Preparation method of granular iridium trichloride hydrate without tetravalent iridium
By reducing the hydrated iridium trichloride raw material with deionized water and methanol, a granular hydrated iridium trichloride without tetravalent iridium was successfully prepared, which solved the problem of tetravalent iridium impurities in existing products, and achieved high-purity raw material preparation, which was suitable for the field of OLED devices.
Patent Information
- Application Number
- CN202410481071.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-22
- Publication Date
- 2025-05-02
AI Technical Summary
There are tetravalent iridium impurities in existing hydrated iridium trichloride products, which affect the luminescence efficiency of iridium phosphorescent molecules. The impurity content of domestic commercial products is relatively high, making it difficult to meet the purity requirements of OLED devices luminescent materials.
The reduction reaction was carried out using hydrated iridium trichloride raw materials, deionized water and methanol, and dried by filtration and rotary evaporation to obtain particulate hydrated iridium trichloride without tetravalent iridium.
It has achieved efficient removal of tetravalent iridium from hydrated iridium trichloride, with a yield of ≥98%. It is suitable for industrial mass production and provides high-purity raw materials for the preparation of iridium phosphorescence complexes.
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Figure CN119911991A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of raw material preparation of OLED device light-emitting materials, and in particular to a method for preparing granular iridium trichloride hydrate that does not contain tetravalent iridium. Background Art
[0002] Iridium is element 77 in the periodic table, with an atomic weight of 192.2 and an outermost electron configuration of 4f. 14 5d 7 6s 2 , density 22.4g / cm 3 , melting point 2454℃, iridium has special physical and chemical properties and is used in aerospace and high-tech fields. Among them, iridium-based phosphorescent materials have the advantages of high luminous efficiency and stability, and have been used in OLED technology and become the luminescent material of OLED devices. OLED is a new type of flexible display technology, showing important application prospects in the fields of televisions, smart phones, etc.
[0003] As one of the key materials for OLED devices, iridium phosphorescent molecules are cyclometallic complexes of iridium. The synthesis requires hydrated iridium trichloride as the starting material, and through chemical reactions, products with a purity of more than 99.5% are obtained. Therefore, the demand for hydrated iridium trichloride continues to increase with the development of the OLED industry, and the demand will continue to increase. Since iridium generally exists in two states, trivalent and tetravalent, in the chlorination system, tetravalent iridium is usually stable in a stronger hydrochloric acid system. Nevertheless, a certain amount of tetravalent iridium is inevitably present in the product of hydrated iridium trichloride. When hydrated iridium trichloride is used as a general intermediate or precursor, the presence of tetravalent iridium does not affect its application. Therefore, the national industry product standard (YS / T643-2007) for hydrated iridium trichloride does not set a limit on tetravalent iridium. Tetravalent iridium is the most easily generated impurity component in the preparation of hydrated iridium trichloride, and it is also a key factor affecting the luminous efficiency of iridium phosphorescent molecules. At present, the hydrated iridium trichloride available in the domestic market does not meet the requirements for the production of iridium phosphorescent molecular materials, especially the content of the impurity tetravalent iridium is between 1 and 2%. Therefore, removing the tetravalent iridium contained in hydrated iridium trichloride plays a very important role in preparing the light-emitting material of OLED devices.
[0004] Therefore, there is an urgent need to develop a method for preparing granular iridium trichloride hydrate that does not contain tetravalent iridium, which has low equipment requirements, high yield, easy operation, stable product batches, and is suitable for industrial mass production. Summary of the invention
[0005] In view of this, the present invention provides a method for preparing granular hydrated iridium trichloride free of tetravalent iridium. The preparation method provided by the present invention can prepare hydrated iridium trichloride free of tetravalent iridium, and has the advantages of simple operation, high yield, and easy batch production. The yield of the obtained granular hydrated iridium trichloride free of tetravalent iridium is ≥98%.
[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0007] A method for preparing granular iridium trichloride hydrate that does not contain tetravalent iridium comprises the following steps:
[0008] A hydrated iridium trichloride raw material, deionized water and methanol are mixed for reduction reaction, the obtained reaction solution is filtered, and the obtained filtrate is rotary evaporated and then dried to obtain granular hydrated iridium trichloride without tetravalent iridium; the content of tetravalent iridium in the hydrated iridium trichloride raw material is 1-2wt%.
