Double-cap organotin carboxylate complex, preparation method and application thereof

Abstract

The present invention discloses a double-capped organotin carboxylate complex and its preparation method and application, belonging to the technical field of metal complexes. The double-capped organotin carboxylate complex is prepared by using meta-substituted benzoic acid as a ligand and organotin dimethyltin oxide as a substrate. The preparation method is simple to operate and has mild conditions. The double-capped organotin carboxylate complex of the present invention can be used as a photocatalyst for photocatalytic production of H2O2, and the photocatalytic production rate of H2O2 is as high as 4.93×10 3 μmol·g ‑1 ·h ‑1 , which is comparable to the catalytic performance of the photocatalyst with the highest reported H2O2 production rate in the existing literature and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of metal complexes, and particularly relates to a double-capped organotin carboxylate complex, a preparation method thereof, and an application thereof. Background Art

[0002] The research on metal complexes in the field of photocatalytic production of hydrogen peroxide (H2O2) mainly stems from the fact that H2O2, as an important chemical, has a wide range of applications in multiple fields. H2O2 is an environmentally friendly oxidant and is widely used in disinfection, chemical production, sewage treatment, bleaching, etc. At the same time, it is also a relatively stable energy carrier and is easier to store than hydrogen energy. Traditional methods for manufacturing H2O2, such as the anthraquinone oxidation process, involve multiple-step hydrogenation reactions, which not only consume a large amount of energy but also produce polluting wastes. Therefore, there is an urgent need to develop greener, more economical, safer, and sustainable H2O2 production technologies. The photocatalytic production of H2O2 technology, that is, using water (H2O) and oxygen (O2) as raw materials and solar energy as the energy source, and synthesizing H2O2 through the action of a photocatalyst, is considered a promising green chemical process. This technology has the advantages of mild reaction conditions, simple and controllable operation, and no secondary pollution. In the process of photocatalytic production of H2O2, metal complexes play a key role as photocatalysts. Coordination compounds are directly formed by the coordination of metals and ligands. Their metal ligands and non-metal ligands can serve as oxidation or reduction sites respectively, which is conducive to shortening the distance between the two types of catalytic sites and improving the charge transfer efficiency between the metal and the ligand. Especially hollow multi-metal clusters can not only achieve metal-non-metal synergistic catalysis, but also their rich cavities are easy to be entered by substrates, increasing the contact between reaction molecules and catalytic active sites, thereby improving the photocatalytic performance. However, the efficiency of photocatalytic production of H2O2 is still limited by various factors, such as the small absorption range of the photocatalyst for sunlight, the low efficiency of photo-generated charge separation and migration, many side reactions, and poor selectivity of H2O2. Therefore, developing metal complex photocatalysts with high photocatalytic performance, high selectivity, and stability is the current research focus. H2O2, as an important chemical, has a wide range of application requirements, while traditional manufacturing methods have problems such as environmental pollution and energy consumption. The photocatalytic production of H2O2 technology, as a green, economical, safe, and sustainable H2O2 production technology, has attracted much attention, and metal complexes play an important role as photocatalysts in improving photocatalytic performance and H2O2 selectivity. Summary of the Invention

[0003] An object of the present invention is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0004] Another object of the present invention is to provide a double-capped organotin carboxylate complex, which is a novel complex with excellent crystallization properties and is easy to recrystallize and recover.

[0005] Another object of the present invention is to provide a method for preparing a double-capped organotin carboxylate complex, which is synthesized by a one-step self-assembly method, is easy to synthesize, and has a low synthesis cost.

[0006] Another object of the present invention is to provide the application of the double-capped organotin carboxylate complex as a photocatalyst in photocatalytic production of H2O2. The rate of photocatalytic production of H2O2 is comparable to that of the photocatalyst with the highest reported H2O2 production rate in the existing literature, and it has good application prospects.

[0007] To achieve these and other advantages in accordance with the present invention, there is provided a double-capped organotin carboxylate complex having the structure of the following formula (I):

[0008]

[0009] (I)

[0010] Wherein, R is an alkyl group or an alkoxy group.

[0011] Preferably, R is a methoxy group.

