A method for one-step synthesis of biomimetic water-splitting catalysts containing rare earth ions

Abstract

The application provides a method for one-step synthesis of a rare earth ion-containing biomimetic water splitting catalyst. The method of the application uses a trivalent manganese salt, a trivalent rare earth X salt, an organic carboxylic acid R1COOH, an amide group-containing small molecule and a tetrabutylammonium permanganate salt as raw materials, and efficiently synthesizes a Mn4XO4- or Mn4XO5- cluster under mild conditions through one-step reaction. Compared with the method disclosed in the literature, the synthesis method is simpler in operation, milder in reaction condition, cheaper in raw material and higher in product yield, and is more suitable for large-scale preparation of the cluster.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a one-step method for synthesizing Mn4XO4- or Mn4XO5- clusters of biomimetic water splitting catalysts containing rare earth ions. Background Technology

[0002] The process of using solar energy to split water, releasing oxygen and simultaneously producing hydrogen, is considered an ideal way to solve the energy crisis, environmental pollution, and greenhouse effect problems facing human society. Water molecules are highly thermally stable, and their efficient and safe splitting requires the presence of a catalyst. Currently, the lack of efficient, inexpensive, and environmentally friendly artificial water splitting catalysts is a key bottleneck preventing humans from achieving large-scale utilization of solar energy to split water and produce hydrogen.

[0003] The oxygen-evolving center (OEC) of photosynthesis is the only biocatalyst in nature capable of efficiently and safely catalyzing water splitting, formed through over 3 billion years of biological evolution. The structure and artificial synthesis of the OEC have long been a subject of great interest. Since the 21st century, researchers have successfully revealed through structural analysis of photosystem II in photosynthetic organisms that the OEC is an asymmetric Mn4CaO5- cluster composed of four manganese ions, one calcium ion, and five oxygen bridges. Its peripheral ligands are provided by seven amino acid residues (one imidazole group and six carboxylic acid groups) and four water molecules. Recent research has further discovered that one of the oxygen bridges in the OEC may directly participate in oxygen formation during the catalytic process. The elucidation of the OEC structure provides important evidence for the development of efficient and inexpensive biomimetic water splitting catalysts.

[0004] Synthesizing stable, inexpensive, and efficient biomimetic water splitting catalysts is an extremely challenging scientific problem. Patent ZL201510065238.7 discloses a water splitting catalyst containing a [Mn4CaO4] core structure, its preparation method, and its applications; Patent ZL201711059799.1 discloses a water splitting catalyst with a [Mn4SrO4] core structure, its preparation method, and its applications. These two patents respectively protect two cluster compounds having formulas A and B, as shown below.

[0005]

[0006] Recent studies have discovered these two types of alkaline earth metal ions (Ca... 2+ or Sr 2+ Biomimetic clusters are very sensitive to water and have poor stability in aqueous solutions, which severely restricts their large-scale application research.

[0007] To address the challenge of poor stability in biomimetic water splitting catalysts, in 2021 the inventors utilized rare earth metal ions (such as Y2)3+ Replace alkaline earth metal ions (Ca) 2+ or Sr 2+ The company developed a biomimetic water splitting catalyst containing rare earth ions, and disclosed the rare earth ion-containing Mn4XO4 catalyst in patent document CN 115710292 A. - Cluster compound (formula C) and Mn4XO5 - The clusters (Formula D) (where X is selected from at least one of scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium) have the structures shown below. The patent document describes a method for preparing these Mn4XO4-clusters using divalent manganese salts and rare earth ions to first prepare Mn3XO2-clusters; the Mn3XO2-clusters then react with an organic base to generate Mn4XO4-clusters through a rearrangement reaction; the Mn4XO4-clusters are then further reacted with water to finally obtain Mn4XO5-clusters. This preparation method is cumbersome, requires harsh conditions, and has a low yield. Meanwhile, the large number of byproducts makes it difficult to purify the final product Mn4XO4- or Mn4XO5- cluster compounds, which seriously affects the large-scale preparation and application of catalysts such as Mn4XO4- or Mn4XO5- cluster compounds.

[0008] Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a one-step, highly efficient method for synthesizing biomimetic water-splitting catalysts containing rare earth ions, specifically Mn4XO4- or Mn4XO5- clusters (where X is selected from the rare earth elements scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). The method uses trivalent manganese salts, trivalent rare earth X salts, organic carboxylic acids R1COOH, small molecules containing amide groups, and tetrabutylammonium permanganate as raw materials. Through a one-step reaction, Mn4XO4- or Mn4XO5- clusters are efficiently synthesized under mild conditions. Compared to methods disclosed in the literature, this synthesis method is simpler to operate, uses milder reaction conditions, uses inexpensive raw materials, and has a higher product yield, making it more suitable for large-scale preparation of clusters. Taking X as an example of yttrium, the one-step synthesis method of the present invention increases the yield of Mn4YO5-cluster compounds from less than 10% in the three-step method in the literature to 53% (based on Y); taking lanthanum as an example, the methods in previous literature or patents could not stably prepare Mn4LaO4-cluster compounds, while the one-step synthesis method of the present invention can achieve a yield of up to 60% for Mn4LaO4-cluster compounds and a yield of 50% for Mn4LaO5-cluster compounds (based on La).

