CN116396336A - Preparation method and application of difluorophenyl-modified aggregation-induced luminescence iridium complex - Google Patents

Abstract

The invention discloses a preparation method and application of a difluorophenyl-modified aggregation-induced luminescent iridium complex, belonging to the field of phosphorescent materials. The present invention uses 2-phenylpyridine derivative 2-(4-(4-(2,4-difluorophenyl)phenyl)phenyl)-5-trifluoromethylpyridine as ring metal ligand, and 2 ,2'-bipyridine and 2-(2-imidazolyl)pyridine prepared two iridium complexes as auxiliary ligands. The study of their photophysical properties showed that the emission intensity of iridium complexes in acetonitrile/water system The ratio of the emission intensity to that in pure acetonitrile exceeds 10, which proves that the iridium complexes prepared by the invention have excellent aggregation-induced luminescent properties, and have important application value in the field of phosphorescent materials.

Description

Preparation method and application of difluorophenyl-modified aggregation-induced luminescence iridium complex

technical field

The invention relates to a preparation method and application of a difluorophenyl-modified aggregation-induced luminescent iridium complex, which belongs to the field of phosphorescent materials.

Background technique

Traditional fluorescent molecules usually have strong fluorescence in dilute solutions, and the fluorescence will be weakened or even quenched at high concentrations. In 2001, Tang Benzhong et al. discovered that a class of small organic molecules had no fluorescence in dilute solution, but showed bright fluorescence emission in the aggregated state (Chem. Commun., 2001, 18, 1740-1741). They described this new The phenomenon is called aggregation-induced emission (Aggregation-Induced Emission, abbreviated as AIE). The discovery of aggregation-induced luminescence provides an effective way to solve the major scientific problem of aggregation-induced luminescence quenching, and greatly promotes the application and development of high-efficiency solid-state luminescent materials. So far, most AIE molecules that have been published in the literature are pure organic small molecules, and there are relatively few novel aggregation-induced phosphorescent emission (AIPE) materials based on transition metal complexes. Cyclometallic iridium complexes, as a phosphorescent material, have been widely used in OLEDs (Small, 2017, 1603780; J. Mater. Chem. C, 2018, 6, 3298-3309), photodynamic therapy (Adv. Sci., 2019 , 1802050, cell imaging (J.Mater.Chem.C, 2014, 2, 5615-5628), sensors (Dalton Trans, 2022, 52, 128-135) and other fields. Therefore, the creation of iridium complexes with excellent aggregation-induced luminescent properties have important application value.

Contents of the invention

The object of the present invention is to provide a preparation method of iridium complexes Ir1 and Ir2 with aggregation-induced luminescence properties and aggregation-induced luminescence properties thereof.

The technical scheme adopted in the present invention is: difluorophenyl-modified aggregation-induced luminescent iridium complexes, iridium complexes are composed of 2-phenylpyridine derivatives as ring metal ligands and N^N auxiliary ligands and iridium metal ions. Bit formation, its structure is as follows:

The 2-phenylpyridine derivative is selected from 2-(4-(4-(2,4-difluorophenyl)phenyl)phenyl)-5-trifluoromethylpyridine; N^N auxiliary ligand selected from 2,2'-bipyridine or 2-(2-imidazolyl)pyridine.

The synthetic steps of described iridium complex are as follows:

(1) Synthesis of cyclometal ligand intermediates: 2-bromo-5-trifluoromethylpyridine and 4-bromophenylboronic acid are used as reactants, potassium carbonate is used as alkali, and palladium acetate is used as catalyst, at 80°C in air A Suzuki cross-coupling reaction occurs, and the reaction process is tracked by thin-layer chromatography. After the reaction is complete, the ring metal ligand intermediate 2-(4-(4-bromophenyl)phenyl)-5- Trifluoromethylpyridine;

The molar ratio of the 2-bromo-5-trifluoromethylpyridine: 4-bromophenylboronic acid: potassium carbonate: palladium acetate is 1:2.5:2:0.015;

(2) Synthesis of ring metal ligands: with ring metal ligand intermediates and 2,4-difluorophenylboronic acid as reactants, sodium carbonate as base, tetrakis (triphenylphosphine) palladium as catalyst, _N under protection A Suzuki cross-coupling reaction occurred at 70°C, and after 24 hours of reaction, the ring metal ligand was separated by column chromatography;

(3) Synthesis of iridium complexes: Add IrCl ₃ .3H ₂ O and 2.5 equivalents of cyclometal ligands to a round bottom flask, and in a mixed solution of ethylene glycol monoethyl ether/water with a volume ratio of 3:1, N ₂ under the protection of magnetic stirring at 120°C, and reacted for 24 hours. After the reaction, the reaction solution was concentrated under reduced pressure to obtain a dichloro bridge intermediate; the dichloro bridge intermediate, 3.0 equivalents of N^N auxiliary ligand 2,2'- Add bipyridine or 2-(2-imidazolyl)pyridine into a round-bottomed flask, and heat to reflux at 120°C for 24h under nitrogen protection; after the reaction, cool to room temperature, then add 20mL KPF ₆ saturated aqueous solution, and stir at room temperature for 12h; The reaction solution was extracted with dichloromethane, and the collected organic phase was concentrated under reduced pressure to obtain a crude product, which was separated by column chromatography with dichloromethane/petroleum ether as eluent, and purified to obtain an iridium complex.

