Biomimetic water-splitting catalysts containing rare earth ions, methods of making and using the same

Abstract

The application discloses a biomimetic water-splitting catalyst containing rare earth ions and a preparation method and application thereof, the catalyst contains [Mn n XO m ] cluster compounds, wherein n is 3 or 4; m is 2, 4 or 5, the cluster compound is a rare earth manganese heteronuclear metal cluster compound containing rare earth ions X and one of the following core structures: [Mn3XO2] heteronuclear metal cluster skeleton core, [Mn4XO4] heteronuclear metal cluster skeleton core and [Mn4XO5] heteronuclear metal cluster skeleton core, and the X is selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium. In the application, the valence of the manganese ions in the cluster compounds is +3 or +4, and the manganese ions have important values in magnetic materials. In addition, the [Mn4XO4] and [Mn4XO5] cluster compounds obtained in the application can be used as artificial water-splitting catalysts, and can be used for catalytic splitting of water on the surface of an electrode or driven by an oxidant (which can be a stable oxidant or a transient oxidant generated by light induction).

Description

TECHNICAL FIELD

[0001] The present application relates to a biomimetic water-splitting catalyst containing rare earth ions and a preparation method and application thereof, and belongs to the technical field of catalysts. BACKGROUND

[0002] Energy crisis and environmental pollution are two key problems restricting the sustainable development of human society in the twenty-first century. If we can use inexhaustible and inexhaustible solar energy to split abundant water on earth, release oxygen, obtain electrons and protons, and produce electric energy or hydrogen energy, we can fundamentally solve the energy crisis and environmental pollution problems faced by mankind. But water is a very stable thermodynamic substance, and to achieve its efficient and safe splitting, a suitable catalyst is needed. Recently, researchers in the prior art have synthesized artificial catalysts with water splitting function by using noble metals such as ruthenium and iridium and some complex ligands, but the use of noble metals and complex ligands leads to high preparation cost of these catalysts and easy environmental pollution, so they are difficult to be popularized and applied. How to prepare an efficient, stable, inexpensive and environmentally friendly water splitting catalyst is still an unsolved scientific problem.

[0003] The photosystem II of photosynthetic organisms is the only biological system in nature that can efficiently and safely use inexpensive metal ions to split water and obtain electrons and protons while releasing oxygen. Photosystem II can efficiently and safely split water because it has a unique [Mn4CaO5] heteronuclear metal cluster catalyst, the periphery of which is provided with six carboxyl groups, an imidazole ring and four water molecules as ligands. During the water splitting process, the biological catalyst undergoes five different states (S0, S1, S2, S3, S4); among them, S1 state is the dark stable state, and the valence states of the four manganese ions correspond to (+3, +3, +4, +4). The revelation of the structure of the water splitting catalytic center of photosynthetic organisms provides an ideal blueprint for the development of efficient, stable, inexpensive and environmentally friendly biomimetic water splitting catalysts.

[0004] How to chemically synthesize a biological water splitting catalyst center is an important scientific frontier, but also a very challenging scientific problem. Patent ZL201510065238.7 discloses a water splitting catalyst containing a [Mn4CaO4] core structure, its preparation method and application; patent ZL201711059799.1 discloses a cluster containing [Mn3SrO4] and [Mn4SrO4] core structure and its preparation method and application. The two patents protect the following structural formula respectively:

[0005]

[0006] In formula 1 and formula 2, R1 is selected from H or C 1-8linear or branched alkyl; L1, L2, L3, L4 are four same or different ligands, each independently selected from carboxylic acid molecules and their derivatives, pyridine, imidazole, pyrazine, quinoline, isoquinoline and their derivatives, or water molecules, alcohol molecules, ketones, nitriles (such as acetonitrile), esters and other small molecules that can be exchanged.

[0007] The two synthetic alkaline earth metal ion-containing clusters [Mn4CaO4] and [Mn4SrO4] are the most similar to the biological water-splitting catalytic center so far, but the stability of the biomimetic cluster needs to be further improved. SUMMARY

[0008] In order to improve the above technical problems, the rare earth ion X (for example, at least one selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium) is introduced into the synthetic catalyst, and three types of rare earth manganese heteronuclear metal clusters with core structures of [Mn3XO2], [Mn4XO4] and [Mn4XO5] are provided, as well as a preparation method and application thereof.

[0009] The present application is achieved by the following technical solutions:

[0010] A rare earth manganese heteronuclear metal cluster has a [Mn n XO m ] heteronuclear metal cluster skeleton core, wherein n is 3 or 4; m is 2, 4 or 5; X is selected from rare earth elements.