[0010] This invention is achieved through the following technical solution:

[0011] A method for one-step synthesis of Mn4XO4- or Mn4XO5- cluster compounds includes: dissolving trivalent manganese salt, trivalent rare earth X salt and small molecules containing amide groups in acetonitrile, then adding organic carboxylic acid R1COOH and tetrabutylammonium permanganate to react, and then crystallizing to prepare Mn4XO4- cluster compounds;

[0012] Alternatively, small molecules containing amide groups can be added to the reaction solution after the reaction is complete, and then crystallized to prepare Mn4XO5-cluster compounds;

[0013] The core of the Mn4XO4-cluster compound contains four Mn ions and one rare earth X ion. 3+ The ions are connected by four μ-O bridges to form a [Mn4XO4] heteronuclear metal-oxygen cluster core, and the outer ligands of this core include nine R1COO ions. - And two neutral ligands (e.g., L1 and L2 in Formula 1, which are a neutral organic carboxylic acid R1COOH and a small molecule containing an amide group, respectively), the valence states of the four Mn ions in this cluster are +3, +3, +4, and +4, respectively; the structure of the Mn4XO4- cluster is shown in Formula 1 below:

[0014]

[0015] or,

[0016] The core of the Mn4XO5-cluster contains four Mn ions and one rare earth X ion. 3+ The ions are connected by five μ-O bridges to form a [Mn4XO5] heteronuclear metal-oxygen cluster core, which is surrounded by eight R1COO ligands. - And two neutral ligands L3 and L4 (such as small molecules containing amide groups); wherein the valence states of the four Mn ions are +3, +3, +4, and +4, respectively; the structure of the Mn4XO5-cluster compound is shown in Equation 2 below:

[0017]

[0018] Alternatively, the core of the Mn4XO4-cluster compound contains four Mn ions and one rare earth X ion. 3+ The ions are connected by four μ-O bridges to form a [Mn4XO4] heteronuclear metal-oxygen cluster core, and the outer ligands of this core include nine R1COO ions. - The cluster contains a neutral ligand and four Mn ions with valence states of +3, +3, +4, and +4, respectively. The structure of the Mn4XO4- cluster is shown in Equation 3 below.

[0019]

[0020] Wherein, X is selected from one of the rare earth elements scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium;

[0021] R1 is selected from the alkyl portion of the organic carboxylic acid R1COOH, and is C1. 1-5 alkyl;

[0022] The two neutral ligands L1 and L2 are organic carboxylic acids R1COOH or small molecules containing amide groups, respectively.

[0023] According to an embodiment of the present invention, the reaction temperature is 0~50°C, for example 30~40°C.

[0024] According to an embodiment of the present invention, X is +3.

[0025] According to an embodiment of the present invention, X is +3 yttrium or lanthanum.

[0026] In some specific embodiments of the present invention, the Mn4XO4-cluster compound is cluster compound 1, and the chemical formula of cluster compound 1 is C. 54 H 100 NO 25 Mn4La contains four Mn ions and one rare earth La ion in its core. 3+ The ions are connected by four μ-O bridges to form the [Mn4LaO4] heteronuclear metal-oxygen cluster core. The outer ligands of this core include nine pentovalerate anions, one neutral pentovalerate, and one DMA molecule. The valence states of the four Mn ions in this cluster are +3, +3, +4, and +4, respectively.

[0027] or,

[0028] The Mn4XO4- cluster compound is cluster compound 3, and the chemical formula of cluster compound 3 is C. 49 H 90 NO 23 Mn4Y contains four Mn ions and one rare earth Y ion in its core. 3+ The ions are connected by four μ-O bridges to form the [Mn4YO4] heteronuclear metal-oxygen cluster core. The core is surrounded by ligands including nine pentovatate anions and a neutral DMA molecule. In this cluster compound, the valence states of the four Mn ions are +3, +3, +4, and +4, respectively.

[0029] Alternatively, the Mn4XO4-cluster compound is cluster compound 5, and the chemical formula of cluster compound 5 is C. 52 H 96 NO 25 Mn4La contains four Mn ions and one rare earth La ion in its core. 3+The ions are connected by four μ-O bridges to form the core of the [Mn4LaO4] heteronuclear metal-oxygen cluster framework. The ligands surrounding this core include nine pentavalerate anions, one neutral pentavalerate molecule, and one neutral NMF molecule. The valence states of the four Mn ions in cluster 5 are +3, +3, +4, and +4, respectively.

