Heterometallic organic complex ltg-rucex and preparation method and application thereof

Abstract

The application discloses an organic complex of different metals LTG-RuCe and a preparation method and application thereof, and belongs to the technical field of catalysts. The preparation method of the organic complex of different metals LTG-RuCe comprises the following steps: synthesizing a ligand HL by using methyl formylbenzoate, 2-acetylpyridine, ethanol, potassium hydroxide and ammonia water; synthesizing a ligand [Ru(HL)2]·(PF6)2 by using trichlororuthenium, the ligand HL, methanol, potassium hydroxide and HPF6; and synthesizing the organic complex of different metals LTG-RuCe by using cerium nitrate hexahydrate, the ligand [Ru(HL)2]·(PF6)2 and N,N-dimethylformamide. The organic complex of different metals LTG-RuCe synthesized by the application has high CO2 catalytic activity, good repeatability and a structure which is not easy to collapse; and the method for preparing the organic complex of different metals provided by the application has high yield and strong operability.

Description

Technical Field

[0001] This invention relates to a complex, its preparation method and application, specifically to the heterometallic organometallic complex LTG-RuCe, its preparation method and application, belonging to the field of catalyst technology. Background Technology

[0002] Excessive carbon dioxide (CO2) emissions have caused serious environmental problems. The green and efficient development and utilization of CO2, and the efficient conversion of CO2 into high-value-added chemicals, are considered the most promising ways to achieve clean production and sustainable energy development in the future. This is crucial for achieving a carbon-neutral economy.

[0003] In recent years, many methods have been developed for the efficient storage and conversion of CO2. Among them, cycloaddition of CO2 with epoxides and direct reduction of CO2 to valuable chemicals such as formic acid are two promising approaches, both of which can convert CO2 into a variety of chemical substances. However, due to the high stability of CO2 molecules, activating CO2 requires a large amount of energy. Therefore, developing effective artificial catalysts to activate and convert CO2 is crucial.

[0004] Heterometallic organometallic complexes are generally more novel and structurally diverse than single-metal organometallic complexes, exhibiting properties of two or more different metals. Therefore, they hold greater application potential in the fabrication of optical conversion instruments and bimetallic crystal functional materials. However, due to the large radii of rare-earth ions, their interactions are typically weak, making it difficult to achieve good performance. But the overall performance of the complex is improved when other metals are introduced. In recent years, heterometallic organometallic complexes have received increasing attention and research in the field of catalysis due to their excellent thermal and chemical stability.

[0005] Currently, most artificial catalysts synthesized in the laboratory contain only one metal. In the field of catalysis, since the combination of different metal ions has a synergistic catalytic effect, developing a heterometallic catalyst with high catalytic activity has become an urgent problem for those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a heterometallic organometallic complex with high CO2 catalytic activity, good reproducibility, and a structure that is not easily collapsed, as well as a method for preparing the heterometallic organometallic complex with high yield and strong operability, and also provides two applications of the heterometallic organometallic complex.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The preparation method of the heterometallic organometallic complex LTG-RuCe includes the following steps:

[0009] (1) Synthesis of ligand HL: Methyl p-formylbenzoate, 2-acetylpyridine, ethanol, potassium hydroxide and ammonia are mixed and reacted at room temperature. Preferably, the molar ratio of methyl p-formylbenzoate to 2-acetylpyridine is 1:2.

[0010] (2) Synthesis of ligand [Ru(HL)2]·(PF6)2: Ruthenium trichloride, ligand HL and methanol are mixed and reacted at 80°C. Then potassium hydroxide is added to continue the reaction. After rotary evaporation of the solvent, a crude product is obtained. The crude product is washed with acetone and dissolved in DMF. HPF6 is added and filtered to obtain ligand [Ru(HL)2]·(PF6)2. Preferably, the molar ratio of ruthenium trichloride to ligand HL is 1:2.

[0011] (3) Synthesis of heterometallic organometallic complex LTG-RuCe: Cerium nitrate hexahydrate, ligand [Ru(HL)2]·(PF6)2 and N,N-dimethylformamide are mixed and reacted at 120°C. Preferably, the molar ratio of cerium nitrate hexahydrate to ligand [Ru(HL)2]·(PF6)2 is 7:1.

[0012] (4) Post-processing: After the reaction mixture is cooled, it is filtered to obtain crystals and filtrate. The crystals are washed and dried to obtain the heterometallic organometallic complex LTG-RuCe.