[0011] According to one specific embodiment of the present application, the rare earth manganese heteronuclear metal cluster has one of the following core structures: a [Mn3XO2] heteronuclear metal cluster skeleton core, a [Mn4XO4] heteronuclear metal cluster skeleton core and a [Mn4XO5] heteronuclear metal cluster skeleton core, and the X is selected from rare earth elements.

[0012] According to the present application, the X is selected from scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium.

[0013] According to one specific embodiment of the present application, the chemical formula of the cluster is Mn3XO2(R1CO2)9(R1CO2H)3, which has a structure as shown in formula I, contains one rare earth ion X and three Mn ions, and is connected into a [Mn3XO2] heteronuclear metal cluster skeleton core through 2 μ3-O bridges;

[0014] The peripheral ligands of the [Mn3XO2] heteronuclear metal cluster skeleton core are provided by nine carboxylate anions R1CO2 - and three neutral carboxylic acid ligands R1CO2H, wherein the valence states of the three Mn ions are +3, +3 and +4, respectively, and the whole cluster is electrically neutral.

[0015]

[0016] wherein X is selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu;

[0017] R1are the same or different, independently of one another, selected from H or C 1-8 linear or branched alkyl.

[0018] According to the present application, the carboxylate anion R1CO2 - may be at least one of formate, acetate, propionate, isopropionate, butyrate, isobutyrate, tert-butyrate, valerate, isovalerate, pivalate, hexanoate, etc. That is, R1may be one of hydrogen (H), methyl (-CH3), ethyl (-C2H5), n-propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), n-butyl (-(CH2)3CH3), isobutyl (-CH(CH3)C2H5), tert-butyl (-C(CH3)3), n-pentyl (-(CH2)4CH3), isopentyl (-CH2CH2CH(CH3)2), pivalyl (-CH2C(CH3)3), or n-hexyl (-(CH2)5CH3), etc.

[0019] According to the present application, R1CO2H can be at least one of formic acid, acetic acid, propionic acid, isopropionic acid, butyric acid, isobutyric acid, tert-butyric acid, valeric acid, isovaleric acid, pivalic acid, hexanoic acid, etc.

[0020] Preferably, the cluster having the structure as shown in Formula I is selected from any one of the following clusters 1-5:

[0021] Cluster 1, with the chemical formula of Mn3YO2(R1CO2)9(R1CO2H)3, wherein R1= tert-butyl.

[0022] Preferably, the cluster 1 is a single crystal; its structure is shown in Formula I-1:

[0023]

[0024] Its single crystal belongs to the triclinic system, with the space group P-1, and the cell parameters are a = 13. 123(3) A, b = 13. 123(3) A, c = 13. 123(3) A, α = 77. 526(3) °, β = 87. 004(2) °, γ = 65. 818(3) °, Z = 2, and the volume is 1737. 1(6) A3. α = 77. 526(3) °, β = 87. 004(2) °, γ = 65. 818(3) °, Z = 2, and the volume is 1737. 1(6) A3.

[0025] Cluster 2, with the chemical formula of Mn3LaO2(R1CO2)9(R1CO2H)3, wherein R1= tert-butyl.

[0026] Preferably, the cluster 2 is a single crystal; its structure is shown as formula I-2:

[0027]

[0028] The single crystal thereof belongs to monoclinic system, space group is P21 / n, cell parameters are α = 90°, β = 107.516(4)°, γ = 90°, Z = 4, and the volume is

[0029] The cluster 3 has a chemical formula of Mn3GdO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0030] Preferably, the cluster 3 is a single crystal; its structure is shown as formula I-3:

[0031]

[0032] The single crystal thereof belongs to triclinic system, space group is P-1, cell parameters are α = 77.898(2)°, β = 87.087(2)°, γ = 65.755(2)°, Z = 2, and the volume is

[0033] The cluster 4 has a chemical formula of Mn3DyO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0034] Preferably, the cluster 4 is a single crystal; its structure is shown as formula I-4:

[0035]

[0036] The single crystal thereof belongs to triclinic system, space group is P-1, cell parameters are α = 77.790(2)°, β = 86.995(2)°, γ = 65.678(2)°, Z = 2, and the volume is

[0037] The cluster 5 has a chemical formula of Mn3LuO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0038] Preferably, the cluster 5 is a single crystal; its structure is shown as formula I-5:

[0039]

[0040] The single crystal thereof belongs to triclinic system, space group is P-1, cell parameters are α = 77.450(3)°, β = 87.291(3)°, γ = 65.954(3)°, Z = 2, volume = 1 1 1 1 A3

[0041] According to one specific embodiment of the present application, the cluster compound has a chemical formula of Mn4X04(R1CO2)8(L1)(L2)(L3) and has a structure as shown in Formula II, which contains four Mn ions and one rare earth ion X, which are connected into a [Mn4X04] heteronuclear metal cluster skeleton core through four μ-0 bridges;

[0042] The peripheral ligands of the [Mn4X04] heteronuclear metal cluster skeleton core are provided by eight carboxylate anions R1CO2 - and three ligands L1, L2 and L3; wherein the valence states of the four Mn ions are +3, +3, +4 and +4, respectively.