[0030] In some specific embodiments of the present invention, the Mn4XO5-cluster compound is cluster compound 2, and the chemical formula of cluster compound 2 is C 48 H 91 N2O 23 Mn4La contains four Mn ions and one rare earth La ion in its core. 3+ These ions are connected by five μ-O bridges to form a [Mn4LaO5] heteronuclear metal-oxygen cluster core, the outer ligands of which include eight pivalate anions and two neutral DMA molecules; the valence states of the four Mn ions are +3, +3, +4, and +4, respectively; or,

[0031] The Mn4XO5 - The cluster compound is cluster compound 4, and the chemical formula of cluster compound 4 is C. 48 H 91 N2O 23 Mn4Y contains four Mn ions and one rare earth Y ion in its core. 3+ The ions are connected by five μ-O bridges to form a [Mn4YO5] heteronuclear metal-oxygen cluster framework. The core framework is surrounded by ligands including eight pivalate anions and two DMA molecules. The valence states of the four Mn ions in this cluster are +3, +3, +4, and +4, respectively.

[0032] According to an embodiment of the present invention, when synthesizing Mn4XO4-, the molar ratio of the organic carboxylic acid R1COOH, tetrabutylammonium permanganate, trivalent rare earth X salt, trivalent manganese salt, and small molecules containing amide groups is (10-120): (4-10):2: (1-3): (4-200), for example (20-100): (5-8):2: (1-3): (10-100), such as (60-100): (5-8):2: (1-3): (20-60); preferably 80:6:2:2:40 or 80:6:2:1:12.

[0033] According to an embodiment of the present invention, when synthesizing Mn4XO5-, the molar ratio of the raw material organic carboxylic acid R1COOH, tetrabutylammonium permanganate, trivalent rare earth X salt and trivalent manganese salt, and small molecules containing amide groups added before the reaction at 0-50°C is (10-120): (4-10): 2: (1-3): (4-200), for example (20-100): (5-8): 2: (1-3): (10-100), such as (60-100): (5-8): 2: (1-3): (20-60); preferably 80: 6: 2: 1: 12;

[0034] After the reaction is completed at 0-50℃, add small molecules containing amide groups at a molar ratio of (50-200), for example (60-180), or (60-160) times that of trivalent rare earth X salt to crystallize.

[0035] According to embodiments of the present invention, the organic carboxylic acid R1COOH can be acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, tert-valeric acid, or hexanoic acid. That is, R1 can be at least one of methyl (-CH3), ethyl (-C2H5), n-propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), n-butyl (-(CH2)3CH3), isobutyl (-CH2CH(CH3)2), tert-butyl (-C(CH3)3), n-pentyl (-(CH2)4CH3), etc.

[0036] In some specific embodiments of the present invention, the organic carboxylic acid R1COOH is pivalic acid.

[0037] According to an embodiment of the present invention, the trivalent rare earth X salt is selected from at least one of trifluoromethanesulfonate, nitrate, perchlorate, and carboxylate of the trivalent rare earth X ion; wherein the carboxylate of the rare earth ion contains a carboxylate anion (R1CO2). - The carboxylate anion has the aforementioned definition.

[0038] In some specific embodiments of the present invention, the trivalent rare earth X salt is lanthanum trifluoromethanesulfonate or yttrium trifluoromethanesulfonate.

[0039] According to an embodiment of the present invention, the trivalent manganese salt has the structural formula MnA3; wherein A is selected from the carboxylate anion (R1CO2). - ), chloride ions, ClO4 - NO3 - CF3SO3 - , acetylacetone anion; the carboxylate anion has the meaning as described above.

[0040] In some specific embodiments of the present invention, the trivalent manganese salt is trivalent manganese acetylacetone [Mn(acac)3].

[0041] According to an embodiment of the present invention, the small molecule containing the amide group is selected from one of N-methylformamide (NMF), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), N-methylacetamide (NMA) and acetamide (MA).

[0042] According to an embodiment of the present invention, the reaction temperature is 20~50°C, for example 35~45°C.

[0043] According to an embodiment of the present invention, the reaction time is 10 to 50 minutes, for example, 20 to 30 minutes.

[0044] According to an embodiment of the present invention, the crystallization is carried out at 0 to 5°C.

[0045] According to an embodiment of the present invention, the method further includes a step of filtering after the reaction is completed, and then crystallizing at 0-5°C. Attached Figure Description

[0046] Figure 1 The crystal structure diagram of cluster compound 1 [Mn4LaO4(C5H9O2)9(C5H9O2H)(DMA)] is shown.

[0047] Figure 2 The image shows the absorption spectrum of cluster 1 in 1,2-dichloroethane solution.

[0048] Figure 3 The crystal structure diagram of cluster compound 2 [Mn4LaO5H(C5H9O2)8(DMA)2].

[0049] Figure 4 The image shows the UV-Vis absorption spectrum of cluster 2 in 1,2-dichloroethane.

[0050] Figure 5 This is a graph showing the electrocatalytic performance of cluster compound 2 supported on the surface of a nano-ITO electrode. Among them, Figure 5 In the figure, A represents the cyclic voltammetric scan curves for ten consecutive cycles. Figure 5 B in the figure represents the electrochemical linear scan curve.

