Alkylamine iridium complex, synthesis method and application thereof

Abstract

The present invention discloses an alkylamine iridium complex, a synthesis method and an application thereof, wherein the molecular formula thereof is [Ir III (R3N) n (NH3) 6‑n ]Cl3 or [Ir III (R4R'N2) n (NH3) 6‑2n ]Cl3, where n is an integer from 1 to 6. The preparation method comprises: 1) weighing ammonium chloroiridate and placing it in a sealed container, introducing NH3 (g), and obtaining an off-white hexaammineiridium trichloride through a gas-solid reaction; 2) slowly adding an alcoholic solution of an alkylamine dropwise to a flask containing solid hexaammineiridium chloride, heating and stirring, and obtaining an alkylamineiridium complex after the reaction. Applications include: use in the preparation of iridium nanomaterials, use as a precursor for the preparation of iridium nanomaterials, or use as a raw material for the synthesis of other alkylamineiridium compounds. The method of the present invention solves the problems of difficult to control iridium nanometer size and uneven dispersion in the prior art. Using the designed and synthesized alkylamineiridium complex, a chemical reduction method can achieve controllable preparation of iridium nanomaterials.

Description

Technical Field

[0001] The invention relates to an alkylamine iridium complex, a synthesis method and application thereof, and belongs to the fields of chemistry and chemical engineering and nano-catalytic materials. Background Art

[0002] Green hydrogen can be used both as an energy carrier and as a promising sustainable chemical fuel, and is considered a key factor in the decarbonization of the global economy.

[0003] Research has found that proton exchange membrane water electrolyzers (PEMWEs) are becoming an ideal material for green hydrogen production due to their high power density and rapid load tracking capabilities. As a key anode material, iridium nanomaterials occupy a key position in PEMWEs due to their strong stability, high activity, low overpotential, and excellent hydrogen adsorption free energy. Furthermore, iridium nanomaterials possess excellent properties such as a high melting point (2443°C), excellent oxidation resistance, electrical conductivity, biocompatibility, and low resistivity, demonstrating their outstanding performance in a wide range of fields, including fuel cells, sensors, automotive catalysis, medical treatment, environmental protection, and chemical synthesis. Therefore, with the advancement of technology and increasing industrial demand, the preparation of high-performance iridium nanoparticles using green and environmentally friendly methods is an urgent challenge. Therefore, the green preparation of iridium nanomaterials will be a highly innovative and challenging research area, with significant room for development both in academic research and practical applications.

[0004] Currently, the commonly used precursor is only IrCl3 [1-5] 、H2IrCl6 [6] 、IrCl4 [7] 、K2IrCl6 [8] , iridium acetylacetonate [9] Compounds such as iridium and iridium phosphate are extremely rare and cannot meet the rapid development of the iridium industry. In the preparation of iridium nanomaterials, surfactants, stabilizers, and other substances are often added to improve their structure and dispersion. These substances not only interfere with their performance but also introduce unwanted impurities, increasing the difficulty of impurity removal and operation. Therefore, surfactant-free and well-dispersed iridium nanoparticles should become a research focus. Based on this starting point, we discovered that the new iridium complex not only meets our precursor requirements, but also has extremely important practical significance for enriching the variety of iridium compounds and optimizing the preparation of iridium nanomaterials.

[0005] The above-mentioned references [1-9] are:

[0006] [1]CN115815617A;

[0007] [2]CN116174737A;

[0008] [3]CN114029504A;

[0009] [4] Cui Malin. Research on the preparation, properties and application of precious metal iridium nanomaterials in the field of analysis and detection[D]. Jiangnan University, 2017.

[0010] [5] Quinson J, Kacenauskaite L, Schroeder J, Simonsen SB, Theil Kuhn L, Vosch T, Arenz M. UV-induced syntheses of surfactant-free precious metalnanoparticles in alkaline methanol and ethanol[J]. Nanoscale Advances, 2020, 2(6): 2288.

[0011] [6]CN103056387A;

[0012] [7]CN116117155A;

[0013] [8] Borisov RV, Belousov OV, Zhizhaev AM, Kirik SD, Mikhlin YL. Characterization of Metallic Iridium Nanoparticles Synthesized underHydrothermal Conditions[J]. Inorganic Materials, 2022, 58(2):215.

