WO2002024816A1

WO2002024816A1 - Rotaxane dyes

Info

Publication number: WO2002024816A1
Application number: PCT/GB2001/004265
Authority: WO
Inventors: Harry Laurence Anderson; Michael Robert Craig; Michael Gordon Hutchings
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-09-25
Filing date: 2001-09-25
Publication date: 2002-03-28
Anticipated expiration: 2003-03-25
Also published as: GB0023446D0; AU2001290094A1; GB2371554A; GB0123041D0

Abstract

A rotaxane type reactive dye comprises a reactive azo chromophoric guest molecule and a macrocyclic host molecule, which dye has the formula (I) wherein (Rm) is a macrocyclic host molecule having a macromolecular aperture through which the reactive azo chromophoric guest molecule extends; each of A and B is an optionally substituted aromatic or heteocaromatic unit having a molecular dimension sufficiently large to prevent molecular separation of the reactive azo chromophoric guest molecule from the macrocyclic host molecule; D, or each D independently, is an arylene unit selected from mono- and diarylene units of the respective formulae (II) and (III) in which R5, or each R5 independently is C¿1-4? alkyl, each of w, y and z independently is zero or 1; and R?6¿ is CH=CH; CH¿2?; C2H4; C3H6; C4H8; O; S; NR?7¿ (in which R7 is hydrogen or C¿1-4? alkyl; or a direct bond; G, or each G independently, is a reactive group; each of m, n and p independently is zero or 1 and m+n+p>1; r is 1, 2 or 3; x is zero, 1, 2 or 3; and when x is 2 or 3 each p respectively may be the same as, or different from each other.

Description

Rotaxane Dyes

This invention relates to rotaxane dyes.

Molecular species known as rotaxanes in general have been described in "Molecular Catenanes, Rotaxanes and Knots - A Journey through the World of Molecular Topology" edited by Jean-Pierre Sauvage and Christiane Dietrich-Buchecker. Publ: Wiley VCH, 1999. These are composed of two or more discrete molecular entities. One of these may be termed the guest. One or more of the others are termed host. In this case, host molecules are macrocyclic molecules, comprising a cyclic molecular unit, thus defining a hole. The hole is large enough for the guest molecule to pass through. So-called pseudo-rotaxanes are molecular species comprising a macrocyclic ring compound, with a host molecule threaded through its hole. Rotaxanes are closely related to this structural type, except that now the ends of the guest molecule are sufficiently large to prevent the host macrocycle from slipping off the guest thread molecule. Thus the macrocyclic host plus its locked in guest behave as a separate molecular entity. An extension of this has more than one host molecule threaded onto the guest.

As to dyestuffs cyclodextrins are known to form inclusion complexes with a variety of dyes, including azo dyes, in aqueous solution. Several of these dye inclusion complexes have been reported to have higher photostability than the uncomplexed dyes; inclusion is also a way of modifying the solubility and surface-affinity of a dye. However, in contrast to rotaxanes, these inclusion complexes are labile and they exist in dynamic equilibrium with the free dyes, which limits potential applications. On the other hand, during the last few years, it has been found possible to obtain, instead of these labile cyclodextrin dye inclusion complexes, highly stable rotaxane dyes (see S.Anderson, T.D.W.CIaridge and H.LAnderson, Angew.Chem.lnt.Ed.Engl., 1997, 36, 1310; M.R.Craig, T.D.W.CIaridge, M.G.Hutchingsand H.LAnderson, Cne/77, Commun., 1999, 1537; and J.E.H.Buston, J.R.Young and H.LAnderson, Chem, Commun., 2000, 905). Bulky stoppers prevent the dye from slipping out of the cavity of the cyclodextrin, so it is permanently encapsulated and shielded from the external environment.

There is also a previous report of rotaxane synthesis using triazine chemistry (see M.Kunitake, K.Kotoo, O.Manabe, T.Muramatsu and N.Nakashima, Chem, Lett., 1993, 1033). However, although the triazine derivative formed fortuitously as intermediate in the reported synthesis would in fact be reactive, for example, towards cellulose, the final product of the synthesis does not contain a reactive triazine group.

We have found surprisingly that coloured rotaxane species comprising a reactive azo dye molecule as guest molecule, threaded through a macrocyclic host, have unusual and beneficial physical properties such as improved light fastness, and improved fastness to other chemical agents.

Such reactive azo dye rotaxanes can be covalently attached to cotton (cellulose) and exhibit superior stability towards both reductive and oxidative bleaching, and photo- bleaching, compared with the unencapsulated dye. Furthermore such dyes also show less photochromic behaviour, i.e they have less of a tendency to change colour on exposure to light. Moreover, the fluorescence yields of chromophores in a rotaxane environment are increased, i.e the dyes have a greater tendency to flouresce.