[0012] The object of the present invention can also be further achieved by a method for preparing a double-capped organotin carboxylate complex, which method comprises: adding a meta-substituted benzoic acid as a ligand, dimethyltin oxide, and an organic solvent into a reaction vessel, stirring and refluxing the reaction, cooling to room temperature after the reaction, filtering, and allowing the filtrate to evaporate naturally and standing for crystallization to obtain crystals of the double-capped organotin carboxylate complex.

[0013] Preferably, the mixing ratio of the ligand, dimethyltin oxide, and the organic solvent is 1 mmol : 1 mmol : 50 mL.

[0014] Preferably, the organic solvent is toluene or dioxane.

[0015] Preferably, the reflux reaction time is 10 h.

[0016] The object of the present invention can also be further achieved by the application of the double-capped organotin carboxylate complex as a photocatalyst in the catalytic production of H2O2.

[0017] Preferably, the rate of photocatalytic production of H2O2 is 4.93×10 3 μmol·g -1 ·h -1 。

[0018] The present invention has at least the following beneficial effects:

[0019] The double-capped organotin carboxylate complex of the present invention is a novel compound, and its preparation method is simple and the synthesis cost is low. The double-capped organotin carboxylate complex of the present invention can be used as a photocatalyst for photocatalytic production of H2O2, and the rate of photocatalytic production of H2O2 is 4.93×10 3 μmol·g -1 ·h -1 , which is equivalent to the rate of photocatalytic production of H2O2 of the photocatalyst with the highest reported rate of production of H2O2 in the existing literature, and has good application prospects.

[0020] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 IR spectrum of the double-capped organotin carboxylate complex prepared in Example 1 of the present invention;

[0022] Figure 2 1H NMR spectrum of the double-capped organotin carboxylate complex prepared in Example 1 of the present invention;

[0023] Figure 3 13C NMR spectrum of the double-capped organotin carboxylate complex prepared in Example 1 of the present invention;

[0024] Figure 4 119Sn NMR spectrum of the double-capped organotin carboxylate complex prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following further describes the present invention in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0026] It should be understood that the terms such as "having", "comprising" and "including" used herein do not preclude the presence or addition of one or more other elements or combinations thereof.

[0027] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0028] Main chemical reagents: dimethyltin oxide (purity ≥ 90%, Aladdin Reagent Co., Ltd.), m-methoxybenzoic acid (purity ≥ 98%, Aladdin Reagent Co., Ltd.), toluene (A.R., Aladdin Reagent Co., Ltd.), dioxane (A.R., Aladdin Reagent Co., Ltd.).

[0029] A double-capped organotin carboxylate complex having the structure of the following formula (I):

[0030]

[0031] (I)

[0032] Wherein, R is an alkyl group or an alkoxy group. The alkyl group is an alkyl group having 1 to 5 carbon atoms, and the alkoxy group is an alkoxy group having 1 to 5 carbon atoms.

[0033] Example 1

[0034] A double-capped organotin carboxylate complex having the following structure:

[0035]

[0036] The specific synthesis steps are as follows:

[0037] Method 1: Add 1 mmol of m-methoxybenzoic acid, 1 mmol of dimethyltin oxide, and 50 mL of toluene to a reaction vessel (150 mL round-bottom flask), stir and reflux for 10 h. After the reaction, cool to room temperature, filter, and allow the filtrate to evaporate naturally for 10 days to obtain colorless crystals, which are the double-capped organotin carboxylate complex.