[0014] [9]CN113894288A. Summary of the Invention

[0015] In view of this, the purpose of the present invention is to solve the current bottleneck problems such as easy agglomeration of iridium nanoparticles, serious interference from surfactants, and limited variety of iridium sources, and to provide a method for synthesizing an alkylamine iridium complex that can overcome the above problems and its use as a precursor in the preparation of iridium nanomaterials.

[0016] In order to achieve the above object, the present invention provides an alkylamine iridium complex, the molecular formula of which is [Ir III (R3N) n (NH3) 6-n ]Cl3 or [Ir III (R4R'N2) n (NH3) 6-2n ]Cl3, wherein n is an integer from 1 to 6.

[0017] Furthermore, the internal alkylamine ligand is a tertiary amine R3N or R4R'N2, and the corresponding structure is:

[0018]

[0019] The present invention also provides a method for synthesizing the above-mentioned alkylamine iridium complex and its application in preparing iridium nanomaterials, which comprises the following three steps:

[0020]

[0021] (1) Step 1: Weigh a certain amount of ammonium chloroiridate (NH4)3Ir III Cl6 is placed in a sealed container, and NH3(g) is introduced. Under the conditions of reaction temperature of 100℃~150℃, reaction time ≥24h, and NH3(g) pressure ≥6.67kPa, a gas-solid reaction is performed to obtain off-white hexaammineiridium trichloride;

[0022] (2) Step 2: Slowly add the alcohol solution of alkylamine dropwise into the flask containing solid hexaammineiridium chloride, with the molar ratio of iridium to alkylamine being 1:1.2-10, and heat and stir the reaction at a temperature of 40-80°C for 6-18 hours to obtain an alkylamineiridium complex;

[0023] Furthermore, the molecular formula of the alkylamine iridium complex is [Ir III (R3N) n (NH3) 6-n ]Cl3 and [Ir III (R4R'N2) n (NH3) 6-2n ]Cl3, wherein n is an integer from 1 to 6;

[0024] Furthermore, the inner alkylamine ligands are tertiary amines R3N and R4R'N2, and the corresponding structures are:

[0025]

[0026] (3) Dissolve the synthesized alkylamine iridium complex in a low-grade alcohol or formic acid under low-temperature conditions, introduce nitrogen to displace the air in the reaction system, then add a certain amount of iodine I2 fine particles, slowly raise the temperature to 60°C, and continue stirring until black flocs are observed, i.e., iridium nanomaterials. Continue the reaction for 6 hours, and obtain iridium nanomaterials of uniform size through filtration, washing, and freeze-drying. The method of the present invention solves the problem of difficult to control iridium nanometer size and uneven dispersion in the prior art. By using the designed and synthesized alkylamine iridium complex, controllable preparation of iridium nanomaterials can be achieved through chemical reduction.

[0027] Furthermore, the lower alcohols are: methanol, ethanol, propanol and butanol;

[0028] Furthermore, the lower alcohol serves as both a reducing agent and a solvent, and I2 serves as a reaction reagent, wherein the molar ratio of iridium to elemental iodine I2 is 1:1.5-9.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] (1) Compared to the traditional chemical reduction method for preparing iridium nanomaterials, the present invention utilizes a designed iridium complex internal structure to construct tertiary amine ligands R3N and R4R'N2, iodine I2 particles, and a reducing solvent system to prepare uniformly sized Ir nanomaterials. The preparation process does not require the addition of surfactants, is simple to operate, and is low-cost, making it suitable for large-scale applications.

[0031] (2) The present invention can prepare a variety of alkylamine iridium complexes with different structures by changing the synthesis conditions, thereby realizing the controllable preparation of iridium nanomaterials;

[0032] (3) Based on the structural characteristics of the alkylamine iridium complex, the present invention uses iodine particles I2 + methanol or formic acid as a reducing solvent, which can effectively prevent the agglomeration of nanomaterials and solve the problems of uneven size and difficult to control morphology of traditional preparation of iridium nanoparticles. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 : Schematic diagram of the reaction process of the alkylamine iridium complex and iridium nanomaterial prepared by the present invention.