According to one aspect, the present invention provides a rotaxane type reactive dye comprising a reactive azo chromophoric guest molecule and a macrocyclic host molecule,

[ lπ ( i )

wherein:

g a macromolecular aperture through which the reactive azo chromophoric guest molecule extends;

each of A and B is an optionally substituted aromatic or heteroaromatic unit having a molecular dimension sufficiently large to prevent molecular separation of the reactive azo chromophoric guest molecule from the macrocyclic host molecule;

D, or each D independently, is an arylene unit selected from mono- and diarylene units of the respective formulae (II) and (III)

in which R⁵, or each R⁵ independently, is C_M alkyl;

each of w, y and z independently is zero or 1; and

R⁶ is CH=CH; CH₂; C₂H₄; C₃H₆; C₄H₈; O; S; NR⁷ (in which R⁷ is hydrogen or C,_₄ alkyl); or a direct bond;

G, or each G independently, is a reactive group;

each of m, n and p independently is zero or 1 and m+n+p>1;

r is 1, 2 or 3;

x is zero, 1, 2 or 3; and

when x is 2 or 3 each p respectively may be the same as, or different from, each other.

The units A and B are sufficiently large to prevent the macrocyclic ring slipping off, and thus regenerating the individual host and guest molecules. This bulk may be provided by at least one of the aromatic or heteroaromatic nucleus, reactive group G substituted thereon or any other substituent which either together with or independently of the nucleus, provides a sufficiently large unit.

Thus each of A and B independently may be selected from benzene units (XVI) and more particularly, naphthalene units (XVII) and (XVIII), substituted by one or more substituents X

[XL (XVIII)

wherein:

X, or each X independently, is sulphonic acid, sulphonate ion salt, sulphonamide, N-substituted, for example N-alkylated, sulphonamide, N,N-disubstituted, for example, N,N-dialkylated, sulphonamide, sulphonate ester, carboxylic acid, carboxylate ion salt, carbonamide, N-substituted, for example, N-alkylated, carbonamide, N,N-disubstituted, for example, N,N-diaikylated, carbonamide, carboxylic ester, fluoro, chloro, bromo, iodo, nitro, ureido, optionally substituted acylamino, optionally substituted aryl, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted alkylamino, optionally substituted dialkylamino, and optionally substituted alkylsulphonyl; and e is zero or from 1 to 6, especially 1 , 2, 3 or 4.

Preferred values of R_M are macrocyclic molecules large enough to accommodate the azo dye guest. Example macrocycles are cyclic polyethers such as crown ethers, cyclic polyamines, polylactones, cyclic poiyamides, cyclic oligomers of carbohydrates, cyclic oligomers of ureas such cucurbituril and cyclophanes. Especially preferred are carbohydrate-derived macrocycles such as cyclodextrins (see Chemical Reviews (1998), 98(5), 1921). Cyclodextrins are ring compounds composed of a number of 1,4- linked glucose units linked head-to-tail in a macrocycle. Common cyclodextrins of value in rotaxane dyes (1) are those containing six glucose units (alpha-cyclodextrin, structure A), seven glucose units (beta-cyclodextrin, structure B), and eight glucose units (gamma-cyclodextrin, structure C).

B Another preferred variant for the macrocyclic ring of (1) are cyclodextrins some or ail of whose hydroxy groups, present as part of the glucose sub-units, are methylated or otherwise alkylated.

The reactive group G, or each reactive group G independently, is preferably selected from

(a) a triazinylamino unit of formula (V)

where:

L is a leaving group, which may be selected from F, Cl, Br and quaternary amino groups such as optionally substituted pyridinium;

T is C,^ alkoxy or C,_₄ thioalkoxy each of which may be optionally substituted by, for example, OH or alkoxy or T is N(R¹)(R²);

R¹ or each R¹ independently is H or optionally substituted C_lJt alkyl;

R² is H, optionally substituted C-,^ alkyl, or is phenyl or naphthyl optionally substituted by, for example, suIpTio, acyloxy, or optionally substituted C_M alkyl; ,

(b) a pyrimidinylamino unit of formula (VI) or (VII)

where:

L is as defined above;

R³ is Cl, CN, C-,.₄ alkyl or C_M alkylsulphonyl; and a is zero or 1; and

R¹ is as defined above; (c) a vinyl or allyl sulphonyl group of formula SO₂(CH₂)_bCH=CH₂ (viii) (where b is zero or 1); more preferably of formula SO₂CH=CH₂;

(d) a vinyl sulphone precursor of formula (IX)

-SO₂-CH₂CH₂-R⁴ (IX) where:

R⁴ is an eliminatable group, such as sulphate, phosphate, chloride, acyloxy especially acetoxy, or quaternary ammonium such as optionally substituted pyridinium, removable under alkaline conditions to provide a vinyl sulphonyl group of formula (VIII). [Thus, when G has formula (IX) treatment by base during processing to increase the pH above 7 liberates the vinyl sulphone reactive group SO₂CH=CH₂]; and

(e) a group of the formula (X)

-W-C(R¹⁰)=CH₂ (X)

wherein: R¹⁰ is hydrogen, C,^ alkyl or halogen; and W is -OC(=O)- or -N(R¹¹)C(=O)- in which R¹ is H or C^ alkyl.

