Water-soluble iridium complex, phosphorescent film prepared therefrom and use thereof

Abstract

The application discloses a water-soluble iridium complex and a phosphorescent film prepared from the same and application, relates to the technical field of functional materials, and the structural formula of the iridium complex is as follows: wherein n is an integer of 4-7. By introducing specific alkoxy with hydrogen bonding ability, the water-solubility of the iridium complex and the uniform dispersibility of the iridium complex in water are remarkably improved, and the compatibility of the iridium complex with CMC, SA, CS and other natural polymer materials is ensured. Meanwhile, the biodegradable natural polymer material is selected as a matrix, and the composite material system is endowed with good biocompatibility and environmental sustainability.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to a water-soluble iridium complex and phosphorescent thin films prepared therefrom, and their applications. Background Technology

[0002] Iridium metal complexes have demonstrated significant advantages in organic light-emitting diodes (OLEDs), bioimaging, and chemical sensing due to their high quantum efficiency, long excited-state lifetime, and tunable emission wavelength. However, most traditional iridium complexes contain hydrophobic groups, making them poorly soluble in water and biocompatible, which severely limits their application in environmentally friendly optoelectronic devices. To improve water solubility, existing research has focused on introducing hydrophilic groups (such as carboxyl, sulfonic acid, glycosyl, or polyethylene glycol chains) into the ligands. However, such modifications often face challenges such as complex synthesis, high cost, or reduced luminescence efficiency. For example, while carboxyl modification can enhance water solubility, it may lead to quenching (ACQ) effects due to aggregation; alkoxy chains (such as methoxy) can improve solubility through hydrogen bonding, but their short-chain structure has limited effect on improving water solubility, and the mechanism for regulating emission wavelength remains unclear.

[0003] On the other hand, natural polymers such as sodium carboxymethyl cellulose (CMC), sodium alginate (SA), and chitosan (CS) are widely used in the preparation of functional thin films due to their excellent film-forming properties, biodegradability, and environmental compatibility. The composite system of CMC and SA can form a stable network structure through hydrogen bonding and electrostatic interactions, but existing research mainly focuses on optimizing basic properties (such as mechanical strength and barrier properties), with insufficient exploration of photofunctionalization design. Although some studies have attempted to introduce fluorescent substances into polymer matrices, the composite of iridium complexes with natural polymers still faces the following challenges: hydrophobic iridium complexes are difficult to disperse uniformly in aqueous film-forming systems; excessive addition can easily lead to aggregation quenching, while insufficient addition results in insufficient luminescence intensity; and the interaction mechanism between components is unclear, affecting the durability of the film's optical properties.

[0004] Therefore, developing an iridium complex-natural polymer composite film that combines excellent water solubility, high luminous efficiency, and good environmental compatibility is of great significance for promoting the practical application of flexible optoelectronic devices and biosensing materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a water-soluble iridium complex and a phosphorescent film prepared therefrom. By combining the alkoxy chain-modified water-soluble iridium complex with natural polymer materials, the problems of strong hydrophobicity, poor processing performance and poor compatibility with bio-based materials of traditional iridium complexes are solved, while the controllable luminescence performance and environmentally friendly properties of the film are achieved.

[0006] The technical problem to be solved by this invention is achieved by the following technical solution:

[0007] The first objective of this invention is to provide a water-soluble iridium complex with the following structural formula:

[0008] ;

[0009] Where n is an integer from 4 to 7.

[0010] A second objective of this invention is to provide a method for preparing a water-soluble iridium complex, comprising the following steps:

[0011] (1) The main ligand was reacted with iridium trichloride trihydrate to obtain an iridium chloride bridged dimer;

[0012] (2) The iridium chloride bridged dimer was reacted with an auxiliary ligand and hexafluorophosphate to obtain an iridium complex;

[0013] The main ligand is 2-phenylquinoline; the auxiliary ligand is alkoxy-chain modified 2-(2-pyridyl)benzimidazole.

[0014] Furthermore, the hexafluorophosphate is at least one of potassium hexafluorophosphate, sodium hexafluorophosphate, and ammonium hexafluorophosphate.

[0015] Furthermore, the molar ratio of the main ligand to iridium trichloride trihydrate is 2:(1~1.5).

[0016] Furthermore, the molar ratio of the iridium chloride bridged dimer to the auxiliary ligand and hexafluorophosphate is 1:(1~2):(1~2).