[0043]

[0044] In Formula II, the rare earth ion X and R1 have the meanings as above;

[0045] L1, L2 are the same or different and each is independently selected from carboxylic acid molecules and their derivatives, pyridine, imidazole, pyrazine, quinoline, isoquinoline and their respective derivatives, or is a water molecule, an alcohol molecule, an ether, a ketone, a nitrile, an ester, an amide and their respective derivatives, or L1 and L2 are connected to form a bidentate chelating ligand.

[0046] L3 is selected from carboxylic acid molecules and their derivatives, pyridine, imidazole, pyrazine, quinoline, isoquinoline and their respective derivatives, or is a water molecule, an alcohol molecule, an ether, a ketone, a nitrile, an ester, an amide and their respective derivatives.

[0047] According to the present application, in Formula II, L1 and L2 are preferably connected to form a pivalate, and L3 is preferably isoquinoline.

[0048] According to the present application, the nitrile can be, for example, acetonitrile. The ester can be, for example, ethyl acetate; and the amide can be, for example, one of N-methylformamide, N-methylacetamide, N,N-dimethylformamide and N,N-dimethylacetamide.

[0049] According to the present application, the cluster compound having the structure as shown in Formula II is selected from any one of the following cluster compounds 6 to 8:

[0050] Cluster 6, with the formula Mn4YO4(R1CO2)8(L1)(L2)(L3), wherein R1 = t-butyl, L1 and L2 together are a pivalate (e.g. trimethylacetate, i.e. R2 is t-butyl in formula II-1), and L3 = isoquinoline.

[0051] Preferably, the cluster 6 is a single crystal; its structure is shown in formula II-1:

[0052]

[0053] Its single crystal belongs to the monoclinic system, with space group P21 / n, and cell parameters of a = 10. 7990(10) A, b = 12. 7990(10) A, c = 20. 7990(10) A, a = 90. 00°, b = 101. 6590(10)°, g = 90. 00°, Z = 4, and a volume of 2, 7990(10) A3. a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and a volume of 2, 7990(10) A3.

[0054] Cluster 7, with the formula Mn4GdO4(R1CO2)8(L1)(L2)(L3), wherein R1 = t-butyl, L1 and L2 together are a pivalate (e.g. trimethylacetate, i.e. R2 is t-butyl in formula II-2), and L3 = isoquinoline.

[0055] Preferably, the cluster 7 is a single crystal; its structure is shown in formula II-2:

[0056]

[0057] Its single crystal belongs to the monoclinic system, with space group P21 / n, and cell parameters of a = 10. 7990(10) A, b = 12. 7990(10) A, c = 20. 7990(10) A, a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and a volume of 2, 7990(10) A3. a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and a volume of 2, 7990(10) A3.

[0058] Cluster 8, with the formula Mn4LuO4(R1CO2)8(L1)(L2)(L3), wherein R1 = t-butyl, L1 and L2 together are a pivalate (e.g. trimethylacetate, i.e. R2 is t-butyl in formula II-3), and L3 = isoquinoline.

[0059] Preferably, the cluster 8 is a single crystal; its structure is shown in formula II-3:

[0060]

[0061] Its single crystal belongs to the monoclinic system, with space group P21 / n, and cell parameters of a = 10. 7990(10) A, b = 12. 7990(10) A, c = 20. 7990(10) A, a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and a volume of 2, 7990(10) A3. a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and a volume of 2, 7990(10) A3.