According to one preferred embodiment, the invention provides a rotaxane dye of the formula (XIV)

wherein each of A, B, R_M, G, m and n is as defined above.

According to another preferred embodiment, the invention provides a dye of the formula (XV)

wherein: each of

A,B,R_M> G, r, m and n is as defined above; and

D is an arylene unit (II),

preferably

[ R⁵ ]_y (II) [ R⁵

where

R⁵ is optionally substituted C._₄ alkyl, and y is zero or 1 ; or

D is a diarylene unit (III)

where: R⁵ is as defined above, and

R⁶ is CH=CH, CH₂, C₂H₄, C₃H₆, C₄H₈, O, S, NR⁷ (in which R⁷ is H or C_M alkyl), or a direct bond.

Dyes of formula (XIV) or (XV) which contain one or more reactive groups G are particularly useful for the colouration of substrates which contain a nucleophilic molecular unit which may react with the reactive group G thus binding the coloured species to the substrate via a covalent bond. Reaction between reactive group and substrate leads to fixation of the rotaxane dye on the substrate, and may be effected by altering the pH, or temperature, or both temperature and pH, of the system. In this way, the coloured component may not be easily removed from the substrate by washing or other natural or unnatural agency, such as weathering or rubbing.

A major feature of the current invention is the relationship between the dimensions of the cavity defined by the macrocyclic host ring R_M and the dimensions of each end of the azo dye guest molecule. The molecular dimensions of each of the latter should be greater than that of the diameter of the macrocyclic cavity at least at room temperature, say at 25°C, so as to prevent the macrocyclic ring slipping off the azo dye guest molecule.

An example of an unsubstituted aromatic nucleus of sufficiently large dimensions for retention of at least most macrocycles is anthracene, attached to the azo group at the 9- position, while an example of a substituent which, even when present in an otherwise unsubstituted benzene ring, is of sufficiently large dimensions is the adamantyl group. An example of a reactive group substituted on an aromatic or heteroaromatic group which is of sufficiently large dimensions is a triazinylamino group having at least one reactive substituent.

For cyclodextrin host macrocycles, the breadthwise dimension of the ends of the azo dye guest should be greater than 5.7 A for alpha-cyclodextrin, greater than 7.8 A for beta-cyclodextrin, and greater than 9.5 A for gamma-cyclodextrin. Dimensions of - components of azo dye guest molecules may be estimated by commonly available molecular modelling packages, such as Hyperchem, or from physical molecular models.

As examples of substituent combinations may be mentioned the following. To prevent a benzene ring of a phenyl azo molecule from passing through alpha-cyclodextrin, two methyl groups oriented 3,5 to the azo linkage are satisfactory. For a 2-linked naphthylazo group, two sulphonate groups oriented 5,7 are satisfactory. For a 1 -linked naphthyl group, two sulphonated groups oriented 3,6 are satisfactory.

Rotaxane azo dyes may be prepared by any of the following methods. An arylamine may be diazotised by conventional means, a macrocycle R_M added, and conventional azo coupling continued in the presence of a coupling component. Alternatively a unit containing two diazotisable arylamine groups may be tetrazotϊsed, macrocycle R_M added, and then azo coupling with conventional coupling components continued. In the case of reactive rotaxane azo dyes of formula (XIV) or (XV), a conventional azo dyebase with a free arylamine unit is treated in solution with a macrocycle R_M, and then reacted with the elements of a reactive group G. As examples, we mention arylaminodihalotriazines, or dϊ- or trihalopyrimidines. On reaction with the dyebase in the presence of macrocycle, the arylaminoheterocycle traps the macrocycle on the dyebase thread. All these methods may be carried out in solution, especially aqueous solution. Rotaxane dyes embodying the invention are useful for the colouration of various substrates. Amongst these may be mentioned paper, hair, textiles, leather, wood, polymers, glasses, and ceramics. Most especially favoured are paper and textiles.

Amongst textile materials which may be coloured by the rotaxane dyes may be mentioned cotton, cotton blends with other textile fibres, other cellulose-based textiles, including cellulose regenerated from trees, known as Lyocell, polyamide fibres such as nylon, wool, and silk, polyurethane fibres including Lycra, polyester and polyester blends with other textile fibres, and polyacrylonitrile. Amongst these are especially favoured cotton and other cellulose based fibres, and polyamide-based fibres.