[0038] Method 2: Add 1 mmol of m-methoxybenzoic acid, 1 mmol of dimethyltin oxide, and 50 mL of dioxane to a reaction vessel (150 mL round-bottom flask), stir and reflux for 10 h. After the reaction, cool to room temperature, filter, and evaporate the solvent of the filtrate under reduced pressure. Then, recrystallize with toluene to obtain colorless crystals, which are the double-capped organotin carboxylate complex. The yield is 82%, and the melting point is 185 °C. Elemental analysis was performed using a Perkin-Elmer PE2400 type carbon, hydrogen, and nitrogen elemental analyzer. The theoretical calculated values of elemental analysis for C 18 H 20 O6Sn: C, 47.93; H, 4.47; O, 21.28 %. The measured values: C, 47.90; H, 4.43; O, 21.27%. Infrared spectrum analysis IR (cm -1 ): v as (COO) 1555; v s (COO) 1405; v (Sn-C) 654; ν (Sn-O) 503. Nuclear magnetic resonance hydrogen spectrum analysis 1 H NMR (500 MHz, Chloroform- d )δ 7.77 (d, J J = 7.6 Hz, 2H, Ar-H), 7.66 (s, 2H, Ar-H), 7.40 (t, J J = 7.9 Hz, 2H, Ar-H), 7.16 (s, 2H, Ar-H), 3.90 (s, 6H, -OCH3), 1.17 (s, 6H, Sn-CH3). 1H NMR spectrum analysis 13 13C NMR (126 MHz, CDCl3, ppm) δ 13 13C NMR (126 MHz, Chloroform- d ) δ 176.23 (2C, COO), 159.57 (2C, Ar-C), 131.05 (2C, Ar-C), 129.39 (2C, Ar-C), 123.06 (2C, Ar-C), 120.39 (2C, Ar-C), 114.40 (2C, Ar-C), 55.50 (2C, -O-CH3), 4.70 (2C, Sn-CH3). 13C NMR spectrum analysis 119 119Sn NMR (187 MHz, CDCl3, ppm): - 120.80 ppm.

[0039] Among them, the IR spectrum of the double-capped organotin carboxylate complex is as Figure 1 shown, the 1H NMR spectrum is as Figure 2 shown, the 13C NMR spectrum is as Figure 3 shown, and the 119Sn NMR spectrum is as Figure 4 shown.

[0040] Comparative Example

[0041] A tetra-nuclear ladder-shaped organotin carboxylate complex has a structure of the following formula:

[0042]

[0043] The specific synthesis steps are as follows:

[0044] Method 1: Add 1 mmol of p-methoxybenzoic acid, 2 mmol of dimethyltin oxide, and 50 mL of toluene to a reaction vessel (150 mL round-bottom flask), stir and reflux for 10 h, cool to room temperature after the reaction, filter, and allow the filtrate to evaporate naturally for 8 days to obtain colorless crystals, which are the tetra-nuclear ladder-shaped organotin carboxylate complex.

[0045] Method 2: Add 1 mmol of p-methoxybenzoic acid, 2 mmol of dimethyltin oxide, and 50 mL of dioxane to a reaction vessel (150 mL round-bottom flask), stir and reflux for 10 h. After the reaction, cool to room temperature, filter, and evaporate the solvent of the filtrate under reduced pressure. Then, recrystallize with toluene to obtain colorless crystals, which are the tetranuclear ladder-shaped organotin carboxylate complex with a yield of 81% and a melting point of 175 °C. Elemental analysis was carried out using a Perkin-Elmer PE2400 type CHN elemental analyzer. The theoretical calculated values of the elements are C 24 H 38 O 10 Sn4: C, 29.98; O, 16.64; H, 3.98%. The measured values are: C, 29.94; O, 16.66; H, 3.96%. Infrared spectroscopy analysis IR (cm -1 ): v as (COO) 1712; v s (COO) 1598; v (Sn-C) 649; ν (Sn-O) 532. Nuclear magnetic resonance hydrogen spectrum analysis 1 H NMR (500 MHz, Chloroform- d , ppm) δ 8.10 (d, J =8.9 Hz, 4H, Ar-H), 6.96 (d, J = 8.9 Hz, 4H, Ar-H), 3.90 (s, 6H, -OCH3), 1.14(s, 24H, -CH3). Nuclear magnetic resonance carbon spectrum analysis 13 C NMR (126 MHz, CDCl3, ppm) δ 175.04(2C, COO),163.84 (2C, Ar-C), 132.61 (4C, Ar-C), 123.48 (2C, Ar-C), 113.63 (4C, Ar-C),55.44 (2C, -O-CH3), 13.47 (8C, Sn-CH3). Nuclear magnetic resonance tin spectrum analysis 119 Sn NMR(187 MHz,CDCl3,ppm): -124.27 ppm。

[0046] Among them, the crystal structure parameters of the tetranuclear ladder-shaped organotin carboxylate complex prepared in the comparative example are shown in Table 1 below.

