable compounds comprising in their molecular formula the radical of formula

(VIII):

[54] In the context of the present invention, the term “cyanoacrylate” and its plural refer to polymerizable compounds comprising in their molecular formula the triradical of formula (IX):

[55] In the context of the present invention, the term “vinyl ether” and its plural refer to polymerizable compounds comprising in their molecular formula the triradical of formula

(X):

[56] In the context of the present invention, the term “vinyl ester” and its plural refer to polymerizable compounds comprising in their molecular formula the triradical of formula

(XI):

[57] In the context of the present invention, the term “chain transfer agent” and its plural refer to a substance able to react with a chain carrier by a reaction in which the original chain carrier is deactivated and a new chain carrier is generated.

[58] In the context of the present invention, the term “polymer block” and its plural refer to the product of the polymerization of a polymerizable mass, such as an olefin compound, such that the formed polymer has a single type of repeating units in its molecular formula. For instance, polymethylacrylate is a polymeric block resulting from the polymerization of methyl acrylate. Similarly, polyethylene is a polymeric block resulting from the polymerization of ethylene.

[59] According to the first aspect of the invention, as already noted above, the present invention refers to a compound of formula (I) as defined above.

[60] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein when q is 0, Ri is a radical selected from the group consisting of a branched (C3-Ci₂)alkyl radical attached to the carbonyl group of the compound of formula (I) through a tertiary or quaternary carbon atom; a ring system attached to the carbonyl group of the compound of formula (I) through a quaternary carbon atom and comprising from one to four rings, wherein each ring is saturated, each ring comprises from 3 to 7 members selected from the group consisting of C, CH, CH₂, NH, O and S, and each ring is optionally substituted at any available position with one or more radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Cr C₆)acylamido, (Ci-C₆)acyloxy and nitro; and a (C₆-C₂₀)aryl group substituted at one or both carbon atoms adjacent to the carbon atom of the (C₆-C₂o)aryl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci₂)alkyl, and further substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr Cejalkylamino, (Ci-C₆)acylamido, (Ci-C₆)acyloxy and nitro.

[61] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 1 .

[62] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 1 , X and Y are each independently selected form the group consisting of (Ci-C₆)alkyl or, alternatively, X and Y together with the carbon atom to which they are attached form a (C3-C₈)cycloalkyl ring. [63] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 1 , X and Y are each a methyl group or, alternatively, X and Y together with the carbon atom to which they are attached form a (C3-C₆)cycloalkyl ring.

[64] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 1 , X and Y are each a methyl group.

[65] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 1 and Ri is a substituent selected from the group consisting of cyano, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl, an amidine group and a phenyl group optionally substituted at any available position with one or more substituents selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Cr C₆)alkylcarbonyl, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Ci-C₆)perfluoroalkyl, halo, nitro, di(Ci-C₆)alkylamino and cyano.

[66] In certain embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 1 and Ri is a substituent selected from the group consisting of cyano, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl and a phenyl group.

[67] In certain embodiments of the first aspect of the invention, the compound of formula

(I) is one wherein q is 1 , X and Y are each independently selected form the group consisting of (Ci-C₆)alkyl or, alternatively, X and Y together with the carbon atom to which they are attached form a (C3-C₈)cycloalkyl ring; and Ri is a substituent selected from the group consisting of cyano, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Cr

C₆)alkylaminocarbonyl, an amidine group and a phenyl group optionally substituted at any available position with one or more substituents selected from the group consisting of (Cr C₆)alkyl, (Ci-C₆)alkyloxy, (Ci-C₆)alkylcarbonyl, (Ci-C₆)alkyloxycarbonyl, (Cr C₆)alkylcarbonyloxy, (Ci-C₆)perfluoroalkyl, halo, nitro, di(Ci-C₆)alkylamino and cyano; preferably, X and Y are each a methyl group.

[68] In certain embodiments of the first aspect of the invention, the compound of formula

C₆)alkylaminocarbonyl and a phenyl group; preferably, X and Y are each a methyl group. [69] In other particular embodiments of the first aspect of the invention, the compound of formula (I) is one wherein q is 0.

[70] Preferably, in the compound of formula (I) of the present invention, q is 0 and Ri is a radical selected from the group consisting of a branched (C3-C₈)alkyl radical attached to the carbonyl group of the compound of formula (I) through a tertiary or quaternary carbon atom; a ring system attached to the carbonyl group of the compound of formula (I) through a quaternary carbon atom and comprising from one to four rings, wherein each ring is saturated, each ring comprises from 3 to 7 members selected from the group consisting of C, CH and CH₂, and each ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci₂)alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro.

[71] More preferably, in the compound of formula (I) of the present invention, q is 0 and Ri is a radical selected from the group consisting of a branched (C3-C₈)alkyl radical attached to the carbonyl group of the compound of formula (I) through a quaternary carbon atom; a ring system attached to the carbonyl group of the compound of formula (I) through a quaternary carbon atom and comprising from one to four rings, wherein each ring is saturated, each ring comprises from 3 to 7 members selected from the group consisting of C, CH and CH₂, and each ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl and halo; and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci₂)alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (Cr Cejacyloxy and nitro.

[72] More preferably, in the compound of formula (I) of the present invention, q is 0 and Ri is a radical selected from the group consisting of isopropyl; 1 -methylpropyl; 1 - ethylpropyl; tert-butyl; 1 , 1 -dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 -diethylpropyl; 1- methylcyclohexyl; 1-methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; ad am an ty I; and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (CrCi₂)alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo.

[73] More preferably, in the compound of formula (I) of the present invention, q is 0 and

Ri is a radical selected from the group consisting of isopropyl; 1 -methylpropyl; 1 - ethylpropyl; tert-butyl; 1 ,1 -dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 -diethylpropyl; 1- methylcyclohexyl; 1-methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; ad am an ty I; and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a methyl group, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (Cr Cejalkyloxy and halo.

[74] More preferably, in the compound of formula (I) of the present invention, q is 0 and

Ri is a radical selected from the group consisting of isopropyl; 1 -methylpropyl, 1 - ethylpropyl, tert-butyl, 1 ,1 -dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1 -diethylpropyl, 1- methylcyclohexyl, 1-methylcyclopentyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl.

[75] Even more preferably, in the compound of formula (I) of the present invention, q is 0 and Ri is a radical selected from the group consisting of tert-butyl, 1 ,1 -dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1 -diethylpropyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl.

[76] In a preferred embodiment, in the compound of formula (I) of the present invention, q is 0 and Ri is a radical selected from the group consisting of adamantyl and 2,4,6- trimethylphenyl.

[77] Also preferably, in the compound of formula (I) of the present invention, Ri is as defined in any of the embodiments described above, R₂ and R are each a radical independently selected from the group consisting of (CrCi₂)alkyl group; (C₅-C₂₀)heteroaryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Cr C₆)acylamido, (CrC₆)acyloxy and nitro; and (C₆-C2o)aryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (Cr C₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃ together with the nitrogen atom to which they are attached, form a non-aromatic ring system as defined above, said ring system consisting of a non-aromatic cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, (Ci-C₆)alkylamino, halo and nitro, and the ring is further optionally fused through two shared carbon atoms with one or two (C₆-C₂o)aryl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci- C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[78] More preferably, in the compound of formula (I) of the present invention, Ri is as defined in any of the embodiments described above, R₂ and R₃ are each a radical independently selected from the group consisting of (CrCi₂)alkyl group; (C₅-C₂₀)heteroaryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Cr C₆)acylamido, (CrC₆)acyloxy and nitro; and (C₆-C₂o)aryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (Cr C₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃ together with the nitrogen atom to which they are attached, form a non-aromatic ring system as defined above, said ring system consisting of a saturated cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, (Ci-C₆)alkylamino, halo and nitro, and the ring is further optionally fused through two shared carbon atoms with one or two (C₆-C₂o)aryl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci- C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro. [79] More preferably, in the compound of formula (I) of the invention, R₂ and R₃ are each a radical independently selected from the group consisting of (Ci-C₆)alkyl group and a phenyl group optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, and nitro, and the ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Cr C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[80] More preferably, in the compound of formula (I) of the present invention, R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, and S, wherein the ring is optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, halo, (Cr C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[81] More preferably, in the compound of formula (I) of the present invention, R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Cr C₆)alkyl, (CrC₆)alkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Cr C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[82] More preferably, in the compound of formula (I) of the present invention, R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of methyl and methoxy; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups.

[83] In a preferred embodiment, in the compound of formula (I) of the present invention, R₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4-methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

[84] Therefore, in a particular embodiment, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (CrCi₂)alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and

R₂ and R₃ are each a radical independently selected from the group consisting of (Cr Cejalkyl group; and a phenyl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino and nitro, and the ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[85] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci₂)alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and

R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Cr Cejalkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, and S, wherein the ring is optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr Cejalkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr Cejacylamido, (CrC₆)acyloxy, cyano and nitro.

[86] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci )alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl; and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr Cejalkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr Cejalkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr Cejacylamido, (CrC₆)acyloxy, cyano and nitro.

[87] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (CrCi₂)alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of methyl and methoxy; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups.

[88] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci )alkyl, and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4-methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

[89] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a methyl group and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl; and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (Cr Cejacyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, and S, wherein the ring is optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr Cejalkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro. [90] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a methyl group and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (Cr Cejacyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Cr Cejalkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr Cejacylamido, (CrC₆)acyloxy, cyano and nitro.

[91] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a methyl group and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of methyl and methoxy; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups.

[92] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of isopropyl; 1- methylpropyl; 1 -ethylpropyl; tert-butyl; 1 ,1-dimethylpropyl; 1 -methyl- 1-ethylpropyl; 1 ,1 - diethylpropyl; 1-methylcyclohexyl; 1 -methylcyclopentyl; bicyclo[2.2.1]heptyl; bicyclo[2.2.2]octyl; adamantyl and a phenyl group substituted at one or both carbon atoms adjacent to the carbon atom of the phenyl group that is attached to the carbonyl group of the compound of formula (I) with a methyl group and further optionally, yet preferably, substituted at any available position with a radical selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy and halo; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4-methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

[93] In other particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of tert-butyl, 1 ,1- dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1-diethylpropyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of (CrC₆)alkyl group; and a phenyl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Cr Cejalkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr Cejalkyloxy, halo, (Ci-C₆)alkylamino and nitro, and the ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr Cejalkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr Cejacylamido, (CrC₆)acyloxy, cyano and nitro. [94] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of tert-butyl, 1 ,1- dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1-diethylpropyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (Ci-C₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, and S, wherein the ring is optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, halo, (Cr C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (Ci-C₆)acyloxy, cyano and nitro.

[95] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of tert-butyl, 1 ,1- dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1-diethylpropyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (Ci-C₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Cr C₆)alkyl, (Ci-C₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Cr C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (Ci-C₆)acyloxy, cyano and nitro.

[96] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of tert-butyl, 1 ,1- dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1-diethylpropyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of methyl and methoxy; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups.

[97] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of tert-butyl, 1 ,1- dimethylpropyl, 1 -methyl-1 -ethylpropyl, 1 ,1-diethylpropyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,6-trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4- methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

[98] In other particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of adamantyl and 2,4,6- trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of (CrC₆)alkyl group and a phenyl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino, and nitro, and the ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[99] In other more particular embodiments, in the compound of formula (I) as defined above, q is 0, Ri is a radical selected from the group consisting of adamantyl and 2,4,6- trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, and S, wherein the ring is optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[100] In other more particular embodiments, in the compound of formula (I) as defined above, q is 0, Ri is a radical selected from the group consisting of adamantyl and 2,4,6- trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, and S, wherein the ring is optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[101] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of adamantyl and 2,4,6- trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro;or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, halo, (Ci- C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (Ci-C₆)acyloxy, cyano and nitro.

[102] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of adamantyl and 2,4,6- trimethylphenyl; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of methyl and methoxy;or; alternatively, R and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups.

[103] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 0, Ri is a radical selected from the group consisting of adamantyl and 2,4,6-trimethylphenyl; andR₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4-methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

[104] In a more preferred embodiment, the compound of formula (I) of the present invention is selected from the group consisting of the compounds of formulae (la), (lb), (lc), (Id), (le), (If), (Ig) and (Ih)

[105] In this more preferred embodiment it is contemplated that the compound of formula (I) is the compound of formula (la) wherein q is 0, Ri is 2,4,6-trimethylphenyl and each of R2 and R3 is ethyl. Also, in this more preferred embodiment it is contemplated that the compound of formula (I) is the compound of formula (lb) wherein q is 0, Ri is 2,4,6- trimethylphenyl and wherein R₂ and R3 form a pyrrolidine ring with the nitrogen atom to which they are attached. In this more preferred embodiment, it is also contemplated that the compound of formula (I) is the compound of formula (lc) wherein q is 0, Ri is 2,4,6- trimethylphenyl, R₂ is phenyl and R₃ is methyl. In this more preferred embodiment, it is also contemplated that the compound of formula (I) is the compound of formula (Id) wherein q is 0, Ri is adamantyl and wherein R₂ and R₃ form a pyrrolidine ring with the nitrogen atom to which they are attached. In this more preferred embodiment, it is also contemplated that the compound of formula (I) is the compound of formula (le) wherein q is 0, Ri is adamantyl and each of R₂ and R₃ is ethyl. In this more preferred embodiment, it is also contemplated that the compound of formula (I) is the compound of formula (If) wherein q is 0, Ri is 2,4,6-trimethylphenyl and each of R₂ and R3 is phenyl. In this more preferred embodiment, it is contemplated that the compound of formula (I) is the compound of formula (Ig) wherein q is 0, Ri is 2,4,6-trimethylphenyl and wherein R₂ and R3 form a phenothiazine ring with the nitrogen atom to which they are attached. In this more preferred embodiment, it is contemplated that the compound of formula (I) is the compound of formula (Ih) wherein q is 0, Ri is 2,4,6-trimethylphenyl, R₂ is 4- methoxyphenyl and R₃ is 4-methylphenyl.

