A bipyridyloxyxanthene ligand-based mononuclear rhenium complex, a preparation method and application thereof

Abstract

The application discloses a kind of bipyridine oxanthrene as ligand mononuclear rhenium complex and its preparation method and application.The molecular formula of mononuclear rhenium complex with bipyridine oxanthrene as ligand provided by the application is 4-bibpyRe(CO)3Cl, and the crystal thereof belongs to triclinic system, space group is P-1, and cell parameter is the method for synthesizing mononuclear rhenium complex in the application is to mix ligand 4-bibpy and chloropentacarbonylrhenium, then add toluene under argon atmosphere, stir at normal temperature after reaction, and the light yellow precipitate obtained can be washed and dried after reaction.The method for synthesizing mononuclear rhenium complex in the application has the advantages of simple process, mild reaction condition, simple product purification treatment method, etc.The mononuclear rhenium complex with bipyridine oxanthrene as ligand synthesized in the application has good catalytic activity for photocatalytic reduction of carbon dioxide under normal temperature and pressure conditions, and conversion number (TON) can reach 1206, and has good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of metal complexes, and particularly relates to a mononuclear rhenium complex with bispyridineoxanthracene as a ligand, its preparation method and application. Background Technology

[0002] Since the Industrial Revolution, with the massive use of fossil fuels, greenhouse gas emissions have continuously increased, and the current concentration of carbon dioxide (CO2) in the atmosphere exceeds 415 ppm (415 mg / L, 0.0415%). The accumulation of large amounts of CO2 in the atmosphere will cause increasingly serious environmental pollution, global warming, and energy crises. Therefore, CO2 emission reduction and resource utilization have attracted widespread global attention. In nature, CO2 is also an important carbon resource; for example, green plants, algae, and certain bacteria can absorb energy from sunlight and then use it to drive water oxidation and CO2 reduction, forming carbohydrates and oxygen, thus converting solar energy into chemical energy stored in carbohydrates. Therefore, simulating natural photosynthesis and constructing artificial photosynthesis systems to convert CO2 into high-value-added chemicals or liquid fuels is one of the most ideal ways to solve problems such as environmental pollution, global warming, and energy crises.

[0003] In the 1980s, Lehn et al. synthesized the tricarbonyl bipyridine-rhenium complex Re(bpy)(CO)3X (bpy = 2,2′-bipyridine; X = Cl, Br) by reacting bipyridine with tricarbonyl rhenium. The synthesized rhenium complex can efficiently and selectively photocatalytically reduce CO2 to CO (Jeannot Hawecker, Jean-Marie Lehn and Raymond Ziessel, Efficient photochemical reduction of CO2 to CO by visible light irradiation of systems containing Re(bipy)(CO)3X or Ru(bipy)3). 2+ –Co 2+Combinations as homogeneous catalysts[J]. J. Chem. Soc., Chem. Commun., 1983, 536-538.). Since then, the photo / electrocatalytic reduction of CO2 by the tricarbonyl diamine rhenium complex Re(N^N)(CO)3X (N^N = diamine ligand) has attracted great attention from researchers (GoSahara and Osamu Ishitani, Efficient Photocatalysts for CO2 Reduction[J]. Inorg. Chem. 2015, 54, 5096-5104). However, the current application of tricarbonyl diamine rhenium complex in CO2 photocatalysis still faces problems such as complex catalyst preparation methods and low catalytic efficiency. Summary of the Invention

[0004] Therefore, the first objective of this invention is to provide a photocatalytic carbon dioxide reduction catalyst with good catalytic activity, namely, a mononuclear rhenium complex 4-bibpyRe(CO)3Cl with bispyridineoxane as a ligand.

[0005] A second objective of this invention is to provide a method for preparing the above-mentioned mononuclear rhenium complex with bispyridine oxanthracene as a ligand.

[0006] A third objective of this invention is to provide the application of the above-mentioned mononuclear rhenium complex with bispyridineoxanthracene as a ligand as a catalyst.

[0007] Therefore, the technical solution provided by the present invention is as follows:

[0008] A mononuclear rhenium complex with bis-bipyridine oxanthracene as a ligand, the complex having the molecular formula 4-bibpyRe(CO)3Cl; wherein 4-bibpy represents 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand; the complex is crystallized in a triclinic system with space group P-1 and cell parameters of [missing information].

[0009] A method for synthesizing mononuclear rhenium complexes using bispyridineoxanthracene as ligands, specifically comprising the following steps:

[0010] Under an inert atmosphere, 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand and pentacarbonyl rhenium chloride were mixed and added to a solvent. After stirring the mixture, a pale yellow precipitate was obtained. The precipitate was washed with detergent and dried to prepare the mononuclear rhenium complex with bispyridine oxanthracene as the ligand.

[0011] Furthermore, the solvent is dried toluene.

