Iridium complex and iridium complex / natural polymer composite material, and preparation method and application thereof

Abstract

The application discloses an iridium complex and an iridium complex / natural polymer composite material and a preparation method and application thereof, relates to the technical field of organic photoelectric functional materials, and solves the problem of traditional iridium complex aggregation fluorescence quenching at high concentration or in solid state, significantly improves the aggregation-induced emission effect, and optimizes the hydrophobicity, film uniformity and photophysical properties of the composite material, so that high-intensity stable light emission of adjustable (yellow light to orange light) is realized under 365 nm ultraviolet excitation.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic functional materials technology, specifically to an iridium complex and an iridium complex / natural polymer composite material, as well as their preparation methods and applications. Background Technology

[0002] Iridium complexes have attracted much attention in the field of optoelectronic devices due to their high quantum efficiency, tunable emission color, and long excited-state lifetime. However, traditional iridium complexes are prone to aggregation and quenching (ACQ) in the solid state or at high concentrations, and their poor hydrophobicity and poor film-forming properties severely limit their practical applications. To address this issue, researchers have attempted to introduce alkyl chains to modify the ligand structure to improve hydrophobicity and molecular stacking. For example, introducing lipophilic alkyl chains can suppress π-π stacking interactions, improve solvent solubility, and optimize film uniformity; at the same time, the flexible design of alkyl chains can enhance molecular self-assembly capabilities and reduce non-radiative transitions, thereby improving luminescence efficiency. Nevertheless, single iridium complexes still suffer from low mechanical strength and poor environmental stability.

[0003] Natural polymers (such as chitosan and sodium alginate) are considered ideal matrices due to their biocompatibility, biodegradability, and excellent film-forming properties. Chitosan forms a transparent, flexible film at pH 5, and its amino / hydroxyl groups can form hydrogen bonds with iridium complexes, inhibiting phase separation. Sodium alginate's carboxyl anions stabilize the dispersion of iridium complexes through electrostatic interactions. However, precise control of matrix concentration, pH value, and iridium complex doping amount is crucial during the composite process; otherwise, phase separation or luminescence quenching can easily occur. Current technologies have not effectively combined the optical advantages of lipophilic iridium complexes with the film-forming properties of natural polymers, necessitating the development of a composite film preparation method that balances high luminescence efficiency, environmental stability, and processability. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide an iridium complex and an iridium complex / natural polymer composite material and a method for preparing the same. By using long alkyl chains to modify the structure of the ligands of the iridium complex, an oleophilic iridium complex is designed and synthesized, which can effectively control the photophysical properties of the iridium complex, especially the luminescence properties of optical functional thin films.

[0005] The technical problem to be solved by the present invention is achieved by the following technical solution:

[0006] One objective of this invention is to provide an iridium complex with the following structural formula:

[0007] ;

[0008] Where n takes the value of an integer from 7 to 13.

[0009] The second objective of this invention is to provide a method for preparing the iridium complex, comprising the following steps:

[0010] (1) The main ligand was reacted with iridium trichloride trihydrate to obtain an iridium chloride bridged dimer;

[0011] (2) The iridium chloride bridged dimer was reacted with an auxiliary ligand and hexafluorophosphate to obtain an iridium complex;

[0012] The main ligand is 2-phenylbenzimidazole modified with a long alkyl chain; the auxiliary ligand is 2-(2-pyridyl)benzimidazole modified with a long alkyl chain.

[0013] Furthermore, the hexafluorophosphate is at least one of potassium hexafluorophosphate, sodium hexafluorophosphate, and ammonium hexafluorophosphate.

[0014] Furthermore, the molar ratio of the main ligand, auxiliary ligand, iridium trichloride trihydrate, and hexafluorophosphate is 2:1:(1~1.5):(1~1.5).

[0015] The third objective of this invention is to provide a method for preparing an iridium complex / natural polymer composite material, wherein a natural polymer material is dissolved in a solvent to prepare a solution, then an iridium complex is added, mixed evenly, and dried to obtain the iridium complex / natural polymer composite material.

[0016] Furthermore, the natural polymeric material includes, but is not limited to, at least one of chitosan and sodium alginate. When the natural polymeric material is chitosan, the pH of the solution is adjusted to 3.0-6.0 with glacial acetic acid to ensure complete dissolution of the chitosan.