[0009] Preferably, the usage ratio of the hydrated iridium trichloride raw material and deionized water is 1 g: (6-12) mL.
[0010] Preferably, the usage ratio of the hydrated iridium trichloride raw material and methanol is 1 g: (1.0-1.6) mL.
[0011] Preferably, the method of mixing the hydrated iridium trichloride raw material, deionized water and methanol comprises: firstly dissolving the hydrated iridium trichloride raw material in deionized water, and then adding methanol.
[0012] Preferably, the dissolving temperature is 80-100°C.
[0013] Preferably, the reduction reaction temperature is 75-95° C., and the reaction time is 2-4 hours.
[0014] Preferably, the volume of the remaining solution after the rotary evaporation is 1 / 3 to 1 / 5 of the initial volume of the deionized water.
[0015] Preferably, the drying is reduced pressure drying, the temperature of the reduced pressure drying is 30 to 50° C., and the time is 24 to 48 hours.
[0016] Preferably, the filtration is hot filtration; a solid is obtained after the filtration, and the precious metal iridium in the solid is recovered.
[0017] The invention provides a method for preparing granular tetravalent iridium-free hydrated iridium trichloride, comprising the following steps: mixing a hydrated iridium trichloride raw material, deionized water and methanol for reduction reaction, filtering the obtained reaction solution, and drying the obtained filtrate after rotary evaporation to obtain granular tetravalent iridium-free hydrated iridium trichloride; the content of tetravalent iridium in the hydrated iridium trichloride raw material is 1-2wt%. The invention uses commercially available hydrated iridium trichloride as a raw material, deionized water as a solvent, and methanol as a reducing agent to reduce a small amount of tetravalent iridium contained in the commercially available hydrated iridium trichloride to trivalent iridium. The invention realizes the efficient synthesis of granular tetravalent iridium-free hydrated iridium trichloride through simple process changes.
[0018] Usually, iridium trichloride hydrate and cyclometal ligand are used as raw materials, and coordination reaction is used to generate iridium phosphorescent complexes. However, commercially available iridium trichloride hydrate contains a small amount of tetravalent iridium, and impurities are formed during the coordination process. Impurities are difficult to handle, resulting in the purity of the synthesized iridium phosphorescent complex always failing to reach more than 99.5%. Therefore, the inventor tried to reduce a small amount of tetravalent iridium in commercially available iridium trichloride hydrate to trivalent iridium as a raw material for producing iridium phosphorescent complexes. The inventor selected a variety of reducing agents and conducted repeated tests. Finally, it was found that selecting methanol as a reducing agent would generate a granular iridium trichloride hydrate that does not contain tetravalent iridium. Multiple tests have shown that the purity of the granular iridium trichloride hydrate synthesized by this method as a raw material for preparing iridium phosphorescent complexes can reach more than 99.5%.
[0019] In summary, the reducing agent methanol selected in the present invention can just reduce the tetravalent iridium in the hydrated iridium trichloride to trivalent iridium, the process operation is simple, the yield is high, the cost is low, and it is easy to achieve batch preparation. The prepared product is used as a raw material to prepare iridium phosphorescent complexes with high purity, and can provide high-quality raw materials for the field of OLED devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 A process flow chart of the preparation method of granular iridium trichloride hydrate containing no tetravalent iridium provided by the present invention;
[0021] Figure 2 The appearance of the granular hydrated iridium trichloride without tetravalent iridium prepared in Example 1 (left) and the commercially available hydrated iridium trichloride (right);
[0022] Figure 3 HPLC chromatogram of Ir(ppy)2(acac) prepared in Example 3;
[0023] Figure 4 This is the high performance liquid chromatogram of Ir(mpmq)2(tmd) prepared in Example 4. DETAILED DESCRIPTION
[0024] The present invention provides a method for preparing granular iridium trichloride hydrate without tetravalent iridium, comprising the following steps:
[0025] A hydrated iridium trichloride raw material, deionized water and methanol are mixed for reduction reaction, the obtained reaction solution is filtered, and the obtained filtrate is rotary evaporated and then dried to obtain granular hydrated iridium trichloride without tetravalent iridium; the content of tetravalent iridium in the hydrated iridium trichloride raw material is 1-2wt%.
[0026] Figure 1 The process flow chart of the preparation method of the granular iridium trichloride hydrate without tetravalent iridium provided by the present invention is shown below in combination with Figure 1 Provide detailed explanation.