[106] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 1 , X and Y are each (Ci-C₆)alkyl or, alternatively, X and Y together with the carbon atom to which they are attached form a (C₃-C₈)cycloalkyl ring (preferably, X and Y are each a methyl group); Ri is a substituent selected from the group consisting of cyano, (CrC6)alkyloxycarbonyl, (Ci-C6)alkylcarbonyloxy, (Ci-C6)alkylaminocarbonyl and a phenyl group; and R₂ and R3 are each a radical independently selected from the group consisting of (CrC6)alkyl group and a phenyl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or, alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, (Ci-C₆)alkylamino and nitro, and the ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[107] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 1 , X and Y are each (CrC₆)alkyl or, alternatively, X and Y together with the carbon atom to which they are attached form a (C3-C₈)cycloalkyl ring (preferably, X and Y are each a methyl group); Ri is a substituent selected from the group consisting of cyano, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl and a phenyl group; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, halo, (Cr C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

[108] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 1 , X and Y are each (Ci-C₆)alkyl or, alternatively, X and Y together with the carbon atom to which they are attached form a (C₃-C₈)cycloalkyl ring (preferably, X and Y are each a methyl group); Ri is a substituent selected from the group consisting of cyano, (CrC₆)alkyloxycarbonyl, (CrC₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl and a phenyl group; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of methyl and methoxy; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups.

[109] In other more particular embodiments, in the compound of formula (I) of the present invention, q is 1 , X and Y are each (CrC₆)alkyl or, alternatively, X and Y together with the carbon atom to which they are attached form a (C₃-C₈)cycloalkyl ring (preferably, X and Y are each a methyl group); Ri is a substituent selected from the group consisting of cyano, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl and a phenyl group; and R₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4-methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

[110] Preferably, in the compound of formula (I) of the present invention and as defined above, R₂ and R₃ are such that none or one of the carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) is member of an aromatic group. While such compounds of formula (I) absorb light in the visible range of the spectrum (this is, between 400 and 800 nm), the products of photolytic degradation of these compounds do not absorb in the visible light range of the spectrum. This advantageously allows differentiating with the human eye polymerized products (uncoloured) over non-polymerized products (coloured composition).

[111] Thus, in an even more preferred embodiment, the compound of formula (I) of the present invention is selected from the group consisting of the compounds of formulae (la), (lb), (lc), (Id) and (le). It is also further preferred that none of the carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) are members of an aromatic group. Thus, in an even more preferred embodiment, the compound of formula (I) of the present invention is selected from the group consisting of the compounds of formulae (la), (lb), (Id) and (le). In an even more preferred embodiment, the compound of formula (I) of the present invention is selected from the group consisting of the compounds of formulae (lb), (Id) and (le).

[112] In other preferred embodiments, in the compound of formula (I), R₂ and R₃ are such that at least one of the two carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) are members of an aromatic group.

[113] In other more preferred embodiments, in the compound of formula (I), R₂ and R₃ are such that both carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) are members of an aromatic group. Such compounds were advantageously and surprisingly found to provide polymers with a narrow distribution of molecular weight, that is, a low polydispersity index (PDI), when used as photoinitiators, and more particularly, as photoiniferters, for the bulk polymerization of methyl acrylate.

[114] Thus, in more preferred embodiments, the first aspect of the present invention relates to a compound of formula (I) that is selected from the group consisting of the compounds of formulae (If), (Ig), and (Ih). In an even more preferred embodiment, the compound of formula (I) of the present invention is a compound of formula (If). The compound of formula (If), when used as a photoiniferter, advantageously produces polymers with low values of PDI.

[115] As noted above and as can be derived from the examples included below, the compounds of the present invention solve the technical problems present in the state of the art and mentioned above, as they are effective initiators of living free-radical polymerization triggered by irradiation with light, more preferably, visible light.

[116] In a second aspect, as mentioned above, the invention also provides a process for the preparation of a compound of formula (I) of the present invention, such process comprising the steps of:

(i) contacting a compound of formula HNR₂R₃ with carbon disulfide in the presence of a base, wherein R₂ and R₃ are as defined above;

(ii) contacting the product obtained in step (i) with a compound of formula Ri(CXY)_qCOCI or a compound of formula Ri(CXY)_qCOOCORi, wherein q, X, Y and Ri are as defined in any of the embodiments defined above; and

(iii) isolating the compound obtained in step (ii).

Suitable bases to carry out step (i) are known in the state of the art and are, preferably, selected from the group consisting of salts of alkali metal hydroxides or (Ci-C₆)alkyloxides (such as NaOH, KOH, LiOH, CsOH, NaOEt, KOEt and KOtert-Bu). Step (ii) is preferably carried out under anhydrous conditions and in the presence of an aprotic anhydrous solvent.

[117] The compound of formula (I) of the present invention obtained by means of the process of this second aspect of the present invention, is as explained above.

[118] According to the third aspect of the present invention, the compounds of formula (I) or of formula (XII) as defined above are useful as photoinitiators for polymerization. Therefore, said third aspect of the present invention refers to the use of a compound of formula (I) or of formula (XII) as defined above as a photoinitiator for polymerization.

[119] Preferably, the polymerization is a living free-radical polymerization reaction, more preferably a RAFT-polymerization reaction. Thus, in preferred embodiments, the third aspect of the present invention refers to the use of a compound of formula (I) or of formula (XII) as defined above as a photoiniferter for polymerization.

[120] In preferred embodiments, the third aspect of the invention refers to the use of a compound of formula (I) as defined in any of the embodiments mentioned above or of a compound of formula (XII) as defined above in the first aspect of the present invention as photoinitiator for a polymerization that is carried out under irradiation of light having a wavelength of from 300 nm to 600 nm.

[121] In more preferred embodiments, the use in this third aspect of the present invention is as photoinitiator for a polymerization that is carried out under irradiation of light having a wavelength of from 300 nm to 500 nm, more preferably, of from 350 nm to 500 nm, more preferably, of from 365 nm to 430 nm. Therefore, more preferably, the polymerization is carried out under irradiation of a light source selected from the group consisting of a LED (light-emitting diode) emitting at 365 nm, a LED emitting at 405 nm, a LED emitting at 415 nm, a LED emitting at 430 nm, a LED emitting at 450 nm, a LED emitting at 460 nm, a Hg lamp or combinations thereof. In a most preferred embodiment, the use in this third aspect of the present invention is as photoinitiator for a polymerization that is carried out under irradiation of a LED emitting at 460 nm. This is advantageous as it allows avoiding the use of UV light, which can be damaging for tissues of an exposed user.

[122] Thus, in preferred embodiments, the third aspect of the present invention refers to the use of a compound of formula (I) or of formula (XII) as defined above (as defined in any of the embodiments of the first aspect of the present invention) as photoinitiator for a polymerization that is carried out under irradiation of visible light. [123] When used as photoinitiators in polymerization reactions, the compounds of formula (I) or of formula (XII) as defined above allow for the production of a polymer according to a RAFT mechanism, as described in the state of the art. The polymerization, thus, takes place under the control of a chain transfer agent.

[124] The above-mentioned polymerization allows for the production of a compound of formula (IV), as mentioned above in relation with the fourth aspect of the invention

wherein q, X, Y, Ri, R₂ and R are as defined in any of the embodiments described above for the first aspect of the invention and wherein each P is a polymeric block consisting of a polymerized product of a monomeric composition comprising a monomer having a polymerizable carbon-carbon double bond and n is an integer comprised of from 1 to 5.

[125] Preferably, each P is a polymeric block comprising from 2 to 1000 repeating monomer units, more preferably from 10 to 1000 repeating monomer units. More preferably, each P is a polymeric block comprising from 10 to 500 repeating monomer units, more preferably, each P is a polymeric block comprising from 10 to 200 repeating monomer units, even more preferably, each P is a polymeric block comprising from 10 to 100 repeating monomer units.

[126] In a preferred embodiment of the fourth aspect of the present invention, n is 1. Preferably, each P is a polymeric block consisting of a polymerized product of a monomeric composition comprising a monomer selected from any suitable monomer for photopolymerization comprising a carbon-carbon double bond known in the state of the art; more preferably a monomer selected from the group consisting of (C₂-C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, terpenes or combinations thereof; more preferably a monomer selected from the group consisting of acrylates, methacrylates, acrylamides, cyanoacrylates or combinations thereof; more preferably a monomer selected from the group consisting of acrylates, methacrylates or combinations thereof. Therefore, in a preferred embodiment, each P is a polymeric block consisting of a polymerized product of a monomeric composition comprising a monomer selected from the group consisting of acrylates. In a most preferred embodiment, each P is a polymeric block consisting of a polymerized product of methyl acrylate.

[127] In another embodiment of the fourth aspect of the invention, the compound of formula (IV) is a compound of formula (IV^')

that is a compound of formula (IV) wherein each P is a polymeric block consisting of a polymerized product of a composition consisting of a monomer having a polymerizable carbon-carbon double bond and wherein each of Ri’, R₂’, R₃’ and R ’ are each independently a radical such that the monomer having a polymerizable carbon-carbon double bond of formula (RI’R₂’)C=C(R₃’R₄’) is selected from the group consisting of (C₂- C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, and terpenes and wherein n’ is an integer comprised of from 2 to 1000.

[128] In another embodiment of the fourth aspect of the invention, the compound of formula (IV) is a compound of formula (IV^') as described above wherein n is 1 .

[129] The compound of formula (IV’) is preferably one wherein RT, R₂’, R₃’ and R₄’ are each independently selected from the group consisiting of hydrogen, (Ci-C₆)alkyl, (Cr C₆)alkyloxy, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylaminocarbonyl, cyano and (C₆-C₂o)aryl; and wherein more preferably, at least two of Ri’, R₂’, R ’ and R₄’ are hydrogen. The compound of formula (IV’) is more preferably one wherein Ri’, R₂’, R₃’ and R₄’ are each independently selected from the group consisiting of hydrogen, methyl, (CrC₆)alkyloxy, methyloxycarbonyl, butyloxycarbonyl, dimethylaminocarbonyl, cyano and phenyl; and wherein more preferably, Ri’ and R₂’ are hydrogen. The compound of formula (IV’) is even more preferably one wherein R₃’ is methyloxycarbonyl, and Ri’, R’₂and R₄’ are hydrogen.

[130] The compound of formula (IV’) is preferably one wherein n’ is an integer of from 2 to 1000; preferably of from 10 to 1000; more preferably, of from 10 to 500; even more preferably, of from 10 to 200 and even more preferably, of from 10 to 100.

[131] In other preferred embodiments of the fourth aspect of the present invention, the compound of formula (IV) is a compound of formula (IVa) or (IVb)

wherein I is an integer comprised of from 2 to 1000. According to the mechanism for RAFT, the value of I may be controlled by adjusting the molar ratio of compound of formula (I) or of formula (XII) as defined above to monomer to 1 : 1 in the mixture comprising (preferably, consisting of) the monomer and the compound of formula (I) or of formula (XII) as defined above. In preferred embodiments, I is from 10 to 1000; more preferably, I is from 10 to 500; more preferably, I is from 10 to 200; even more preferably, I is comprised of from 10 to 100. The compounds of formulae (IVa) and (IVb) are compounds of formula (IV) wherein n is equal to 1 and P is a polymeric block resulting from the polymerization of methyl acrylate and containing I repeating units. The compound of formula (IVa) is also a compound of formula (IV’) wherein n’ is I, R’i, R and R’₄ are hydrogen; R’ is methyloxycarbonyl; R₂ and R₃ form a pyrrolidine ring with the nitrogen atom to which they are attached, q is 0 and Ri is 2,4,6-trimethylphenyl. The compound of formula (IVb) is also a compound of formula (IV’) wherein n’ is I, R’_I, R’₂ and R’ are hydrogen; R’₃ is methyloxycarbonyl; R₂ and R₃ are each a phenyl group, q is 0 and Ri is 2,4,6- trimethylphenyl.

[132] In certain embodiments, it is preferred that, in the compound of formula (IV), R₂ and R₃ are such that at least one, preferably both, of the two carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (IV) are members of an aromatic group, such as phenyl optionally substituted as defined above. This advantageously provides chain transfer agents which are highly useful for controlling the length of the formed polymer, i.e. they allow forming polymers with narrow polydispersity.

[133] A process for the preparation of a compound of formula (IV) of the present invention is also part of the present invention, as a fifth aspect thereof. Such process comprises the step of (i) irradiating with light a mixture comprising (preferably, consisting of) a compound of formula (I) or of formula (XII) as defined above and a monomer having a polymerizable carbon-carbon double bond wherein the molar ratio of the compound of formula (I) or of formula (XII) as defined above to the monomer is preferably from 1 :1000 to 1 :10; and, when n is higher than 1 in the compound of formula (IV) of the present invention, the process further comprises step (ii) of contacting the product of step (i) with a monomer having a polymerizable carbon-carbon double bond in the presence of a suitable initiation system.

[134] More preferably, in the process of the fifth aspect of the present invention, in step (i), the molar ratio of the compound of formula (I) or of formula (XII) as defined above to the monomer is from 1 :500 to 1 :10; more preferably from 1 :200 to 1 :10.

[135] More preferably, in the process of the fifth aspect, step (i) is carried out under irradiation of light having a wavelength of from 300 nm to 600 nm, more preferably of from 350 nm to 500 nm, more preferably of from 365 nm to 430 nm. Therefore, in a preferred embodiment, in the process of the fifth aspect, step (i) is carried out under irradiation of a light source selected from the group consisting of a LED emitting at 365 nm, a LED emitting at 405 nm, a LED emitting at 415 nm, a LED emitting at 430 nm, a LED emitting at 450 nm, a LED emitting at 460 nm, a Hg lamp or combinations thereof; more preferably, step (i) is carried out under irradiation of a blue LED emitting at 460 nm.

[136] In a sixth aspect, the present invention refers to the use of the compound of formula (IV) of the present invention (and as defined in the fourth aspect of the present invention) as chain transfer agent.

[137] Preferably, the compound of formula (IV) of the present invention is used as chain transfer agent in a polymerization reaction, more preferably, in a living free-radical polymerization reaction, even more preferably in a RAFT polymerization reaction.