[0034] Figure 2 : N2- adsorption-desorption curve of iridium nanomaterial prepared in Application Example 1-(1).

[0035] Figure 3 TEM test image of iridium nanomaterial prepared in application example 1-(1)

[0036] Figure 4 : Particle size distribution diagram of iridium nanomaterial prepared in Application Example 1-(1).

[0037] Figure 5 : XPS spectrum of iridium nanomaterials prepared in Application Example 1-(1). DETAILED DESCRIPTION

[0038] Example 1:

[0039] The complex 1([Ir III The synthesis of (Et3N)2(NH3)4]Cl3) comprises:

[0040] Step 1: Weigh 100mg (NH4)3Ir IIICl6 was placed in a sealed tube container, NH3 (g) was introduced, the pressure in the tube was maintained at ≥6.67 kPa, the temperature was gradually raised to 120 ° C, the gas-solid reaction was maintained for 24 h, and after cooling to room temperature, 82 mg of off-white solid [Ir III (NH3)6]Cl6, with a yield of about 71.4%.

[0041] Step 2: Slowly add a mixed solution of 37.6 mg (0.372 mmol) of triethylamine and 100 mL of ethanol dropwise to a solution containing 50 mg (0.124 mmol) of [Ir III (NH3)6]Cl6 solid was placed in a flask, stirred evenly, and then heated to 60℃ for 6h. After the reaction was complete, it was cooled to room temperature, washed with ethanol several times, and dried at 45℃ for 6h. 38mg of white solid [Ir III (Et3N)2(NH3)4]Cl3, with a yield of about 53.7%.

[0042] [Ir III (Et3N)2(NH3)4]Cl3 was subjected to relevant characterization tests, and the results are as follows:

[0043] (1) Elemental analysis:

[0044] Ir N Cl C Measured value 33.60％ 14.72％ 18.58％ 25.27％ Theoretical value 33.80％ 14.77％ 18.73％ 25.32％

[0045] (2)IR(cm -1 ,KBr):1356(ms,δ(NH3)),1342(vs,ν(NH3)),489(w,ν(Ir-NH3)),312(ms,ν(Ir-Cl) ),1276 / 1102(ms,δ(CN)),3445(w,ν(NH)),2987(ws,ν(-CH3)),2940(s,ν(-CH2-));

[0046] (3) 13 C NMR(CDCl3,ppm):15.3(-CH3), 34.1(-CH2-N)

[0047] (4) HREI-MS: m / z 569.720 [M+H] + ([Ir III (Et3N)2(NH3)4]Cl 3, 568.720)

[0048] The characterization results show that the [Ir III (Et3N)2(NH3)4]Cl3 was successfully prepared.

[0049] Application example 1-(1):

[0050] The complex 1([Ir III (Et3N)2(NH3)4]Cl3) for the preparation of iridium nanomaterials

[0051] Weigh 100 mg (0.176 mmol) [Ir III (Et3N)2(NH3)4]Cl3 was completely dissolved in 150mL of methanol. After N2 was passed through the system for 30 minutes to expel the air in the system, 67mg (0.264mmol) of fine I2 particles were slowly added. The temperature was slowly raised to 60°C and stirring was continued until a black flocculent precipitate was observed. Stirring was then continued for another 6h until the reaction was complete. The waste liquid was filtered to remove the waste liquid, and the black solid was repeatedly washed with water and ethanol several times. Finally, 27mg of black iridium nanoparticles were obtained after freeze-drying with a yield of about 80%.

[0052] Application example 1-(2):

[0053] The complex 1([Ir III (Et3N)2(NH3)4]Cl3) is used in the compound [Ir III Preparation of (Et3N)2(NH3)4](NO3)3

[0054] Weigh 100 mg (0.176 mmol) [Ir III (Et3N)2(NH3)4]Cl3 is completely dissolved in ethanol and reacts with OH - Type ion exchange resin, respectively, with 0.05mol / L and 0.10mol / L NaOH solution elution, repeat this operation 3-5 times, with AgNO3 test effluent Cl - , until no Cl is detected - The collected effluent was evaporated and concentrated to 20 mL, and then neutralized with 30% nitric acid. The obtained white solid was washed with 15% nitric acid and ethanol in turn, and then vacuum dried at 50°C to obtain 52 mg [Ir III (Et3N)2(NH3)4](NO3)3 white crystals, yield 52%.