The iridium complex is used in the field of phosphorescent materials.

Further, the preparation method of iridium complexes Ir1 and Ir2 is to synthesize an intermediate by 2-bromo-5-trifluoromethylpyridine and 4-bromophenylboronic acid as reactants, and then by intermediate and 2,4-difluoro The ring metal ligand synthesized by phenylboronic acid and the N^N auxiliary ligand coordinate with the iridium metal ion at the same time, and finally synthesized by replacing anion. Its structure is as follows:

The preparation method of the ring metal ligand and iridium complexes Ir1 and Ir2, the specific synthesis steps are as follows:

(1) Synthesis of ring metal ligand intermediates: under air conditions, add 1.0 mmol of 2-bromo-5-trifluoromethylpyridine, 4-bromophenylboronic acid (2.5 equiv.), carbonic acid Potassium (2.0 equiv.), palladium acetate (1.5% equiv.), and then add 12 mL of ethanol-water mixed solution with a volume ratio of 3:1, magnetically stir at 80°C for Suzuki cross-coupling reaction, followed by thin-layer chromatography Reaction process, after the reaction is complete, it is extracted three times with dichloromethane, the organic phases are combined, concentrated under reduced pressure, and separated by column chromatography to obtain the ring metal ligand intermediate 2-(4-(4-bromophenyl)phenyl) -5-Trifluoromethylpyridine.

(2) Synthesis of cyclometal ligands: Add 1.0 mmol of cyclometal ligand intermediates, 2,4-difluorophenylboronic acid (1.5 equiv.), sodium carbonate (2.0 equiv.), tetra( Triphenylphosphine) palladium (3.0% equiv.), then add 16mL of tetrahydrofuran-water mixed solution with a volume ratio of 5:3, and carry out Suzuki cross-coupling reaction at 70°C under nitrogen protection. After 24 hours of reaction, dichloro Methane was extracted three times, the organic phases were combined, concentrated under reduced pressure, and separated by column chromatography to obtain the cyclometal ligand.

(3) Synthesis of iridium complexes: Add IrCl ₃ 3H ₂ O and 2.5 equivalents of cyclometal ligands to a round bottom flask, and mix them in ethylene glycol monoethyl ether/water with a volume ratio of 3:1 for deoxygenation respectively In the solution, under the protection of N ₂ , the reaction was performed under magnetic stirring at 120° C. for 24 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure to obtain a dichloro bridge intermediate product. Add the dichloro bridge intermediate product and 3.0 equivalents of N^N auxiliary ligand into a round bottom flask, use ethylene glycol monoethyl ether as solvent, and heat to reflux at 120°C for 24h under the protection of nitrogen. After the reaction was completed, cool to room temperature, then add 20 mL KPF ₆ saturated aqueous solution, and stir at room temperature for 12 h. The reaction solution was extracted with dichloromethane, concentrated under reduced pressure to obtain a crude product, which was separated and purified by column chromatography using dichloromethane/petroleum ether as eluent to obtain the target product, and the structure of the product was confirmed by ¹ H NMR and high-resolution mass spectrometry.

The above-mentioned iridium complexes include the following derivatives:

Compound Ir1: the ring metal ligand is selected from 2-(4-(4-(2,4-difluorophenyl)phenyl)phenyl)-5-trifluoromethylpyridine; N^N auxiliary ligand is selected from 2,2'-bipyridine;

Compound Ir2: the ring metal ligand is selected from 2-(4-(4-(2,4-difluorophenyl) phenyl) phenyl)-5-trifluoromethylpyridine; N^N auxiliary ligand is selected from 2-(2-imidazolyl)pyridine.

Beneficial effects of the present invention:

1. The method of synthesizing cyclometal ligands by Suzuki cross-coupling reaction is environmentally friendly, simple and efficient.

2. Cyclometallic iridium complexes modified with different auxiliary ligands Through modular design, iridium complexes with excellent aggregation-induced luminescent properties can be obtained.

Description of drawings

Figure 1 is the emission spectrum of compound Ir1 at different water contents (the solvent is acetonitrile/water, 5×10 ^-5 mol/L).