[0062] According to one specific embodiment of the present application, the cluster compound has a chemical formula of Mn4XO5H(R1CO2)8(L4)(L5) and a structure as shown in formula III, which contains four Mn ions and one rare earth ion, and they are connected into a [Mn4XO5] heteronuclear metal cluster skeleton core through five μ-O; the peripheral ligand of the [Mn4XO5] heteronuclear metal cluster skeleton core is provided by eight carboxylate anions R1CO2 - and two ligands L4 and L5; the [Mn4XO5] heteronuclear metal cluster skeleton core has one μ2-O bridge; the valence states of the four Mn ions are +3, +3, +4, +4;

[0063]

[0064] In formula III, the rare earth ion X and R1 have the meanings as above; L4 and L5 are the same or different and are independently selected from carboxylic acid molecules and their derivatives, pyridine, imidazole, pyrazine, quinoline, isoquinoline and their respective derivatives, or are water molecules, alcohol molecules, ethers, ketones, nitriles, esters, amides and their respective derivatives, or L4 and L5 are connected to form a bidentate chelating ligand.

[0065] According to the present application, in formula III, L4 and L5 are the same or different and are independently selected from one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylformamide.

[0066] Preferably, the cluster compound having a structure as shown in formula III is selected from any one of the following cluster compounds 9 to 11:

[0067] Cluster compound 9 has a chemical formula of Mn4YO5H(RCO2)8(L4)(L5), wherein R1 = tert-butyl; L4 and L5 are both N,N-dimethylacetamide.

[0068] Preferably, the cluster compound 9 is a single crystal; and its structure is as shown in formula III-1:

[0069]

[0070] The single crystal of the cluster compound 9 belongs to the orthorhombic system, has a space group of Pbca, and has a unit cell parameter of a = 1. 2 1 A, b = 1. 2 1 A, c = 1. 2 1 A, α = 90°, β = 90°, γ = 90°, Z = 8, and a volume of 3. 2 1 A3. α = 90°, β = 90°, γ = 90°, Z = 8, and a volume of 3. 2 1 A3.

[0071] Cluster compound 10 has a chemical formula of Mn4DyO5H(RCO2)8(L4)(L5), wherein R1 = tert-butyl; L4 and L5 are both N,N-dimethylacetamide.

[0072] Preferably, the cluster 10 is a single crystal; its structure is shown in formula III-2:

[0073]

[0074] The single crystal thereof belongs to the orthorhombic system, the space group is Pbca, the cell parameters are a= 13. 01 A, b= 13. 01 A, c= 27. 01 A, and the volume is 3, 657. 3 A3. α = 90°, β = 90°, γ = 90°, Z = 8, and the volume is 3, 657. 3 A3.

[0075] The cluster 11 has a chemical formula of Mn4LuO5H(RCO2)8(L4)(L5), wherein R1 = tert-butyl; L4 and L5 are both N,N-dimethylacetamide.

[0076] Preferably, the cluster 11 is a single crystal; its structure is shown in formula III-3:

[0077]

[0078] The single crystal thereof belongs to the orthorhombic system, the space group is Pbca, the cell parameters are a= 13. 01 A, b= 13. 01 A, c= 27. 01 A, and the volume is 3, 657. 3 A3. α = 90°, β = 90°, γ = 90°, Z = 8, and the volume is 3, 657. 3 A3.

[0079] The present application also provides a preparation method of the rare earth manganese heteronuclear metal cluster, which comprises the following steps: reacting a permanganate anion type oxidant, a rare earth salt and a ligand, optionally adding water or a divalent manganese salt, in a solution to prepare the cluster.

[0080] In one specific embodiment, the present application provides a preparation method of a cluster having a chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3 and a structure shown in formula I, which comprises the following steps:

[0081] Reacting an organic carboxylic acid R1COOH, a permanganate anion type oxidant, a rare earth salt, optionally adding water or a divalent manganese salt, in an acetonitrile solution to prepare the cluster.

[0082] According to the present application, the method specifically comprises: reacting an organic carboxylic acid R1COOH, a permanganate anion type oxidant, a rare earth salt and water, in an acetonitrile solution to prepare a cluster having a chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3 and a structure shown in formula I.

[0083] According to the present application, the method specifically comprises: reacting organic carboxylic acid R1COOH, permanganate anion type oxidant, rare earth salt and divalent manganese salt in acetonitrile solution to prepare a cluster compound with the structure shown in formula I, and the chemical formula of the cluster compound is Mn3XO2(R1CO2)9(R1CO2H)3.

[0084] According to the present application, the molar ratio of the organic carboxylic acid R1COOH, the permanganate anion type oxidant, the rare earth salt, water or the divalent manganese salt is (10-120):(1-10):1:(0-5); preferably (20-120):(2-8):1:(1-2).

[0085] According to the present application, the organic carboxylic acid R1COOH is, for example, at least one selected from formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, tert-pentanoic acid, hexanoic acid and derivatives thereof, and is preferably isobutyric acid or tert-pentanoic acid.

[0086] According to the present application, the permanganate anion type oxidant is, for example, tetrabutylammonium permanganate ((C4H9)4N·MnO4).