[0012] Furthermore, the inert atmosphere is argon.

[0013] Furthermore, the detergent is toluene.

[0014] Furthermore, the drying method is vacuum drying.

[0015] Furthermore, the stirring reaction conditions are as follows: the reaction temperature is room temperature and the reaction time is 48 hours.

[0016] Furthermore, the molar ratio of the 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand to rhenium pentacarbonyl chloride is 1:1.

[0017] The above-mentioned mononuclear rhenium complexes with bispyridineoxanthracene as ligands are used in photocatalytic carbon dioxide reduction.

[0018] The beneficial effects of this invention are as follows:

[0019] 1) The method for synthesizing mononuclear rhenium complexes with bispyridine oxanthracene as ligand provided by the present invention is simple and efficient, with mild reaction conditions, no need for high temperature and high pressure, no need for special equipment, and is suitable for large-scale industrial production. The yield of mononuclear rhenium complexes can be as high as 83%.

[0020] 2) The purification method of the mononuclear rhenium complex with bispyridine oxanthracene as ligand provided by the present invention is simple. The product can be purified by washing the product with toluene to obtain a high-purity final product.

[0021] 3) The mononuclear rhenium complex synthesized in this invention, with dipyridineoxane as the ligand, exhibits excellent catalytic activity for photocatalytic carbon dioxide reduction under mild conditions, achieving a carbon monoxide conversion number (TON) of up to 1206 and a selectivity of 100%. This not only realizes the recycling of carbon dioxide but also provides an ideal artificial photosynthesis simulation system with promising prospects for industrial application. Attached Figure Description

[0022] Figure 1 The structural formula of the mononuclear rhenium complex with bispyridineoxanthracene as the ligand of the present invention is shown below.

[0023] Figure 2 This is a crystal structure diagram of the mononuclear rhenium complex with bispyridineoxanthracene as the ligand of the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should also be understood that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Specific mass, reaction time, temperature, process parameters, etc., in the examples are merely examples within a suitable range. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0025] The specific synthetic steps of the ligand 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine used in the embodiments of this invention are as follows:

[0026] 100 mg of 2,7-di-tert-butyl-9,9-dimethyloxanthracene-4,5-diboronic acid, 125 mg of 4-bromo-2,2'-bipyridine, 29 mg of tetraphenylphosphine palladium, and 53 mg of anhydrous sodium carbonate solid were weighed into 25 mL of Schlenk solution. Under argon protection, 10 mL of a methanol / water mixture (10:1 v / v) was added. The mixture was stirred and heated to 70 °C, then refluxed for 24 hours. Using dichloromethane / petroleum ether (4:1 v / v) as eluent, the resulting solid was purified by alumina column chromatography to obtain 125 mg of 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand (4-bibpy), with a yield of 79%. The prepared ligand was characterized by nuclear magnetic resonance (NMR), and the results are as follows: 1 H NMR (400MHz, CDCl3, ppm): δ8.50(d,2H,J=4.0Hz), 8.30(d,2H,J=8.0Hz), 8.13(d,2H,J=4.0Hz), 7.77 (t,2H,J=8.0Hz),7.51(s,2H),7.22(d,2H,J=4.0Hz),7.19-7.16(m,4H),1.77(s,6H),1.36(s,18H) and 13 C NMR (100MHz, CDCl3, ppm): δ155.97,155.24,148.72,148.25,146.90,145.76,145.15,136.54,129.91,12 6.84,125.49,124.29,123.24,123.13,121.86,121.18,77.32,77.00,76.68,34.90,34.57,32.46,31.51.

[0027] Example 1

[0028] The synthesis of the mononuclear rhenium complex of the present invention using bispyridineoxanthracene as a ligand includes the following steps:

[0029] 1) Synthesis of 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)-bis-2,2'-bipyridine mononuclear rhenium complex:

[0030] Weigh 63 mg of 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)-bis-2,2'-bipyridine ligand and 72 mg of pentacarbonyl rhenium chloride (I) in a two-necked round-bottom flask at a molar ratio of 1:1 and place them in the flask. The mixture is evacuated and purged with argon three times. 50 ml of dry toluene is added under argon atmosphere. The resulting mixture is stirred at room temperature for 48 hours to obtain a pale yellow precipitate. The pale yellow precipitate is washed twice with 10 ml of toluene as detergent and dried under vacuum to prepare the mononuclear rhenium complex 4-bibpyRe(CO)3Cl with bis-bipyridine oxanthracene as the ligand. Its structural formula is as follows: Figure 1 As shown. The obtained 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)-bis-2,2'-bipyridine mononuclear rhenium complex was characterized by high-resolution mass spectrometry, and the results are as follows: ESI-MS (m / z): calcd for: [M-Cl] + :901.2764;found:901.2758.calcdfor:[M-Cl+MeCN] + Found: 942.3029; found: 942.2987. High-resolution mass spectrometry results show that the molecular weight of the synthesized mononuclear rhenium complex is in good agreement with the theoretical molecular weight, proving that the synthesis and purification methods used are feasible.