Amongst suitable application conditions for the reactive rotaxane dyes of formula (XIV) and (XV) may be mentioned those for hydroxy-containing substrates such as paper or celiulosic textiles where preferred pH values lie between 7 and 13, more especially 8 and 13; and amino-containing substrates such as hair, leather, and polyamide textiles, including nylon, wool, and silk, where the preferred application pH may lie between 3 and 8. Proteinaceous substrates such as hair and leather may also react via the sulphur atoms of thiols present in their structure.

Rotaxane dyes embodying the invention may be applied to paper from solution, especially aqueous solution. Solutions of the rotaxane dye may contain between 0.001% and 50% dye, more especially 0.1% and 30%. Solutions of the rotaxane dye may also contain other additives, and may take the form of an ink. Additives may include surfactants, solvents, humectants, biocides and buffers. Application of the rotaxane dye to paper from solution or via an ink may be achieved at pH values between 3 and 13, more especially between 4 and 10, and even more especially between 5 and 9. Application to paper may be carried out between 0 and 100°C, especially between 15 and 90°C. Amongst methods for the application of rotaxane dyes to paper may be mentioned conventional bulk colouration technologies; printing from ink compositions containing the rotaxane dye, including via ink-jet technologies; and printing via thermal diffusion technologies, where the dye is immobilised in an inert polymer film support and transferred to its substrate via close contact and increase in temperature. .

Application of a rotaxane dye to celiulosic textiles such as cotton may be achieved by conventional dyeing methods, such as exhaust, cold-pad-batch, continuous methods involving steam or dry heat, and by printing including printing by ink-jet methods. Dyes may be applied from aqueous solution. The aqueous solution may contain buffers, biocides, and especially acid binding agents which help control the pH of the dyebath. Acid binding agents include alkali metal carbonates, bicarbonates, hydroxides, metasilicates, phosphates, and mixtures thereof, for example, sodium bicarbonate, sodium carbonate, sodium metasilicate, sodium hydroxide, and the corresponding potassium or lithium salts. Dyeing may be carried out at temperatures between 10 and 160°C. The dyes, which contain reactive groups, are additionally immobilised on the textile by covalent bonding.

We find surprisingly that rotaxane dyes embodying the invention confer a major advantage over the same dyes used as conventional non-rotaxanes, that is, without the host macrocyclic molecular component. These advantages include an increase in fastness properties, including fastness to light, and to oxidative and reductive bleaches and other agents contained for example in commercial washing powders. Moreover, the rotaxane dyes are found to be more stable with respect to photoisomerisation and thus more likely to demonstrate undesirable photochromism effects than the free dye.

Especially preferred embodiments of the invention will now be described in more detail with reference to the following Examples and accompanying drawings.

In the drawings,

Fig.1 shows decay curves for reaction of rotaxane 1 and free dye 11 with sodium dithionite under identical conditions (see Application Example 2); and

Fig.2 shows reaction curves for reaction of rotaxane 1 and free dye 11 with Fenton's reagent (see Application Example 3). In Fig.2, A/A₀ is the normalized absorption at 500nm.

Preparation Example 1

(a) Preparation of 6-(4-Methylamino-phenylazo)-naphthalene-1 ,3-disulfonic acid disodium salt (10), the starting material in the reaction of Scheme 1 in part (b) below.

2-Aminonaphthalene-5,7-disulfonic acid disodium salt (11.34 g, 30.0 mmol) was dissolved in water (150 ml) and concentrated hydrochloric acid added dropwise until the solution was acidic to Congo Red indicator paper (pH 3). The solution was cooled to 0—5 °C and a fine, cream coloured precipitate was observed. The suspension was stirred rapidly and sodium nitrite (2.07 g, 30.0 mmol) in water (5 ml) added dropwise. The formation of diazonium salt was monitored with starch-potassium iodide paper. During the addition of sodium nitrite the fine precipitate dissolved, and the solution was allowed to stir for 1 hour. Λ/-methylani!ine (3.22 g, 30.0 mmol) was dissolved in acetone/water (1/1 , 20 ml) and concentrated hydrochloric acid added dropwise until the solution was acidic to Congo Red indicator paper. The solution was cooled to 0-5 °C with stirring. The solution of diazonium salt was added dropwise to the solution of N- methyianiline and the reaction mixture became deep red in colour. When addition of the diazonium salt was completed the solution was allowed to stir for 1 hour. The dye was precipitated by the addition of sodium chloride (30 g) and filtered. Excess sodium chloride was removed by dialysis in water using 12,000 MWCO dialysis tubing. The solution was then evaporated to dryness to yield a dark red/brown solid 6-(4- methy!amino-phenylazo)-naphthalene-1,3-disulfonic acid disodium salt (10) (10.52 g 75%): 1 H NMR (500 MHz, de-DMSO) δ 8.87 (d, 1 H, J = 9.2 Hz), 8.34 (d, 1 H, J = 1.8), 8.27 (d, 1H, J = 1.5 Hz), 8.24 (br, 1H), 7.93 (dd, 1H, J'= 9.2 Hz, J"= 1.8 Hz), 7.82 (d, 2H, J = 8.9 Hz), 6.77 (q, 1 H, J = 4.9), 6.70 (d, 2H, J = 8.9 Hz), 2.81 (d, 3H, J = 4.9 Hz); 13c NMR (125 MHz, dβ-DMSO) δ 153.9, 150.7, 145.8, 144.7, 143.8, 134.3, 130.2, 129.4, 127.0, 126.4, 126.1, 124.5, 117.7, 112.2, 30.2; UV-vis (water) λ_maχ: 453.8 nm, log ε: 4.34; ES-MS (-ve) m/z 420 [M2-]

