KR20090010263A - Phosphorescent Iridium Complex for Fluorine Ion Detection and Its Synthesis Method - Google Patents

Abstract

Dibromobenzene was lithiated with n- BuLi in -78 ° C THF solution and then with dimethylyl boron fluoride in THF solution at room temperature to form boryl phenyl bromide, which was then reacted with 2- (tributylstannyl) pyridine It was dissolved in toluene with Pd (PPh ₃ ) ₄ and refluxed to transform it into a chelating ligand via the Pd-catalyst Stille reaction, which was then converted to a chelated ligand in a 2-EtOEtOH: H ₂ O solution at 140 ° C. under argon (Ar) saturation. After the Nonoyama reaction with IrCl ₃ xH ₂ O to produce a μ -chloride-bridged Ir (III) dimer, chlorine was removed with sodium carbonate in a 2-EtOEtOH solution at 140 ° C. under saturation of argon (Ar). Substitution with 2,4-pentanedione yields a boryl group-containing heterorepetic Ir (III) complex (1). The iridium (III) complex (1) of the present invention exhibits a very high solubility in common organic solvents such as toluene, chloroform dichloride (CH ₂ Cl ₂ ), dioxane, acetonitrile.

Description

Phosphorescent Ir (III) Complex with Boryl Group for Selective Fluoride Sensing and Method of Synthesizing Same}

1 is a graph showing the results of UV-vis absorption titration experiments of the iridium complex of the present invention.

2 is an energy level diagram of HOMO and LUMO of the iridium complex 1 and the fluoride complex 1F of the present invention.

3 is a normalized phosphorescence spectrum of the iridium complex 1 and the fluoride complex 1F of the present invention.

4 is a graph showing phosphorescence selectivity.

Field of invention

The present invention relates to a phosphorescent iridium complex. More specifically, the present invention relates to a phosphorescent iridium complex for selectively detecting fluorine ions and a method for producing the same.

Background of the Invention

Anion sensing refers to the detection of a triggered signal from a transmitter conjugated by a bond between a receptor and a specific anion decomposer. Fluoride sensing among the anions is of particular interest due to their importance in biological and environmental analyses such as dental caries, osteoporosis treatment and drinking water analysis.

Various methods for fluoride sensing have been reported, such as fluoride-selective electrode methods (Frant, MS; Ross, JW Science 1966, 154 , 1533), H-bond alternating methods (Lee, DH et. Al. Angrew . Chem. Int. Ed . 2005, 44 , 2899), and the recent Lewis acid-base alternating method (Chaniotakis, NA et. Al. Eur. J. Inorg. Chem. 2004, 2283). In particular, strong selective Lewis acid-base interactions between boron (B) atoms and fluorides have enabled high efficiency fluoride detection (Chiu, C.-W .. et. Al. J. Am. Chem Soc 2006, 128 , 14248). Furthermore, the charge-neutrality of the boryl group and the protic media tolerability are very advantageous for other receptors. In this regard, research and development on fluoride sensors using boryl receptors is based on absorption color changes, fluorescence changes, NMR spectral shifts, and polargraphic half-wave potential changes. come.

Among these methods, fluorescence detection was considered most advantageous for sensing applications in terms of high sensitivity and large switching ratio. Indeed, efficient and selective fluoride sensing has been studied for various fluorescent receptors having boryl groups. However, it should be noted that the fluorescence is susceptible to contamination due to background emission by scattering or color photographic impurities. One good way to solve this problem is to use phosphorescence, which is easily identified through time-gated acquisition.

Recently, an example of phosphorescent fluoride detection was first reported by Melami et al., Where heteronuclear boron / mercury bidentate Lewis acid is used at 77K (Melaimi, M. et al. J. Am. Chem. Soc . 2005, 127 , 9680). Although not only two-color phosphorescence detection but also fairly high binding constants have been successfully demonstrated in their studies, easy and efficient phosphorescence detection in solution at room temperature is still an important challenge for practical applications.

The inventors have developed an iradium (Ir) (III) -based highly phosphorescent fluoride receptor for fluoride detection with unprecedented high selectivity and sensitivity in solution at room temperature.