[0027] In the present invention, the hydrated iridium trichloride raw material is commercially available hydrated iridium trichloride, wherein the content of tetravalent iridium is 1-2wt%; the usage ratio of the hydrated iridium trichloride raw material to deionized water is 1g:(6-12)mL, more preferably 1g:(7-8)mL; the usage ratio of the hydrated iridium trichloride raw material to methanol is preferably 1g:(1.0-1.6)mL, more preferably 1g:(1.2-1.3)mL.
[0028] In the present invention, the method of mixing the hydrated iridium trichloride raw material, deionized water and methanol preferably comprises: first dissolving the hydrated iridium trichloride raw material in deionized water, and then adding methanol; the dissolution temperature is preferably 80-100°C, more preferably 90°C.
[0029] In the present invention, the temperature of the reduction reaction is preferably 75 to 95° C., more preferably 90° C., and the time of the reduction reaction is preferably 2 to 4 hours, more preferably 2.5 to 3 hours. In a specific embodiment of the present invention, the iridium trichloride raw material is preferably dissolved under heating conditions, and methanol is slowly added dropwise after the temperature is constant, and the isothermal reaction is continued for 2 to 4 hours after the methanol is added dropwise; the time of the reduction reaction is counted from the completion of the methanol addition.
[0030] After the reduction reaction is completed, the present invention filters the obtained reaction solution, and the obtained filtrate is dried after rotary evaporation to obtain granular iridium trichloride hydrate that does not contain tetravalent iridium; the filtration is preferably hot filtration; the volume of the remaining solution after the rotary evaporation is preferably 1 / 3 to 1 / 5 of the initial volume of deionized water, and more preferably 1 / 4; the drying is preferably reduced pressure drying, the temperature of the reduced pressure drying is preferably 30 to 50° C., and more preferably 35 to 40° C., and the time of the reduced pressure drying is preferably 24 to 48 hours, and more preferably 38 to 40 hours.
[0031] In the present invention, a solid is obtained after the filtration. The present invention preferably recovers the precious metal iridium in the solid and recycles the recovered precious metal iridium to reduce costs. In a specific embodiment of the present invention, a reducing agent is preferably added to the waste residue and then calcined and washed to obtain high-purity iridium powder. The reducing agent is preferably sodium borohydride or hydrazine hydrate, and the amount of the reducing agent added is preferably 20-30% of the mass of the waste residue. The calcination temperature is preferably 800-850° C., and the time is preferably 3-5 hours. The high-purity iridium powder is used as a raw material for preparing hydrated iridium trichloride.
[0032] The content of trivalent iridium in the granular tetravalent iridium-free hydrated iridium trichloride prepared by the present invention is preferably 54.21% to 54.23%, and the content of tetravalent iridium is 0.
[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0034] Example 1
[0035] Commercially available hydrated iridium trichloride (200 g, containing 54% iridium, of which the content of tetravalent iridium is 1.37%, with an appearance of Figure 2 The right picture in the figure) and 1400mL of deionized water were added to the reactor. Under argon protection, the mixture was dissolved completely at 85°C. After the constant temperature was maintained at 85°C, 240mL of methanol was slowly added dropwise. The constant temperature reaction was continued for 2.5h. The filtrate was hot filtered and 3 / 4 of the solvent was removed by rotary evaporation. The remaining 1 / 4 of the solution was dried under reduced pressure at 35°C for 40h to obtain 196.5g of granular hydrated iridium trichloride (containing 54.21% iridium, with an appearance of Figure 2 The yield is 98.6% (calculated as iridium). The filter cake is collected and filtered to recover the precious metal iridium for recycling.
[0036] Example 2
[0037] Commercially available hydrated iridium trichloride (300g, containing 54% iridium, wherein the tetravalent iridium content is 1.12%) and 2400mL of deionized water are added to a reactor, and under argon protection, the mixture is dissolved completely after adding at 90°C, and 420mL of methanol is slowly added dropwise at 90°C, and the reaction is continued at a constant temperature for 3.0 hours after the addition. Heat filtration is performed, and 4 / 5 of the solvent is removed by rotary evaporation of the filtrate, and the remaining 1 / 5 of the solution is dried under reduced pressure at 40°C for 38 hours to obtain granular hydrated iridium trichloride 295.5g (containing 54.23% iridium), with a yield of 98.9% (calculated as iridium). The filter cake is collected and filtered to recycle the precious metal iridium.