(b) Preparation of 6-(4-{[4-chloro-6-(3-sulfo-phenylamino)-[1,3,5]triazin-2-yl]-methyl- amino}phenylazo)-naphthalene-1 ,3-disuIfonic acid trisodium salt trimethyl-α- cyclodextrin (1), the product shown in Scheme 1, below.

6-(4-Methylamino-phenylazo)-naphthalene-1 ,3-disulfonic acid disodium salt (10) (380 mg, 0.817 mmol) and trimethyl-α-cyclodextrin (1.16 g, 0.95 mmol) were dissolved in distilled water (50 ml) and cooled to 0 °C with stim^'ng. The solution was maintained at pH 6.5 using 0.2 M aqueous hydrochloric acid and 1.2 M aqueous sodium hydrogen carbonate. Crushed ice (5 g) was added to a rapidly stirred solution of cyanuric chloride in acetone (5 ml), causing a fine white precipitate to form. The suspension of cyanuric chloride was added dropwise to the orange solution of dye and the pH was maintained at pH 6.5 throughout the addition. After the pH of the solution ceased to fall the reaction mixture was allowed to stir for 20 min, adjusted to pH 7.6 and filtered while cold. Metanilic acid (163 mg, 0.833 mmol) was dissolved in distilled water (5 ml) and added dropwise to the reaction mixture. Once addition was complete the temperature of the reaction mixture was taken to 35 °C for 1 hour, and maintained at pH 7.6. The reaction mixture was washed with chloroform (5 x 50 ml), ultrafiltered in water for 17 hours using a 1000 NMWCO membrane, then evaporated to dryness to yield a deep orange solid 6-(4-{[4-chloro-6-(3-sulfo-phenylamino)-[1,3,5]triazin-2-yl]-methyl- amino}phenylazo)-naphthalene-1 ,3-disulfonic acid trisodium salt trimethyl-α- cyclodextrin [2] rotaxane 1 (1.58 g, 96 %): 1H NMR (500 MHz, D2O) δ 9.12 (d, 1H, J = 9 Hz), 9.08 (d, 1 H, J = 2 Hz), 8.76 (d, 1 H, J = 2 Hz), 8.44 (d, 1 H, J = 1 Hz), 8.35 (dd, 1H, J' = 9 Hz, J"= 3 Hz), 7.73 (AA'BB'q, 4H, J'= 6 Hz, J"= 9 Hz), 7.57 (d, 1H, J= 7 Hz), 7.48 (d, 1H, J = 7 Hz), 7.40 (t, 1H, J= 8 Hz), 5.00 (d, 6H, J= 3 Hz), 3.83 (br d, 6H, J= 9 Hz), 3.61 (dd, 6H, J'= 10 Hz, J"= 3 Hz), 3.52 (s, 3H), 3.49 (t, 6H, J= 10 Hz), 3.34 (d, 6H, J = 10 Hz), 3.31 (s, 18H), 3.26 (s, 18H), 3.24 (s, 18H), 3.19 (t, 6H, J = 10 Hz) 3.01 (dd, 6H, J'= 10 H, J"= 3 Hz); 13c NMR (125 MHz, D2O) δ 169.1, 165.4, 164.0, 150.7, 150.5, 147.7, 143.8, 141.5, 138.5, 133.9, 133.1, 131.7, 129.94, 129.93, 129.7, 128.9, 128.1, 124.9, 123.7, 121.3, 118.5, 117.4, 100.0, 82.4, 81.1, 71.4, 71.1, 62.5, 59.0, 57.6, 39.1; UV-vis (water) λ_maχ: 364.15 nm, log ε: 4.34; ES-MS (-ve) m/z 964.2 [M3-+Na⁺] Comparative Preparation Example 1

Preparation of 6-(4-{[4-chloro-6-(3-sulfo-phenylamino)-[1 ,3,5]triazin-2-yl]-methyl- amino}phenylazo)-naphthalene-1,3-disulfonic acid trisodium salt (11)