Recently, charge-neutral and atmospheric-stable trischelated Ir (III) complexes have attracted much attention because of very high phosphorescent quantum yields at room temperature (Tomayo, AB et al. J. Am. Chem. Soc . 2003, 125 , 7377; You, Y. et al. J. Am. Chem. Soc , 2005, 127 , 12438. This property is characterized by core iridium that facilitates efficient radiation decay from the triplet excited state of the complex. It is due to the strong spin-orbit coupling provided by the Ir atoms. Thus, the inventors thought that incorporating boryl groups into the ligand structure of the iridium (III) complex would enable a fluoride-selective phosphorescent sensing system capable of operating in solution.

As a result, the present inventors have studied the synthesis of a new phosphorescent iridium (III) complex having a boryl group and the unusual fluoride sensing behavior of the complex. By introducing a stericically congested demesity boryl group into the phenylpyridine ligand, the present inventors have found that the composite provides a high fluoride-selective sensing in solution state based on phosphorescence modulation of the iridium (III) complex. It could be achieved successfully.

It is an object of the present invention to provide an iradium (Ir) (III) -based highly phosphorescent fluoride receptor for fluoride detection with high selectivity and sensitivity in solution at room temperature.

Another object of the present invention is to provide a phosphorescent iridium complex for selectively detecting fluorine ions in a solution state at room temperature and a method for producing the same.

The above and other objects of the present invention can be achieved by the present invention described below.

Summary of the Invention

Dibromobenzene was lithiated with n- BuLi in -78 ° C THF solution and then with dimethylyl boron fluoride in THF solution at room temperature to form boryl phenyl bromide, which was then reacted with 2- (tributylstannyl) pyridine It was dissolved in toluene with Pd (PPh ₃ ) ₄ and refluxed to transform it into a chelating ligand via the Pd-catalyst Stille reaction, which was then converted to a chelated ligand in a 2-EtOEtOH: H ₂ O solution at 140 ° C. under argon (Ar) saturation. After the Nonoyama reaction with IrCl ₃ xH ₂ O to produce a μ -chloride-bridged Ir (III) dimer, chlorine was removed with sodium carbonate in a 2-EtOEtOH solution at 140 ° C. under saturation of argon (Ar). Substitution with 2,4-pentanedione yields a boryl group-containing heterorepetic Ir (III) complex (1). The iridium (III) complex (1) of the present invention exhibits a very high solubility in common organic solvents such as toluene, chloroform dichloride (CH ₂ Cl ₂ ), dioxane, acetonitrile.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

Detailed Description of the Invention

As studied by Yamaguchi et al., The high steric demand imparted on the dimethylboryl group allows for size-selective anion-boron bond interactions (Yamaguchi et al. J. Am. Chem. Soc). 201, 123 , 11372). In the present invention, the dimethyl boryl group is introduced into the chelating ligand according to the following scheme.

(a) 1) n- BuLi, THF, -78 ° C, then 2) dimesitylboron fluoride, THF, room temp.

(b) 2- (Tributylstannyl) pyridine, Pd (PPh ₃ ) ₄ , toluene, reflux.

(c) 1) IrCl ₃ xH ₂ O, 2-EtOEtOH: H ₂ O, 140 ° C., Ar-saturation, 2) 2,4-pentanedione, Na ₂ CO ₃ , 2-EtOEtOH, 140 ° C., Ar-saturation .

As shown in the above scheme, dibromobenzene is lithiated and then treated with dimesylboron fluoride to form boryl phenyl bromide, which is then transformed into chelating ligands via a Pd-catalyst Stille reaction. In addition, a No -yama reaction between the ligand and IrCl ₃ xH ₂ O produces a μ -chloride-bridged Ir (III) dimer. Finally, in the present invention, with the help of sodium carbonate, chlorine is substituted with 2,4-pentanedione to obtain a boryl group-containing heteroreceptive Ir (III) complex (1). The iridium (III) complex (1) of the present invention exhibits a very high solubility in common organic solvents such as toluene, chloroform dichloride (CH ₂ Cl ₂ ), dioxane, acetonitrile.

The fluoride detection performance of the iridium complex 1 of the present invention was confirmed by UV vs. absorption titration experiment, as shown in FIG. 1 is a graph showing the results of UV-vis absorption titration experiments of the iridium complex of the present invention.