[0051] Figure 6 The crystal structure diagram of cluster compound 3 [Mn4YO4(C5H9O2)9(DMA)] is shown.

[0052] Figure 7 The image shows the UV-Vis absorption spectrum of cluster 3 in 1,2-dichloroethane.

[0053] Figure 8 The crystal structure diagram of cluster compound 4 [Mn4YO5H(C5H9O2)8(DMA)2].

[0054] Figure 9 The image shows the UV-Vis absorption spectrum of cluster 4 in 1,2-dichloroethane.

[0055] Figure 10 The crystal structure diagram of cluster compound 5 [Mn4LaO4(C5H9O2)9(C5H9O2H)(NMF)] is shown.

[0056] Figure 11 The image shows the UV-Vis absorption spectrum of cluster compound 5 in 1,2-dichloroethane. Detailed Implementation

[0057] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, specifically using rare earth element X as an example, with the most representative rare earth elements La and Y as examples. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0058] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0059] Example 1: Preparation method of cluster compound 1, Mn4LaO4(C5H9O2)9(C5H9O2H)(DMA)

[0060] Add lanthanum trifluoromethanesulfonate (1 mmol), manganese acetylacetone [Mn(acac)3] (0.5 mmol), N,N-dimethylacetamide (DMA) (6 mmol), pentyl acid (40 mmol), and tetrabutylammonium permanganate (3 mmol) to a 150 mL round-bottom flask, dissolve in approximately 40 mL of acetonitrile, react at 40 °C for 25 minutes, filter the resulting brown solution, and place at 0 °C. C crystallization. Black crystals precipitate after several days. The obtained crystals are collected, washed with cold acetonitrile, and dried under vacuum, with a yield of approximately 63% (based on La). 3+ (Number of moles of ions).

[0061] Cluster compound 1, with the chemical formula C 54 H 100 NO 25 Mn4La has the structure shown in Equation 1 (where X is La), and its core contains four Mn ions and one rare earth La. 3+The ions are connected by four μ-O bridges to form a [Mn4LaO4] heteronuclear metal-oxygen cluster core. The outer ligands of this core include nine tert-pentanoate anions, one neutral tert-pentanoic acid, and one DMA molecule (corresponding to Formula 1, R1 is tert-butyl, L1 is DMA, and L2 is a tert-pentanoic acid molecule). The valence states of the four Mn ions in this cluster are +3, +3, +4, and +4, respectively. Cluster 1 t Theoretical elemental analysis values ​​(%) for BuCO2H: C, 43.63; H, 6.83; N, 0.86; Experimental values ​​(%): C, 43.56; H, 6.82; N, 0.97.

[0062]

[0063] The crystal structure of cluster 1 is as follows Figure 1 As shown, for clarity, the core framework and ligands of cluster 1 are displayed as ball-and-stick structures and lines, respectively, while hydrogen atoms are omitted. The single-crystal parameters of cluster 1 are shown in Table 1.

[0064] The single crystal of cluster 1 belongs to the triclinic crystal system, space group 1. P -1, with unit cell parameters a = 11.4918(2) Å, b = 15.1080(3) Å, c = 23.3612(5) Å, and α = 101.133(2). , β = 92.684(2) , γ = 102.313(2) Z = 2, volume is 3871.64(14) Å 3 .

[0065] Table 1. Single crystal parameters of cluster 1

[0066]

[0067] The absorption spectrum of cluster 1 in 1,2-dichloroethane solution is as follows: Figure 2 As shown.

[0068] Example 2: Preparation method of cluster compound 2, Mn4LaO5H(C5H9O2)8(DMA)2

[0069] The same method as in Example 1 was used, except that after the reaction at 40 °C for 25 minutes, excess N,N-dimethylacetamide (DMA, 40 mmol) was added to the reaction solution, and then the mixture was placed at 0 °C for crystallization. Dark brown crystals precipitated after several days. The obtained crystals were collected and washed with n-hexane, with a yield of approximately 50% (based on La). 3+ (Number of moles of ions).

[0070] Cluster compound 2, chemical formula C 48 H 91 N2O 23 Mn4La has the structure shown in Equation 2 (where X is La), and its core contains four Mn ions and one rare earth La. 3+ The ions are connected by five μ-O bridges to form a [Mn4LaO5] heteronuclear metal-oxygen cluster core. The outer ligands of this core include eight tert-valerate anions and two neutral DMA molecules (corresponding to formula 2, R1 is tert-butyl, and L1 and L2 are both DMA molecules); the four Mn ions have valence states of +3, +3, +4, and +4, respectively. Elemental analysis of cluster 2: Theoretical values ​​(%): C, 40.52; H, 6.45; N, 1.97; Experimental values ​​(%): C, 40.58; H, 6.60; N, 1.77.