6-(4-Methy!amino-phenylazo)-naphtha!ene-1 ,3-disulfonic acid disodium salt (10) (1.50 g, 3.22 mmol) was dissolved in distilled water (100 ml) and cooled to 0 °C with stirring. The solution was maintained at pH 6.5 using 0.2 M aqueous hydrochloric acid and 1.2 M aqueous sodium hydrogen carbonate. Crushed ice (5 g) was added to a rapidly stirred solution of cyanuric chloride in acetone (10 ml), causing a fine white precipitate to form. The suspension of cyanuric chloride was added dropwise to the orange solution of dye and the pH was maintained at 6.5 throughout the addition. After the pH of the solution ceased to fall the reaction mixture was allowed to stir for 20 min, adjusted to pH 7.6 and filtered while cold. Metanilic acid (629 mg, 3.22 mmol) was dissolved in distilled water (10 ml) and added dropwise to the reaction mixture. Once addition was complete the temperature of the reaction mixture was taken to 35 °C for 1 hour, maintained at pH 7.6. The reaction mixture was ultrafiltered in water for 17 hours using a 500 NMWCO membrane, then evaporated to dryness to yield a deep orange solid 6-(4- [4-chIoro-6-(3-sulfo- phenylamino)-[1,3,5]triazin-2-yl]-methyl-amino}phenylazo)-naphthalene-1 ,3- disulfonic acid trisodium salt (11) (1.51 g, 61 %): 1H NMR (500 MHz, dβ-DMSO, 330K) δ 9.07 (d, 1H, = 10 Hz), 8.88 (br, 1H). 8.75 (d, 1H, J = 1 Hz), 8.68 (d, 1H, J = 2 Hz), 8.38 (dd, 1H, J'= 10 Hz, J"= 2 Hz), 8.03 (br, 1H), 7.97 (d, 1 H, J = 8 Hz), 7.67 (d, 1 H, J = 8 Hz), 7.61 (d, 2H, J = 8 Hz), 7.60 (br,1 H), 7.40 (br, 1H), 3.65 (s, 3H); ¹³C NMR (125 MHz, dβ-DMSO, 330 K) δ 169.1, 165.1 , 163.1, 150.8, 146.5,

144.1 , 141.1, 140.9, 138.4, 134.5, 131.3, 131.2, 130.0, 128.2, 128.0, 127.9, 124.6,

124.2, 124.0, 121.5, 121.0, 119.6, 118.3, 38.8; UV-vis (water) λ_maχ: 350.34 nm, log ε: 4.04; ES-MS (-ve) m/z 233.9 [M3-].

Application Example 1 Application of dyes to cotton

Samples of mercerised cotton were dyed separately with aqueous solutions of dyes 1 and 11 at pH 10 and 70-80 °C using the 'pad batch' method, using sodium carbonate as base. Dyeings were washed with clean cold water until no more colour was removed. Both dyes reacted irreversibly with the cotton to give yellow fabric.

Application Example 2

Comparison of Reactivity of Azo Dye Rotaxanes with Chemical Reductive Bleaching Agents in Solution

The reactivity of rotaxane 1, and the analogous free dye 11, towards reductive bleaching was investigated using aqueous sodium dithionite. This reagent is known to bleach azo dyes by reducing the azo link to a hydrazine; further reduction may also reduce the hydrazine by cleavage to two amϊne units. Simple test tube experiments immediately showed that aqueous solutions of the free dye 11 are bleached by sodium dithionite much more rapidly that the rotaxane 1. The relative rates of reaction were quantified by monitoring the rate of bleaching in a UV cuvette at 500 nm, giving the decay curves plotted in Figures 1a (linear time scale) and 1 b (logarithmic time scale). The experimental data for the bleaching of both compounds are fitted to pseudo first-order curves. It is difficult to estimate the rate of bleaching for the rotaxane because there is so little reaction; it appears to be slower by a factor of about 700. This demonstrates that encapsulation of a reactive dye in a rotaxane, according to the present invention, effectively protects the chromophore against reductive bleaching.

Application Example 3 Comparison of Reactivity of Azo Dye Rotaxanes with Chemical Oxidative Bleaching Agents in Solution

Test reactions were earned out using aqueous hydrogen peroxide containing catalytic amounts of iron(ll) sulfate (Fenton's reagent). This reacted with both the rotaxane and the free dye to give an initial intensification of the orange colour, followed by a fading to an almost colourless solution. The results of monitoring this reaction in a UV cuvette for both compounds under identical conditions are shown in Figure 2. It is evident that the rotaxane 1 reacts much more slowly than the free dye 11.