[0017] Furthermore, the solvent is an organic solvent and / or water. Even further, the organic solvent includes, but is not limited to, at least one of methanol, ethanol, acetone, ethyl acetate, N,N-dimethylformamide, and dimethyl sulfoxide.

[0018] Furthermore, the ratio of the natural polymer material to the iridium complex is 10 mg : (0.5~5) μmol.

[0019] The fourth objective of this invention is to provide an iridium complex / natural polymer composite material obtained by the aforementioned preparation method.

[0020] The fifth objective of this invention is to provide the application of the iridium complex and the iridium complex / natural polymer composite material in photoluminescent materials. The iridium complex / natural polymer composite material of this invention can be formed into a thin film using a solution film-forming method. This thin film combines the advantages of being environmentally friendly, highly flexible, and having high luminous efficiency, and can be used as a photoluminescent thin film in fields such as the light-emitting layer of flexible organic light-emitting diode (OLED) devices, biocompatible optical sensors, and blue light blocking coatings.

[0021] The beneficial effects of this invention are: by modifying iridium complexes with long alkyl chains and combining natural polymer materials with iridium complexes, this invention not only solves the problem of aggregation fluorescence quenching of traditional iridium complexes at high concentrations or in solid states, significantly improving the aggregation-induced emission effect, but also optimizes the hydrophobicity, film uniformity and photophysical properties of the composite material, achieving tunable (yellow to orange) high-intensity stable luminescence under 365 nm ultraviolet excitation. Attached Figure Description

[0022] Figure 1 The UV-Vis absorption spectra of the iridium complex prepared in Example 2 in methanol-water mixed solutions with different water contents;

[0023] Figure 2 The fluorescence emission spectra of the iridium complex prepared in Example 2 in methanol-water mixed solutions with different water contents are shown below.

[0024] Figure 3 The irradiation effects of the iridium complex / chitosan composite film prepared in Example 8 under sunlight and 365 nm ultraviolet light, respectively;

[0025] Figure 4 The UV-Vis absorption spectrum of the iridium complex / chitosan composite film prepared in Example 8;

[0026] Figure 5 The fluorescence emission spectrum of the iridium complex / chitosan composite film prepared in Example 8;

[0027] Figure 6 The effect of iridium complex / sodium alginate composite film prepared in Example 9 under 365 nm ultraviolet light irradiation;

[0028] Figure 7 The UV-Vis absorption spectrum of the iridium complex / sodium alginate composite film prepared in Example 9;

[0029] Figure 8 The fluorescence emission spectrum of the iridium complex / sodium alginate composite film prepared in Example 9 is shown. Detailed Implementation

[0030] 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.

[0031] Example 1

[0032] Synthesis of straight-chain octyl-modified iridium complexes:

[0033]

[0034] (1) 20 mmol of straight-chain octyl-modified 2-phenylbenzimidazole was dissolved in 50 mL of ethylene glycol monoethyl ether, and then 15 mmol of iridium trichloride trihydrate and 50 mL of deionized water were added. The mixture was heated to 120 °C and reacted for 24 h under nitrogen protection. After cooling to room temperature, the mixture was filtered, washed with water, and dried to obtain iridium chloride bridged dimer with a yield of 100%.

[0035] (2) The iridium chloride bridged dimer prepared in step (1) and 10 mmol of straight-chain octyl-modified 2-(2-pyridyl)benzimidazole were added to 100 mL of ethylene glycol monoethyl ether and reacted at 120 °C for 6 h under nitrogen protection. After cooling to room temperature, 15 mmol of potassium hexafluorophosphate was added and stirred for 1 h. The mixture was filtered, washed with water, and purified by column chromatography to obtain the straight-chain octyl-modified iridium complex with a yield of 40%. 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37(t, J = 4.0 Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0Hz, 1H), 7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06(m, 2H), 7.01-6.93 (m, 2H),6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40(d, J = 8.0 Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J=8.0 Hz, 1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m, 2H), 1.88-1.83 (m,4H), 1.26 (s, 30H), 0.90-0.88 (m, 9H).