[0013] The structural formula of ligand HL is as follows:

[0014]

[0015] The structural formula of the ligand [Ru(HL)2]·(PF6)2 is as follows:

[0016]

[0017] An heterometallic organometallic complex, LTG-RuCe, was prepared by the aforementioned method, with the general formula [RuCe(NO3)3DMF(HL)2]2DMF and the following unit cell parameters: α=107.323(3)°, β=105.666(3)°, γ=94.589(4)°.

[0018] The aforementioned heterometallic organometallic complex LTG-RuCe is used as a catalyst in the catalytic cycloaddition reaction of carbon dioxide and in the catalytic reduction of carbon dioxide to formic acid.

[0019] The advantages of this invention are:

[0020] (1) In this invention, the ligand HL is assembled with Ru(III) and Ce(III) ions to successfully synthesize the heterometallic organometallic complex LTG-RuCe containing two different metals. Compared with other complexes, this heterometallic organometallic complex has high CO2 catalytic activity, good reproducibility, and its structure is not easily collapsed (it has good thermal stability). It is a good catalyst for catalyzing CO2 cycloaddition reaction and CO2 reduction to formic acid reaction.

[0021] (2) The synthesis of ligand HL in this invention is carried out at room temperature. The synthesis process is simple, highly operable, can be scaled up in batches, and has good repeatability.

[0022] (3) When synthesizing the heterometallic organometallic complex LTG-RuCe using the method provided by the present invention, a high yield (70%) can be obtained. Attached Figure Description

[0023] Figure 1 This is the powder X-ray diffraction pattern of the heterometallic organometallic complex LTG-RuCe;

[0024] Figure 2 This is the infrared spectrum of the heterometallic organometallic complex LTG-RuCe;

[0025] Figure 3 It is the product obtained by the cycloaddition of CO2 catalyzed by the heterometallic organometallic complex LTG-RuCe. 1 H NMR spectrum;

[0026] Figure 4 This is an ion chromatogram of the product obtained by CO2 reduction to formic acid catalyzed by the heterometallic organometallic complex LTG-RuCe;

[0027] Figure 5 This is a powder X-ray diffraction pattern of CO2 cycloaddition reaction catalyzed by the heterometallic organometallic complex LTG-RuCe;

[0028] Figure 6 This is the thermogravimetric analysis spectrum of the heterometallic organometallic complex LTG-RuCe. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] I. Preparation of the heterometallic organometallic complex LTG-RuCe

[0031] 1. Synthetic ligand HL

[0032] The structural formula of ligand HL is as follows:

[0033]

[0034] The specific method for synthesizing ligand HL is as follows:

[0035] 15 mol of methyl p-formylbenzoate, 30 mol of 2-acetylpyridine, 60 mol of potassium hydroxide and 60 mol of ammonia were ground and mixed and placed in a round-bottom flask. 250 mL of ethanol was added and the mixture was reacted at room temperature for 7 days to synthesize ligand HL.

[0036] 2. Synthetic ligand [Ru(HL)2]·(PF6)2

[0037] The structural formula of the ligand [Ru(HL)2]·(PF6)2 is as follows:

[0038]

[0039] The specific method for synthesizing the ligand [Ru(HL)2]·(PF6)2 is as follows:

[0040] 0.5 mmol of ruthenium trichloride (RuCl3) and 0.99 mmol of ligand HL were mixed in a round-bottom flask, and 10 mL of methanol was added. The mixture was reacted at 80 °C for 24 h. Then, 3.4 mmol of potassium hydroxide (KOH) was added, and the reaction was continued at 80 °C for another 2 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was washed with acetone, dissolved in N,N-dimethylformamide (DMF), and finally, 1 mL of saturated HPF6 solution was added, resulting in the precipitation of a red precipitate. After filtration, the ligand [Ru(HL)2]·(PF6)2 was obtained. The ligand [Ru(HL)2]·(PF6)2 was a red solid.

[0041] 3. Synthesis of the heterometallic organometallic complex LTG-RuCe

[0042] The general formula for the heterometallic organometallic complex LTG-RuCe is:

[0043] [RuCe(NO3)3DMF(HL)2]2DMF

[0044] The specific method for synthesizing the heterometallic organometallic complex LTG-RuCe is as follows:

[0045] 0.01 mmol of ligand [Ru(HL)2]·(PF6)2 was added to 2.5 mL of DMF and sonicated for 5 min. Then, 0.07 mmol of cerium nitrate hexahydrate (Ce(NO3)3·6H2O) was added and mixed, and sonicated for 10 min. Then, 500 mg of o-fluorobenzoic acid was added and sonicated for 5 min. After the mixture was completely dissolved, the solution was transferred to a reaction vessel and placed in an oven at 120 °C for 3 days to synthesize the heterometallic organometallic complex LTG-RuCe.