The iridium complex (1) of the present invention, a compound without fluoride, has its UV-vis spectrum consisting of three special peaks (wavelength / nm (log value of absorption coefficient) = 267 (4.30), 309 (4.22) and 374 (4.04)), these are associated with single ligand-centered transitions with one broad band (454 (3.23)) corresponding to ligand charge-transfer metal (MLCT) or triple ligand-centric transitions. have. However, all of these peak absorptions resulted in a tetrabutylammonium fluoride (TBAF) / THF solution in the iridium complex (1) at the expense of newly growing red-shifted absorption at 276 (4.36) and 486 (3.11) nm wavelengths. Decreases with addition. The new low energy absorption band, particularly related to red-shift phosphorescence emission, exhibits a significant absorption coefficient 486 (3.11), which clearly suggests that low bandgap Ir (III) complexes are formed by fluoride coordination. .

Since the iridium complex 1 has two boryl groups, the 1-to-2 complex 1F has a significant influence on this absorption change. As one expected reactor for this bathochromic shift, a significant stability of the omnidirectional orbital (preferably LUMO) of the complex 1F can be considered by complexing the negative electron fluoride. 2 shows the DFT calculation result of the complex 1F. The performance of the iridium complex (1) for coordinating with fluoride was confirmed by Benesi-Hidebrand analysis using UV-vis absorption titration data, and the binding constant (K) of 9.17 (± 0.32) × 10 ⁴ M ⁻¹ was determined. Which is similar to previous studies on boryl-based fluorescent receptors.

Coordination of fluoride to dimethylboryl groups was demonstrated by ¹¹ B NMR (193 MHz) experiments. The chemical shift of boron shifts from 31.58 ppm (iridium complex (1)) to 0.57 ppm (fluoride complex (1F)) with the expression of characteristic BF splitting patterns. Furthermore, in the present invention, no unbound boron peak was found from the fluoride complex 1F, which shows a high binding affinity of the iridium complex 1 toward the fluoride.

The iridium complex 1 and the fluoride complex 1F exhibit bright room temperature phosphorescence with respective photoluminescence quantum yields of 0.57 and 0.38.

3 is a normalized phosphorescence spectrum of the iridium complex 1 and the fluoride complex 1F of the present invention.

As shown in FIG. 3, when adding fluoride, the blue green phosphorescence (512 nm) of the iridium complex 1 immediately changes to the orange phosphorescence (567 nm) of the fluoride complex 1F. This corresponds to Commission Internationale de L'Eclairage coordinations, varying from (0.19, 0.56) to (0.46, 0.50), which is very good for phosphorescent and ratiometric sensing.

In addition, the lifetime (?) Of the phosphorescence of the iridium complex 1 and the fluoride complex 1F is 0.56 ㎲ and 1.2 각각, respectively, which can easily eliminate immediate background fluorescence emission. Importantly, the fluoride selectivity of the iridium complex 1 is determined very high as summarized in FIG. 4 is a graph showing phosphorescence selectivity.

Iridium complexes (1) have a proprietary coordination with fluoride over large halides (chlorine, bromine and iodine) and polyatomic anions (cyanide, thiocyanide and nitrate) and are about 1000 times more selective. Indicates. In phosphorescent fluoride sensing, this selectivity is the highest possible value ever published. These include: 1) charge neutrality of boryl groups, 2) stericly dense boron atoms, 3) strong boron-fluoride bonds, and 4) high phosphorescence of the iridium complex (1) and fluoride complex (1F) in solution. This is due to the markedly improved phosphorescence change due to yield.

The novel phosphorescent iridium (III) complexes having fluoride-selective dimethylboryl groups of the present invention have at least 1000 times higher selectivity to fluoride and significantly improved phosphorescence behavior (Iridium complex (1) has a Φ _p = 0.57 at 512 nm). The fluoride complex (1F) has Φ _p = 0.38, τ = 1.2 μs at 567 nm, thereby enabling efficient colormetric and rayometric fluoride sensing.

The invention will be further elucidated by the following examples which are set forth only for the purpose of illustrating the invention and are not intended to limit or limit the scope of the invention.