[0087] According to the present application, the rare earth salt can be at least one of triflate, nitrate, perchlorate and carboxylate of rare earth ions, or the rare earth salt further comprises crystal water; wherein the carboxylate of the rare earth ions comprises carboxylate anion (R1CO2 - ) having the aforementioned definition.

[0088] According to the present application, the divalent manganese salt has the following structural formula: MnA2·tH2O; wherein A is selected from carboxylate anion (R1CO2 - ), chloride, ClO4 - , NO3 - , CF3SO3 - , acetylacetonate, and the carboxylate anion has the aforementioned definition; and t is 0-6, preferably 1-5, and more preferably 2-4.

[0089] For example, the divalent manganese salt is selected from at least one of Mn(ClO4)2, MnCl2, Mn(NO3)2, Mn(CF3SO3)2, acetylacetonate manganese, or a manganese salt of each thereof containing crystal water.

[0090] According to the present application, 60-100 milliliters of acetonitrile is used per millimole of rare earth salt.

[0091] The present inventors have found that the preparation method of the cluster compound with the structure shown in formula I and the chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3 can only be carried out in acetonitrile solvent, and the target cluster compound cannot be obtained in alcohol or other organic solvents.

[0092] According to the present application, the reaction temperature is 60-90℃. For example, it can be 60℃, 70℃, 80℃, or 90℃.

[0093] According to the present application, the reaction time can be 10-60 minutes.

[0094] According to the present application, the reaction further comprises a post-treatment step: filtering the reaction product to remove the precipitate, and after the liquid is still, a purified cluster compound with the structure shown in Formula I, with the chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3, is obtained.

[0095] Exemplarily, the stilling time is, for example, 1-7 days.

[0096] As a preferred embodiment of the present application, the preparation method of the cluster compound with the structure shown in Formula I, with the chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3, specifically comprises the following steps:

[0097] The organic carboxylic acid R1COOH, permanganate anion type oxidant, rare earth salt, and water are reacted in acetonitrile solution according to the molar ratio of (10-120):(1-10):1:(0-5) for 10-60 minutes to obtain a brown solution, and the precipitate is filtered out; after being still for 1-7 days, black crystals are obtained, which are the cluster compound with the structure shown in Formula I, with the chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3.

[0098] As a preferred embodiment of the present application, the preparation method of the cluster compound with the structure shown in Formula I, with the chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3, specifically comprises the following steps:

[0099] The organic carboxylic acid R1COOH, permanganate anion type oxidant, rare earth salt, and divalent manganese salt are reacted in acetonitrile solution according to the molar ratio of (10-120):(1-10):1:(0-5) for 10-60 minutes to obtain a brown solution, and the precipitate is filtered out; after being still, black crystals are obtained, which are the cluster compound with the structure shown in Formula I, with the chemical formula of Mn3XO2(R1CO2)9(R1CO2H)3.

[0100] According to the preferred technical scheme of the present application, the molecular formula of the cluster compound 1 is C 60 H 111 Mn3O 26 Y, with the chemical formula of Mn3YO2(R1CO2)9(R1CO2H)3, wherein R1=t-butyl.

[0101] The cluster compound 1 is a single crystal; the single crystal belongs to a triclinic system, with a space group of P-1 and a unit cell parameter of a=12. 1 1 (1) A, b=12. 1 1 (1) A, c=12. 1 1 (1) A, α=90°, β=90°, and γ=90°. α = 77.526(3) °, β = 87.004(2) °, γ = 65.818(3) °, Z = 2, volume = 1 1 1 1. 1 (3) A3. The structure is shown as formula I-1, and the crystal structure is shown as Figure 1 The single crystal parameters are shown in Table 1.

[0102] Table 1: Single crystal parameters of cluster 1

[0103]

[0104]

[0105] According to the preferred technical scheme of the present application, the molecular formula of cluster 2 is C 60 H 111 LaMn3O 26 , the chemical formula is Mn3LaO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0106] Cluster 2 is a single crystal; the single crystal belongs to a monoclinic system, the space group is P21 / n, and the cell parameters are α = 90 °, β = 107.516(4) °, γ = 90 °, Z = 4, volume = 1 1 1 1. 1 (3) A3. The structure is shown as formula I-2, and the crystal structure is shown as Figure 2 The single crystal parameters are shown in Table 2.