[0036] Example 2

[0037] Synthesis of straight-chain nonyl-modified iridium complexes:

[0038] The method of Example 1 is followed, except that the straight-chain octyl-modified 2-phenylbenzimidazole and the straight-chain octyl-modified 2-(2-pyridyl)benzimidazole are replaced with straight-chain nonyl-modified 2-phenylbenzimidazole and straight-chain nonyl-modified 2-(2-pyridyl)benzimidazole, respectively.

[0039] ;

[0040] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37 (t, J = 4.0Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0 Hz, 1H),7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06 (m, 2H),7.01-6.93 (m, 2H), 6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40 (d, J = 8.0Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J= 8.0 Hz,1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m,2H), 1.88-1.83 (m,4H), 1.26 (s, 30H), 0.90-0.88 (m, 9H).

[0041] Example 3

[0042] Synthesis of straight-chain decyl-modified iridium complexes:

[0043] The method of Example 1 is followed, except that the straight-chain octyl-modified 2-phenylbenzimidazole and the straight-chain octyl-modified 2-(2-pyridyl)benzimidazole are replaced with straight-chain decyl-modified 2-phenylbenzimidazole and straight-chain decyl-modified 2-(2-pyridyl)benzimidazole, respectively.

[0044] ;

[0045] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37 (t, J = 4.0Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0 Hz, 1H),7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06 (m, 2H),7.01-6.93 (m, 2H), 6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40 (d, J = 8.0Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J= 8.0 Hz,1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m,2H), 1.88-1.83 (m,4H), 1.26 (s, 36H), 0.90-0.88 (m, 9H).

[0046] Example 4

[0047] Synthesis of straight-chain undecyl-modified iridium complexes:

[0048] The method of Example 1 is followed, except that the straight-chain octyl-modified 2-phenylbenzimidazole and the straight-chain octyl-modified 2-(2-pyridyl)benzimidazole are replaced with straight-chain undecyl-modified 2-phenylbenzimidazole and straight-chain undecyl-modified 2-(2-pyridyl)benzimidazole, respectively.

[0049] ;

[0050] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37 (t, J = 4.0Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0 Hz, 1H),7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06 (m, 2H),7.01-6.93 (m, 2H), 6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40 (d, J = 8.0Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J= 8.0 Hz,1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m,2H), 1.88-1.83 (m,4H), 1.26 (s, 42H), 0.90-0.88 (m, 9H).

[0051] Example 5

[0052] Synthesis of linear dodecyl-modified iridium complexes:

[0053] The method of Example 1 is followed, except that the straight-chain octyl-modified 2-phenylbenzimidazole and the straight-chain octyl-modified 2-(2-pyridyl)benzimidazole are replaced with straight-chain dodecyl-modified 2-phenylbenzimidazole and straight-chain dodecyl-modified 2-(2-pyridyl)benzimidazole, respectively.

[0054] ;

[0055] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37 (t, J = 4.0Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0 Hz, 1H),7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06 (m, 2H),7.01-6.93 (m, 2H), 6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40 (d, J = 8.0Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J= 8.0 Hz,1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m,2H), 1.88-1.83 (m,4H), 1.26 (s, 48H), 0.90-0.88 (m, 9H).

[0056] Example 6

[0057] Synthesis of straight-chain tridecyl-modified iridium complexes:

[0058] The method of Example 1 is followed, except that the straight-chain octyl-modified 2-phenylbenzimidazole and the straight-chain octyl-modified 2-(2-pyridyl)benzimidazole are replaced with straight-chain tridecyl-modified 2-phenylbenzimidazole and straight-chain tridecyl-modified 2-(2-pyridyl)benzimidazole, respectively.

[0059] ;

[0060] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37 (t, J = 4.0Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0 Hz, 1H),7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06 (m, 2H),7.01-6.93 (m, 2H), 6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40 (d, J = 8.0Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J= 8.0 Hz,1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m,2H), 1.88-1.83 (m,4H), 1.26 (s, 54H), 0.90-0.88 (m, 9H).

[0061] Example 7

[0062] Synthesis of straight-chain tetradecyl-modified iridium complexes:

[0063] The method of Example 1 is followed, except that the straight-chain octyl-modified 2-phenylbenzimidazole and the straight-chain octyl-modified 2-(2-pyridyl)benzimidazole are replaced with straight-chain tetradecyl-modified 2-phenylbenzimidazole and straight-chain tetradecyl-modified 2-(2-pyridyl)benzimidazole, respectively.