[0046] 4. Post-processing

[0047] After the reaction mixture cooled, it was filtered to obtain red crystals and filtrate. The red crystals were washed three times with 20 mL of DMF, then three times with 20 mL of acetonitrile, and finally dried to obtain the final product—the heterometallic organometallic complex LTG-RuCe. The final product was a red powder with a yield of 70.0%.

[0048] II. Characterization of the heterometallic organometallic complex LTG-RuCe

[0049] 1. Single-crystal X-ray diffraction analysis

[0050] The prepared heterometallic organometallic complex LTG-RuCe was characterized by single-crystal X-ray diffraction.

[0051] Diffraction data for the heterometallic organometallic complex LTG-RuCe were collected on a D8 ADVANCE diffractometer using graphite-monochromated copper target X-rays (Cu Kα) with continuous scanning in the range of 3.1° to 50°.

[0052] The powder X-ray diffraction pattern of the obtained heterometallic organometallic complex LTG-RuCe is shown in the figure. Figure 1 .

[0053] Depend on Figure 1 It can be seen that the peak position of the heterometallic organometallic complex LTG-RuCe synthesized in this invention matches the peak position of the simulated heterometallic organometallic complex LTG-RuCe, proving that the heterometallic organometallic complex LTG-RuCe was successfully synthesized in this invention.

[0054] The crystallographic data of the heterometallic organometallic complex LTG-RuCe synthesized in this invention are shown in Table 1.

[0055] Table 1. Crystallographic data of the heterometallic organometallic complex LTG-RuCe

[0056]

[0057]

[0058] a R=Σ(||F0|-|F C ||) / Σ|F0|; b wR=[Σw(|F0| 2 -|F C | 2 ) 2 / Σw(F0 2 )] 1 / 2

[0059] 2. Infrared spectroscopy analysis

[0060] A NEXUS 670 spectrometer was used, with potassium bromide pellets (KBr) as the substrate, in the range of 400-4000 cm⁻¹. -1 Infrared spectra of the heterometallic organic complex LTG-RuCe were detected within the specified range.

[0061] The infrared spectrum of the obtained heterometallic organometallic complex LTG-RuCe is shown in the figure. Figure 2 .Depend on Figure 2 It can be seen that at 3085cm -1 Location, 1691cm -1 Location, 1471cm -1 Location, 1384cm -1 Location, 1105cm -1 Location, 792cm -1 Location, 681cm -1 637cm -1 At this point, the peak shapes of [Ru(HL)2]·(PF6)2 and LTG-RuCe are basically consistent, while the wavenumber at 3500 cm⁻¹ is 3500 cm⁻¹. -1 The disappearance of the peak at 1698 cm⁻¹ indicates that the OH group of the ligand [Ru(HL)₂]·(PF₆)₂carboxylic acid has coordinated with the metal ion, while the wavenumber is 1698 cm⁻¹. -1 The disappearance of the peak at the point indicates that the C=O of the ligand [Ru(HL)2]·(PF6)2 carboxylic acid has coordinated with the metal ion, which also indicates that LTG-RuCe has been successfully prepared.

[0062] III. Applications of the heterometallic organometallic complex LTG-RuCe

[0063] 1. Catalyzing CO2 cycloaddition reaction

[0064] The heterometallic organometallic complex LTG-RuCe was used as a catalyst to catalyze the CO2 cycloaddition reaction.

[0065] The method for CO2 cycloaddition catalyzed by the heterometallic organometallic complex LTG-RuCe specifically includes the following steps:

[0066] (1) Without adding any organic sacrificial agent, 0.008 mmol of the newly prepared heterometallic organic complex LTG-RuCe, 10 mmol of epoxy compound (epoxy styrene) and 4 mL of acetonitrile were added to a quartz reactor with magnetic particles.

[0067] (2) Seal the quartz reactor and connect it to the CO2 cylinder. First, replace the air in the quartz reactor with CO2 gas, repeat three times, and then fill it with CO2 at the required pressure.

[0068] (3) Use a 300W xenon lamp as an external light source. The external light source illuminates the inside of the quartz reactor through the quartz window at the top of the quartz reactor. Start the stirrer and stir continuously for 24 hours.