[0107] Table 2: Single crystal parameters of cluster 2

[0108]

[0109]

[0110] According to the preferred technical scheme of the present application, the molecular formula of cluster 3 is C 60 H 111 GdMn3O 26 , the chemical formula is Mn3GdO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0111] Cluster 3 is a single crystal; the single crystal belongs to a triclinic system, the space group is P-1, and the cell parameters are α = 77.898(2) °, β = 87.087(2) °, γ = 65.755(2) °, Z = 2, volume = 1 1 1 1. 1 (3) A3. The structure is shown as formula I-3, and the crystal structure is shown as Figure 3 The single crystal parameters are shown in Table 3.

[0112] Table 3: Single crystal parameters of cluster 3

[0113]

[0114]

[0115] According to a preferred technical scheme of the present application, the cluster 4 has a molecular formula of C 60 H 111 DyMn3O 26 , and a chemical formula of Mn3DyO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0116] The cluster 4 is a single crystal; the single crystal thereof belongs to a triclinic system, a space group is P-1, and a unit cell parameter is α = 77.790 (2) °, β = 86.995 (2) °, γ = 65.678 (2) °, Z = 2, and a volume is The structure thereof is shown as formula I-4, the crystal structure thereof is shown as Figure 4 , and the single crystal parameters thereof are shown in Table 4.

[0117] Table 4: Single crystal parameters of cluster 4

[0118]

[0119] According to a preferred technical scheme of the present application, the cluster 5 has a molecular formula of C 60 H 111 LuMn3O 26 , and a chemical formula of Mn3LuO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0120] The cluster 5 is a single crystal; the single crystal thereof belongs to a triclinic system, a space group is P-1, and a unit cell parameter is α = 77.450 (3) °, β = 87.291 (3) °, γ = 65.954 (3) °, Z = 2, and a volume is The structure thereof is shown as formula I-5, the crystal structure thereof is shown as Figure 5 , and the single crystal parameters thereof are shown in Table 5.

[0121] Table 5: Single crystal parameters of cluster 5

[0122]

[0123] In one specific embodiment, the present application further provides a preparation method of a cluster having a chemical formula of Mn4XO4(R1CO2)8(L1)(L2)(L3) and a structure shown as formula II, and the method specifically comprises the following steps:

[0124] (1) reacting an organic carboxylic acid R1COOH, a permanganate anion type oxidant, a divalent manganese salt and a rare earth salt in acetonitrile solution to prepare an intermediate;

[0125] (2) reacting the intermediate in step (1) with a ligand L3, optionally with a ligand L1 and / or L2 to prepare a cluster compound of formula Mn4XO4(R1CO2)8(L1)(L2)(L3) having the structure shown in formula II;

[0126] wherein the organic carboxylic acid R1COOH, the permanganate anion type oxidant, the divalent manganese salt, the rare earth salt and L1, L2 and L3 have the meanings as above.

[0127] According to the present application, the molar ratio of the organic carboxylic acid R1COOH, the permanganate anion type oxidant, the divalent manganese salt and the rare earth salt is (10-120):(1-10):1:1, preferably (20-100):(2-8):1:1.

[0128] In the present method, the amount of acetonitrile used per millimole of rare earth salt is about 60-100 ml. The reaction can only be carried out in acetonitrile solvent, and the target cluster compound cannot be obtained in alcohol or other organic solvents.

[0129] According to the present application, in step (2), the intermediate is first dissolved in a halogenated hydrocarbon organic solvent and a nitrile solvent, and then reacted with the ligand.

[0130] According to the present application, in step (2), the halogenated hydrocarbon organic solvent can be one of dichloromethane, dichloroethane or chloroform and derivatives thereof; and the nitrile solvent can be one of acetonitrile, propionitrile or butyronitrile and derivatives thereof.

[0131] According to the present application, in step (2), the ligand accounts for 0.1-3% of the total volume of the solvent.

[0132] According to the present application, in step (1), a post-treatment step is further included: the intermediate is filtered to remove the precipitate, and after the static liquid at 0℃, the solid is precipitated, which is the purified intermediate.

[0133] According to the present application, in step (2), a post-treatment step is further included: the reaction product is filtered to remove the precipitate, and after the static liquid, the crystal is precipitated, washed and dried to obtain the purified cluster compound of formula Mn4XO4(R1CO2)8(L1)(L2)(L3) having the structure shown in formula II.

[0134] For example, the static time is 1-7 days.

[0135] According to the present application, the reaction temperature is 60-90℃.

[0136] According to the application, the reaction time can be 10-60 minutes.