[138] The presence of a radical of formula (III) as explained above, in the compound of formula (IV) of the present invention renders possible the use of the compound of formula (IV) of the present invention as a chain transfer agent in further RAFT polymerization reactions, as defined in this sixth aspect of the present invention. It is advantageous since the compound of formula (IV) of the present invention, being a macromolecular compound, can be incorporated in cross-linkable formulations for which a certain viscosity is required, such as dental resins, coatings, adhesives or formulated resins for 3D printing applications. The use of the compound of formula (IV) of the present invention as chain transfer agent may further require the presence of an initiating system suitable to generate a radical of formula (III) (as explained above) allowing for the propagation of the polymerization reaction in a controlled manner. Such initiating systems are known in the art and may be thermal, chemical or photochemical. A suitable photochemical initiating system is, for instance, irradiation with light, such as UV light. A suitable chemical initiating system is, for instance, azoisobutyronitrile (AIBN). The irradiation of a mixture comprising a compound of formula (I) or of formula (XII) as defined above and a monomer with blue light will lead to a compound of formula (IV) of the present invention wherein n is 1 , that can further be put in presence of a monomer and irradiated with UV light to produce a new compound of formula (IV) wherein n is 2. It is advantageous as it allows growing a polymer in two separate phases using two different initiating systems, which provides for a better control over the polymerization process and allows for pausing the polymerization during the curing process.

[139] The seventh aspect of the present invention refers to a composition comprising:

(i) at least one compound of formula (I) or of formula (XII) as defined above, or at least one compound of formula (IV) of the present invention, or a combination of a compound of formula (I) or of formula (XII) as defined above and a compound of formula (IV) of the present invention; and

(ii) at least one of: a) a monomer comprising in its molecular formula at least one carbon-carbon double bond, and b) an oligomer comprising in its molecular formula at least one carbon-carbon double bond.

[140] In preferred embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (I) or of formula (XII) as defined above; and at least one of: a) a monomer comprising in its molecular formula at least one carbon-carbon double bond, and b) an oligomer comprising in its molecular formula at least one carbon-carbon double bond.

[141] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (IV) of the present invention; and at least one of: a) a monomer comprising in its molecular formula at least one carbon-carbon double bond, and b) an oligomer comprising in its molecular formula at least one carbon-carbon double bond.

[142] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (IV) of the present invention and at least a monomer comprising in its molecular formula at least one carbon-carbon double bond.

[143] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising both a compound of formula (I) or of formula (XII) as defined above and a compound of formula (IV) of the present invention; and at least one of: a) a monomer comprising in its molecular formula at least one carbon-carbon double bond, and b) an oligomer comprising in its molecular formula at least one carbon-carbon double bond.

[144] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising both a compound of formula (I) or of formula (XII) as defined above and a compound of formula (IV) of the present invention; and at least a monomer comprising in its molecular formula at least one carbon-carbon double bond.

[145] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (I) or of formula (XII) as defined above; and at least a monomer comprising in its molecular formula at least one carbon-carbon double bond.

[146] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising at least a compound of formula (I) that is selected from the compounds of formulae (la), (lb), (lc), (Id), (le), (If) and (Ig).

[147] In other preferred embodiments, the seventh aspect of the present invention refers to a composition comprising at least a compound of formula (I) that is selected from the compounds of formulae (lb) and (Id).

[148] Suitable monomers comprising in their molecular formula at least one carbon- carbon double bond are known in the state of the art and will become apparent to the skilled person upon reduction of the invention to practice. In preferred embodiments of the seventh aspect of the present invention, the monomer comprising in its molecular formula at least one carbon-carbon double bond is selected from the group consisting of (C - C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, terpenes or combinations thereof; more preferably the monomer is selected from the group consisting of acrylates, methacrylates, acrylamides, cyanoacrylates or combinations thereof; more preferably the monomer is selected from the group consisting of acrylates, methacrylates or combinations thereof.

[149] In other preferred embodiments, the composition of the seventh aspect comprises one or more monofunctional monomers, one or more bifunctional monomers, one or more trifunctional monomers, one or more tetrafunctional monomers or a mixture of at least two thereof. A monofunctional monomer is a monomer comprising one polymerizable carbon- carbon double bond. A bifunctional monomer is a monomer comprising two polymerizable carbon-carbon double bonds. A trifunctional monomer is a monomer comprising three polymerizable carbon-carbon double bonds. A tetrafunctional monomer is a monomer comprising four polymerizable carbon-carbon double bonds.

[150] Suitable monofunctional monomers are known in the art and may be selected from the group consisting of N-vinyl-s-caprolactam, N-vinyl formamide, N-vinyl pyrrolidone, N- vinyl-N-methylacetamide, b-carboxyethyl acrylate, octyl acrylate, decyl acrylate, oxyethylated phenol acrylate, 2-phenoxyethyl acrylate, tertiobutyl cyclohexanol acrylate (TBCHA), 2-(2-ethoxyethoxy)ethyl acrylate (EOEOEA), (Ci₆-Ci₈)alkyl acrylate, tetrahydrofurfuryl acrylate (THFA), lauryl acrylate, (C12-C14) acrylate, 2-phenoxyethyl acrylate (2-PEA), isodecyl acrylate (IDA), ethoxylated 4-phenyl acrylate (P4EOA), 3,3,5- trimethyl cyclohexanol acrylate (TMCHA), iso octyl acrylate (IOA), octyl decyl acrylate (ODA), tridecyl acrylate (TDA), polycaprolactone acrylate (CAPA), ethoxylated-4-nonyl phenol acrylate (NP4EOA), isobornyl acrylate (IBOA), cyclic trimethylolpropane formal acrylate (CTFA), ethoxylated-(5)-hexanediol diacrylate (HD5EODA), stearyl acrylate, behenyl acrylate, tricyclodecanemethanol acrylate (TCDA) and ethoxylated-4-lauryl acrylate (L(4EO)A).

[151] Suitable bifunctional monomers are known in the art and may be selected from the group consisting of dipropylene glycol diacrylate, 1 ,6-hexanediol diacrylate, neopentyl glycol propoxylate, diacrylate, tripropylene glycol diacrylate, tricyclodecanediol diacrylate, bisphenol A ethoxylate diacrylate, 1 ,6-hexanediol diacrylate (HDDA), polyethylene glycol (200) diacrylate (PEG200DA), tetraethylene glycol diacrylate (TTEGDA), triethylene glycol diacrylate (TIEGDA), tripropylene glycol diacrylate (TPGDA), polybutadiene diacrylate (PBDDA), 3-methyl 1 ,5-pentanediol diacrylate (MPDA), polyethylene glycol (400) diacrylate (PEG400DA), ethoxylated-3-bisphenol A diacrylate (BPA3EODA), dipropylene glycol diacrylate (DPGDA), 1 ,10-decanediol diacrylate (DDDA), ethoxylated-4-bisphenol A diacrylate (BPA4EODA), ethoxylated-10-bisphenol A Diacrylate (BPA10EODA), esterdiol diacrylate (EDDA), polyethylene glycol 600 diacrylate (PEG600DA), alkoxylated diacrylate, tricyclodecanedimethanol diacrylate (TCDDMDA) and propoxylated 2- neopentyl glycol diacrylate (PONPGDA).

[152] Suitable trifunctional monomers are known in the art and may be selected from the group consisting of propoxylated glycerol triacrylate, trimethylolpropane ethoxy triacrylate, trimethylolpropane triacrylate (TMPTA), tris(2-hydroxyethyl) isocyanurate triacrylate (THEICTA), pentaerythritol triacrylate (PETIA), ethoxylated-3-trimethylolpropane triacrylate (TMP3EOTA), propoxylated-3-trimethylolpropane triacrylate (TMP3POTA), ethoxylated-6-trimethylolpropane triacrylate (TMP6EOTA), ethoxylated-9- trimethylolpropane triacrylate (TMP9EOTA), propoxylated-3-glyceryl triacrylate (GPTA), ethoxylated-15-trimethylolpropane triacrylate (TMP15EOTA), trimethylolpropane triacrylate (TMPTA), ethoxylated-12 glyceryl-triacrylate (G12EOTA), ethoxylated trimethylolpropane triacrylate (TMP20EOTA), ethoxylated-3-trimethylolpropane triacrylate (TMP(3EO)TA) and ethoxylated-4-pentaerythritol tetraacrylate (P(4EO)TTA).

[153] Suitable tetrafunctional monomers are known in the art and may be selected from the group consisting of pentaerythritol tri-tetraacrylate, acrylated dipentaerythritol, ditrimethyolpropane tetraacrylate, ethoxylated 4 pentaerythritol tetraacrylate (PETTA), di- trimethylolpropane tetraacrylate (Di TMPTTA) and ethoxylated-4-pentaerythritol tetraacrylate (P(4EO)TTA).

[154] Other monomers are known in the art and are not excluded for use in the composition of the seventh aspect. For instance, monomers such as dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate may be used.

[155] In other embodiments, the composition of the seventh aspect of the invention comprises a monomer selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, pentaerythritol tetraacrylate, isodecyl acrylate, dipropylene glycol diacrylate, tricyclodecanedimethanol diacrylate, trimethylolpropane triacrylate, 1 ,6- hexanediol diacrylate, diacrylate of 1 ,10-decanediol, triethylene glycol dimethacrylate, 2- [[(butylamino)carbonyl]oxy]ethyl acrylate and mixtures thereof.

[156] A composition according to the seventh aspect of the invention may comprise any chemically compatible combination of the compound of formula (I) or of formula (XII) and/or of formula (IV) with one or more of the monofunctional, bifunctional, trifunctional or tetrafunctional monomers described above.

[157] Suitable oligomers comprising in their molecular formula at least one carbon- carbon double bond are known in the state of the art and will become apparent to the skilled person upon reduction of the invention to practice. Preferably, the oligomer comprising in its molecular formula at least one carbon-carbon double bond is an oligomer selected from the group consisting of the oligomers of (C -C₆)alkene, oligomers of acrylates, oligomers of methacrylates, oligomers of acrylamides, oligomers of styrenes, oligomers of cyanoacrylates, oligomers of vinyl ethers, oligomers of vinyl esters, oligomers of terpenes or combinations thereof. In preferred embodiments, an oligomer comprises from 2 to 100 monomer units.

[158] Other suitable oligomers are known in the art and may be selected from the group consisting of polyester (meth)acrylate, polyester multi-(meth)acrylate, urethane (meth)acrylate, urethane multi-(meth)acrylate, epoxy (meth)acrylate, epoxy multi- (meth)acrylate, silicone (meth)acrylate, silicone multi-(meth)acrylate, amino (meth)acrylate, amino multi-(meth)acrylate, mercapto (meth)acrylate and mercapto multi- (meth)acrylate.

[159] In other embodiments, the composition of the the seventh aspect of the invention comprises an oligomer selected from the group consisting of an oligomer of an aliphatic polyester ether urethane acrylate, an aliphatic urethane hexaacrylate oligomer, an aliphatic urethane diacrylate, an aliphatic urethane acrylate oligomer, ethoxylated (4) bisphenol A dimethacrylate, urethane dimethacrylate, ethoxylated bisphenol A diacrylate and a mixture thereof.

[160] A composition according to the seventh aspect of the invention may thus comprise any chemically compatible combination of the compound of formula (I) or of formula (XII) and/or of formula (IV) with one or more of the oligomers described above.

[161] In addition, a composition according to the seventh aspect of the invention may thus comprise any chemically compatible combination of the compound of formula (I) or of formula (XII) and/or of formula (IV) with one or more of the monofunctional, bifunctional, trifunctional or tetrafunctional monomers described above and further comprising one or more of the oligomers described above.

[162] The oligomer may in a preferred embodiment be an aliphatic urethane acrylate. Such a composition is particularly useful for coating applications.

[163] The oligomer may in a preferred embodiment be a diepoxyde methacrylate. Such a composition is particularly useful for dental resin applications.

[164] The oligomer may in a preferred embodiment be an epoxyde diacrylate. Such a composition is particularly useful for 3D printing applications.

[165] In particular embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (I) or of formula (XII) as defined above; and a polymerizable compound selected from the group consisting of (C -C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, terpenes, oligomers thereof or combinations thereof. More particularly the polymerizable compound is selected from the group consisting of acrylates, methacrylates, acrylamides, cyanoacrylates or combinations thereof; more particularly the polymerizable compound is selected from the group consisting of acrylates, methacrylates or combinations thereof.

[166] In other embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (IV) of the present invention; and a polymerizable compound selected from the group consisting of (C2-C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, terpenes, oligomers thereof or combinations thereof. More preferably the polymerizable compound is selected from the group consisting of acrylates, methacrylates, acrylamides, cyanoacrylates or combinations thereof; more preferably the polymerizable compound is selected from the group consisting of acrylates, methacrylates or combinations thereof.

[167] In other embodiments, the seventh aspect of the present invention refers to a composition comprising both a compound of formula (I) or of formula (XII) as defined above and a compound of formula (IV) of the present invention; and a polymerizable compound selected from the group consisting of (C -C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, terpenes, oligomers thereof or combinations thereof. More preferably the polymerizable compound is selected from the group consisting of acrylates, methacrylates, acrylamides, cyanoacrylates or combinations thereof; more preferably the polymerizable compound is selected from the group consisting of acrylates, methacrylates or combinations thereof.

[168] In other embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (I) or of formula (XII) as defined above and/or a compound of formula (IV) of the present invention; and a polymerizable compound selected from the group consisting of acrylates, oligomers thereof or combinations thereof.

[169] In other embodiments, the seventh aspect of the present invention refers to a composition comprising a compound of formula (I) or of formula (XII) as defined above and/or a compound of formula (IV) of the present invention; and a polymerizable compound selected from the group consisting of methyl acrylate, oligomers thereof or combinations thereof.

[170] In other embodiments, when the composition of the seventh aspect of the present invention does not comprise a compound of formula (I) or of formula (XII) as defined above, the composition of the seventh aspect further comprises a polymerization initiation system. Suitable polymerization initiation systems, in particular for the initiation of free-radical polymerization, are known in the state of the art and may be selected, for instance, from the group consisting of phosphine oxides, metal oxides, hydroxyketones, benzophenones, azoisobutyronitrile (AIBN) or combinations thereof. Alternatively, or in combination with the above-mentioned initiation systems, a suitable polymerization initiation system may be irradiation with light, in particular with UV light.