[0047] Table 1. Single crystal structure parameters of the tetranuclear ladder-type organotin carboxylate complexes prepared in the comparative examples

[0048]

[0049] Example 2

[0050] The double-capped organotin carboxylate complex prepared in Example 1 and the tetranuclear ladder-type organotin carboxylate complex prepared in the comparative example were used as photocatalysts in the photocatalytic production of H2O2.

[0051] Photocatalytic production of H2O2 experiment:

[0052] Weigh 5 mg of the double-capped organotin carboxylate complex prepared in Example 1 or the tetranuclear ladder-type organotin carboxylate complex prepared in the comparative example as the photocatalyst, disperse it in 25 mL of deionized water, after ultrasonic treatment for 5 min, use O2 to purge for 20 min in the dark to dissolve sufficient oxygen. Turn on the light source, the reaction light source is a 425 nm LED light source (15 W), use a constant temperature water circulation system to control the reaction temperature, take 1 - 2 mL of the reaction solution from the photoreactor every 20 min, filter the reaction solution sample with a 0.22 µm nylon filter head, react for a total of 120 min to obtain 6 samples. Take 10 μL of the sample, add 90 μL of ultrapure water (dilute the sample concentration by 10 times), then add 0.5 mL each of 0.04 mol / L KI solution and 0.04 mol / L potassium hydrogen phthalate solution (dilute the sample concentration by 2 times again), react for 30 min, use ultrapure water as the blank sample, measure the absorbance at λ = 352 nm, and calculate the H2O2 concentration of the sample using the H2O2 standard curve.

[0053] Quantitative detection method of H2O2 (KI method):

[0054] Prepare 0.04 mol / L potassium iodide solution: Take 0.664 g of potassium iodide and make up the volume to 100 mL with distilled water.

[0055] Prepare 0.04 mol / L potassium hydrogen phthalate solution: Take 0.817 g of potassium hydrogen phthalate and make up the volume to 100 mL with distilled water.

[0056] The content of H2O2 was determined by potassium iodide titration method.

[0057] Potassium hydrogen phthalate was used as a buffer solution in the reaction to maintain the acidic environment of the system:

[0058] 1. Potassium hydrogen phthalate is a weak acid with a pKa value of 4.27. It can be used as a buffer to provide a stable weakly acidic buffer environment to maintain the pH stability of the reaction system, enabling the reaction to proceed under relatively stable conditions, which is conducive to ensuring the accuracy and repeatability of the reaction.

[0059] 2. Potassium hydrogen phthalate can also inhibit side reactions and prevent the disproportionation reaction of I2.

[0060] Detection principle:

[0061] Hydrogen peroxide is quantitatively calculated according to the following formula:

[0062] 2KI + H2O2 + 2H + → I2 + 2K + + 2H2O

[0063] KI is colorless, and the I2 solution is colored. The amount of I2 generated can calibrate the yield of H2O2.

[0064] Drawing of the H2O2 standard curve:

[0065] Prepare H2O2 solutions with concentrations of 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L, 0.05 mol / L, and 0.06 mol / L respectively. Take 1 mL of each solution and add 0.5 mL of 0.04 mol / L KI solution and 0.5 mL of 0.04 mol / L potassium hydrogen phthalate solution respectively. React for 20 min, and collect the absorbance at λ = 352 nm (I2 has the maximum absorption here) using a UV-visible spectrophotometer. The fitting formula for the absorbance-concentration standard curve of I2 is as follows:

[0066] A = 0.283 + 31.3C

[0067] Take 10 μL of the sample, add 90 μL of water (dilute the sample concentration by 10 times), then add 0.5 mL of 0.04 mol / L KI solution and 0.5 mL of 0.04 mol / L potassium hydrogen phthalate solution respectively (dilute the sample concentration by 2 times again). React for 30 min. The blank sample is 1 mL of ultrapure water + 0.5 mL of 0.04 mol / L KI solution + 0.5 mL of 0.04 mol / L potassium hydrogen phthalate solution. Measure the absorbance at λ = 352 nm, substitute it into the standard curve, and calculate the concentration of H2O2 in each sample.