[0137] According to a preferred scheme of the application, the preparation method is specifically as follows:

[0138] First step: organic carboxylic acid R1COOH, permanganate anion type oxidant, divalent manganese salt and rare earth salt are heated to react in acetonitrile solution for 10-60 minutes according to the molar ratio of (10-120):(1-10):1:1 to obtain a brown solution, and the precipitate is removed by filtration; the brown crystals, i.e. the intermediate, are obtained by standing at 0°C for 1-6 days.

[0139] Second step: the synthesis intermediate is dissolved in a mixed solvent of halogenated hydrocarbon organic solvent and nitrile, ligand L3 is added, and further reaction is carried out, optionally with ligand L1 and / or L2, to obtain the cluster compound with the structure shown in formula (II) by crystallization.

[0140] According to a preferred scheme of the application, the molecular formula of the cluster compound 6 is C 54 H 88 Mn4NO 22 Y, and the chemical formula is Mn4YO4(R1CO2)9(C9H7N), wherein R1=t-butyl.

[0141] The cluster compound 6 is a single crystal. The single crystal belongs to a monoclinic system, the space group is P21 / n, the unit cell parameters are a=13.8580(10) A, b=13.8580(10) A, c=20.8580(10) A, α=90.00°, β=101.6590(10)°, γ=90.00°, and Z=4, and the volume is 3, 593. 6(3) A3. α=90.00°, β=101.799(2)°, γ=90.00°, Z=4, and the volume is 3, 593. 6(3) A3. The structure is shown in formula II-1, the crystal structure is shown in Figure 6 , and the single crystal parameters are shown in Table 6.

[0142] Table 6: Single crystal parameters of the cluster compound 6

[0143]

[0144]

[0145] According to a preferred scheme of the application, the molecular formula of the cluster compound 7 is C 54 H 88 GdMn4NO 22 , and the chemical formula is Mn4GdO4(R1CO2)9(C9H7N), wherein R1=t-butyl.

[0146] The cluster compound 7 is a single crystal. The single crystal belongs to a monoclinic system, the space group is P21 / n, the unit cell parameters are a=13.8580(10) A, b=13.8580(10) A, c=20.8580(10) A, α=90.00°, β=101.799(2)°, γ=90.00°, and Z=4, and the volume is 3, 593. 6(3) A3. α=90.00°, β=101.799(2)°, γ=90.00°, Z=4, and the volume is 3, 593. 6(3) A3. The structure is shown as formula II-2, and the crystal structure is shown as Figure 7 , and the single crystal parameters are shown in Table 7.

[0147] Table 7: Single crystal parameters of cluster 7

[0148]

[0149]

[0150] According to a preferred technical scheme of the present application, the molecular formula of the cluster 8 is C 54 H 88 LuMn4NO 22 , and the chemical formula is Mn4LuO4(R1CO2)9(C9H7N), wherein R1=t-butyl.

[0151] The cluster 8 is a single crystal; the single crystal belongs to a monoclinic system, the space group is P21 / n, the cell parameters are α=90.00°, β=101.7670(10)°, γ=90.00°, Z=4, and the volume is The structure is shown as formula II-3, and the crystal structure is shown as Figure 8 , and the single crystal parameters are shown in Table 8.

[0152] Table 8: Single crystal parameters of cluster 8

[0153]

[0154] In one specific embodiment, the present application further provides a preparation method of a cluster with a chemical formula of Mn4XO5H(R1CO2)8(L4)(L5) and a structure shown as formula III, and the method comprises:

[0155] The cluster with a structure shown as formula II is dissolved in a halogenated hydrocarbon and / or an ester solvent, water is added, and optionally, ligand L4 and ligand L5 are added or not added, and then reacted to obtain the cluster with a structure shown as III.

[0156] According to the present application, the ester solvent can be one of methyl acetate, ethyl acetate and the like.

[0157] wherein the halogenated hydrocarbon, ligand L4 and L5 have the meanings as above.

[0158] According to the present invention, the preparation method further includes a post-processing step: filtering the reaction product to remove a small amount of precipitate, allowing the reaction solution to stand, washing the precipitated crystals with n-hexane, and drying to prepare a purified cluster compound having the structure shown in Formula III and the chemical formula Mn4XO5H(R1CO2)8(L4)(L5).

[0159] According to the present invention, the reaction temperature is 20°C to 60°C.

[0160] According to the present invention, the reaction time may be 1 to 15 minutes.

[0161] According to the preferred technical solution of the present invention, the molecular formula of cluster compound 9 is C 48 H 91 Mn4N2O 23 Y, chemical formula is Mn4YO5H(R1CO2)8(L4)(L5), wherein R1=tert-butyl; L4 and L5 are both N,N-dimethylacetamide.