[171] The composition of the seventh aspect of the invention may further comprise additional components which may be selected from the group consisting of synergists for preventing oxygen from inhibiting the curing of the composition, dyes or pigments for providing a colour to the composition, flame-retarding agents, matting agents, UV blocking agents, UV stabilizers, fillers, adhesion promoters, defoaming agents, rheology modifiers and mixtures thereof. More preferably, the composition of the seventh aspect of the invention, further comprises at least one synergist, even more preferably one or two synergists, still more preferably, one synergist. The presence of the synergist, surprisingly, provides for a reduction in the initiation time of the polymerization reaction and provides a faster curing process.

[172] Suitable synergists for preventing oxygen from inhibiting the curing of the composition are known in the art. Suitable synergists may thus be selected from the group consisting of amines, thiols, phosphines, phosphites, organometallic compounds, boranes, silanes and dienes.

[173] Amine synergists are known in the art and comprise aliphatic or aromatic primary, secondary or tertiary amines. An amine synergist may in particular be selected from the group consisting of dimethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylamide, 3-dimethylamino neopentyl (meth)acrylate, ethyl-3-dimethylamino (meth)acrylate, N-(meth)acrylate-N’-methyl piperazine, N,N-dimethyldodecylamine, N,N- dimethylamino-propylamine, N,N-dimethyltoluidine, triphenylamine, diethylamine, N,N- diethyl-aminoethanol, N,N-dimethylamino propanol, N,N-dimethylamino-propanamine, ethyldimethylamine, octyldimethyl-amine, N,N-dimethylaminoethylmethacrylate, N-(N,N- dimethylamino)-propyl-2-pyrrolidone, 1 ,3-bis(dimethylamino)propane, 1 ,6-bis- (dimethylamino)hexane, tetramethyl bis(aminoethyl) ether, pentamethyldiethyleneamine, ethyl 4-dimethylaminobenzoate, pentamethyldipropyleneamine, N’,N’-dimethylaminoethyl morpholine, 4-(2-(dimethylamino)ethyl)morpholine, N-methyl diethanolamine, trimethylamine, tributylamine, N,N-dimethylaniline, N,N-dimethyl-benzylamine, N,N- diisopropyl-ethylamine, pyridine, N-methylpiperidine, N-methylmorpholine, N,N- dimethylaminopyridine, diazabicyclooctane, diazabicyclononene, diazabicycloundecene, triethylamine, dimethylbenzylamine, N,N,N',N'-tetramethyldiaminodiethyl ether, bis (dimethylaminopropyl) urea, N-methyl- or N-ethylmorpholine, N,N,N',N'- tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N'- tetramethylethylenediamine, N,N',N'-tetramethylhexane-1 ,6-diamine, triamine, dimethylpiperazine, N-dimethylaminoethylpiperidine, 1 ,2-dimethylimidazole, N- hydroxypropylimidazole, triethanolamine, triisopropanolamine, N-methyl- or N- ethyldiethanolamine, (2-dimethylaminoethyl) methacrylate, dimethylaminoethanol, 2- (dimethylaminoethoxy) ethanol, N-tris(dialkylaminoalkyl)hexahydrotriazine, tris- (dimethylaminopropyl)-hexahydrotriazine, diazabicyclononane, diazabicyclododecane, 1 ,1 ,3,3-tetramethylguanidine, tris[2-(2-methoxyethoxy)ethyl]amine, 2-

(dimethylamino)ethyl methacrylate, N-phenylglycine, N, N-dibenzylaniline, tris[2- (dimethylamino)ethyl]amine and diethyl 1 ,4-dihydro-2,6-dimethyl-3,5- pyridinedicarboxylate.

[174] Thiol synergists are known in the art and comprise aliphatic and aromatic thiols. A thiol synergist may in particular be selected from the group consisting of pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), (3- mercaptopropyl)methyldimethoxysilane, methyl thioglycolate, (3- mercaptopropyl)trimethoxysilane, m-carborane-9-thiol, cyclohexanethiol, 2-, 3-, 10- mercaptopinane, ethylene glycol bis(3-mercaptopropionate), thiosalicylic acid, 4- mercaptobenzoic, triphenylmethanethiol, 7-mercapto-4-methylcoumarin, 2,2 - (ethylenedioxy)diethanethiol, 2-mercaptoimidazole, methimazole, 2-thiazoline-2-thiol, 4- trifluoromethylbenzyl mercaptan, 4-methoxythiophenol, 4-isopropylbenzenethiol, 2- phenylethanethiol, 4-methylbenzenethiol, 4-tert-butylbenzyl mercaptan, 4,4'- dimercaptobiphenyl, glutathione, furfuryl mercaptan, mercaptopropionic acid, 1- dodecanethiol, thioglycerol, n-acetyl-l-cysteine, benzyl mercaptan, 1-adamantanethiol, thiocholesterol, 3-mercaptopropyl polyhedral oligomeric silsequioxane (poss), meso-2,3- dimercaptosuccinic acid, 2,3,4,5,6-pentafluorothiophenol, cystein, para-mentha-8-thiol-3- one, 4,4'-thiobisbenzenethiol, 2-mercaptobenzothiazole, pentaerythritol tetrakis(3- mercaptobutylate), tris(3-mercaptobutyloxyethyl) isocyanurate, 1 ,4-bis(3- mercaptobutyryloxy)butane. Tertiary and quaternary aliphatic or aromatic thiols are preferred.

[175] Suitable phosphine synergists are known in the art and may be selected from the group consisting of triphenylphosphine, 4-(diphenylphosphino)styrene, trioctyl phosphine, 2-(diphenylphosphino)benzoic acid, 4-(dimethylamino)phenyldiphenylphosphine, 1 ,5- bis(diphenylphosphino)pentane, 1 ,4-bis(diphenylphosphino)butane, 1 ,3- bis(diphenylphosphino)propane.

[176] Suitable phosphite synergists are known in the art and may be selected from the group consisting of 3,9-Bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9- diphosphaspiro[5.5]undecane, dioleyl hydrogen phosphite, poly(dipropyleneglycol) phenyl phosphite, triphenyl phosphite, tris(tridecyl) phosphite, tributylphosphite, 2-propenoic acid, trianhydride with phosphonic acid nitrilotri-2, 1 -ethanediyl ester, tetraphenyl dipropyleneglycol diphosphate.

[177] Suitable organometallic compounds synergists may be selected from zinc 2- ethylexanoate, tri-butylstannane, stannous 2-ethylhexanoate, zirconium(IV) propoxide, bis(cyclopentadienyl)dimethyl zirconium(IV), tetrakis(dimethylamido) zirconium(IV), and tetrakis(triethanolaminato)-zirconium(IV).

[178] Suitable diene synergists may be selected from 1 ,3-bis[(3-methyl-2-buten-1- yl)oxy]propan-2-ol, 1 ,1-diethoxy-3-methyl-2-butene, prenyl acetate, geranyl acetate, di(3- methyl-2-enyl)ether, prenyl ethyl ether, 1 -[(tetrahydro-2h-pyran-2-yl)oxy]-3-methyl-2- butene, vinyl-beta-ionol, 1-methoxycyclohexa-1 ,4-diene, terpinyl methyl ether and citronellyl acetate.

[179] Suitable borane synergists may be selected from borane, borane triphenylphosphine complex, borane morpholine complex, catecholborane, bis(pinacolato)diboron and bis(catecholato)diborane.

[180] Suitable borate synergists may be selected from tri(Ci-C₆)alkyl borate, tritetradecyl borate, triisopropyl borate, trio-tolyl borate, tritetradecyl borate, trimethylene borate, tri-i- propylborate and tri-o-phenylene bis-borate.

[181] Suitable silane synergists may be selected from tris(trimethyl silyl) silane, triethylsilane, dimethylphenylsilane, oligomeric silane.

[182] Other types of synergists, such as aldehydes, ethers and iodonium salts are known in the art and may be comprised in the composition of the seventh aspect of the invention. Such synergists include propylene ether, thioether, diethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethyleneglycoldiacrylate, benzaldehyde, 1 - dodecanal, 3,7-dimethyl-2,6-octadienal, 2,6-dimethyl-5-heptenal, anthraldehyde and bis(4-methylphenyl)iodonium hexafluorophosphate.

[183] In other embodiments, the composition of the seventh aspect of the invention further comprises a synergist selected from the group consisting of N-methyl diethanolamine, N-phenylglycine, pentaerythritol tetrakis(3-mercaptopropionate), (2- dimethylaminoethyl) methacrylate, 1-adamantanethiol, ethyl 4-dimethylaminobenzoate, trimethylborate, triphenylphosphine, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) and mixtures thereof.

[184] In more preferred embodiments, the composition of the seventh aspect of the invention further comprises a synergist that is pentaerythritol tetrakis(3- mercaptopropionate). This advantageously provides optimal results in reducing inhibition by oxygen during the curing of the composition, when used as synergist for a photoiniator of formula(l).

[185] When the the composition of the seventh aspect of the invention further comprises a synergist, said synergist is preferably present in an amount from 0.1% to 10% in weight of the composition. When the the composition of the seventh aspect of the invention further comprises a synergist, said synergist is more preferably present in an amount from 0.1% to 6% in weight of the composition. When the the composition of the seventh aspect of the invention further comprises a synergist, said synergist is even more preferably present in an amount from 1% to 5% in weight of the composition.

[186] Suitable UV blocking agents are known in the art and comprise UV absorbing compounds. Suitable UV blocking agents may in particular be selected from the group consisting of avobenzone, 2,5-bis(5-tert-butylbenzoxazol-2-yl)thiophene, disodium 4,4’- bis(2-sulfonatostyryl)biphenyl, benzenepropanoic acid, 2,3,6,7-tetrahydro-9-methyl- 1 H,5H-inolizino(9,1 -gh)coumarin, Martius yellow, morin hydrate, nitrofurazone, 2- nitrophenylphenylsulfide, 5,12-naphthacenequinone, octocrylene, phenazine, 1 ,4-bis-(2- (5-henyloxazolyl))-benzene, quinoline yellow, 3,3’,4’,5,6-pentahydroxyflavone, salicylaldehyde, Sudan I, triamterene, UV386A, and 9,10-diethoxyanthracene. A preferred UV blocking agent may be 2,5-bis(5-tert-butylbenzoxazol-2-yl)thiophene.

[187] Suitable UV stabilizers are known in the art and may in particular be selected from the group consisting of substituted 2-hydroxybenzophenones, 2-(2-hydroxyphenyl)-2H- benzotriazoles, 2-(2-hydroxyphenyl)-4,6-phenyl-1 ,3,5-triazines, benzylidenemalonates, and oxalanilides, o-hydroxyphenyltriazenes, o-hydroxybenzotriazoles, oxanilides, 2, 2, 6, 6- tetramethylpiperidine, N-2,2,6,6-pentamethylhydroxypiperidinyl diester of 4- methoxyphenylmethylenemalonic acid.

[188] Suitable fillers are known in the art and may in particular be inert fillers selected from the group consisting of calcium carbonate, aluminum silicates, magnesium silicate minerals, silicon dioxide, barium sulfate, polystyrene latex and aramid fibers. Suitable fillers may alternatively be fillers for paint applications, such as silica, talc, sand, glass beads, carbonate powder, alumina hydrate powder, steel powder, aluminum powder, polymer particles, titanium oxide, alumina or polymer particle impact modifier. Suitable fillers may alternatively be fillers for dental resin applications such as lanthanum oxide, aluminum oxide, bismuth(lll) oxide, cobalt(ll, III) oxide, zinc oxide, tungsten(VI) oxide, zirconium(IV) oxide, boron nitride, potassium hexafluorotitanate or barium zirconate, hydroxyapatite, strontium carbonate, aluminum metaphosphate, lithium phosphate, sodium hexafluorosilicate, terbium(lll) nitrate pentahydrate, zinc hexafluorosilicate hydrate, potassium hexafluoroantimonate, erbium(lll) nitrate pentahydrate, praseodymium(lll) nitrate hexahydrate or iron(lll) oxide nanopowder, calcium phosphate, europium(lll) oxide or bismuth(lll) oxide. Suitable fillers may alternatively be active fillers such as a thickening attapulgite clay, a pyrogenic silicon dioxide powder, pentabromobenzyl acrylate, tribromoneopentyl (meth)acrylate, phosphorous and silicon containing oligomers, matting agent such as silicon dioxide, corrosion protecter such as zinc metal pigment, biocide as zinc oxide or cuprous oxide.

[189] Suitable adhesion promoters are known in the art and may in particular be selected from the group consisting of thiol, 1 ,6-hexanedioldiacrylate, acrylic acid derivative, acidic (meth)acrylate and chlorine-acid-base promoter. Monomers having afunctional group may also be used to promote adhesion.

[190] Suitable defoaming agents are known in the art and may in particular be selected from the group consisting of mineral oil, waxes, hydrocarbons, fluorinated and/or silicated- polymer and fatty acid esters.

[191] Suitable rheology modifiers are known in the art and may in particular be selected from the group consisting of fatty acid, silicon, clay derivatives, wax emulsion, polyurethane thickener and mixtures thereof.

[192] Suitable inorganic pigments include, among others, white rutile Ti0 , white zinc oxide, yellow iron oxide, chrome yellow, monoarylide yellows, bismuth vanadate yellow, carbon black, red iron oxide, ferric ammonium ferrocyanide blue and acetylene black. Suitable additive dyes include, among others, irgazin red, inkjet magenta, heliogen blue, inkjet yellow, special black, benzimidazolone orange, isoindoline yellow, diarylide yellows, toluidine red, copper phthalocyanine blue, halogenating copper and phthalocyanine green.

[193] In preferred embodiments, the composition of the seventh aspect of the invention further comprises titanium dioxide as an inorganic pigment.

[194] A composition according to the seventh aspect of the invention may thus comprise any chemically compatible combination of the compound of formula (I) or of formula (XII) and/or of formula (IV) with one or more of the monofunctional, bifunctional, trifunctional or tetrafunctional monomers described above and further comprising one or more of the oligomers described above and one or more of the synergists, dyes, pigments, UV filters, UV stabilizers and fillers described above.