Application Example 4

Chemical Bleaching of Dyed Cotton

Reductive and oxidative bleaching experiments were conducted with the cellulose- bound samples of 1 and 11, under the same conditions as the solution experiments. The trend in behaviour was the same as in solution, with the rotaxane 1 being scarcely affected in both cases. Both dyes reacted more slowly on the cloth than in solution. Sodium dithionite almost completely bleached cellulose-bound free dye 11 after 1 hour, whereas bound dye 1 was only slightly faded after 20 hours. Bound dye 11 turned brown after about 1 hour in Fenton's reagent, whereas these conditions had little effect on bound dye 1.

Application Example 5

Photobleaching experiments of dyed cotton Cotton dyed by samples of the conventional dye 11 and the corresponding rotaxane dye 1 were irradiated in a commercial fadeometer. On assessment against Blue Wool standards irradiated simultaneously in the same machine, the conventional dyeing was assessed to have a light fastness of 3-4 (Blue Wool scale), while the dyeing of the reactive rotaxane dye 1 was assessed to have appreciably higher light fastness 5.

Comparative Preparation Example 2

Preparation of Free Reactive Dye

Azophenoi (12) (300mg, 1.24 mmol) was ground and then dissolved in water/ethanol (1 :1 , 30ml). The pH was adjusted to pH2 by dropwise addition of hydrochloric acid and the red solution cooled to below 5°C with stirring. Sodium nitrite (85.6mg, 1.24mmol) was dissolved in water (2ml) and added dropwise to the solution of anilinium salt. The solution of diazonium salt was allowed to stir for 1 hour. H-acid-chlorotriazine-metanilic acid (833.0mg, 1.24mmol) was dissolved in water (20ml) and the pH adjusted to pH6 by dropwise addition of 10% NaHCO₃ then cooled to below 5°C with stirring. The solution of diazonium salt was added dropwise to the solution of H-acid derivative with the pH of the H-acid solution maintained at pH7.5 using 10% NaHCO₃. On addition of the diazonium salt a blueish purple colour developed. When addition of the diazonium salt was complete the solution was allowed to stir for 1 hour. The solution was neutralised with 2N HCI to give a blueish-purple solution with a dark precipitate. 5 volumes of ethanol were added and the suspension allowed to stir for 1 hour. The dark purple solid ^"was filtered off and washed with ethanol. The product was purified by gel permeation chromatography (sephadex G25 / water) to yield (13) as a dark purple solid (984.5mg, 85%) ¹H NMR (500MHz, d₆-DMSO) δ 15.64 (s, br, 1H), 10.52 (s, 1H), 8.96 (s, 1H), 8.21 (br, 1H), 7.89 (d, 2H), 7.65 (br, 1H), 7.85 (d, 2H), 7.52 (s, 2H), 7.45-7.35 (br m, 4H), 2.26 (s, 6H); UV-vis (water) λ_max: 550, 575; ES-MS (-ve) m/z 284.2 [M-3H^3"], matches isotope pattern.

Preparation Example 2

Preparation of Rotaxane-type dye

1.24mmol) was dissolved in water (20ml) and the pH adjusted to pH6.5 by dropwise addition of 10% NaHCO₃then cooled to below 5°C with stirring. The solution of H-acid derivative was added dropwise to the solution of diazonium salt complex. On completion the pH of the solution was adjusted to pH7.5 10% NaHCO₃. On addition of the H-acid a blueish-purple colour developed. When addition of the H-acid derivative was complete the solution was allowed to stir for 1 hour. Excess (12) and TM-α-CD were removed by washing with ethyl acetate. The aqueous phase was concentrated to 50ml then salted out by the addition of 20% w/v NaCI. The dark purple solid (2) was filtered off then dialysed to remove excess salt (2.02g, 75.8%). ¹H NMR (500MHz, d₆-DMSO) δ 15.60 (s, br, 1 H), 10.21 (s, 1 H), 8.73 (s, 1 H), 8.27 (br, 1H) 8.26 (s, br, 1 H), 7.73 (br, 4H), 7.53 (s, br, 1 H), 7.52 (s, 2H), 7.40 (s, 1 H), 7.33 (s, 1H), 7.31 (s, 1H), 4.80 (d, 6H), 3.82 (d, 6H), 3.63 (d, 6H), 3.40 (t, 6H), 3.36 (s, 18H), 3.29 (s, 18H), 3.22 (s, 18H), 2.91 (m, 6H), 2.41 (s, 6H); UV-vis (water) λ_max: 542, 569; ES-MS (-ve) Isotope pattern starts at m/z 692.5 [M-3H^3"], matches calculated isotope pattern well.

Application Example 6

Photoisomerisation (photochromism) When the free dye, (II) was irradiated at 261 nm, the absorbance dropped until a photostationary state was reached. This resulted from a trans to cis photoisomerisation of the azo linkage. When the resultant solution was irradiated at 255 nm, the original absorbance was regained, due to cis to trans isomerisation (regeneration of starting species). This process could be repeated. However, irradiation at 361 nm of a solution of corresponding rotaxane dye (2) in aqueous solution led to essentially no change in optical absorbance. This demonstrates that rotaxane formation inhibits photoisomerisation of the azo bond.