[0038] Comparative Example 1
[0039] Commercially available hydrated iridium trichloride (10 g, containing 54% iridium, of which the content of tetravalent iridium is 1.37%) and 70 mL of deionized water were added to a reactor, and dissolved completely after adding at 85°C under argon protection. After isothermal heating at 85°C, 12 mL of formaldehyde was slowly added dropwise, and the isothermal reaction was continued for 2.5 hours after the addition. Hot filtration was performed, and 3 / 4 of the solvent was removed from the filtrate by rotary evaporation. The remaining 1 / 4 of the solution was dried under reduced pressure at 35°C for 40 hours to obtain 9.8 g of solid (containing 54.21% iridium, of which 0.37% tetravalent iridium), with a yield of 98.4% (calculated as iridium).
[0040] Comparative Example 2
[0041] Commercially available hydrated iridium trichloride (10 g, containing 54% iridium, of which the content of tetravalent iridium is 1.37%) and 70 mL of deionized water were added to a reactor, and dissolved completely after adding at 85°C under argon protection. After being kept constant at 85°C, 12 mL of hydrazine hydrate was slowly added dropwise, and the constant temperature reaction was continued for 2.5 hours after the addition. Hot filtration was performed, and 3 / 4 of the solvent was removed from the filtrate by rotary evaporation. The remaining 1 / 4 of the solution was dried under reduced pressure at 35°C for 40 hours to obtain 9.7 g of solid (containing 54.21% iridium, of which 0.27% tetravalent iridium), with a yield of 97.4% (calculated as iridium).
[0042] Performance Test:
[0043] The iridium content and the trivalent and tetravalent iridium content of the granular hydrated iridium trichloride obtained in Example 1 and Example 2 were tested by titration. The test results are shown in Table 1. It can be seen from Table 1 that the granular hydrated iridium trichloride prepared by the preparation method of the present invention does not contain tetravalent iridium, and the content of trivalent iridium is basically maintained at about 54.2%.
[0044] Table 1 Test of iridium metal content in hydrated iridium trichloride particles / % (mass fraction)
[0045]
[0046]
[0047] The metal impurity content of the granular hydrated iridium trichloride obtained in Example 1 and Example 2 was tested by ICP emission spectrometer, i.e., inductively coupled plasma spectrometer. The test results are shown in Table 2. From the test results, it can be seen that other metal impurities fully meet the requirements of the national industry product standard (YS / T643-2007).
[0048] Table 2 Chemical composition of metal impurities in hydrated iridium trichloride particles / % (mass fraction)
[0049]
[0050] Example 3
[0051] The iridium phosphorescent molecular material Ir(ppy)2(acac) is synthesized by using granular iridium trichloride hydrate that does not contain tetravalent iridium as a raw material. The specific steps are as follows:
[0052] Synthesis of dimer (ppy)4Ir2Cl4: Add 7.07g 2-phenylpyridine to a 250mL round-bottom flask, dissolve it with 120mL ethylene glycol monoethyl ether, add 7.16g granular iridium trichloride hydrate (prepared in Example 1, containing 54.21% iridium) and 40mL deionized water, degas three times, and heat to reflux at 120°C for 24h under nitrogen protection. Cool to room temperature, filter, wash the filter cake with acetone, deionized water, and acetone in turn, and dry. The obtained solid crude product can be directly used in the next step reaction to obtain 10.51g of yellow solid with a yield of 97.2%. Add a large amount of water to the filtrate, and filter the precipitated solid to recover the precious metal iridium.
[0053] Synthesis of complex Ir(ppy)2(acac): 6.53g of dimer (ppy)4Ir2Cl2, 3.23g of anhydrous sodium carbonate, and 3.14mL of acetylacetone were added to a 250mL three-necked flask, and then 180mL of ethylene glycol monoethyl ether was added, stirred, degassed three times, heated to reflux at 130°C under a nitrogen atmosphere, reacted for 3 hours under reflux and stirring, cooled to room temperature, poured the mixture into a large amount of water, filtered, dried the filter cake, and washed and separated the pure product with petroleum ether and dichloromethane (volume ratio of 1:1) during column separation. 7.12g of yellow solid was obtained by chromatographic column separation, with a yield of 97.4% and a purity of 99.84%. The HPLC chromatogram of the obtained Ir(ppy)2(acac) is shown in Figure 3 , HPLC data analysis is shown in Table 3.