[0071]

[0072] The single-crystal structure of cluster 2 is as follows Figure 3 As shown, for clarity, the core framework and ligands of the cluster are shown in the form of ball-and-stick and lines, respectively, while all hydrogen atoms are omitted. The single-crystal parameters of cluster 2 are shown in Table 2.

[0073] The single crystal of cluster 2 belongs to the triclinic crystal system, with space group 2. P-1 The unit cell parameters are a = 11.9465(3) Å, b = 14.0068(3) Å, c = 24.1395(5) Å, and α = 85.242(2). , β = 77.292(2) , γ = 76.291(2) Z = 2, and the volume is 3826.09(16) Å. 3 .

[0074] Table 2. Single crystal parameters of cluster 2

[0075]

[0076] The UV-Vis absorption spectrum of cluster 2 in 1,2-dichloroethane solution is as follows: Figure 4 As shown.

[0077] The catalytic water splitting function of cluster 2 on the electrode surface was tested using a Metrohm PGSTAT302N electrochemical workstation. An integrated reaction cell was used. A three-electrode setup was employed, with the working electrode being an ITO-nanoITO electrode adsorbing cluster 2. The setup consisted of a 1*1 cm electrode. 2The nanoITO region contained 10 nmol Mn₄LaO₅H(DMA)₂ and was spin-coated with a 2% Nafion solution. The counter electrode was a platinum mesh electrode, and the reference electrode was a silver / silver nitrate electrode (the reference solution was an acetonitrile solution of 10 mM MgNO₃ and 100 mM LiClO₄). The electrolyte was an acetonitrile solution containing 100 mM LiClO₄, 100 mM DMF, and 1.2 M water (H₂O). The scan rate was 10 mV / s. Figure 5 These are the test results of the electrocatalytic performance of cluster compound 2 supported on the surface of a nano-ITO electrode. Among them, Figure 5 A is the voltammetric scan curve for ten consecutive cycles. Figure 5 A indicates that the catalytic current intensity given by cluster 2 in the water splitting reaction remains basically unchanged, which shows that the structure and performance of cluster 2 remain stable during the catalytic reaction. Figure 5 B is the electrochemical linear scan curve, compared to the control without a catalyst (dashed line).

[0078] Example 3: Preparation method of cluster compound 3, Mn4YO4(C5H9O2)9 (DMA)

[0079] Add 0.5 mmol of trivalent manganese acetylacetone [(Mn(acac)3], 1 mmol of yttrium trifluoromethanesulfonate, 6 mmol of N,N-dimethylacetamide (DMA), 40 mmol of tervaponic acid, and 3 mmol of tetrabutylammonium permanganate to a 150 mL round-bottom flask, dissolve in approximately 40 mL of acetonitrile, and react at 40 °C for 25 minutes. After filtration, the reaction solution is placed in a 0 °C container. C crystals form. Black crystals precipitate after about 2 weeks. The obtained crystals are collected, washed with cold acetonitrile, and dried under vacuum.

[0080] Cluster compound 3, chemical formula C 49 H 90 NO 23 Mn4Y has the structure shown in Equation 3, with its core containing four Mn ions and one rare earth Y ion. 3+ The ions are connected by four μ-O bridges to form the [Mn4YO4] heteronuclear metal-oxygen cluster core. The ligands surrounding this core include nine tert-valerate anions and a neutral DMA molecule (corresponding to R1 as tert-butyl and L1 as DMA molecule in Formula 3). In this cluster compound, the valence states of the four Mn ions are +3, +3, +4, and +4, respectively.

[0081]

[0082] The single-crystal structure of cluster 3 is as follows Figure 6As shown, for clarity, the core framework and ligands are displayed as ball-and-stick structures and lines, respectively, while hydrogen atoms are omitted. The single-crystal parameters of cluster 3 are shown in Table 3.

[0083] The single crystal of cluster 3 belongs to the triclinic crystal system, space group 3. P -1, with unit cell parameters a = 12.3868(3) Å, b = 13.9528(3) Å, c = 20.5181(4) Å, and α = 83.610(2). , β = 89.457(2) , γ = 70.065(2) Z = 2, and the volume is 3311.42(13) Å. 3 .

[0084] Table 3. Single crystal parameters of cluster 3

[0085]

[0086] The UV-Vis absorption spectrum of cluster 3 in 1,2-dichloroethane solution is as follows: Figure 7 As shown.

[0087] Example 4: Preparation method of cluster compound 4, Mn4YO5H(C5H9O2)8(DMA)2

[0088] Add 0.5 mmol of trivalent manganese acetylacetone [(Mn(acac)3], 1 mmol of yttrium trifluoromethanesulfonate, 6 mmol of N,N-dimethylacetamide (DMA), 40 mmol of tervamol, and 3 mmol of tetrabutylammonium permanganate to a 150 mL round-bottom flask. Dissolve these in approximately 40 mL of acetonitrile. After reacting at 40 °C for 25 minutes, add excess N,N-dimethylacetamide (80 mmol) to the reaction mixture. Filter and place at 0 °C. Crystallization occurred, and crystals precipitated approximately 2 weeks later. The obtained crystals were collected, washed with cold n-hexane, and dried under vacuum, with a yield of 53% (based on Y). 3+ (number of moles).