[0017] Further, the alkoxy-chain modified 2-(2-pyridyl)benzimidazole is obtained by reacting 2-(2-pyridyl)benzimidazole with a haloglycol monomethyl ether. More specifically, the haloglycol monomethyl ether is one of halotetraethylene glycol monomethyl ether, halopentethylene glycol monomethyl ether, halohexaethylene glycol monomethyl ether, and haloheptaethylene glycol monomethyl ether. Preferably, the molar ratio of 2-(2-pyridyl)benzimidazole to haloglycol monomethyl ether is 1:(1.2~1.4).

[0018] The third objective of this invention is to provide a method for preparing a phosphorescent thin film, wherein the iridium complex and a natural polymer material are combined by solution film formation to form a thin film, thereby obtaining a phosphorescent thin film.

[0019] Further, the natural polymeric material includes, but is not limited to, at least one of sodium carboxymethyl cellulose (CMC), sodium alginate (SA), and chitosan (CS). Preferably, the natural polymeric material is CMC and SA in a mass ratio of (2.5~3.5):1; or the natural polymeric material is CS and SA in a mass ratio of (1.5~2.5):1.

[0020] Furthermore, the ratio of the natural polymer material to the iridium complex is (15~20) mg : (0.5~5) μmol.

[0021] Furthermore, the solution film-forming method refers to preparing a solution by dissolving the iridium complex and a natural polymer material in a solvent, and then forming a thin film from the solution by coating or other methods. The solvent can be an organic solvent and / or water, or a dilute acid or dilute alkali. The organic solvent includes, but is not limited to, at least one of methanol, ethanol, acetone, ethyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide.

[0022] A fourth object of the present invention is to provide a phosphorescent film prepared by the method described above.

[0023] A fifth objective of this invention is to provide the application of the iridium complex or the phosphorescent film in photocatalytic films, photoluminescent devices, and surface coatings for optical devices.

[0024] The beneficial effects of this invention are: by introducing specific alkoxy groups with hydrogen bonding capabilities, this invention significantly improves the water solubility of iridium complexes and their uniform dispersion in the aqueous phase, ensuring their compatibility with natural polymer materials such as CMC, SA, and CS; at the same time, by selecting biodegradable natural polymer materials as the matrix, the composite material system is endowed with good biocompatibility and environmental sustainability. Attached Figure Description

[0025] Figure 1 The film prepared in Example 5 was subjected to sunlight and ultraviolet light irradiation, respectively;

[0026] Figure 2 The effect of ultraviolet light irradiation on the thin film prepared in Example 6;

[0027] Figure 3 The effect of ultraviolet light irradiation on the thin film prepared in Example 7;

[0028] Figure 4 The film prepared in Example 8 was subjected to sunlight and ultraviolet light irradiation, respectively;

[0029] Figure 5 The ultraviolet-visible absorption spectrum of the thin film prepared in Example 5;

[0030] Figure 6 The ultraviolet-visible absorption spectrum of the thin film prepared in Example 6;

[0031] Figure 7 The ultraviolet-visible absorption spectrum of the thin film prepared in Example 7;

[0032] Figure 8The UV-Vis absorption spectrum of the thin film prepared in Example 8. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.

[0034] Example 1

[0035] (1) Synthesis of 2-(2-pyridyl)benzimidazole modified with tetraethylene glycol monomethyl ether:

[0036] Under nitrogen protection, 2-(2-pyridyl)benzimidazole (200 mg, 1.02 mmol), (polyimide-cinnamyl)palladium(II) chloride dimer (5.2 mg, 0.01 mmol), potassium tert-butoxide (175 mg, 1.56 mmol), 5-di-tert-butylphosphine-1',3',5'-triphenyl-1'H-[1,4']dipyrazole (20.3 mg, 0.04 mmol), bromotetraethylene glycol monomethyl ether (336 mg, 1.24 mmol) and 20 mL of toluene were added to a dry reaction flask, and the mixture was heated to 110 °C and stirred for 24 h. After the reaction was completed, the reaction solution was purified by extraction (using dichloromethane as the extractant and collecting the lower layer liquid), rotary evaporation, and column chromatography (using dichloromethane and petroleum ether in a volume ratio of 3:1 as the eluent) to obtain tetraethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole.