Claims

CLAIMS:

1. A rotaxane type reactive dye comprising a reactive azo chromophoric guest molecule and a macrocyclic host molecule, which dye has the formula (I)

wherein: acrocyclic host molecule (R_M)

having a macromolecular aperture through which the reactive azo chromophoric guest molecule extends; each of A and B is an optionally substituted aromatic or heteroaromatic unit having a molecular dimension sufficiently large to prevent molecular separation of the reactive azo chromophoric guest molecule from the macrocyclic host molecule;

in which R⁵, or each R⁵ independently is C,^ alkyl, each of w, y and z independently is zero or 1; and

R⁶ is CH=CH; CH₂; C₂H₄; C₃H₆; C₄H₈; O; S; NR⁷ (in which R⁷ is hydrogen or G,^ alkyl); or a direct bond;

G, or each G independently, is a reactive group; each of m, n and p independently is zero or 1 and m+n+p>1; r is 1, 2 or 3; x is zero, 1, 2 or 3; and when x is 2 or 3 each p respectively may be the same as, or different from each other.

2. A rotaxane dye according to claim 1, wherein the reactive group G, or each reactive group G independently, is selected from

(a) a triazinylamino unit of formula (V)

L

R¹ where:

L is a leaving group

T is Cπ alkoxy or C_1jf thioalkoxy each of which is optionally substituted or T is N(R¹)(R²)

R\ or each R¹ independently, is H or optionally substituted C- alkyl; R² is H, optionally substituted C,^ alkyl, or is phenyl or naphthyl optionally substituted by sulpho, acyloxy or optionally substituted

C^ alkyl;

(b) a pyrimidinylamino unit of formula (VI) or (VII)

where:

L is a leaving group R³ is Cl, CN, C.,.₄ alkyl or C_M alkylsulphonyl; a is zero or 1 ; and R is as defined above ₂₀ (c) a vinyl or allyl sulphonyl group of formula SO₂(CH₂)_bCH=CH₂ (VIII); where b is zero or 1 ;

(d) a vinyl sulphone precursor of formula (IX)

-SO₂-CH₂CH₂- R⁴ (IX)

where:

R⁴ is an eliminable group removable under alkaline conditions to provide the vinyl sulphonyl group of formula (VIII); and

(e) a group of formula (X)

-W-C(R¹⁰)=CH (X)

wherein: R¹⁰ is hydrogen, G,^ alkyl or halogen; and

W is -OC(=O)- or -N(R¹¹)C(=O)- in which R¹¹ is H or C,.₄ alkyl.

A rotaxane dye according to claim 2, which has a reactive group G selected from a triazinylamino unit of formula (V) and a pyrimidinyl unit of formula (VI) or (VII) and in which L, or each L independently, is F, Cl, Br or a quaternary ammonium group.

A rotaxane dye according to claim 2, which has a reactive group G which is a vinylsulphonyi precursor of the formula (IX) in which R⁴ is selected from sulphate, phosphate, chloride, acyloxy and quarternary ammonium.

A rotaxane dye according to any preceding claim, wherein each of units A and B is independently selected from

wherein:

X, or each X independently, is sulphonic acid, sulphonate ion salt, sulphonamide, N-substituted sulphonamide, N,N-disubstituted sulphonamide, sulphonate ester, carboxylic acid, carboxylate ion salt, carbonamide, N-substituted carbonamide, N,N-disubstituted carbonamide, carboxylic ester, fluoro, chloro, bromo, iodo, nitro, ureido, optionally substituted acylamino, optionally substituted aryl, optionally substituted alkyl, optionally substituted alkoxy, optionally substituted alkylamino, optionally substituted dialkylamino, and optionally substituted alkylsulphonyl; and x is zero or from 1 to 6.

6. A rotaxane dye according to any preceding claim, wherein R_M or each R_M independently is selected from cyclic polyethers, cyclic polyamines, polyactones, cyclic polyamides, cyclic oligomers of carbohydrates and cyclic oligomers of ureas.

7. A rotaxane dye according to claim 6, wherein R_M is a cyclodextrin selected from alpha-cyclodextrin (structure A), beta-cyclodextrin (structure B), and gamma-cyclodextrin (structure C) or O-alkylated derivatives of A, B and C.

A B

8. A rotaxane dye of the formula (XIV)

wherein: each of A, B, R_M, G, m and n is as defined in claim 1.

. A dye of the formula (XV)

[G^-A = N-D-N =

R ^B-fG]_n (XV)

wherein: each of A, B, R_M) G, m and n is as defined in claim 1 and

D is an arylene unit of the formula (II) or (III), each given and defined in claim 1.

10. A rotaxane type dye of the formula

11. A rotaxane type dye of the formula