[0089] The chemical formula of cluster 4 is C 48 H 91 N2O 23 Mn4Y, elemental analysis theoretical values ​​(%): C, 41.99; H, 6.68; N, 2.04, experimental values ​​(%): C, 42.02; H, 6.70; N, 2.33.

[0090] Cluster compound 4 has the structure shown in Formula 2 (X is Y) 3+ (ion), whose core contains four Mn ions and one rare earth Y ion.3+ The ions are connected by five μ-O bridges to form a [Mn4YO5] heteronuclear metal-oxygen cluster framework. The outer ligands of this core framework include eight tert-valerate anions and two DMA molecules (corresponding to Formula 2, R1 is tert-butyl, and L1 and L2 are both DMA molecules). The valence states of the four Mn ions in this cluster are +3, +3, +4, and +4, respectively.

[0091] The single-crystal structure of cluster 4 is as follows Figure 8 As shown, for clarity, the core framework and ligands are displayed as ball-and-stick structures and lines, respectively, while hydrogen atoms are omitted. The single-crystal parameters of cluster 4 are shown in Table 4.

[0092] The single crystal of cluster 4 belongs to the tetragonal crystal system, space group 4. Pbca The unit cell parameters are a = 24.6696(2) Å, b = 20.9290(2) Å, c = 24.8321(2) Å, and α = 90. β = 90 γ = 90 Z = 2, volume is 12821.06(19) Å 3 .

[0093] Table 4. Single crystal parameters of cluster 4

[0094]

[0095] The UV-Vis absorption spectrum of cluster compound 4 in 1,2-dichloroethane solution is as follows: Figure 9 As shown.

[0096] Example 5: Preparation method of cluster compound 5, Mn4LaO4(C5H9O2)9(C5H9O2H)(NMF)

[0097] Add 0.5 mmol of trivalent manganese acetylacetone, 1 mmol of lanthanum trifluoromethanesulfonate, 6 mmol of N-methylformamide (NMF), 40 mmol of tervamol, and 3 mmol of tetrabutylammonium permanganate to a 150 mL round-bottom flask, dissolving them in approximately 40 mL of acetonitrile. React at 40 °C for 25 minutes. After filtration, the reaction solution is placed in a 0 °C container. C crystallization. Several days later, brownish-black crystals precipitated. The obtained crystals were collected, washed with cold acetonitrile, and dried under vacuum, with a yield of approximately 60% (based on La). 3+ (Number of moles of ions).

[0098] The chemical formula of cluster 5 is C 52 H 96 NO 25Mn4La has the structure shown in Equation 1 above (where X is La), and its core contains four Mn ions and one rare earth La. 3+ The ions are connected by four μ-O bridges to form the core of the [Mn4LaO4] heteronuclear metal-oxygen cluster framework. The ligands surrounding this core include nine tert-valerate anions, one neutral tert-valerate molecule, and one neutral NMF molecule (corresponding to formula 1, R1 is tert-butyl, L1 is tert-valerate molecule, and L2 is NMF molecule); the valence states of the four Mn ions in cluster 5 are +3, +3, +4, and +4, respectively.

[0099] The single-crystal structure of cluster 5 is as follows Figure 10 As shown, for clarity, its core framework and ligands are displayed as ball-and-stick structures and lines, respectively, while hydrogen atoms are omitted. The single-crystal parameters of cluster 5 are shown in Table 5.

[0100] The single crystal of cluster 5 belongs to the monoclinic crystal system, with space group 5. P 21, with unit cell parameters a = 14.3115(4) Å, b = 20.4059(5) Å, c = 15.1136(4) Å, and α = 90. β = 117.287 γ = 90 Z = 2, volume is 3922.6(2) Å 3 .

[0101] Table 5. Single crystal parameters of cluster 5

[0102]

[0103] The absorption spectrum of cluster compound 5 in 1,2-dichloroethane solution is as follows: Figure 11 As shown.

[0104] Comparative Example 1: The preparation method of the Mn4YO5H(C5H9O2)8(DMA)2 cluster compound (i.e., cluster compound 4 above) disclosed in patent document CN 115710292 A

[0105] First, add tetrabutylammonium permanganate (Bu) to a 100 ml round-bottom flask. n 4NMnO4, 4 mmol), yttrium trifluoromethanesulfonate (Y(CF3SO3)3, 1 mmol), manganese acetylacetone [Mn(acac)2, 1 mmol], and pentanoic acid [(CH3)3CCO2H, 40 mmol], at 80 After reacting in acetonitrile for 25 minutes, the reaction was stopped, a small amount of precipitate was removed by filtration, and the resulting brown mother liquor was allowed to stand for 2 minutes. C. Several days later, a brown synthetic intermediate was precipitated.