[0031] Cultivation of 4-bibpyRe(CO)3Cl crystals: Single crystals of 4-bibpyRe(CO)3Cl can be obtained by slowly diffusing dichloromethane into a 4-bibpyRe(CO)3Cl acetonitrile solution at room temperature.

[0032] The crystals obtained above were characterized as follows:

[0033] Table 1

[0034]

[0035] (1) Structural characterization:

[0036] Select a single crystal with a regular shape and appropriate size, and place it in a Rigaku Oxford Diffraction Supernova DualSource single crystal diffractometer with graphite-monochromated Cu-Kα rays at 100.00(10) K. As the incident light source, within a certain range of θ Diffraction points were collected using a scanning method for structure analysis and correction. Non-hydrogen atoms were solved directly, and their coordinates and anisotropic thermal parameters were corrected using full-matrix least squares. For mixed hydrogen addition, isotropic thermal parameters were used for hydrogen atoms, and anisotropic thermal parameters were used for non-hydrogen atoms. Crystal structure analysis and correction were performed using the SHELXT (Sheldrick, 2015) and SHELXL-2015 (Sheldrick, 2015) packages, respectively. Detailed crystallographic and structural correction data are shown in Table 1. Figure 2 As shown.

[0037] The single-crystal structure analysis above shows that 4-bibpyRe(CO)3Cl belongs to the triclinic crystal system, with space group P-1 and cell parameters of [missing information].

[0038] Example 2

[0039] The experimental procedure for photocatalytic carbon dioxide reduction using the 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)-bis-2,2'-bipyridine mononuclear rhenium complex is as follows: 0.05 mmol of the 4,4”-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)-bis-2,2'-bipyridine mononuclear rhenium complex and 0.2 mmol of tris(2,6-bipyridine)ruthenium dichloride were respectively... 0.1 mol of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzimidazole, 0.1 mol of phenol, and 10 mL of carbon dioxide (1 atm) were added to 2 mL of acetonitrile solution. The resulting mixture was stirred thoroughly and irradiated under natural light for 3.5 hours. The final reactant was then analyzed by gas chromatography. The results showed that the final product was carbon monoxide with 100% selectivity and a TON (conversion number) as high as 1206.

[0040] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A mononuclear rhenium complex with bispyridineoxanthracene as a ligand, characterized in that, The molecular formula of the complex is 4-bibpyRe(CO)3Cl; wherein 4-bibpy represents 4,4''-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand; the crystal of the complex belongs to the triclinic crystal system, space group P-1, and the unit cell parameters are a = 12.3825 Å, b = 13.8329 Å, c = 15.2513 Å, V = 2173.3 Å. 3 .

2. A method for synthesizing a mononuclear rhenium complex using bispyridineoxanthracene as a ligand as described in claim 1, characterized in that, Specifically, the steps include the following: Under an inert atmosphere, 4,4''-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand and pentacarbonyl rhenium chloride were mixed and added to a solvent. The resulting mixture was stirred and reacted to obtain a pale yellow precipitate. The precipitate was washed with detergent and dried to prepare the mononuclear rhenium complex with bispyridine oxanthracene as the ligand. The inert atmosphere was argon. The stirring reaction conditions were: room temperature and 48 hours.

3. The method for synthesizing mononuclear rhenium complexes using bispyridineoxanthracene as ligands according to claim 2, characterized in that, The solvent is dried toluene.

4. The method for synthesizing mononuclear rhenium complexes using bispyridineoxanthracene as ligands according to claim 2, characterized in that, The detergent is toluene.

5. The method for synthesizing mononuclear rhenium complexes using bispyridineoxanthracene as ligands according to claim 2, characterized in that, The drying method described is vacuum drying.

6. The method for synthesizing mononuclear rhenium complexes using bispyridineoxanthracene as ligands according to claim 2, characterized in that, The molar ratio of the 4,4''-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)bis-2,2'-bipyridine ligand to rhenium pentacarbonyl chloride is 1:

1.

7. The application of the mononuclear rhenium complex with bispyridineoxanthracene as a ligand as described in claim 1, or the mononuclear rhenium complex prepared by the preparation method according to claims 2-6, in photocatalytic carbon dioxide reduction, characterized in that... The experimental procedure is as follows: 4,4''-(2,7-di-tert-butyl-9,9-dimethyl-9H-oxanthracene-4,5)-bis-2,2'-bipyridine mononuclear rhenium complex, tris(2,6-bipyridine) dichloride, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzimidic acid, phenol, and dioxide were added to an acetonitrile solution. After stirring the mixture thoroughly, it was irradiated under natural light for 3.5 hours.

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