[0064] ;

[0065] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.56 (d, J = 8.0 Hz, 1H), 8.37 (t, J = 4.0Hz, 1H), 8.13 (d, J = 4.0 Hz, 1H), 7.78-7.72 (m, 2H), 7.52 (d, J = 8.0 Hz, 1H),7.43-7.38 (m, 2H), 7.36-7.32 (m, 2H), 7.25-7.20 (m, 2H), 7.11-7.06 (m, 2H),7.01-6.93 (m, 2H), 6.83-6.76 (m, 3H), 6.47 (d, J = 8.0 Hz, 1H), 6.40 (d, J = 8.0Hz, 1H), 6.32 (d, J = 8.0 Hz, 1H), 5.89 (d, J = 8.0 Hz, 1H), 5.67 (d, J= 8.0 Hz,1H), 4.83-4.79 (m, 2H), 4.74-4.65 (m, 2H), 4.63-4.56 (m, 2H), 2.06-2.00 (m,2H), 1.88-1.83 (m,4H), 1.26 (s, 60H), 0.90-0.88 (m, 9H).

[0066] Example 8

[0067] Aggregation-induced emission of iridium complexes:

[0068] Figure 1 The UV-Vis absorption spectra of the iridium complex prepared in Example 2 in methanol-water mixed solutions with different water contents (0–90%). Figure 1 It can be seen that all spectra have obvious high-intensity absorption peaks in the range of 245-330 nm, and relatively weak absorption peaks in the range of 400-500 nm. The absorption peak at 320 nm indicates that when the water content in the methanol-water mixed solution is less than 50%, a red shift phenomenon is observed, which indicates that the iridium complex molecules exhibit J-type aggregation at this time. This aggregation mode is conducive to the generation of aggregation-induced emission (AIE).

[0069] Figure 2 The fluorescence emission spectra of the iridium complex prepared in Example 2 in methanol-water mixed solutions with different water contents (0–90%) are shown. Figure 2 It can be seen that all spectra exhibit fluorescence emission peaks in the 520–650 nm range. The fluorescence intensity increases with increasing water content in the methanol-water mixture; however, it decreases when the water content exceeds 50%. As the intermolecular distance of the iridium complex molecules gradually decreases, the iridium complexes exhibit J-shaped packing in solution, demonstrating AIE properties.

[0070] Example 9

[0071] Preparation of iridium complex / chitosan composite films:

[0072] 10 mg of chitosan was dissolved in 5 mL of a methanol-water (1:1, v / v) mixture, and the pH of the solution was adjusted to 5.0 with 0.1 M glacial acetic acid to obtain a chitosan solution. Different volumes (5 μL, 10 μL, 15 μL, 20 μL, 25 μL, 30 μL, 35 μL, 40 μL, 45 μL, 50 μL) of a methanol solution (0.1 M) of the iridium complex prepared in Example 2 were added dropwise to 10 portions of the chitosan solution. After thorough mixing, the mixture was uniformly coated onto the surface of a glass slide and air-dried at room temperature for 24 h to obtain an iridium complex / chitosan composite film.

[0073] Figure 3 The effect of iridium complex / chitosan composite films under sunlight and 365 nm ultraviolet light irradiation. From Figure 3 It can be seen that films prepared with low concentrations of iridium complexes (5–20 μL) emit a faint yellow light, while those prepared with iridium complexes emit a deep yellow light as the concentration increases (25–50 μL). The film formation is optimal when the volume of the iridium complex solution is 40 μL.

[0074] Figure 4 The UV-Vis absorption spectrum of the iridium complex / chitosan composite film. Figure 4 It can be seen that at an absorption wavelength of 370 nm, the film has the lowest absorbance when the volume of the iridium complex solution is 25 µL. This moderate absorption characteristic can effectively reduce the non-radiative energy loss caused by molecular aggregation at high concentrations and selectively block the ultraviolet and blue light bands, making it suitable as a surface coating for optical protective devices. When the volume of the iridium complex solution is 30 µL, the film has the highest absorbance. This strong ultraviolet capture capability makes it valuable for application in photocatalytic films or photoluminescent devices.