[0106] In the second step, the obtained intermediate was dissolved in dichloromethane and acetonitrile (volume ratio 1:2), and then 1% isoquinoline was added. After several days, brown crystals precipitated. The obtained crystals were collected, washed with n-hexane, and dried under vacuum to obtain the Mn4YO4(C5H9O2)9(C9H7N) cluster compound.

[0107] The third step involves dissolving the Mn4YO4(C5H9O2)9(C9H7N) cluster in dichloromethane and ethyl acetate (volume ratio 3:1), then adding 5% N,N-dimethylacetamide (volume ratio) and water (water to cluster molar ratio 2:1). The reaction is carried out at 40°C for 5 minutes. The reaction product is filtered to remove a small amount of precipitate. The reaction solution is allowed to stand for several days, after which brown crystals precipitate. The obtained crystals are collected, washed with n-hexane, and dried under vacuum, with a yield of 9.88% (based on the molar number of Y ions). Molecular formula: H 91 C 48 N2O 23 Mn4Y. Elemental analysis theoretical values ​​(%): C, 39.97; H, 6.41; N, 2.33; Experimental values ​​(%): C, 40.08; H, 6.39; N, 2.33.

[0108] In summary, the preparation method of this invention can achieve the preparation of biomimetic water splitting catalyst Mn4XO4- or Mn4XO5- clusters in a one-step reaction. Compared with the methods disclosed in the literature, the method of this invention is simpler and more efficient, with milder reaction conditions and a significantly improved product yield. Post-processing only requires a simple crystallization operation to obtain the corresponding single crystals. Therefore, the preparation method of this invention has certain application prospects.

[0109] The exemplary embodiments of the present invention have been described above. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for one-step synthesis of Mn4X04" or Mn4X05" cluster compounds, wherein, Comprise: Mn4XO4- cluster is prepared by dissolving trivalent manganese salt, trivalent rare earth X salt and small molecule containing amide group in acetonitrile, then adding organic carboxylic acid R1COOH and tetrabutylammonium permanganate salt and reacting at 0-50℃, and then crystallizing; Or, small molecule containing amide group is added to the reaction liquid after the reaction in the above step is completed, and then crystallization is carried out to prepare Mn4XO5- cluster; The core of the Mn4XO4-cluster contains four Mn ions and one rare earth X 3+ ion, which are connected into a [Mn4XO4] heteronuclear metal-oxygen cluster core by four μ-O bridges, the peripheral ligands of the core include nine R1COO - , one neutral organic carboxylic acid R1COOH and one small molecule containing amide group, the valence states of the four Mn ions in the cluster are +3, +3, +4, +4 respectively; the structure of the Mn4XO4-cluster is shown in the following formula 1: Formula 1 In formula 1, L1 and L2 are neutral organic carboxylic acid R1COOH and small molecule containing amide group, respectively; Alternatively, the Mn4X05- cluster core contains four Mn ions and one rare earth X 3+ ions, which are linked by five μ-0 bridges into a [Mn4X05] heteronuclear metal oxo-cluster core, the periphery ligands of which include eight R1COO - and two neutral small molecules containing amide groups; wherein the valence states of the four Mn ions are +3, +3, +4, +4, respectively; the structure of the Mn4X05- cluster is shown in the following formula 2: Formula 2 In formula 2, L3 and L4 are two neutral ligands; Or, The core of the Mn4X04- cluster contains four Mn ions and one rare earth X 3+ ions, which are connected by four μ-0 bridges into a [Mn4X04] heteronuclear metal oxygen cluster core, the peripheral ligands of which include nine R1COO - and one neutral ligand, the valence states of the four Mn ions in the cluster are +3, +3, +4, +4 respectively; the structure of the Mn4X04- cluster is shown in the following formula 3: Formula 3 Wherein, X is selected from one of the rare earth elements scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium; R1is selected from the alkyl moiety of the organic carboxylic acid R1COOH, is C 1-5 alkyl; The two neutral ligands L1 and L2 are organic carboxylic acid R1COOH or small molecule containing amide group, respectively; MnA3; wherein A is selected from the group consisting of carboxylate anions, chloride, CIO4 - , NO3 - , CF3SO3 - , acetylacetonate; the carboxylate anions are selected from the group consisting of formate, acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, pivalate or hexanoate; The small molecule containing amide group is selected from one of N-methyl formamide, N, N-dimethyl formamide, N, N-dimethyl acetamide, N-methyl acetamide and acetamide; The trivalent rare earth X salt is selected from one of triflate, nitrate, perchlorate and carboxylate of trivalent rare earth X ion; wherein the carboxylate of rare earth ion contains carboxylate anion, and the carboxylate anion is selected from formate, acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, tert-pentanoate or hexanoate; When synthesizing Mn4XO4-, the molar ratio of the organic carboxylic acid R1COOH, tetrabutylammonium permanganate salt, trivalent rare earth X salt, trivalent manganese salt and small molecule containing amide group is (10-120) : (4-10) : 2 : (1-3) : (4-200) before the reaction at 0-50℃; When synthesizing Mn4XO5-, the molar ratio of the raw materials organic carboxylic acid R1COOH, tetrabutylammonium permanganate salt, trivalent rare earth X salt, trivalent manganese salt and small molecule containing amide group before the reaction at 0-50℃ is (10-120) : (4-10) : 2 : (1-3) : (4-200) ; After the reaction at 0-50℃ is completed, small molecule containing amide group in (50-200) times of the molar amount of trivalent rare earth X salt is added for crystallization.