Figure 2 is the emission spectrum of compound Ir2 at different water contents (the solvent is acetonitrile/water, 5×10 ^-5 mol/L).

Detailed ways

The synthesis of embodiment 1 compound Ir1

(1) Synthesis of cyclometal ligand intermediates:

Under air conditions, 1.0 mmol of 2-bromo-5-trifluoromethylpyridine, 4-bromophenylboronic acid (2.5 equiv.), potassium carbonate (2.0 equiv.), palladium acetate (1.5% equiv.), then add 12mL of ethanol-water mixed solution with a volume ratio of 3:1, and carry out Suzuki cross-coupling reaction with magnetic stirring at 80°C, follow the reaction process by thin-layer chromatography, after the reaction is complete, add saturated saline 20 mL was extracted three times with dichloromethane, the organic phases were combined, concentrated under reduced pressure, and separated by column chromatography to obtain a cyclometal ligand intermediate with a yield of 50%.

(2) Synthesis of cyclometal ligands:

Add cyclic metal ligand intermediate 1.0mmol, phenylboronic acid (1.5equiv.), sodium carbonate (2.0equiv.), tetrakis(triphenylphosphine)palladium (3.0%equiv.) to the round bottom flask successively, and then add volume 16 mL of tetrahydrofuran-water mixed solution with a ratio of 5:3, Suzuki cross-coupling reaction was carried out at 70 °C with magnetic stirring under the protection of _N2 . After 24 hours of reaction, 20 mL of saturated saline was added, extracted three times with dichloromethane, and the organic phases were combined. Concentrate under reduced pressure and separate by column chromatography to obtain the cyclometal ligand with a yield of 79%.

(3) Synthesis of iridium complexes:

Add IrCl ₃ 3H ₂ O and 2.5 equivalents of cyclometallic ligands to the round bottom flask, in the ethylene glycol monoethyl ether/water mixed solution with a volume ratio of 3:1 for deoxygenation respectively, under the protection of N ₂ at 120 °C magnetic stirring, and reacted for 24 hours. After the reaction, the reaction solution was concentrated under reduced pressure to obtain a dichloro bridge intermediate product. Add the dichloro bridge intermediate product and 3.0 equivalents of 2,2'-bipyridine into a round bottom flask, and react at 120°C for 24 hours with ethylene glycol monoethyl ether as a solvent under the protection of nitrogen. After the reaction was completed, cool to room temperature, then add 20 mL KPF ₆ saturated aqueous solution, and stir at room temperature for 12 h. The reaction liquid was extracted with dichloromethane, and concentrated under reduced pressure to obtain a crude product, which was separated and purified by column chromatography with dichloromethane/petroleum ether as eluent to obtain the target product with a yield of 54%. The structural characterization data are as follows: ¹ H NMR (400MHz, DMSO-d ₆ )δ8.94 (d, J=8.3Hz, 2H), 8.61 (d, J=8.8Hz, 2H), 8.46 (dd, J=8.8, 1.6Hz, 2H), 8.36 (td,J=8.0,1.5Hz,2H),8.20(d,J=8.3Hz,2H),8.07(d,J=4.7Hz,2H),7.84-7.74(m,4H),7.60(td, J=8.9,6.7Hz,2H),7.56-7.51(m,4H),7.49(td,J=4.5,2.4Hz,6H),7.40-7.31(m,2H),7.20(td,J=8.3, 1.9Hz, 2H), 6.47 (d, J = 1.6Hz, 2H) _. HRMS (MALDI-TOF, m/z): Calculated: C ₅₈ H 34 F ₁₀ N ₄ Ir[M-PF ₆ ] ⁺ 1169.2248, Measured value: 1169.2272.

The synthesis of embodiment 2 compound Ir2

The preparation method of embodiment 2 is the same as that of embodiment 1, except that: the N^N auxiliary ligand used in the synthesis of the iridium complex in embodiment 2 is 2-(2-imidazolyl)pyridine.

The yield of Ir2 is 68%, and the structural characterization data are as follows: ¹ H NMR (400MHz, DMSO-d ₆ ) δ14.55(s, 1H), 8.63-8.52(m, 2H), 8.43(d, J=9.5Hz, 3H ), 8.30(td, J=7.9, 1.4Hz, 1H), 8.17(t, J=8.1Hz, 2H), 7.95(d, J=5.2Hz, 1H), 7.88(d, J=12.4Hz, 2H ),7.82(d,J=1.3Hz,1H),7.67-7.58(m,3H),7.57-7.41(m,10H),7.40-7.31(m,2H),7.20(td,J=8.3,1.9 Hz,2H),6.74(d,J=1.3Hz,1H),6.56(d,J=1.7Hz,1H),6.46(d,J=1.7Hz,1H).HRMS(MALDI-TOF,m/z ): Calculated value: C ₅₆ H ₃₃ F ₁₀ N ₅ Ir[M-PF ₆ ] ⁺ 1158.2200, found value: 1158.2208.