[0055] [Ir III (Et3N)2(NH3)4](NO3)3 were characterized and the results are as follows:

[0056] (1) Elemental analysis:

[0057] Ir N Measured value 29.27％ 14.98％ Theoretical value 29.65％ 15.12％

[0058] (2)IR(cm -1 ,KBr):484(w,ν(Ir-NH3)), 823(ms,NO3- ),1270(ms,δ(CN)),1337(vs,ν(NH3)),1383(vs,NO3 - ),2973(ws,ν(-CH3)),3464(w,ν(NH)),

[0059] The characterization results show that the [Ir III Successful preparation of (Et3N)2(NH3)4](NO3)3.

[0060] Example 2 to Example 7:

[0061] According to the method of Example 1, [Ir III (R3N) n (NH3) 6-n ]Cl3 and [Ir III (R4R'N2) n (NH3) 6-n ]Cl3 compound, wherein the preparation conditions of step 1 are exactly the same, the difference lies in the reaction conditions in step 2, the specific conditions are as follows:

[0062]

[0063]

[0064] Application Example 2-Application Example 7:

[0065] Iridium nanomaterials were prepared according to the method of Application Example 1. The steps were basically the same, except that the molar ratio of iridium to elemental I2 was different. The specific conditions and results are as follows:

[0066]

[0067] 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An alkylamine iridium complex, characterized in that The molecular formula is [Ir III (R3N) n (NH3) 6-n ]Cl3 or [Ir III (R4R'N2) n (NH3) 6-2n ]Cl3, wherein n is an integer from 1 to 6; its internal alkylamine ligand is a tertiary amine R3N or R4R'N2, and its corresponding structure is: 。 2. A method for synthesizing an alkylamine iridium complex according to claim 1, characterized in that: The following steps are involved: Step 1: Weigh a certain amount of ammonium chloroiridate (NH4)3Ir III Cl6 is placed in a sealed tube container, and NH3 gas is introduced to obtain gray-white hexaammineiridium trichloride through gas-solid reaction; Step 2: Then, slowly add the alcohol solution of alkylamine dropwise into the flask containing solid hexaammineiridium chloride, heat and stir, and react for a certain period of time to obtain the alkylamineiridium complex.

3. The synthesis method according to claim 2, wherein The parameters set in the sealed tube in step 1 are: reaction temperature 100°C~150°C, reaction time ≥24h, NH3 gas pressure ≥6.67 kPa.

4. The synthesis method according to claim 2 or 3, characterized in that The reaction conditions in step 2 are: heating temperature 40-80° C., reaction time 6-18 h, and a molar ratio of iridium to alkylamine of 1:1.2-10.

5. Use of an alkylamine iridium complex according to claim 1 in preparing an iridium nanomaterial, the preparation steps comprising: The alkylamine iridium complex is dissolved in ice-cold lower alcohol or formic acid under low temperature conditions, and after nitrogen is introduced to replace the air in the reaction system, a certain amount of iodine I2 fine particles is added, and the temperature is slowly raised to 60°C and continuously stirred until black flocs are observed, i.e., iridium nanomaterials. The reaction is continued for 6 hours, and iridium nanomaterials with uniform size are obtained by filtration, washing, and freeze-drying. The lower alcohol includes any one of methanol, ethanol, propanol and butanol.

6. The use according to claim 5, characterized in that The lower alcohol serves as both a reducing agent and a solvent.

7. The use according to any one of claims 5 to 6, characterized in that: The I2 is a reaction reagent, wherein the molar ratio of iridium to elemental iodine I2 is 1:1.5~9.

8. Use of an alkylamine iridium complex according to claim 1 as a raw material for synthesizing other alkylamine iridium compounds, wherein the reaction process is: 。

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