[0037] (2) Synthesis of iridium-chlorine bridged dimers:

[0038] Under nitrogen protection, 2-phenylquinoline (958 mg, 1.86 mmol), iridium trichloride trihydrate (294 mg, 0.93 mmol), 30 mL of ethylene glycol monoethyl ether, and 10 mL of deionized water were added to a dry reaction flask, and the mixture was heated to 130 °C and stirred for 24 h. After the reaction was completed, the product was purified by extraction (using dichloromethane as the extractant and collecting the lower layer), rotary evaporation, and column chromatography (using dichloromethane and petroleum ether in a volume ratio of 3:1 as the eluent) to obtain the iridium chloride bridged dimer.

[0039] (3) Synthesis of tetraethylene glycol monomethyl ether-modified iridium complexes:

[0040]

[0041] Under nitrogen protection, iridium chloride-bridged dimer (200 mg, 0.15 mmol), tetraethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole (122 mg, 0.31 mmol), potassium hexafluorophosphate (20 mg, 0.11 mmol), and 40 mL of ethylene glycol monoethyl ether were added to a dry reaction flask. The mixture was heated to 130 °C and stirred for 24 h. After the reaction was completed, the reaction solution was concentrated, and the product was purified by column chromatography (eluent: dichloromethane and methanol, v / v) to obtain the tetraethylene glycol monomethyl ether-modified iridium complex. 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.25-8.17 (m, 4H), 8.03-7.89 (m, 5H), 7.72(d, J = 8.0 Hz, 1H), 7.65 (d, J = 8.0 Hz, 1H), 7.49 (d, J = 8.0 Hz, 1H), 7.39-7.28(m, 4H), 7.20-7.14 (m, 4H), 7.07 (t, J = 8.0 Hz, 1H), 7.00-6.93 (m, 1H), 6.86-6.79 (m, 3H), 6.60 (d, J = 8.0 Hz, 1H), 6.66 (d, J = 8.0 Hz, 1H), 6.50 (d, J = 8.0Hz, 1H), 4.94-4.72 (m, 2H), 3.90-3.84 (m, 4H), 3.59-3.51 (m, 8H), 3.46-3.43(m,2H), 3.33 (s, 3H).

[0042] Example 2

[0043] Synthesis of iridium complexes modified with pentaethylene monomethyl ether:

[0044]

[0045] The method of Example 1 was followed, except that the tetraethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole was replaced with pentaethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole to obtain a pentaethylene glycol monomethyl ether-modified iridium complex. 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.76 (d, J= 12.0 Hz, 1H), 8.25-8.17 (m, 3H), 8.05-8.01 (m, 2H), 7.93-7.90 (m, 3H), 7.72 (d, J = 8.0 Hz, 1H), 7.66 (d, J = 8.0Hz, 1H), 7.55 (d, J = 8.0 Hz, 1H), 7.43-7.40 (m, 1H), 7.37-7.29 (m, 2H), 7.21-7.13 (m, 4H), 7.07 (t, J = 8.0 Hz, 1H), 6.95 (t, J = 8.0 Hz, 1H), 6.86-6.79 (m,3H), 6.62-6.56 (m, 2H), 6.50 (d, J = 8.0 Hz, 1H), 4.86-4.81 (m, 2H), 3.79 (t, J =4.0 Hz, 2H), 3.63-3.59 (m, 12H), 3.54-3.52 (m, 4H), 3.43 (t, J = 4.0 Hz, 2H), 3.33 (s, 3H).

[0046] Example 3

[0047] Synthesis of hexaethylene glycol monomethyl ether-modified iridium complexes:

[0048]

[0049] The method of Example 1 was followed, except that the tetraethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole was replaced with hexaethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole to obtain a hexaethylene glycol monomethyl ether-modified iridium complex. 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.75 (d, J = 8.0 Hz, 1H), 8.25-8.17 (m, 3H), 8.04-8.01 (m, 2H), 7.93-7.90 (m, 3H), 7.72 (d, J = 8.0 Hz, 1H), 7.66 (d, J = 8.0Hz, 1H), 7.54 (d, J= 8.0 Hz, 1H), 7.43-7.40 (m, 1H), 7.37-7.28 (m, 3H), 7.21-7.13 (m, 4H), 7.07 (t, J = 8.0 Hz, 1H), 6.97-6.93 (m, 1H), 6.87-6.79 (m, 3H), 6.61 (d, J = 8.0 Hz, 1H), 6.57 (d, J = 4.0 Hz, 1H), 6.50 (d, J = 8.0 Hz, 1H), 4.84-4.80 (m, 1H), 4.72-4.67 (m, 1H), 3.81-3.77 (m, 2H), 3.63-3.55 (m, 10H), 3.53-3.51 (m, 10H), 3.34 (s,3H).