Example

Commercially available raw materials were used without purification unless otherwise stated. All glass containers, syringes, magnetic stir bars, and needles were dried in a convection oven for at least 4 hours. The reaction was observed by thin layer chromatography (TLC). Commercial TLC plates (silica gel 60F ₂₅₄ , Merck Co.) were developed to show spots under 254 and 365 nm UV light and were colored with p-anisaldehyde. Silica column chromatography was performed with silica gel 60G (particle size 5-40 탆, Merck Co.).

Synthesis of 2-dimethyl boryl bromobenzene:

THF solution (80 mL) of 1,3-dibromobenzene (2.07 g, 8.76 mmol) was stirred in an argon (Ar) atmosphere and cooled to -78 ° C. n-BuLi (1.6M in hexane, 5.48 mL, 9.03 mL) was added dropwise to the solution, and the reaction mixture was kept at -78 ° C for 30 minutes. Dimesylboron fluoride (2.47 g, 9.20 mmol) in THF (20 mL) was added to the stomach reaction vessel by syringe. After 30 minutes, the temperature was raised to room temperature and the reaction mixture was stirred overnight. Concentration and silica gel column purification (n-hexane: EtOAc = 49: 1) yielded a white powder (2.53 g, 6.24 mmol) with a yield of 71%: ¹ H NMR (500 MHz, CDCl ₃ ) δ: 2.01 (s, 12H), 2.30 (s, 6H), 6.82 (s, 4H), 7.21 (t, J = 7.6 Hz, 1H), 7.41 (d, J = 7.4 Hz, 1H), 7.58 (d, J = 7.9 Hz, 1H), 7.61 (s, 1 H). ¹³ C NMR (125 MHz, CDC1 ₃ ) δ: 21.39, 21.45, 22.51, 22.63, 23.66, 123.14, 128.32, 128.55, 128.59, 130.04, 134.68, 134.79, 138.48, 138.66, 139.14, 139.32, 141.04, 141.08. HRMS (EI) m / z: calcd for C ₂₄ H ₂₆ BBr, 404.1313. Anal. Calcd for C ₂₄ H ₂₆ BBr: C, 71.14: H, 6.47. Found: C, 70.97; H, 6.45.

Synthesis of 2- (2 '-(dimesylboryl) phenyl) pyridine:

2-dimethylyl boryl bromobenzene (2.40 g, 5.92 mmol), tetrakis (triphenylphosphine) palladium (0.90 g, 0.77 mmol), and tri-n-butylstannylpyridine (4.36 g, 11.9 mmol) Was dissolved in toluene (60 mL). The reaction mixture was refluxed for 2 days in argon atmosphere. Concentration and silica gel column purification (n-hexane: EtOAc = 30: 1) yielded a yellow white powder (0.75 g, 1.86 mmol) with a yield of 31%: ¹ H NMR (500 MHz, CDCl ₃ ) δ: 2.02 (s , 12H), 2.30 (s, 6H), 6.82 (s, 4H), 7.17 (t, J = 5.0 Hz, 1H), 7.46 (t, J = 7.6 Hz, 1H), 7.56 (d, J = 7.3 Hz , 1H), 7.60 (d, J = 7.9 Hz, 1H), 7.66 (td, J = 5.6, 0.3 Hz, 1H), 8.05 (s, 1H), 8.17 (d, J = 7.7 Hz, 1H), 8.64 (d, J = 3.6 Hz, 1H). ¹³ C NMR (125 MHz, CDCl ₃ ) δ: 13.78, 17.48, 21.35, 23.70, 26.96, 28.44, 121.05, 122.16, 128.44, 128.49, 128.77, 129.24, 130.95, 134.49, 136.83, 137.12, 138.90, 138.32, 141.06, 141.87, 146.54, 149.80, 157.88. HRMS (EI) m / z: calcd for C ₂₉ H ₃₀ BN, 430.2471; found, 430.2470. Anal. Calcd for C ₂₉ H ₃₀ BN: C, 86.35; H, 7. 50; N, 3.47 Found: C, 86.21; H, 7. 44; N, 3.51.