[0075] Fluorescence emission spectra were measured on iridium complex / chitosan composite films prepared from 25 µL and 30 µL iridium complex solutions. Figure 5 As shown. From Figure 5 It can be seen that the emission intensity of the thin film is highest when the volume of the iridium complex solution is 30 µL.

[0076] Example 10

[0077] Preparation of iridium complex / sodium alginate composite films:

[0078] Dissolve 100 mg of sodium alginate in 1 mL of a methanol-water (1:1, v / v) mixture to obtain a sodium alginate solution. Add different volumes (5 μL, 10 μL, 15 μL, 20 μL, 25 μL, 30 μL, 35 μL, 40 μL, 45 μL, 50 μL) of a methanol solution (0.1 M) of the iridium complex prepared in Example 2 to 10 portions of the sodium alginate solution, respectively. After thorough mixing, coat the mixture evenly onto a glass slide and air dry at room temperature for 24 h to obtain an iridium complex / sodium alginate composite film.

[0079] Figure 6 The effect of iridium complex / sodium alginate composite film under sunlight and 365 nm ultraviolet light irradiation. From Figure 6 It can be seen that the film emits orange light as the iridium complex content increases.

[0080] Figure 7The UV-Vis absorption spectrum of the iridium complex / sodium alginate composite film. Figure 7 It can be seen that at an absorption wavelength of 350 nm, the film exhibits the lowest absorbance when the volume of the iridium complex solution is 5 µL. This moderate absorption characteristic effectively reduces non-radiative energy loss caused by molecular aggregation at high concentrations and selectively blocks ultraviolet and blue light bands, making it suitable as a surface coating for optical protective devices. The film shows the highest absorbance when the volume of the iridium complex solution is 45 µL. This strong ultraviolet trapping capability has application value in photocatalytic films or photoluminescent devices.

[0081] Fluorescence emission spectra of iridium complex / sodium alginate composite films prepared from 5 µL and 45 µL iridium complex solutions were measured. Figure 8 As shown. From Figure 8 It can be seen that the emission intensity of the thin film is highest when the volume of the iridium complex solution is 45 µL.

[0082] In summary, this invention prepares an iridium complex modified with a long alkyl chain, and by combining it with natural polymer materials such as chitosan or sodium alginate, a photofunctional thin film can be obtained, which has potential applications in the protection of strong ultraviolet or blue light bands or as a photoluminescent layer.

[0083] 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. An iridium complex, characterized in that, The structural formula of the iridium complex is shown below: ； Where n takes the value of an integer from 7 to 13.

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-phenylbenzimidazole modified with a long alkyl chain; the auxiliary ligand is 2-(2-pyridyl)benzimidazole modified with a long alkyl chain.

3. The method for preparing the iridium complex according to claim 2, characterized in that: The hexafluorophosphate is at least one of potassium hexafluorophosphate, sodium hexafluorophosphate, and ammonium hexafluorophosphate.

4. The method for preparing the iridium complex according to claim 2, characterized in that: The molar ratio of the main ligand, auxiliary ligand, iridium trichloride trihydrate, and hexafluorophosphate is 2:1:(1~1.5):(1~1.5).

5. A method for preparing an iridium complex / natural polymer composite material, characterized in that: The natural polymer material is dissolved in a solvent to prepare a solution, and then the iridium complex described in claim 1 is added. The mixture is mixed evenly and dried to obtain an iridium complex / natural polymer composite material.

6. The method for preparing the iridium complex / natural polymer composite material according to claim 5, characterized in that: The natural polymer material is at least one of chitosan and sodium alginate.

7. The method for preparing the iridium complex / natural polymer composite material according to claim 5, characterized in that: The solvent is an organic solvent and / or water.

8. The method for preparing the iridium complex / natural polymer composite material according to claim 5, characterized in that: The ratio of the natural polymer material to the iridium complex is 10 mg : (0.5~5) μmol.

9. An iridium complex / natural polymer composite material obtained by the preparation method according to any one of claims 5 to 8.

10. The application of the iridium complex of claim 1 or the iridium complex / natural polymer composite material of claim 9 in photoluminescent materials.

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