[0050] Example 4

[0051] Synthesis of heptaethylene glycol monomethyl ether-modified iridium complexes:

[0052]

[0053] The method of Example 1 was followed, except that the tetraethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole was replaced with heptaethylene glycol monomethyl ether-modified 2-(2-pyridyl)benzimidazole to obtain a heptaethylene glycol monomethyl ether-modified iridium complex. 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.25-8.12 (m, 4H), 8.03-8.01 (m, 2H), 7.93-7.90 (m, 3H), 7.73-7.71 (m, 1H), 7.66-7.64 (m, 2H), 7.47 (t, J = 8.0 Hz, 1H),7.38-7.27 (m, 3H), 7.20-7.14 (m, 4H), 7.09-7.05 (m, 1H), 7.00-6.93(m, 1H),6.87-6.79 (m, 3H), 6.60 (d, J = 8.0 Hz, 1H), 6.56 (d, J = 8.0 Hz, 1H), 6.50 (d, J=8.0 Hz, 1H), 4.64-4.60 (m, 2H), 3.79-3.75 (m, 2H), 3.63-3.61 (m, 20H), 3.54-3.53 (m, 4H), 3.36 (s, 3H).

[0054] Example 5

[0055] Take CMC (15 mg) and SA (5 mg), add water / methanol (1 mL / 0.5 mL) and stir to dissolve. Then add iridium complex solution (the iridium complex prepared in Example 1 is dissolved in methanol at a concentration of 0.1 mol / L and a volume of 5~50 μL). After thorough mixing, uniformly drop-coat the solution onto a glass plate and dry at room temperature to form a film.

[0056] Figure 1 The film prepared in Example 5 was subjected to irradiation under sunlight and ultraviolet light, respectively. Figure 1 It can be seen that the film prepared in Example 5 gradually deepens in color and turns pale yellow under sunlight as the concentration of the iridium complex increases; under ultraviolet light, it emits orange-red light, and the luminescence intensity increases with the increase of the iridium complex content.

[0057] Figure 5 The UV-Vis absorption spectrum of the thin film prepared in Example 5. From... Figure 5 It can be seen that when the amount of iridium complex solution is 10 μL, the absorbance of the film prepared by it is the lowest, which can reduce non-radiative transitions caused by aggregation. Therefore, the film can be used on the surface of optical devices to selectively block blue light and ultraviolet light. When the amount of iridium complex solution is 40 μL, the absorbance of the film prepared by it is the highest. The strong ultraviolet absorption capability of the film can be used to apply it to photocatalytic films or photoluminescent devices.

[0058] Example 6

[0059] Take CMC (15 mg) and SA (5 mg), add water / methanol (1 mL / 0.5 mL) and stir to dissolve. Then add iridium complex solution (the iridium complex prepared in Example 2 is dissolved in methanol at a concentration of 0.1 mol / L and a volume of 5~50 μL). After thorough mixing, uniformly drop-coat the solution onto a glass plate and dry at room temperature to form a film.

[0060] Figure 2 The effect of ultraviolet light irradiation on the thin film prepared in Example 6. From Figure 2 It can be seen that the film prepared in Example 6 emits orange light under ultraviolet light irradiation, and the luminescence intensity increases with the increase of iridium complex content.

[0061] Figure 6The UV-Vis absorption spectrum of the thin film prepared in Example 6. From... Figure 6 It can be seen that when the amount of iridium complex solution is 15 μL, the film prepared by it has the lowest absorbance, which can reduce non-radiative transitions caused by aggregation. Therefore, the film can be used on the surface of optical devices to selectively block blue light and ultraviolet light. When the amount of iridium complex solution is 50 μL, the film prepared by it has the highest absorbance. The strong ultraviolet absorption capacity of the film can be used to apply it to photocatalytic films or photoluminescent devices.

[0062] Example 7

[0063] Take CS (10 mg) and SA (5 mg), add water / methanol (1 mL / 0.5 mL), adjust the pH to 5-6 with acetic acid, stir to dissolve, then add iridium complex solution (the iridium complex prepared in Example 3 is dissolved in methanol at a concentration of 0.1 mol / L and a volume of 5-50 μL), mix thoroughly, and then uniformly drop-coat onto a glass plate. Dry at room temperature to form a film.

[0064] Figure 3 The effect of ultraviolet light irradiation on the thin film prepared in Example 7. From Figure 3 It can be seen that the film prepared in Example 7 emits orange light under ultraviolet light irradiation, and the luminescence intensity increases with the increase of content.