[195] In preferred embodiments, the seventh aspect of the invention relates to a composition comprising a compound of formula (lb) or of formula (Id), pentaerythritol tetraacrylate as a monomer, and, optionally at least one synergist selected from the group consisting of N-methyl diethanolamine, N-phenylglycine, pentaerythritol tetrakis(3- mercaptopropionate), (2-dimethylaminoethyl) methacrylate, 1 -adamantanethiol, ethyl 4- dimethylaminobenzoate, trimethylborate, triphenylphosphine, and phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO). In such preferred embodiments, the compound of formula (lb) is preferably in an amount of 0.6% in weight. In such preferred embodiments, the compound of formula (Id) is preferably in an amount of 1 .2% in weight. In such preferred embodiments, the synergist is preferably in an amount of from 0.1% to 6% in weight.

[196] In other embodiments, the seventh aspect of the present invention refers to a composition as defined above wherein the molar ratio of the polymerizable mass consisting of monomers and/or the oligomers to the initiating system consisting of the compounds of formula (I) or of formula (XII) as defined above and/or formula (IV) of the present invention is from 10000:1 to 10:1 ; preferably, it is from 1000:1 to 10:1.

[197] In other embodiments, the seventh aspect of the present invention refers to a composition as defined above wherein the weight ratio of the polymerizable mass consisting of monomers and/or the oligomers to the initiating system consisting of the compounds of formula (I) or of formula (XII) as defined above and/or formula (IV) as defined above is from 10000:1 to 10:1 ; preferably, it is from 1000:1 to 10:1 ; more preferably it is from 1000:1 to 20:1. [198] The composition of the seventh aspect of the invention may preferably be a composition suitable for coating applications. Such a composition preferably comprises an oligomer selected from the group consisting of an oligomer of an aliphatic polyester ether urethane acrylate, an aliphatic urethane hexaacrylate oligomer, an aliphatic urethane diacrylate, and an aliphatic urethane acrylate oligomer. Said oligomer is preferably comprised in the composition in the range of 20% to 60% in weight; preferably of from 30% to 50% in weight. Such composition further preferably comprises a first monomer selected from the group consisting of pentaerythritol tetraacrylate, isodecyl acrylate, dipropylene glycol diacrylate, tricyclodecanedimethanol diacrylate, and tricyclodecanedimethanol diacrylate. Said first monomer is preferably comprised in the composition in the range of 10% to 70% in weight; preferably of from 20% to 65% in weight. Such composition further optionally comprises a second monomer selected from the group consisting of 1 ,6- hexanediol diacrylate, trimethylolpropane triacrylate and 1 ,10-decanediol diacrylate. Said second monomer being comprised in the composition in the range of 0% to 50% in weight; preferably of from 0% to 40% in weight.

[199] The composition of the seventh aspect of the invention may thus be a composition suitable for coating applications comprising an oligomer of an aliphatic polyester ether urethane acrylate in an amount of from 40% to 60% in weight, pentaerythritol tetraacrylate in an amount of from 25% to 35% in weight and 1 ,6-hexanediol diacrylate in an amount of from 15% to 25% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight. Said composition further preferably comprises a synergist as defined above.

[200] The composition of the seventh aspect of the invention may also be a composition suitable for coating applications comprising an oligomer of an aliphatic polyester ether urethane acrylate in an amount of from 20% to 40% in weight, dipropylene glycol diacrylate in an amount of from 60% to 70% in weight and 1 ,6-hexanediol diacrylate in an amount of from 5% to 15% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight. Said composition further preferably comprises a synergist as defined above.

[201] The composition of the seventh aspect of the invention may also be a composition suitable for coating applications comprising an aliphatic urethane hexaacrylate oligomer in an amount of from 30% to 50% in weight, isodecyl acrylate in an amount of from 15% to 35% in weight and trimethylolpropane triacrylate in an amount of from 30% to 50% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight. Said composition further preferably comprises a synergist as defined above.

[202] The composition of the seventh aspect of the invention may also be a composition suitable for coating applications comprising an aliphatic polyester based urethane diacrylate oligomer in an amount of from 30% to 50% in weight and tricyclodecanedimethanol diacrylate in an amount of from 40% to 60% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight. Said composition further preferably comprises a synergist as defined above.

[203] The composition of the seventh aspect of the invention may also be a composition suitable for coating applications comprising an aliphatic urethane acrylate oligomer in an amount of from 30% to 50% in weight, tricyclodecanedimethanol diacrylate in an amount of from 20% to 40% in weight and 1 ,10-decanediol diacrylate in an amount of from 10% to 30% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight. Said composition further preferably comprises a synergist as defined above.

[204] The composition of the seventh aspect of the invention may also be a composition suitable for coating applications comprising an aliphatic urethane acrylate oligomer in an amount of 42% in weight, tricyclodecanedimethanol diacrylate in an amount of 25% in weight, 1 ,10-decanediol diacrylate in an amount of 17% in weight, a compound of formula (Id) in an amount of 3% in weight, rutile titanium dioxide in an amount of 10% in weight and (2-Dimethylaminoethyl) methacrylate in an amount of 3% in weight. Such a composition is suitable as tack-free white paint for coating metal substrates.

[205] The composition of the seventh aspect of the invention may also preferably be a composition suitable for dental resin applications. Such a composition preferably comprises an oligomer selected from the group consisting of ethoxylated (4) bisphenol A dimethacrylate and urethane dimethacrylate, preferably in an amount of from 60% to 80% in weight. Such composition preferably further comprises triethylene glycol dimethacrylate, preferably in an amount of from 20% to 40% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight.

[206] The composition of the seventh aspect of the invention may also preferably be a composition suitable for 3D printing applications. Such a composition preferably comprises ethoxylated (4) bisphenol A dimethacrylate in an amount of from 60% to 80% in weight and 1 ,10-decanediol diacrylate in an amount of from 20% to 40% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight.

[207] The composition of the seventh aspect of the invention may thus be a composition suitable for 3D printing applications comprising ethoxylated (4) bisphenol A dimethacrylate in an amount of from 40% to 60% in weight, 2-[[(butylamino)carbonyl]oxy]ethyl acrylate in an amount of from 10% to 30% in weight and pentaerythritol tetraacrylate in an amount of from 20% to 40% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight.

[208] The composition of the seventh aspect of the invention may also be a composition suitable for 3D printing applications comprising ethoxylated (4) bisphenol A dimethacrylate in an amount of from 30% to 50% in weight, dipropylene glycol diacrylate in an amount of from 20% to 40% in weight, and 2-[[(butylamino)carbonyl]oxy]ethyl acrylate in an amount of from 20% to 40% in weight. Said composition further preferably comprises a compound of formula (I) or of formula (XII) and/or of formula (IV) in an amount of from 0.1% to 5% in weight.

[209] As described above, in an eighth aspect the present invention refers to a process for the preparation of a cross-linked material comprising the step of irradiating the composition as defined in any of the embodiments of the seventh aspect of the present invention with light, preferably with blue light.

[210] In the process of the eighth aspect of the present invention, when the composition of the seventh aspect of the present invention does not comprise a compound of formula (I) or of formula (XII) as defined above, said composition further comprises a polymerization initiation system. The polymerization initiation system is as defined above.

[211] In preferred embodiments, in the eighth aspect of the present invention the irradiation is carried out with light having a wavelength of from 300 nm to 600 nm, more preferably, of from 300 nm to 500 nm, even more preferably, of from 350 nm to 500 nm, even more preferably, of from 365 nm to 430 nm. Therefore, in a preferred embodiment, the irradiation is carried out using a light source selected from the group consisting of a LED emitting at 365 nm, a LED emitting at 405 nm, a LED emitting at 415 nm, a LED emitting at 430 nm, a LED emitting at 450 nm, a LED emitting at 460 nm, a Hg lamp or combinations thereof. In the most preferred embodiment, irradiation is carried out using blue light, more preferably, a blue LED emitting at 460 nm.

[212] In further preferred embodiments of the eighth aspect of the present invention, when the composition does not comprise a compound of formula (I) or of formula (XII) as defined above, it further comprises a polymerization initiation system that is selected from the group consisting of phosphine oxides, metal oxides, hydroxyketones, benzophenones, 1 ,1 '-azobis(cyclohexanecarbonitrile) (ACHN), azoisobutyronitrile (AIBN) or combinations thereof. Alternatively, or in combination with the above-mentioned initiation systems, when the composition does not comprise a compound of formula (I) or of formula (XII) as defined above, it further comprises a polymerization initiation system consisting of irradiation with UV light.

[213] In other preferred embodiments, the eighth aspect of the present invention refers to a process as defined above that is carried out under irradiation of light having an intensity of irradiation of at least 100 mW per cm², preferably of at least 200 mW per cm², even more preferably of 400 mW per cm². In more preferred embodiments, the eighth aspect of the present invention refers to a process as defined above that is carried out under irradiation of light having an intensity of irradiation of from 100 to 1000 mW per cm², preferably of from 200 to 1000 mW per cm² and even more preferably of 400 mW per cm².

[214] In preferred embodiments, the eighth aspect of the present invention refers to a process as defined above wherein the conversion of the one or more monomer comprising at least one carbon-carbon double bond and/or the one or more oligomer comprising at least one carbon-carbon double bond is higher than 61%, more preferably, higher than 70%, more preferably, higher than 80%, more preferably, higher than 85%, even more preferably, higher than 90%.

[215] In preferred embodiments, the eighth aspect of the present invention refers to a process as defined above wherein the polydispersity index of the prepared cross-linked material is from 1 to 3, more preferably, from 1 to 2.6, more preferably, from 1 to 2, even more preferably, from 1 to 1 .5.

[216] The ninth aspect of the invention refers to a cross-linked material obtainable by means of the process of the eighth aspect of the invention.

[217] In preferred embodiments, the cross-linked material of the ninth aspect is obtainable by means of the process as defined in any embodiment of the eighth aspect of the invention using a composition as defined in any embodiment of the seventh aspect of the invention.

[218] Throughout the description and claims the word “comprises" and variations of the word, are not intended to exclude other technical features, additives, components or steps. Furthermore, the word “comprise” encompasses the case of “consist of”. Additional objects, advantages and features of the invention will become apparent to those skilled in the art upon examination of the description or may be learned by practice of the invention. The following examples are provided by way of illustration, and they are not intended to be limiting of the present invention.

EXAMPLES

[219] All reagents were obtained from commercial suppliers and used without further purification unless otherwise stated. All solvents were commercially obtained and used without further purification. Routine ¹H NMR (nuclear magnetic resonance) and ¹³C{¹H} NMR spectra were recorded on a Bruker Avance 300 (300 MHz for ¹H NMR and 75 MHz for ¹³C NMR), Bruker Avance 400 (400 MHz for ¹H NMR and 100 MHz for ¹³C NMR), Bruker Avance 500 (500 MHz for ¹H NMR and 125 MHz for ¹³C NMR). Deuterated solvents used are indicated in the characterization and chemical shifts are given in ppm (parts-per- million). Residual solvent peaks were used as reference (Chloroform d 7.26 ppm). All NMR J values are given in Hz. IR (infrared) spectra were recorded on a Bruker Optics FTIR (Fourier-transform infrared spectroscopy) Alpha spectrometer equipped with a Deuterated TriGlycine Sulfate detector, KBr beam splitter at 4 cm^-1 resolution using a one bounce Attenuated Total Reflectance accessory with diamond windows. Column chromatography purifications were performed with silica gel technical grade (Sigma- Aldrich), pore size 60 A, 230^100 mesh particle size, 40-63 pm particle size and Thin Layer Chromatography (TLC) analysis on silica gel 60 F254.

Example 1 : Preparation of compounds of formulae (la)-(lh)

Example 1a: Diethylcarbamothioic 2,4,6-trimethylbenzoic thioanhydride (la).

[220] Commercial sodium diethylcarbamodithioate trihydrate (142 mg, 0.629 mmol, 1.15 equivalent - hereinafter, eq) was added to a dry amber round-bottomed flask, and then it was placed under vacuum at 60 ^eC for 15 minutes to partially remove the water. Ethyl acetate (5 mL) was added and the mixture was cooled to 0 - 5 ^eC thanks to an ice/water bath, and then 2,4,6-trimethylbenzoyl chloride (0.1 ml_, 0.600 mmol, 1 eq) was added dropwise. The mixture was stirred for 20 minutes in the ice/water bath, and afterwards at room temperature for 20 minutes more. The mixture was partitioned between ethyl acetate and HNaC0₃ (2% w/w, 2 times), washed with water (1 time), brine (1 time), and dried over anhydrous Na₂S0 . The solvent was evaporated under vacuum to afford a solid, which was stirred in pentanes, filtered, further washed with pentanes, air-dried, and placed under vacuum. Result: Yellow solid, 151 mg, 85% yield. ¹ H NMR (400 MHz, CDCI₃) d 7.02 - 6.67 (s, 2H), 3.99 (dq, J = 73.9, 7.2 Hz, 4H), 2.36 (s, 6H), 2.28 (s, 3H), 1.37 (dt, J = 23.7, 7.2 Hz, 6H). ¹³C NMR (101 MHz, CDCI₃) d 191.87, 181.87, 140.30, 136.29, 134.29, 128.66, 50.52, 48.86, 21.33, 19.21 , 14.09, 11.36.

Hence, diethylcarbamothioic 2,4,6-trimethylbenzoic thioanhydride (compound of formula la) was effectively obtained in this example.