[0069] (4) After the reaction is complete, stop stirring and take an appropriate amount of sample for testing. 1 ¹H NMR is used to determine the yield of the reaction.

[0070] The obtained sample 1 H NMR see Figure 3 .Depend on Figure 3 As can be seen in the figure, a is the substrate peak and b is the product peak. By calculating the integral area, the yield of the product obtained by the cycloaddition of CO2 catalyzed by the heterometallic organometallic complex LTG-RuCe prepared in this invention is 92%.

[0071] 2. Catalytic CO2 reduction to formic acid production reaction

[0072] The heterometallic organic complex LTG-RuCe was used as a catalyst to catalyze the CO2 reduction of formic acid.

[0073] The method for CO2 reduction to formic acid catalyzed by the heterometallic organometallic complex LTG-RuCe specifically includes the following steps:

[0074] (1) The newly prepared heterometallic organic complex LTG-RuCe was soaked in acetonitrile for 3 days, and the acetonitrile was changed twice a day to remove the influence of possible adsorbed substances on the catalyst activity.

[0075] (2) Disperse 0.008 mmol of the heterometallic organic complex LTG-RuCe into 40 mL of acetonitrile, add 5 mL of triethanolamine as an organic sacrificial agent, and then transfer it into a 250 mL quartz reactor. Add a reflux water device, seal and stir, continuously bubble high-purity CO2 into the quartz reactor for 30 min, and continuously remove the gas in the quartz reactor to remove the gaseous oxygen and dissolved oxygen in the water remaining in the quartz reactor. Seal the quartz reactor, and then slowly introduce CO2 into the quartz reactor.

[0076] (3) Use a 300W xenon lamp as an external light source. The external light source illuminates the inside of the quartz reactor through the quartz window at the top of the quartz reactor. Start the stirrer and stir continuously for 6 hours.

[0077] (4) After the reaction is complete, stop stirring, take an appropriate amount of sample, and use ion chromatography with sodium carbonate and sodium bicarbonate as eluent to detect the content of formic acid.

[0078] The ion chromatography of the obtained sample is shown in the figure. Figure 4 .Depend on Figure 4 It can be seen that the production of formic acid increases with the extension of time.

[0079] Calculations show that the heterometallic organometallic complex LTG-RuCe prepared in this invention catalyzes the reduction of CO2 to formic acid, achieving an average formic acid conversion rate of 81 μmol / g. -1 h -1 .

[0080] It is evident that the heterometallic organic complex LTG-RuCe prepared in this invention exhibits high CO2 catalytic activity.

[0081] IV. Other properties of the heterometallic organometallic complex LTG-RuCe

[0082] 1. Repeatability

[0083] Powder X-ray diffraction (PXRD) was performed on the powder obtained after the heterometallic organometallic complex LTG-RuCe underwent a cycloaddition reaction with CO2. The PXRD pattern of the obtained heterometallic organometallic complex LTG-RuCe is shown in the figure. Figure 5 .

[0084] Depend on Figure 5 It can be seen that the powder X-ray diffraction patterns before and after the reaction are basically consistent, indicating that the heterometallic organometallic complex LTG-RuCe prepared in this invention has good reproducibility and can maintain structural stability after repeated use.

[0085] 2. Thermal stability

[0086] The thermogravimetric analysis (TGA) of the obtained heterometallic organometallic complex LTG-RuCe was performed in the temperature range of 30 °C to 800 °C. The obtained TGA spectra are shown below. Figure 6 .

[0087] Depend on Figure 6 It can be seen that the residual mass of the heterometallic organometallic complex LTG-RuCe is close to 50% after the measurement, indicating that the heterometallic organometallic complex LTG-RuCe prepared in this invention has good thermal stability and its structure is not easy to collapse.

[0088] It should be noted that the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the protection scope of this invention.

Claims

1. Use of a heterometallic organometallic complex LTG-RuCe as a catalyst in catalyzing a carbon dioxide cycloaddition reaction, characterized in that, The general formula of the heterometallic organic complex LTG-RuCe is [RuCe(NO3)3DMF(L)2]2DMF, and the cell parameters are as follows: a=12.9541(13)Å, b=14.1758(16)Å, c=16.3320(16)Å, alpha=107.323(3)°, beta=105.666(3)°, gamma=94.589(4)°, wherein the structural formula of the ligand L is as follows: 。

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