Iridium (III) bis [2- (2 '-(dimethylboryl) phenyl) pyridinato-N, C ^2' ] Synthesis of acetylacetonato (iridium complex (1)):

Iridium complex (1) was synthesized according to a two step procedure. 2- (2 '-(dimethylboryl) phenyl) pyridine (530mg, 1.31mmol) and iridium (III) chloride hydrate (Aldrich, 131mg, 0.438mmol) with 2-ethoxyethanol (32mL) and water (11mL ) In a two-solvent system. Under Ar atmosphere, the reaction mixture was stirred at 145 ° C. for 12 hours. After cooling to room temperature, the yellow precipitate was filtered off and washed thoroughly with water (100 mL), ethanol (60 mL), and finally cooled acetone (20 mL). The precipitate was dissolved in CH ₂ C1 ₂ and recrystallized in a mixed solution of hexanes: toluene (10 mL: 25 mL) to give μ -chloride-bridge iridium (III) dimer (fine yellow crystals, 318 mg, 0.154 mmol) in 35% yield. Obtained with: ¹ H NMR (500 MHz, CDCl ₃ ) δ: 1.22 (t, J = 7.0, 2H), 1.26 (s, 3H), 1.89 (s, 48H), 2.26 (s, 24H), 3.54 (m , 2H), 3.74 (m, 1H), 5.88 (t, J = 7.8 Hz, 2H), 5.92 (d, J = 8.0 Hz, 1H), 6.64 (m, 3H), 6.73 (s, 16H), 6.80 (m, 2H), 7.59 (s, 3H), 7.65 (m, 3H), 7.73 (m, 3H), 9.20 (d, J = 5.4 Hz, 2H), 9.44 (m, 1H). ¹³ C NMR (125 MHz, CDCl ₃ ) δ: 15.37, 21.39, 23.61, 29.59, 29.92, 62.14, 66.80, 71.69, 118.95, 119.05, 122.47, 122.55, 122.81, 128.12, 130.10, 130.20, 130.47, 130.59, 131.82, 131.88, 131.98, 136.59, 136.65, 138.04, 138.05, 138.56, 138.68, 140.94, 142.17, 143.87, 143.96, 144.01, 144.10, 152.08, 153.74, 155.89, 156.33, 156.87, 168.11.168.29.168. MALDI-TOF-MS m / z 2102.88 (M + K ⁺ ), calcd for C ₁₁₆ H ₁₁₆ B ₄ C1 ₂ Ir ₂ N ₄ : 2064.77. Anal. Calcd for C ₁₁₆ H ₁₁₆ B ₄ C1 ₂ Ir ₂ N ₄ : C, 67.48; H, 5.66; N, 2.71. Found: C, 67.40; H, 5.77; N, 2.84.

Well-dried μ -chloride-bridged iridium (III) dimer (100 mg, 0.0484 mmol), sodium carbonate (51.3 mg, 0.484 mmol), and 2.4-pentanedione (24.2 mg, 0.242 mmol) 2-ethoxyethanol (20 mL) Dissolved in. After degassing, the reaction vessel was kept in an Ar atmosphere. The temperature was raised to 140 ° C. and the reaction mixture was stirred for 3 hours. The cooled rough mixture was poured into EtOAc (150 mL) and extracted with water (100 mL × 3 times) to remove 2-ethoxyethanol. Silica gel column purification with n-hexane: EtOAc = 4: 1 and reprecipitation in ether: n-hexane = 10 mL: 40 mL gave yellow powder (79.4 mg, 0.0724 mmol) in 75% yield: ¹ H NMR δ: 1.82 (s, 3H), 1.93 (br m, 27H), 2.27 (s, 12H), 5.26 (s, 1H), 6.21 (d, J = 7.7 Hz, 2H), 6.74 (s, 8H), 7.10 ( t, J = 6.0 Hz, 2H), 7.65 (m, 6H), 7.71 (d, J = 7.9 Hz, 2H), 8.48 (d, J = 5.5 Hz, 2H). ¹³ C NMR (125 MHz, CDCl ₃ ) δ: 21.39, 23.61, 28.95, 29.92, 100.68, 119.05, 121.68, 128.10, 132.06, 132.90, 137.20, 137.90, 137.99, 140.93, 142.34, 145.07, 148.46, 158.74,168.74,168. 185.08. FAB-MS (DIP) m / z 1096 (M ⁺ ), 997, 595, 403, 154, 136. Anal Calcd for C ₆₃ H ₆₅ B ₂ IrN ₂ O ₂ : C, 69.04; H, 5.98; N, 2.56. Found: C, 68.95; H, 6. 12; N, 2.56.