Example 1b: 2,4,6-trimethylbenzoic pyrrolidine-1 -carbothioic thioanhydride (lb)

[221] Pyrrolidine (1 ml_, 11.98 mmol) was dissolved in 120 ml. of methanol (hereinafter, MeOH). Equal molar 47% (w/w) KOH aqueous solution was added to the methanol solution. The reaction mixture was placed in an ice/water bath, and carbon disulfide (2.17 ml_, 35.9 mmol, 3 eq) was slowly dropped into the reaction flask. The reaction was stirred at room temperature overnight. The solvent was removed by rotary evaporation and the obtained solid was stirred in diethyl ether (100 ml.) for 1 hour, filtered, washed with diethyl ether, air dried, and placed under high vacuum for 1 h (2.10 g, 95% yield). A fraction of the obtained Potassium pyrrolidine-1 -carbodithioate (0.233 g, 1.259 mmol, 1.05 eq) was dissolved in ethyl acetate, cooled to 0 - 5 ^eC thanks to an ice/water bath, and then 2,4,6- trimethylbenzoyl chloride (0.2 ml_, 1 .20 mmol, 1 eq) was added dropwise. The mixture was stirred for 20 minutes in the ice/water bath, and then at room temperature for 15 minutes more. The mixture was partitioned between ethyl acetate and water, washed with water (2 times), brine (1 time), and dried over anhydrous Na₂S0 . Upon solvent evaporation, a solid was obtained, which was stirred in pentanes, filtered, washed with pentanes, air-dried, and placed under vacuum. Result: A pale yellow solid was obtained. 297 mg, 84% yield. ¹H NMR (300 MHz, Chloroform-d) d 6.85 (s, 2H), 4.06 - 3.81 (m, 4H), 2.36 (s, 6H), 2.28 (s, 3H), 2.23 - 2.02 (m, 4H). ¹³C NMR (101 MHz, CDCI₃) d 191.97, 178.91 , 140.34, 136.05, 134.22, 128.68, 55.29, 54.47, 26.36, 25.23, 21.32, 19.23.

Hence, 2,4,6-trimethylbenzoic pyrrolidine-1 -carbothioic thioanhydride (compound of formula lb) was effectively obtained in this example. Example 1c: Methyl(phenyl)carbamothioic 2,4,6-trimethylbenzoic thioanhydride (lc)

[222] To an oven dried 25-mL round bottom flask, containing argon and equipped with a stir bar and a septum, N-methyl aniline (0.2 ml_, 1.861 mmol, 1 eq.) and potassium tert- butoxide (tert-BuOK, 209 mg, 1 .861 mmol, 1 .0 eq.) were added. The flask was cooled in ice/water bath and anhydrous tetrahydrofuran (THF, 20 ml.) was added. The mixture was stirred for 30 minutes, and then, carbon disulfide (0.146 ml_, 2.419 mmol, 1.3 eq) was added dropwise using a syringe. The stirring was continued in the ice/water bath for 90 minutes and the 2,4,6-trimethylbenzoyl chloride (0.310 ml_, 1.861 mmol, 1.0 eq) was added dropwise. The reaction mixture was protected from light using aluminium foil and stirred for 15 min in the ice/water bath and 45 minutes more at room temperature. The mixture was portioned between ethyl acetate and water in a separatory funnel. The ethyl acetate layer was washed with water (25 ml_, 3 times), brine (1 time), and dried over anhydrous Na2S04. After treatment under vacuum a solid formed which was stirred in pentanes, filtered, washed with pentanes and air dried for 2 minutes, and then placed under vacuum. Result: Pale yellow solid, 285 mg, 47% yield. ¹H NMR (400 MHz, CDCI3) d 7.45 - 7.29 (m, 5H), 6.71 (s, 2H), 3.86 (s, 3H), 2.21 (s, 3H), 1 .93 (s, 6H). ¹³C NMR (101 MHz, CDCI3) d 190.72, 184.15, 146.84, 140.07, 135.88, 134.25, 129.46, 128.78, 128.42, 126.10, 47.08, 21.25, 18.71.

Hence, methyl(phenyl)carbamothioic 2,4,6-trimethylbenzoic thioanhydride (compound of formula lc) was effectively obtained in this example.

Example 1d: Adamantane-1 -carboxylic pyrrolidine-1 -carbothioic thioanhydride (Id).

[223] Potassium pyrrolidine-1 -carbodithioate (214 mg, 1.155 mmol, 1 eq), prepared as described in Example 1 b, was dispersed in chloroform (10 ml.) in an oven dried amberized round-bottomed flask, equipped with a stir bar and containing argon atmosphere. Solid adamantane-1 -carbonyl chloride (229 mg, 1.155 mmol, 1 eq) was added, while stirring. The flask was covered with a septum, and the mixture was stirred for 20 minutes (solid disappearance), and then 10 mL of 2% (w/w) aqueous HNaC0 was added. The mixture was transferred to a separation funnel. The mixture was washed with 2% (w/w) HNaC0 (1 time), water (250 mL, 1 time), and brine (1 time), and then dried through anhydrous Na S0 . The solvent was totally removed by rotary evaporation, and the resulting solid was placed under high vacuum. The solid was dispersed in diethyl ether, stirred for 5 minutes, then the solvent was partially removed almost to dryness and then pentanes were added, the mixture was sonicated and stirred, and the solid collected by filtration. The product was placed under high vacuum to obtain a pale yellow solid, 247 mg, 69.1% yield. ¹H NMR (500 MHz, CDCI₃) d 3.78 (q, J= 5.0, 3.1 Hz, 4H), 2.05 (tdd, J= 7.0, 5.2, 3.0 Hz, 7H), 1.92 (d, J= 3.0 Hz, 6H), 1.71 (dt, J= 12.4, 2.5 Hz, 6H). ¹³C NMR (126 MHz, CDCI₃) d 200.49, 180.57, 54.79, 49.88, 39.11 , 36.38, 28.23, 25.77.

Hence, adamantane-1 -carboxylic pyrrolidine-1 -carbothioic thioanhydride (compound of formula Id) was effectively obtained in this example.

Example 1e: Adamantane-1 -carboxylic diethylcarbamothioic thioanhydride (le)

[224] Commercial sodium diethylcarbamodithioate trihydrate (119 mg, 0.528 mmol, 1 .05 eq) was added to a dry flask, and then it was placed under vacuum at 60 ^eC for 20 minutes to partially remove the water. Dry ethyl acetate (4 ml.) was added and the mixture was cooled to 0 - 5 ^eC thanks to an ice/water bath and then solid adamantane-1 -carbonyl chloride (100 mg, 0.503 mmol, 1 eq) was added in one portion. The mixture was stirred for 20 minutes in the ice/water bath, and then at room temperature for 40 minutes more. The mixture was partitioned between ethyl acetate and HNaC0₃ (2% w/w, 2 times), washed with water (1 time), brine (1 time), and dried over anhydrous Na S0 . The resulting mixture was evaporated under vacuum, and a solid was formed, which was placed under high vacuum. The solid was stirred in pentanes, filtered, washed with pentanes, air-dried, and placed under vacuum. Result: Yellow solid, 109 mg, 69.5% yield. ¹H NMR (400 MHz, CDCI₃) d 3.87 (q, J = 7.1 Hz, 4H), 2.07 (p, J = 3.1 Hz, 3H), 1 .93 (d, J = 2.9 Hz, 6H), 1 .79 - 1.64 (m, 6H), 1.30 (t, J = 7.1 Hz, 6H). ¹³C NMR (101 MHz, CDCI₃) d 200.64, 183.48, 49.97, 49.63, 39.14, 36.40, 28.26, 12.50.

Therefore, adamantane-1 -carboxylic diethylcarbamothioic thioanhydride (this is, compound le) was effectively synthesized in this example.

Example 1f: 2,4,6-trimethylbenzoic diphenylcarbamothioic thioanhydride (If).

[225] To an oven dried 50-mL round bottom flask, containing argon and equipped with a stir bar and a septum, tert-BuOK (178 mg, 1.59 mmol, 1.3 eq), diphenylamine (213 mg, 1.259 mmol, 1 eq), and anhydrous THF (12 ml.) were added. The mixture was placed in an ice/water bath, and stirred for 30 minutes, and then, carbon disulfide (0.1 ml_, 1.636 mmol, 1 .3 eq) was added dropwise by means of a syringe. The stirring was continued in the ice/water bath for 60 minutes and 2,4,6-trimethylbenzoyl chloride (0.21 ml_, 1.259 mmol, 1 eq) was added dropwise. The reaction mixture was stirred for 15 min in the ice/water bath and then 45 minutes more at room temperature. The solvents were removed by rotary evaporation and the resulting mixture was partitioned between ethyl acetate and water in a separatory funnel. The mixture was washed with sodium bicarbonate (25 ml_, 3 times), water (1 time), and dried over anhydrous Na₂S0 . After solvent evaporation, the mixture was stirred in 5:1 pentanes:ethyl ether and filtered. Result: A yellow solid was obtained which was placed under high vacuum overnight. 392 mg, 80% yield. ¹H NMR (400 MHz, CDCIs) d 7.71 - 7.27 (m, 10H), 6.74 (s, 2H), 2.23 (s, 3H), 1 .95 (s, 6H). ¹³C NMR (101 MHz, CDCIs) d 190.36, 187.17, 140.15, 135.74, 134.29, 129.82, 129.33, 128.47, 128.29, 127.40, 21.26, 18.68.

2,4,6-trimethylbenzoic diphenylcarbamothioic thioanhydride (this is, compound If) was effectively obtained in this example.

Example 1g: 2,4,6-trimethylbenzoic 10H-phenothiazine-10-carbothioic thioanhydride (Ig) [226] To an oven dried vial, containing argon and equipped with a stir bar and a septum, tert-BuOK (68 mg, 0.602 mmol, 1.1 eq) was mixed with anhydrous THF (5 ml_). The mixture was cooled in an ice/water bath (< 5 ^eC), and then, 10H-phenothiazine (109 mg, 0.547 mmol, 1 eq) was added while stirring. The stirring was continued for 20 minutes, and then, carbon disulfide (0.043 ml_, 0.711 mmol, 1 .3 eq) was added dropwise by means of a syringe. The stirring was continued in the ice/water bath for 45 minutes and 2,4,6- trimethylbenzoyl chloride (0.602 mmol, 1.1 eq) was added dropwise. The reaction mixture was stirred 15 min more in the ice/water bath, then 45 minutes more at room temperature. The solvents were removed by rotary evaporation and the resulting mixture was partitioned between ethyl acetate and water in a separation funnel. The mixture was washed with water (20 ml_, 2 times), HNaC0₃ (0.5%, w/w, 1 time), brine (1 time), and dried over anhydrous Na₂S0 . After solvent evaporation the mixture was placed under high vacuum for 30 minutes, then dispersed in a solution of diethyl ether in pentanes (10% v/v [volume/volume]), filtered, air dried for one minute, and placed under high vacuum to remove solvent traces. Result: A yellowish solid was obtained, 163 mg, 71% yield. ¹H NMR (400 MHz, CDCIa) d 2.11 (6H, s), 2.24 (3H, s), 6.77 (2H, s), 7.28 (2H, m), 7.34 (2H, m), 7.53 (2H, dd, J=1 .40, 7.72 Hz), 7.82 (2H, d, J=5.72 Hz). ¹³C NMR (101 MHz, CDCI₃) d 18.87, 21.16, 126.49, 127.64, 128.22 (br), 128.35, 133.82, 134.18, 136.03, 140.13, 140.41 , 185.67, 190.61.

Therefore, 2,4,6-trimethylbenzoic 10H-phenothiazine-10-carbothioic thioanhydride (this is, compound Ig) was effectively obtained in this example.

Example 1 h: (4-methoxyphenyl)(p-tolyl)carbamothioic 2,4,6-trimethylbenzoic thioanhydride (Ih).

[227] To an oven dried 50-mL round bottom flask, containing argon and equipped with a stir bar and a septum, tert-BuOK (80 mg, 0.717 mmol, 1.02 eq), 4-methoxy-N-(p- tolyl)aniline (150 mg, 0.703 mmol, 1 eq), and anhydrous THF (previously degassed, 8 ml.) were added. The mixture was placed in an ice/water bath, and stirred for 30 minutes, and then, carbon disulfide (0.055 ml_, 0.914 mmol, 1.3 eq) was added dropwise by means of a syringe. The stirring was continued in the ice/water bath for 60 minutes and 2,4,6- trimethylbenzoyl chloride (0.117 ml_, 0.703 mmol, 1 eq) was added dropwise. The reaction mixture was stirred for 15 min in the ice/water bath and then 45 minutes more at room temperature. The solvents were removed by rotary evaporation and the resulting mixture was partitioned between ethyl acetate and water in a separatory funnel. The mixture was washed with sodium bicarbonate (25 ml_, 3 times), water (1 time), and dried over anhydrous Na S0 . The resulting solid was purified by filtration over silica gel. After solvent evaporation, the mixture was stirred in 10:1 pentanes:ethyl ether (volume) and filtered. Result: A yellow solid was obtained (95 mg), which was placed under high vacuum for 30 minutes, 135 mg, 44% yield. ¹ H NMR (400 MHz, CDCI₃) d 7.51 - 7.10 (m, 6H), 7.02 - 6.81 (m, 2H), 6.74 (s, 2H), 3.80 (d, J = 2.9 Hz, 3H), 2.34 (d, J = 5.7 Hz, 3H), 2.23 (s, 3H), 1.97 (d, J= 9.0 Hz, 6H). ¹³C NMR (101 MHz, CDCI₃) d 190.42, 187.01 , 140.11 , 135.85, 134.32, 130.56, 129.73, 128.47, 128.31 , 126.93, 126.81 , 115.03, 114.35, 55.72, 21.28, 18.71. Hence, (4-methoxyphenyl)(p-tolyl)carbamothioic 2,4,6-trimethylbenzoic thioanhydride (this is, compound Ih) was effectively obtained in this example.

Comparative example 1 : Benzoic pyrrolidine-1 -carbothioic thioanhydride (G)

[228] Potassium pyrrolidine-1 -carbodithioate (0.168 g, 0.905 mmol, 1.05 eq) was dissolved in dry ethyl acetate, cooled to 0 - 5 ^eC thanks to an ice/water bath, and then benzoyl chloride (0.1 ml_, 0.862 mmol, 1 eq) was added dropwise. The mixture was stirred for 20 minutes in the ice/water bath, and then at room temperature for 20 minutes more. The mixture was partitioned between ethyl acetate and HNaC0₃ (2% w/w, organic layer is washed twice with NaHC0₃2% w/w), washed with water (1 time), brine (1 time), and dried over anhydrous Na₂S0₄. Upon solvent evaporation under vacuum, an oil was received, which was placed under high vacuum, The mixture was filtered through silica (CycloHexane:EtOAc 3:1). Result: Pale yellow oil. 207 mg, 96% yield. ¹H NMR (400 MHz, CDCI₃) d 7.89 (dd, J= 8.4, 1.4 Hz, 2H), 7.60 (t, J= 7.4 Hz, 1 H), 7.46 (dd, J = 8.6, 7.1 Hz, 2H), 3.89 (s, 4H), 2.08 (t, J = 5.9 Hz, 4H). ¹³C NMR (101 MHz, CDCI₃) d 186.63, 178.67, 135.88, 134.31 , 129.03, 127.77, 55.07, 25.81.