2. The method of claim 1, wherein, The Mn4X04-cluster is cluster 1, which has a chemical formula of C 54 H 100 NO 25 Mn4La, which has a core containing four Mn ions and one rare earth La 3+ ion, which are connected by four μ-0 bridges into a [Mn4La04] heteronuclear metal-oxygen cluster core, the peripheral ligands of which include nine pivalate anions, one neutral pivalic acid and one DMA molecule; the valence states of the four Mn ions in the cluster are +3, +3, +4, +4, respectively. Or, The Mn4X04-cluster is cluster 3, which has a chemical formula of C 49 H 90 NO 23 Mn4Y, which has a core containing four Mn ions and one rare earth Y 3+ ion, which are connected by four μ-0 bridges into a [Mn4YO4] heteronuclear metal oxygen cluster core, the core peripheral ligand including nine tert-pentanoate anions and one neutral DMA molecule, in which the valence states of the four Mn ions are +3, +3, +4, +4, respectively; Or, The Mn4X04-cluster is cluster 5, which has a chemical formula of C 52 H 96 NO 25 Mn4La, which has a core containing four Mn ions and one rare earth La 3+ ion, which are connected by four μ-0 bridges into a [Mn4La04] heteronuclear metal oxo-cluster skeleton core, the core peripheral ligands include nine tert-pentanoate anions, one neutral tert-pentanoic acid molecule and one neutral NMF molecule; the valence states of the four Mn ions in cluster 5 are +3, +3, +4, +4, respectively. Or, The Mn4X05-cluster is cluster 2, which has a chemical formula of C 48 H 91 N2O 23 Mn4La, which has a core containing four Mn ions and one rare earth La 3+ ion, which are connected by five μ-0 bridges into a [Mn4LaO5] heteronuclear metal oxo-cluster core, the periphery ligands of which include eight tert-pentanoate anions and two neutral DMA molecules; wherein the valence states of the four Mn ions are +3, +3, +4, +4, respectively. Or, The Mn4X05-cluster is cluster 4, which has a chemical formula of C 48 H 91 N2O 23 Mn4Y, which has a core containing four Mn ions and one rare earth Y 3+ ion, which are connected by five μ-0 bridges into a [Mn4YO5] heteronuclear metal oxo-cluster skeleton, the peripheral ligands of the core skeleton include eight tert-pentanoate anions and two DMA molecules, the valence states of the four Mn ions in the cluster are +3, +3, +4, +4 respectively.

3. The method of claim 1, wherein, The crystallization is crystallization at 0-5℃.

4. The method of claim 1 or 2, wherein, The organic carboxylic acid R1COOH is selected from one of acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, tert-pentanoic acid and hexanoic acid.

5. The method of claim 1 or 2, wherein, When synthesizing Mn4XO4-, the molar ratio of the organic carboxylic acid R1COOH, tetrabutylammonium permanganate salt, trivalent rare earth X salt, trivalent manganese salt and small molecule containing amide group is (20-100) : (5-8) : 2 : (1-3) : (10-100).

6. The method of claim 1 or 2, wherein, When synthesizing Mn4XO4-, the molar ratio of the organic carboxylic acid R1COOH, tetrabutylammonium permanganate salt, trivalent rare earth X salt, trivalent manganese salt and small molecule containing amide group is (60-100) : (5-8) : 2 : (1-3) : (20-60).

7. The method of claim 1 or 2, wherein, When synthesizing Mn4XO5-, the molar ratio of the raw materials, organic carboxylic acid R1COOH, tetrabutylammonium permanganate salt, trivalent rare earth X salt and trivalent manganese salt, and small molecules containing amide groups, added before the reaction at 0-50℃, is (20-100) : (5-8) : 2 : (1-3) : (10-100).

8. The method of claim 1 or 2, wherein, When synthesizing Mn4XO5-, the molar ratio of the raw materials, organic carboxylic acid R1COOH, tetrabutylammonium permanganate salt, trivalent rare earth X salt and trivalent manganese salt, and small molecules containing amide groups, added before the reaction at 0-50℃, is (60-100) : (5-8) : 2 : (1-3) : (20-60).

9. The method of claim 1 or 2, wherein, The trivalent manganese salt is acetylacetone trivalent manganese.

10. The method of claim 1, wherein, The trivalent rare earth X salt is lanthanum triflate or yttrium triflate.

11. The method of claim 1 or 2, wherein, The method further comprises the steps of filtering first after the reaction is completed, and then crystallizing at 0-5℃.

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