characteristic:

¹ H and ¹³ C NMR spectra were obtained in CDCl ₃ of a 500 MHz instrument (Bruker, Advance 500). Shifts were reported in ppm. Redundancy was expressed as s (singlet), d (doublet), t (triplet), td (triplet of doublet), m (multiplet) and br (broad). Coupling constant ( J ) is the hells (Hz). Mass spectrum (MS) was obtained with JEOL, JMS-AX505WA. Elemental analysis (EA) was performed with CE instrument, EA1110. Absorption spectra in solution were recorded with SHIMAZU UV-1650PC from 280 nm to 700 nm. Photocooling spectra were obtained with a SHIMAZU RF 5301 PC spectrophotometer in the 400-700 nm range. Ar-saturated 10 μmol solutions were prepared to measure absorption and PL spectra. For elapsed PL measurement, the quartz cuvette containing the Ar-saturated solution of the iridium (III) complex was tightly sealed under Ar atmosphere. An excitation pulse of 355 nm was generated from the third harmony result of the Q-switched Nd: YAG laser (Continuum, Surelite). The time of the excitation pulse is ca. It was 6 ns. Emission light was aimed before entering the monochromator slit and spectroscopically analyzed using a 15 cm monochromator (Acton Research, SP150) with 600 grooves / mm grating after passing through the sample. This spectroscopic analysis was about 3 nm for the elapsed photocooling experiment. The optical signal was detected through a photomultiplier tube (PMT) (Hamamatsu, R928). The output signal from the PMT was recorded with a 500 MHz digital storage oscilloscope (Tektronix, TDS3052) for transient profile measurements.

Anion Sensing Test:

Tetrabutylammonium fluoride tetrabutylammonium fluoride (1 M in THF, Aldrich), tetrabutylammonium chloride (Fluka), tetrabutylammonium bromide (Fluka), tetrabutylammonium iodide (Fluka), tetrabutylammonium cyanide (Aldrich ), Tetrabutylammonium thianide (Aldrich) and tetrabutylammonium nitrate (Aldrich) were used for the anion sensing test. Usually, 5 mL of tetrabutylammonium anion solution (10 μmol to 330 μmol ) and 5 mL of 10 μmol acetonitrile containing the iridium complex (1) are placed in a reagent bottle, and 10 minutes later into a cuvette. The coordination reaction was carried out in the atmosphere. Ar was saturated for phosphorescence measurement.

The present invention provides an iradium (Ir) (III) -based highly fluorescent fluoride receptor and a novel method for preparing the phosphorescent iridium complex thereof for the detection of fluoride having high selectivity and sensitivity in solution at room temperature. Has

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (4)

Dibromobenzene was lithiated with n- BuLi in a -78 ° C THF solution followed by dimesylboron fluoride in THF solution at room temperature to produce boryl phenyl bromide; The boryl phenyl bromide is dissolved in toluene with 2- (tributylstannyl) pyridine and Pd (PPh ₃ ) ₄ and modified to chelate ligands via a Pd-catalyst Stille reaction while refluxing; A bridge Ir (Ⅲ) dimer (dimer) - chloride-eyed - μ via the ligand and IrCl ₃ · xH ₂ O with the Nonoyama reaction in H ₂ O solution: 2-EtOEtOH of 140 ℃ the ligand in an argon (Ar) saturation After production, chlorine is substituted with 2,4-pentanedione with the aid of sodium carbonate in a 2-EtOEtOH solution at 140 ° C. under argon (Ar) saturation; A process for producing a boryl group-containing heteroleptic Ir (III) complex (1), characterized in that it comprises a step. Boryl group-containing heteroleptic Ir (III) complex (1) prepared according to the method of claim 1 and having the structure 3. The boryl group-containing compound according to claim 2, wherein the iridium (III) complex (1) exhibits a significantly higher solubility in toluene, chloroform dichloride (CH ₂ Cl ₂ ), dioxane, or acetonitrile organic solvent. Heteroleptic Ir (III) complex. 3. The boryl group-containing heteroreplicate (I) complex according to claim 2, wherein the iridium (III) complex (1) has high selectivity and sensitivity to fluoride in a solution state at room temperature.

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