Benzoic pyrrolidine-1 -carbothioic thioanhydride (compound G) was effectively synthesized in this example.

Example 2: Bulk polymerization of methyl acrylate

[229] Polymerization inhibitor was removed by filtering commercial grade methyl acrylate through a pad of basic alumina, afterwards all the monomers and solvents were degassed by pump-freeze thaw. Polymerization experiments were carried out using two different set ups:

Set-up 1 : A mixture of methyl acrylate and the corresponding compound of formula (I), (BEC) or (G) was placed in 1 ml. vial in a glove box in the amounts indicated below, minimizing the exposition to ambient light, such that the height of the mixture within the vial was about 2 mm (0.1 ml. volume of methyl acrylate) or 4 mm (0.2 ml. of methyl acrylate). The High-Performance Liquid Chromatography (hereinafter, HPLC) vials were equipped with their respective caps (with septum) and covered with aluminium foil until they were placed in their cell holder.

Set-up 2: A mixture of methyl acrylate and the corresponding compound of formula (I), (BEC) or (G) was placed in a 1-mm-path quartz cell suitable for spectroscopic measurements such that the area of the mixture in the cell covered a surface of 1 cm². The cells were sealed with a tap and covered with aluminium foil until they were placed in their cell holder. Quartz cells were rotated 45^e to allow simultaneous irradiation and measurements. Irradiation experiments were carried out as soon as possible.

[230] The LEDs (light-emitting diode) used for irradiation were equipped with a heat sink and a focusing lens that allowed irradiating from about 3 cm of distance, minimizing the vial or quartz cell heating, and focusing the light thoroughly onto the reaction mixture; the irradiating light bean was set up for approximately 90^e, and assuring that the entire sample was irradiated. Once the polymerization finished, samples for Gel Permeation Chromatography (GPC) and NMR were taken by dissolving the entire polymer in the vials or quartz cells using DCCI (deuterated chloroform) or THF; the deuterated chloroform solvent was removed in vacuum for the GPC samples.

[231] Using set-up 2, real time monitoring of bulk polymerizations was carried out using transmission near infrared spectroscopy (NIR), monitoring the signal absorbance at 1620.6 nm. The spectra before and after irradiation were set to zero absorption at 1590.6 nm, and a straight line was typically traced from 1590.6 to 1638.6 nm. The value of the line at 1620.6 nm was used for correcting the measured absorbance values. Absorbance and temperature readings were done every second. Monomer conversion quantification was also carried out by ¹H-NMR by integrating the signals of the reacted and unreacted monomer (ratio of integration of the two singlet signals between 3.5 and 4 ppm).

[232] High Luminous Efficacy LED Emitters on a star-shaped Printed Circuit Board from LED ENGIN, equipped with a heat sink, were employed for the reaction irradiations (Violet 405 nm: LZ1-10UB00-00U7, Blue 457 nm: LZ1-00B202; green 523 nm: LZ110G102; Amber 590 nm: LZ110A102). Current and voltage was controlled using discontinuous (DC) power supply (EA-PS2084-03B or Geti GLPS1502C or Velleman LABPS3005N), setting the voltage typically to 3.3V, and controlling the irradiance by limiting the current. A calibrated photodiode BPW-21 (OSRAM Opto Semiconductors) was employed for irradiance measurements.

[233] Molecular weight determination was carried out using a GPC (Agilent) equipped with a PSS SDV Analytical Linear M column, and refractive index detector (RID). The column temperature was set to 30 ^eC. Calibration curve was done using narrow dispersity index polystyrene standards. THF was employed as mobile phase, with a flow of 1.00 mL/min and 20 mΐ of injection volume.

Example 2-1

[234] Using set-up 2, bulk polymerization of methyl acrylate was studied using separately each of the compounds of formulae (la), (lb), (lc), (Id), (le), (G) and BEC (Ph-C(=0)-S- C(=S)-N-(C₂H₅)2) as described above and using in each case a molar ratio of compound of formula (I) to methyl acrylate of 1 :200 and using an irradiation system as described above with a blue LED (460 nm, 400 mW/cm² intensity). The conversion of methyl acrylate was monitored by NIR spectroscopy as defined above. Figure 1 shows the evolution over time of the conversion of the monomer for each of the studied initiating systems. Table 1 shows the following properties of the resulting polymer after 15 minutes of irradiation: the observed conversion of methyl acrylate as measured by ¹H NMR or NIR according to the methods described above, molecular weight, polydispersity index (PDI) and degree of polymerization (X_n) as measured by GPC and NMR. Figure 3 shows the UV-Vis absorption spectra of the reaction mixture before irradiation with light (plain line) and after 15 minutes of irradiation with light (dashed line) when the compound of formula (Id) was used as initiator. Table 1 . Summary of the results obtained in example 2-1 for the polymerization.

^a Entries related to compound (G) and BEC represent comparative studies. ^* Target degree of polymerization according to RAFT mechanism: 200. ^b After 60 minutes of irradiation

[235] In these experiments, and as shown in Figure 3, while the mixture of the compounds of formula (I) is slightly yellow-coloured, the cured polymer does not present detectable colouration. This is particularly observed when, in the compounds of formula (I), at least one of R and R is not an aromatic group. This advantageously allows for identifying visually whether the curing process has occurred in a simple and straightforward manner. In addition, the results of Table 1 also show that the compounds of the invention allow obtaining higher degrees of conversion of monomer, while maintaining a similar index of polydispersity, with respect to the carboxylic dithiocarbamic acid anhydride compounds described in the art. As suggested in Table 1 , the photopolymerization of methyl acrylate is more efficient in the sense that it reaches a higher conversion of monomer when a carboxylic dithiocarbamic acid anhydride compound bearing a Ri group suitable for stabilizing the acyl radical of formula (II) generated in reaction (1) through steric hindrance (explained above), as is the case with the compounds of formula (I) or (XII) as defined above, is used as a photoinitiator. The results of Table 1 also show that the compounds of formula (I) act as a chain transfer agent, through the radical of formula (III) generated in reaction (1) (explained above), since the produced polymer has a degree of polymerization in accordance with such polymerization mechanism. The combination of q, Ri, R₂ and R₃ in the compounds of the invention is responsible for an improved control over the molecular weight of the formed polymer combined with an acceptable achieved conversion of monomer to polymer. A conversion above 70% within the 15 minutes of irradiation is considered acceptable, while a conversion of 85% or more is considered a good result.

Example 2-2

[236] Following the procedure of Example 2-1 with the compounds of formulae (If), (Ig), (Ih) and BEC (used as a comparative example), the results concealed in Table 2 for the bulk polymerization of methyl acrylate were obtained. Figure 2 shows the evolution over time of the conversion of the monomer for each of the studied initiating systems.

Table 2. Summary of the results obtained in example 2-2 for the polymerization.

[237] The results of Table 2 show that the compounds of the invention allow obtaining higher degrees of conversion of monomer, together with an improved index of polydispersity, with respect to the carboxylic dithiocarbamic acid anhydride compounds described in the art. The results of Table 2 also show that the compounds of formula (I) act as a chain transfer agent, since the produced polymer has a degree of polymerization in accordance with such polymerization mechanism. The molecular weight distribution of the formed polymer is particularly narrow when R₂ and R₃ are such that both carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) are members of an aromatic group.

Example 2-3

[238] Using set-up 1 explained above and the compound of formula (lb), a mixture of the compound of formula (lb) and methyl acrylate with a molar ratio (lb) to monomer as indicated in Table 3 was placed in a 1 ml. vial and irradiated with different sources of light. After one minute of irradiation with an intensity of 400 mW per cm², the mixture was analysed by ¹ H NMR and GPC in order to determine the conversion of methyl acrylate into polymer (monomer conversion), the amount of unreacted compound of formula (lb) (remaining initiator), as well as the molecular weight and polydispersity of the formed polymer. Table 3 describes the obtained results.

T able 3. Summary of the results obtained in example 2-3 for the different conditions tested.

[239] When a molar ratio of compound of formula (lb) to monomer of 1 :25 was used, the solubility of the compound of formula (lb) in methyl acrylate at this molar ratio did not allow for the full dissolution of the introduced amount of compound of formula (lb), which accounts for the observed values of X_n being separate from the targeted value of 25. The high values of PDI are attributed to the polymerization having taken place in a reduced amount of time and within a saturated solution of (lb) in methyl acrylate.

[240] When a molar ratio of compound of formula (lb) to monomer of 1 :100 was used, Table 3 shows that the compounds of formula (I) or (XII) allow reaching high conversions of monomer with different sources of light emitting in the UV-Visible range after only one minute of irradiation. Table 3 shows that the compounds of formula (I) or (XII) are particularly useful photoiniferters when the polymerizable composition consisting of a compound of formula (I) or (XII) and methyl acrylate is irradiated with light having a wavelength comprised of from 350 nm to 500 nm. Preferred wavelengths of irradiation are those ranging from 365 to 430 nm.

[241] The product of entry 1 (Table 3, first experiment) was further purified by precipitation from diethyl ether and further characterized by ¹ H NMR. The resulting product is a compound of formula (IVa) as defined above.

¹H NMR (400 MHz, CDCI₃) d 6.83 (s, 2H), 3.91 (t, J = 7.0 Hz, 2H), 3.67 (s, 166H), 3.12 (dd, J = 18.5, 8.7 Hz, 1 H), 3.01 - 2.76 (m, 1 H), 2.49 - 2.22 (m, 57H), 2.19 (s, 6H), 2.14 - 2.04 (m, 4H), 2.04 - 1.87 (m, 29H), 1.76 - 1.61 (m, 57H), 1.50 (dtt, J = 20.3, 13.1 , 6.7 Hz,

Example 3: Bulk polymerization of methyl acrylate under discontinuous irradiation [242] Polymethylacrylate was prepared from a polymerizable composition consisting of the compound of formula (lb) and methyl acrylate in a molar ratio of 1 to 400, using set-up 2 explained above and irradiation of blue light (460 nm, 400 mW per cm²). Irradiation was stopped after 67 seconds and resumed after 364 seconds (counted from the time of first irradiation). Irradiation was further stopped after 434 seconds and resumed after 734 seconds (counted from the time of first irradiation). Figure 4 shows the evolution of the conversion of methyl acrylate over time (in minutes) during this experiment. The progress of the polymerization can advantageously be controlled by controlling the irradiation with light. Example 3 shows that light can be used to control the progress of the polymerization process.

Example 4: Controlled bulk polymerization of methyl acrylate

[243] Compound (If), as prepared according to Example 1 (1.1 mg, 2.8 micromole, 1 eq) was added to a transparent vial, then methyl acrylate (50 microliter, 0.56 mmol, 200 eq) was added using a micro syringe. The thickness of the reaction was approximately 1 mm. The vial was irradiated, through the bottom (LED with lens, 460 nm, 400 mW/cm²). The irradiation was stopped once the reaction solidified (after 40 minutes). The formed gel was washed several times with diethyl ether inside the same vial by sonicating and mixing with a spatula, and the diethyl ether was removed by decanting. The sticky solid was placed under high vacuum to remove solvent traces. The resulting compound (IVb) was obtained as a colorless sticky solid, mass = 28 mg, M_n = 13732 Da, M_w= 17892 Da, PDI = 1.30.

Example 5: Polymerization of methyl acrylate promoted bv compounds of formula (IV)

[244] The reaction of free-radical polymerization of methyl acrylate was carried out in a glovebox, employing previously degassed and anhydrous acetonitrile and monomer. The compound of formula (IV) indicated in Table 4 (11 micromole, 0.010 eq) and methyl acrylate (100 microliter, 1.1 mmol, 1 eq) were added to an ambered vial, followed by the addition of 1 ,1 '-azobis(cyclohexanecarbonitrile) (ACHN) or azobisisobutyronitrile (AIBN) (2.2 micromole, 0.002 eq) from a previously prepared ACHN stock solution (1 .086 mg/ml_ in acetonitrile). The vial cap was tight strong to avoid leaking, and the mixture was placed to react at the temperature indicated in Table 4. Aliquots (20 microliter) were taken at different times of reaction, and analyzed by GPC (THF), and ¹H NMR. [245] Table 4 discloses the results obtained with compounds (IVa) and (IVb) in terms of molecular weight, polydispersity and degree of polymerization, as measured by GPC, at different time points of the polymerization.

Table 4. Summary of the results obtained in example 5 for the different conditions tested

¹ M_n of (IVa) before reaction is 6.87 kDa; ² M_n of (IVb) before reaction is 13.73 kDa; ³ measured conversion of monomer of 86%; ⁴ measured conversion of monomer of 97%; ⁵ measured conversion of monomer of 98%.

[246] The results of Table 4 show that the compound of formula (IV) according to the invention is useful as chain transfer agent in controlled free radical polymerization reactions because it allows obtaining a polymer with a narrow polydispersity if compared with the non-controlled free radical polymerization. Particularly, the product of the polymerization presents a very narrow index of polydispersity when the compound of formula (IV) is one where at least one of the carbon atoms of R and R that are attached to the nitrogen atom in the compound of formula (I), preferably both carbon atoms, are members of an aromatic group. This is the case of the compound of formula (IVb) for which the product of polymerization initiated using (IVb) exhibits a polydispersity that remains close to that of the compound of formula (IVb) engaged in the polymerization progresses. Example 6: Photopolymerization of pentaerythritol tetraacrylate using compound of formula (Id) or (lb) in the presence of synergists [247] General procedure: The compound of formula (lb) or of formula (Id) was solubilized in pentaerythritol tetraacrylate (PETA) with magnetic stirring, such that a weight ratio of 0.6% of the compound of formula (lb) and 1 .2% of the compound of formula (Id) is present in the PETA respectively, in a vial protected from light, one day before analysis. The synergists were added 3 hours before the experiment in amounts as indicated in Table 5. [248] Raman spectroscopy was used to measure the decrease of the concentration of double bond from the acrylate function with the area under the band at 1635cm^-1 with 1s of integration time. The laser has emission spectrum around 532nm and the i-Raman was from B&W Tek. A LED irradiating at 460nm was mounted on an air-cooler and the irradiation intensity was fixed at 600mW/cm² with the control of a calibrated photodiode. The incident light angle was 45° on the formulation of approximately 0.7mm spread on a microscopic glass slide. By plotting the conversion of PETA over time, it was possible to deduce three different parameters: (i) induction time (Expressed in seconds) corresponds to the time required for polymerization to start, (ii) rate of conversion (Rc expressed in percentage per second - that is the percentage of monomer that has been converted during one second) corresponds to the slope of the polymerization curve during the curing process, (iii) maximal conversion achieved (corresponds to the monomer conversion achieved at the end of the curing process, expressed as the percentage related to the ratio of the amount of converted monomer at the end of the reaction over the amount of monomer engaged). Table 5 Summary of the results obtained in example 6 for the different conditions tested with compound of formula (lb).