[0054] Table 3 HPLC data analysis of Ir(ppy)2(acac)
[0055]
[0056]
[0057] Example 4
[0058] The iridium phosphorescent molecular material Ir(mpmq)2(tmd) is synthesized by using granular iridium trichloride hydrate that does not contain tetravalent iridium as a raw material. The specific steps are as follows:
[0059] Synthesis of dimer (mpmq) 4Ir2Cl4: Add 11.27g 2,3-dimethylphenyl-4-methylquinoline to a 250mL round-bottom flask, dissolve it with 120mL ethylene glycol monoethyl ether, add 7.16g (prepared in Example 2, containing 54.23% iridium) granular iridium trichloride hydrate without tetravalent iridium and 40mL deionized water, degas three times, heat and reflux at 120℃ for 24h under nitrogen protection. Cool to room temperature, filter, wash the filter cake with acetone, deionized water, acetone in turn, dry, and the obtained solid crude product can be directly used in the next step reaction to obtain 14.24g of red solid with a yield of 97.94%. Add a large amount of water to the filtrate, and filter the precipitated solid to recover the precious metal iridium.
[0060] Synthesis of complex Ir(mpmq)2(tmd): 8.78g of dimer (mpmq)4Ir2Cl2, 3.23g of anhydrous sodium carbonate, and 3.14mL of acetylacetone were added to a 250mL three-necked flask, and then 180mL of ethylene glycol monoethyl ether was added, stirred, degassed three times, heated to reflux at 130°C under a nitrogen atmosphere, reacted for 3 hours under reflux and stirring, cooled to room temperature, poured the mixture into a large amount of water, filtered, and the filter cake was dried. During the column separation process, petroleum ether and dichloromethane (volume ratio of 1:1) were used to wash and separate the pure product. 10.45g of red solid was obtained by chromatographic column separation, with a yield of 98.77% and a purity of 99.97%. The HPLC chromatogram of the obtained Ir(mpmq)2(tmd) is shown in Figure 4 , HPLC data analysis is shown in Table 4.
[0061] Table 4 HPLC data analysis of Ir(mpmq)2(tmd)
[0062] Peak Time / minute Area / (micropayment per second) area / % Peak 1 17.398 1530 0.01 Peak 2 17.458 5220 0.03 Peak 3 20.265 20627289 99.97
[0063] In summary, the present invention provides a method for preparing granular hydrated iridium trichloride without tetravalent iridium. The preparation method has few reaction steps, is easy to operate, has low requirements on equipment, is suitable for mass production, and the prepared granular hydrated iridium trichloride has a tetravalent iridium content of 0, which can provide high-quality raw materials for the field of OLED devices.
[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing granular iridium trichloride hydrate that does not contain tetravalent iridium, characterized in that: The following steps are involved: A hydrated iridium trichloride raw material, deionized water and methanol are mixed for reduction reaction, the obtained reaction solution is filtered, and the obtained filtrate is rotary evaporated and then dried to obtain granular hydrated iridium trichloride without tetravalent iridium; the content of tetravalent iridium in the hydrated iridium trichloride raw material is 1-2wt%.
2. The preparation method according to claim 1, characterized in that: The usage ratio of the hydrated iridium trichloride raw material and deionized water is 1g:(6-12)mL.
3. The preparation method according to claim 1, characterized in that: The usage ratio of the hydrated iridium trichloride raw material and methanol is 1 g: (1.0-1.6) mL.
4. The preparation method according to claim 1, characterized in that: The method of mixing hydrated iridium trichloride raw material, deionized water and methanol comprises: firstly dissolving hydrated iridium trichloride raw material in deionized water, and then adding methanol.
5. The preparation method according to claim 4, characterized in that: The dissolving temperature is 80-100°C.
6. The preparation method according to claim 1, characterized in that: The temperature of the reduction reaction is 75-95° C., and the reaction time is 2-4 hours.
7. The preparation method according to claim 1, characterized in that: The volume of the remaining solution after the rotary evaporation is 1 / 3 to 1 / 5 of the initial volume of the deionized water.
8. The preparation method according to claim 1, characterized in that: The drying is reduced pressure drying, the temperature of the reduced pressure drying is 30 to 50° C., and the time is 24 to 48 hours.
9. The preparation method according to claim 1, characterized in that: The filtration is hot filtration; a solid is obtained after the filtration, and the precious metal iridium in the solid is recovered.