[0068] Rate of H2O2 production = (μmol·g -1 ·h -1 );

[0069] In the formula, C×10 -3 : The amount of H2O2 in 1 mL of the sample (mol);

[0070] 25×10 -3 : The amount of H2O2 in 25 mL of water in the total reaction system (mol);

[0071] ×2: Dilute 2 times after sampling;

[0072] ×10: Dilute 10 times after sampling;

[0073] ×10 6 : Convert the unit to μmol;

[0074] 5×10 -3 : The mass of the photocatalyst (g);

[0075] 1h: The reaction time;

[0076] Experimental results of photocatalytic production of H2O2:

[0077] As shown in Tables 2 and 3 below.

[0078] Table 2. Results of the production of H2O2 using the double-capped organotin carboxylate complex prepared in Example 1 as a photocatalyst

[0079]

[0080] Table 3. Results of the production of H2O2 using the tetranuclear ladder-shaped organotin carboxylate complex prepared in the comparative example as a photocatalyst

[0081]

[0082] Calculated according to Table 2 above and the above formula:

[0083] Rate of H2O2 production = 4.93×10 3 μmol·g -1 ·h -1 .

[0084] Calculated according to Table 3 above and the above formula:

[0085] Rate of H2O2 production = 715.7 μmol·g -1 ·h -1 .

[0086] The double-capped organotin carboxylate complex prepared in Example 1 of the present invention has a novel complex structure. Using dimethyltin oxide and o-methoxybenzoic acid as raw materials, the ligand o-methoxybenzoic acid coordinates with tin atoms to form a specific double-capped organotin carboxylate complex structure. It is easy to synthesize, with low raw materials and synthesis costs, has optoelectronic properties, and can be used as a photocatalyst for photocatalytic production of H2O2. The rate of photocatalytic production of H2O2 is 4.93×10 3 h -1 μmol·g -1 ·h -1 , which is much higher than the rate of the complex as a photocatalyst for photocatalytic production of H2O2 in the comparative example. In addition, the double-capped organotin carboxylate complex prepared in Example 1 of the present invention has comparable catalytic performance to the photocatalyst with the highest reported H2O2 production rate in the existing literature. It has good application prospects. The photocatalyst with the highest reported H2O2 production rate in the existing literature is the SO3H-COF catalyst (Custom-Design of Strong Electron / Proton Extractor on COFs for EfficientPhotocatalytic H2O2Production, Angew. Chem. Int. Ed. 2024, 63 , e202320218), which has a H2O2 production rate of 4971 μmol·g -1 ·h -1 .

[0087] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the examples shown and described here.

Claims

1. A double-cap type organotin carboxylate complex, characterized in that, It has the structure of the following formula (I): （I） Among them, R is a methoxy group.

2. A method for preparing the double-capped organotin carboxylate complex as described in claim 1, characterized in that, It includes: Add m-methoxybenzoic acid as a ligand, dimethyltin oxide, and an organic solvent into a reaction vessel, stir and reflux the reaction. After the reaction, cool it to room temperature, filter, and let the filtrate evaporate naturally and stand for crystallization to obtain double-capped organotin carboxylate complex crystals.

3. The method according to claim 2, wherein The mixing ratio of the ligand, dimethyltin oxide, and the organic solvent is 1 mmol : 1 mmol : 50 mL.

4. The method according to claim 2, wherein The organic solvent is toluene or dioxane.

5. The method according to claim 2, wherein The reflux reaction time is 10 h.

6. Application of the double-capped organotin carboxylate complex as claimed in claim 1 as a photocatalyst in the catalytic production of H2O2.

7. Use of the double-capped organotin carboxylate complex as claimed in claim 6 as a photocatalyst in the catalytic production of H2O2, wherein the photocatalytic production rate of H2O2 is 4.93×10 3 μmol·g -1 ·h -1 .

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