Table 6 Summary of the results obtained in example 6 for the different conditions tested with compound of formula (Id).

Using the general procedure described above but with the variations indicated in Table 7, compounds of formulae (lb) and (Id) have been compared with commercial photoinitiating systems such as BAPO and camphorquinone (CAQ).

Table 7. Summary of the results obtained in example 6 for the further different conditions tested with compound of formula (lb) or compound of formula (Id) or BAPO.

The results of Table 5, 6 and 7 show that the compounds of formulae (lb) and (Id) are suitable photoinitiators and are comparable in activity with existing commercial systems, such as BAPO and camphorquinone. The results also show that it is preferred that the composition according to the seventh aspect comprises a synergist compound, as this allows reducing the induction period and provide a faster curing process.

CITATION LIST

1. Australian patent application AU2009900271

2. Rizzardo E., Moad G., Thang S.H. (2008) RAFT Polymerization in Bulk Monomer or in (Organic) Solution in Handbook of RAFT polymerization (ed Christopher Barner- Kowollik) John Wiley & Sons, Inc., ISBN: 978-3-527-31924-4.

3. Zhou D. Zhu X., Zhu J., Yin H. Journal of Polymer Science: Part A: Polymer Chemistry 2005 (43), 4849-4856.

4. Lalevee, J., Blanchard, N., El-Roz, M., Alonaz. X., Fouassier, J.P. Macromolecules 2008, 41 , 2347 5. Cabannes-Boue, B.; Yang, Q.; Lalevee, J.; Morlet-Savary, F.; Poly, J. Polymer

Chemistry 2017, 8, 1760-1777.

6. Patent application WO2019123182A1 .

7. Ashirbaev, S.; Levin, V.; Struchkova, M.; Dilman, A. J. Org. Chem. 2018, 83, 478-483. 8. Hoffmeister, E.; Tarbell, D.; Tetrahedron 1965, 21 , 61(10), 2857-2864.

Claims

1. A compound of formula (I)

wherein q is 0 or 1 , when q is 0, Ri is a radical selected from the group consisting of a branched (C3-Ci₂)alkyl radical attached to the carbonyl group of the compound of formula (I) through a tertiary or quaternary carbon atom; a ring system attached to the carbonyl group of the compound of formula (I) through a quaternary carbon atom and comprising from one to four rings, wherein each ring is saturated, each ring comprises from 3 to 7 members selected from the group consisting of C, CH, CH₂, NH, O and S, and each ring is optionally substituted at any available position with one or more radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; and a (C₆-C₂o)aryl group substituted at one or both carbon atoms adjacent to the carbon atom of the (C₆-C₂o)aryl group that is attached to the carbonyl group of the compound of formula (I) with a radical selected from the group consisting of bromo and (Ci-Ci₂)alkyl, and further optionally substituted at any available position with a radical selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, halo, (Cr Cejalkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; when q is 1 , X and Y are each independently selected form the group consisting of (Cr C₆)alkyl optionally substituted at any available position with one group selected from (Cr C₆)alkyloxycarbonyl and (Ci-C₆)alkyloxy; or, alternatively, X and Y together with the carbon atom to which they are attached form a (C3-C₈)cycloalkyl ring; and Ri is a substituent selected from the group consisting of cyano, (Ci-C₆)alkyloxycarbonyl, (Cr C₆)alkylcarbonyloxy, (Ci-C₆)alkylaminocarbonyl, an amidine group and a substituent deriving from a hydrocarbon aromatic ring system comprising from one to two fused rings, the rings being further optionally substituted at any available position with one or more substituents selected from the group consisting of (Ci-C₆)alkyl, (Ci-C₆)alkyloxy, (Cr C₆)alkylcarbonyl, (Ci-C₆)alkyloxycarbonyl, (Ci-C₆)alkylcarbonyloxy, (Ci-C₆)perfluoroalkyl, halo, nitro, di(Ci-C₆)alkylamino and cyano; R₂ and R₃ are each a radical independently selected from the group consisting of (Cr Ci₂)alkyl group; (C₅-C₂₀)heteroaryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (Cr C₆)alkyloxy, halo, (Ci-C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; and (C₆- C₂₀)aryl group optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (CrC₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring of 5 to 6 members selected from the group consisting of C, CH, CH₂, NH, N, S and O, wherein the ring is optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, halo, ( Ci-C₆)alkylamino and nitro, and the ring is further optionally fused with one or two (C₆-C₂₀)aryl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (Cr C₆)alkyl, (CrC₆)alkyloxy, (CrC₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Cr C₆)alkylaminocarbonyl, (Ci-C₆)acylamido, (CrC₆)acyloxy, cyano and nitro; with the proviso that the compound of formula (I) is other than a compound of formula (XII)

2. The compound according to claim 1 wherein q is 1 .

3. The compound according to claim 2 wherein X and Y are each a methyl group.

4. The compound according to claim 2 or 3 wherein Ri is selected from cyano, (Ci-

C₆)alkyloxycarbonyl, (CrC₆)alkylcarbonyloxy and a phenyl ring optionally substituted at any available position with one or more substituents selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (CrC₆)alkylcarbonyl, (CrC₆)alkyloxycarbonyl, (Cr C₆)alkylcarbonyloxy, (CrC₆)perfluoroalkyl, halo, nitro, di(Ci-C₆)alkylamino and cyano.

5. The compound according to claim 1 wherein q is 0. 6. The compound according to claim 5 wherein Ri is a radical selected from the group consisting of isopropyl, 1-methylpropyl, 1-ethylpropyl, tert-butyl, 1 , 1 -dimethylpropyl, 1- methyl-1-ethylpropyl, 1 , 1 -diethylpropyl, 1-methylcyclohexyl, 1-methylcyclopentyl, bicyclo[2.2.1]heptyl, bicyclo[2.2.2]octyl, adamantyl, 2,6-dimethylphenyl and 2,4,

6- trimethylphenyl.

7. The compound according to any one of the claims 5 and 6 wherein Ri is a radical selected from the group consisting of adamantyl and 2,4,6-trimethylphenyl.

8. The compound according to any one of the claims 1 to 7 wherein R₂ and R₃ are each a radical independently selected from the group consisting of methyl; ethyl; propyl; butyl and phenyl optionally substituted at any available position with one or more radicals selected from the group consisting of (Ci-C₆)alkyl, (CrC₆)alkyloxy, halo, (Cr C₆)alkylamino, (Ci-C₆)acylamido, (CrC₆)acyloxy and nitro; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic ring system consisting of a cyclic ring selected from the group consisting of pyrrolidine, piperazine, morpholine, thiomorpholine, oxazolidine, thioxazolidine and piperidine, wherein said ring is further optionally fused with one or two phenyl groups optionally substituted at any available position with one or more radicals selected from the group consisting of (CrC₆)alkyl, (CrC₆)alkyloxy, (Cr C₆)alkyloxycarbonyl, halo, (Ci-C₆)alkylamino, (Ci-C₆)alkylaminocarbonyl, (Cr C₆)acylamido, (CrC₆)acyloxy, cyano and nitro.

9. The compound according to any one of the claims 1 to 8 wherein R₂ and R₃ are each a radical independently selected from the group consisting of methyl, ethyl, 4- methylphenyl and 4-methoxyphenyl; or; alternatively, R₂ and R₃, together with the nitrogen atom to which they are attached form a non-aromatic cyclic ring system selected from the group consisting of pyrrolidine and phenothiazine.

10. The compound according to any one of the claims 1 to 9, characterized in that q, Ri, R₂ and R₃ are such that the compound is selected from the group consisting of the compounds of formulae (la), (lb), (lc), (Id), (le), (If), (Ig) and (Ih)

11 . The compound according to any one of the claims 1 to 10 wherein R₂ and R₃ are such that none or one of the carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) is member of an aromatic group; preferably the compound is selected from the group consisting of the compounds as defined in claim 10 of formulae (la), (lb), (lc), (Id), and (le).

12. The compound according to any one of the claims 1 to 10 wherein R₂ and R₃ are such that both carbon atoms of R₂ and R₃ that are attached to the nitrogen atom in the compound of formula (I) are members of an aromatic group; preferably the compound is selected from the group consisting of the compounds as defined in claim 10 of formulae (If), (Ig), and (Ih).

13. Use of a compound of formula (I) or of formula (XII) according to any one of the claims 1 to 12 as a photoinitiator for polymerization; preferably, as a photoiniferter for polymerization.

14. Use according to claim 13 wherein the polymerization is carried out under irradiation of visible light, preferably under irradiation of blue light.

15. A compound of formula (IV)

wherein n is an integer comprised of from 1 to 5; q is 0 or 1 ; each P is a polymeric block consisting of a polymerized product of a composition comprising a monomer having a polymerizable carbon-carbon double bond and wherein each of X and Y is as defined in claim 1 or 3,

Ri is as defined in any one of claims 5 to 7 when q is 0,

Ri is as defined in any one of claims 3 to 4 when q is 1 , and

R₂ and R₃ are as defined in any one of the claims 1 , 8, 9, 10, 11 and 12.

16. The compound according to claim 15 wherein P is a polymeric block consisting of a polymerized product of a monomeric composition comprising a monomer selected from the group consisting of (C2-C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, terpenes or combinations thereof.

17. The compound according to claim 15 or claim 16 wherein each P comprises from 2 to 1000 repeating monomer units; preferably from 10 to 500 repeating units.

18. The compound according to any one of claims 15 to 17 that is a compound of formula (IV^')

that is a compound of formula (IV) wherein each P is a polymeric block consisting of a polymerized product of a composition consisting of a monomer having a polymerizable carbon-carbon double bond and wherein each of Ri’, R₂’, R₃’ and R ’ are each independently a radical such that the monomer having a polymerizable carbon-carbon double bond of formula (R_I’R₂’)C=C(R₃’R₄’) is selected from the group consisting of (C₂- C₆)alkene, acrylates, methacrylates, acrylamides, styrenes, cyanoacrylates, vinyl ethers, vinyl esters, and terpenes and wherein n’ is an integer comprised of from 2 to 1000.

19. The compound according to any one of claims 15 to 18 wherein n is 1 .

20. The compound according to any one of claims 15 to 19 that is a compound of formula (IVa) or (IVb)

that are compounds of formula (IV) wherein each P is a polymeric block consisting of a polymerized product of methyl acrylate and wherein n’ is an integer comprised of from 10 to 100.

21 . Use of the compound of formula (IV) as defined in any one of the claims 15 to

20 as chain transfer agent.

22. A composition comprising (i) at least one compound of formula (I) or (XII) as defined in any one of the claims 1 to 12, or at least one compound of formula (IV) as defined in any one of the claims 15 to 20, or a combination of a compound of formula (I) or (XII) as defined in any one of the claims 1 to 12 and a compound of formula (IV) as defined in any one of the claims 15 to 20; and (ii) at least one of: a) a monomer comprising in its molecular formula at least one carbon-carbon double bond, and b) an oligomer comprising in its molecular formula at least one carbon-carbon double bond.

23. The composition as defined in claim 22 comprising a monomer selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, pentaerythritol tetraacrylate, isodecyl acrylate, dipropylene glycol diacrylate, tricyclodecanedimethanol diacrylate, trimethylolpropane triacrylate, 1 ,6-hexanediol diacrylate, diacrylate of 1 ,10- decanediol, triethylene glycol dimethacrylate, 2-[[(butylamino)carbonyl]oxy]ethyl acrylate and mixtures thereof.

24. The composition as defined in claim 22 or 23 comprising an oligomer selected from the group consisting of an oligomer of an aliphatic polyester ether urethane acrylate, an aliphatic urethane hexaacrylate oligomer, an aliphatic urethane diacrylate, an aliphatic urethane acrylate oligomer, ethoxylated (4) bisphenol A dimethacrylate, urethane dimethacrylate, ethoxylated bisphenol A diacrylate and a mixture thereof.

25. The composition as defined in any one of claims 22 to 24 further comprising one or more additional components selected from the group consisting of synergists, dyes, pigments, flame-retarding agents, matting agents, UV blocking agents, UV stabilizers, fillers, adhesion promoters, defoaming agents, rheology modifiers and mixtures thereof.

26. The composition as defined in claim 25 further comprising a synergist selected from the group consisting of amines, thiols, phosphines, phosphites, organometallic compounds boranes, silanes, dienes and mixtures thereof.

27. The composition as defined in claim 25 or 26 further comprising a synergist selected from the group consisting of N-methyl diethanolamine, N-phenylglycine, pentaerythritol tetrakis(3-mercaptopropionate), (2-dimethylaminoethyl) methacrylate, 1 - adamantanethiol, ethyl 4-dimethylaminobenzoate, trimethylborate, triphenylphosphine, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) and mixtures thereof; preferably, the synergist is pentaerythritol tetrakis(3-mercaptopropionate).

28. The composition as defined in any one of claim 25 to 27 further comprising an inorganic pigment; preferably the inorganic pigment is titanium dioxide.

29. A process for the preparation of a cross-linked material comprising the step of irradiating the composition according to any one of the claims 22 to 28 with light, preferably with blue light, wherein when the composition according to any one of the claims 22 to 28 does not comprise a compound of formula (I) or (XII), it further comprises a polymerization initiation system.

30. A cross-linked material obtainable by the process of claim 29.