The AIE property test of embodiment 3 compound Ir1

Dissolve Ir1 in acetonitrile to prepare a solution with a concentration of 5×10 ^-4 mol/L, then mix the above solution, acetonitrile and water according to different volume ratios to prepare mixed solutions with different water contents (the concentration is 5×10 ^{-4 5} mol/L), and then test its emission spectrum. The results shown in Figure 1 show that in the acetonitrile/water mixed solution, with the increase of the water content of the poor solvent, the luminescence of the compound is basically unchanged at first, and when the water content increases to 70%, the emission wavelength is blue-shifted and the emission intensity increases significantly. When the content is 75%, the emission intensity reaches the maximum, and I/I ₀ reaches 7.18 (I represents the emission intensity of Ir1 in acetonitrile/water system, and _I0 represents the emission intensity of Ir1 in pure acetonitrile). The results indicated that compound Ir1 has excellent aggregation-induced luminescence properties.

The AIE property test of embodiment 4 compound Ir2

Dissolve Ir2 in acetonitrile to prepare a solution with a concentration of 5×10 ^-4 mol/L, then mix the above solution, acetonitrile and water according to different volume ratios to prepare mixed solutions with different water contents (concentration is 5×10 ^{-4 5} mol/L), and then test its emission spectrum. The results shown in Figure 2 show that in the acetonitrile/water mixed solution, with the increase of the water content of the poor solvent, the luminescence of the compound gradually increases, and when the water content is 70%, the emission intensity reaches the maximum, and the I/I ₀ reaches 10.92. The results indicated that compound Ir2 has excellent aggregation-induced luminescent properties.

Claims (3)

1. The aggregation-induced luminescence iridium complex modified by difluorophenyl is characterized in that: the iridium complex is formed by using 2-phenylpyridine derivatives as ring metal ligands and N^N auxiliary ligands to coordinate with iridium metal ions , whose structure is as follows:

The 2-phenylpyridine derivative is selected from 2-(4-(4-(2,4-difluorophenyl)phenyl)phenyl)-5-trifluoromethylpyridine; N^N auxiliary ligand selected from 2,2'-bipyridine or 2-(2-imidazolyl)pyridine. 2. The preparation method of the aggregation-induced luminescent iridium complex modified by difluorophenyl according to claim 1, characterized in that: the synthesis steps of the iridium complex are as follows: (1) Synthesis of cyclometal ligand intermediates: 2-bromo-5-trifluoromethylpyridine and 4-bromophenylboronic acid are used as reactants, potassium carbonate is used as alkali, and palladium acetate is used as catalyst, at 80°C in air A Suzuki cross-coupling reaction occurs, and the reaction process is tracked by thin-layer chromatography. After the reaction is complete, the ring metal ligand intermediate 2-(4-(4-bromophenyl)phenyl)-5- Trifluoromethylpyridine; The molar ratio of the 2-bromo-5-trifluoromethylpyridine: 4-bromophenylboronic acid: potassium carbonate: palladium acetate is 1:2.5:2:0.015; (2) Synthesis of ring metal ligands: with ring metal ligand intermediates and 2,4-difluorophenylboronic acid as reactants, sodium carbonate as base, tetrakis (triphenylphosphine) palladium as catalyst, _N under protection A Suzuki cross-coupling reaction occurred at 70°C, and after 24 hours of reaction, the ring metal ligand was separated by column chromatography; (3) Synthesis of iridium complexes: Add IrCl ₃ .3H ₂ O and 2.5 equivalents of cyclometal ligands to a round bottom flask, and in a mixed solution of ethylene glycol monoethyl ether/water with a volume ratio of 3:1, N ₂ under the protection of magnetic stirring at 120°C, and reacted for 24 hours. After the reaction, the reaction solution was concentrated under reduced pressure to obtain a dichloro bridge intermediate; the dichloro bridge intermediate, 3.0 equivalents of N^N auxiliary ligand 2,2'- Add bipyridine or 2-(2-imidazolyl)pyridine into a round-bottomed flask, and heat to reflux at 120°C for 24h under nitrogen protection; after the reaction, cool to room temperature, then add 20mL KPF ₆ saturated aqueous solution, and stir at room temperature for 12h; The reaction solution was extracted with dichloromethane, and the collected organic phase was concentrated under reduced pressure to obtain a crude product, which was separated by column chromatography with dichloromethane/petroleum ether as eluent, and purified to obtain an iridium complex. 3. The application of the difluorophenyl-modified aggregation-induced luminescent iridium complex according to claim 1, characterized in that: the iridium complex is used in the field of phosphorescent materials.

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