[0065] Figure 7 The UV-Vis absorption spectrum of the thin film prepared in Example 7. From... Figure 7 It can be seen that when the amount of iridium complex solution is 10 μL, the film prepared by it has the highest absorbance, and its strong ultraviolet absorption capability can be used to apply it to photocatalytic films or photoluminescent devices; when the amount of iridium complex solution is 20 μL, the film prepared by it has the lowest absorbance, which can reduce non-radiative transitions caused by aggregation. Therefore, this film can be used on the surface of optical devices to selectively block blue light and ultraviolet light.

[0066] Example 8

[0067] Take CMC (15 mg) and SA (5 mg), add water / methanol (1 mL / 0.5 mL) and stir to dissolve. Then add iridium complex solution (the iridium complex prepared in Example 4 is dissolved in methanol at a concentration of 0.1 mol / L and a volume of 5~50 μL). After thorough mixing, uniformly drop-coat the solution onto a glass plate and dry at room temperature to form a film.

[0068] Figure 4 The film prepared in Example 8 was subjected to irradiation under sunlight and ultraviolet light, respectively. Figure 4It can be seen that the film prepared in Example 8 emits red light under ultraviolet light irradiation, and the luminescence intensity increases with the increase of content.

[0069] Figure 8 The UV-Vis absorption spectrum of the thin film prepared in Example 8. From... Figure 8 It can be seen that when the amount of iridium complex solution is 45 μL, the film prepared by it has the highest absorbance, and its strong ultraviolet absorption capability can be used to apply it to photocatalytic films or photoluminescent devices; when the amount of iridium complex solution is 15 μL, the film prepared by it has the lowest absorbance, which can reduce non-radiative transitions caused by aggregation. Therefore, this film can be used on the surface of optical devices to selectively block blue light and ultraviolet light.

[0070] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A water-soluble iridium complex, characterized in that, The structural formula of the iridium complex is as follows: Where n is an integer from 4 to 7.

2. The method for preparing the iridium complex according to claim 1, characterized in that, Includes the following steps: (1) The main ligand was reacted with iridium trichloride trihydrate to obtain an iridium chloride bridged dimer; (2) The iridium chloride bridged dimer was reacted with an auxiliary ligand and hexafluorophosphate to obtain an iridium complex; The main ligand is 2-phenylquinoline; the auxiliary ligand is alkoxy-chain modified 2-(2-pyridyl)benzimidazole.

3. The preparation method according to claim 2, characterized in that: The hexafluorophosphate is at least one of potassium hexafluorophosphate, sodium hexafluorophosphate, and ammonium hexafluorophosphate.

4. The preparation method according to claim 2, characterized in that: The molar ratio of the main ligand to iridium trichloride trihydrate is 2: (1~1.5); The molar ratio of the iridium chloride bridged dimer to the auxiliary ligand and hexafluorophosphate is 1:(1~2):(1~2).

5. The preparation method according to claim 2, characterized in that: The alkoxy-chain modified 2-(2-pyridyl)benzimidazole is obtained by reacting 2-(2-pyridyl)benzimidazole with haloglycol monomethyl ether; The haloglycol monomethyl ether is one of halotetraethylene glycol monomethyl ether, halopentethylene glycol monomethyl ether, halohexaethylene glycol monomethyl ether, and haloheptaethylene glycol monomethyl ether. The molar ratio of 2-(2-pyridyl)benzimidazole to haloglycol monomethyl ether is 1:(1.2~1.4).

6. A method for preparing a phosphorescent thin film, characterized in that: Phosphorescent films are obtained by forming a thin film with the iridium complex described in claim 1 and a natural polymer material using a solution film-forming method.

7. The preparation method according to claim 6, characterized in that: The natural polymer material is selected from at least one of sodium carboxymethyl cellulose, sodium alginate, and chitosan.

8. The preparation method according to claim 6, characterized in that: The ratio of the natural polymer material to the water-soluble iridium complex is (15~20) mg : (0.5~5) μmol.

9. A phosphorescent thin film prepared by the preparation method according to any one of claims 6 to 8.

10. The application of the water-soluble iridium complex of claim 1 or the phosphorescent thin film of claim 9 in photocatalytic thin films.

11. The application of the water-soluble iridium complex of claim 1 or the phosphorescent thin film of claim 9 in photoluminescent devices.

12. The application of the water-soluble iridium complex of claim 1 or the phosphorescent thin film of claim 9 in the surface coating of optical devices.

Images