[0162] Cluster compound 9 is a single crystal; its single crystal belongs to the orthorhombic system, the space group is Pbca, and the unit cell parameters are α=90°,β=90°,γ=90°,Z=8,the volume is Its structure is shown in formula III-1, and its crystal structure is shown in Figure 9 , the single crystal parameters are shown in Table 9.

[0163] Table 9: Single crystal parameters of cluster 9

[0164]

[0165]

[0166] According to the preferred technical solution of the present invention, the molecular formula of the cluster compound 10 is C 48 H 91 DyMn4N2O 23 The chemical formula is Mn4DyO5H(R1CO2)8(L4)(L5), where R1 = tert-butyl; L4 and L5 are both N,N-dimethylacetamide.

[0167] Cluster compound 10 is a single crystal. Its single crystal belongs to the orthorhombic system, the space group is Pbca, and the unit cell parameters are α=90°,β=90°,γ=90°,Z=8,the volume is Its structure is shown in formula III-2, and its crystal structure is shown in Figure 10 , the single crystal parameters are shown in Table 10.

[0168] Table 10: Single crystal parameters of cluster 10

[0169]

[0170] According to the preferred technical scheme of the present application, the molecular formula of the cluster 11 is C 48 H 91 Mn4N2O 23 Lu, the chemical formula is Mn4LuO5H(R1CO2)8(L4)(L5), wherein R1 = tert-butyl; L4, L5 are both N,N-dimethylacetamide.

[0171] The cluster 11 is a single crystal; the single crystal belongs to the orthorhombic system, the space group is Pbca, the cell parameters are a = 1. 0 nm, b = 1. 0 nm, c = 1. 0 nm, α = 90°, β = 90°, γ = 90°, Z = 8, and the volume is 1. 0 nm3. α = 90°, β = 90°, γ = 90°, Z = 8, and the volume is 1. 0 nm3. The structure is shown as formula III-3, the crystal structure is shown as Figure 11 , and the single crystal parameters are shown in Table 11.

[0172] Table 11: Single crystal parameters of the cluster 11

[0173]

[0174] The present application also provides a biomimetic water splitting catalyst, which contains the rare earth manganese heteronuclear metal cluster described above.

[0175] The present application also provides the application of the biomimetic water splitting catalyst described above, which is applied to catalyze the splitting of water.

[0176] According to the present application, the catalytic process is carried out on the surface of an electrode, or in the presence of an oxidizing agent.

[0177] The present application has the following beneficial effects:

[0178] The present application introduces a rare earth ion X with stronger coordination ability, and synthesizes a series of [Mn n XO mCluster compounds with core of heteronuclear metal cluster skeleton, such as cluster compounds with core structure of [Mn3XO2], [Mn4XO4] and [Mn4XO5]. The cluster compounds are a new type of biomimetic water splitting catalyst. In particular, the cluster compounds with core structure of [Mn4XO4] and [Mn4XO5] are very similar to biological water splitting catalyst center in both geometric structure and Mn ion valence. The new biomimetic cluster compounds containing rare earth break through the traditional concept and are no longer limited to alkali earth metals identical to biology. The introduction of rare earth metal ions greatly improves the stability of the cluster compounds, and the catalytic splitting of water on the electrode surface is driven by oxidizing agent (which can be a stable oxidizing agent or a transient oxidizing agent generated by light induction). In addition, the unique magnetic properties of the tetravalent Mn ions and some rare earth elements in the cluster compounds have important application value in magnetic materials, and the combination of spectroscopy and tracking characterization may lay an important foundation for future mechanism research.

[0179] (1) In the present application, compared with [Mn4CaO4] and [Mn4SrO4] cluster compounds containing divalent alkali earth metal ions, the introduction of trivalent rare earth ions into [Mn3XO2], [Mn4XO4] and [Mn4XO5] cluster compounds significantly increases the stability of the cluster compounds, and the catalytic water splitting can be carried out more stably. In addition, since the alkali earth or rare earth ions are in the core of the cluster compounds, they cannot be exchanged without destroying the overall structure. However, there are obvious differences in charge and hydrated ion pKa value between alkali earth and rare earth metal ions, which will lead to great differences in the structure and performance of the final product.

[0180] (2) The present application uses rare earth ions, manganese ions and carboxylic acids as raw materials, and high permanganate anions as oxidizing agents to synthesize cluster compounds with core structure of [Mn3XO2], [Mn4XO4] and [Mn4XO5]. The valence of manganese ions in these cluster compounds is +3 or +4, which has important value in magnetic materials. In addition, the cluster compounds with core structure of [Mn4XO4] and [Mn4XO5] obtained by the present application can be used as artificial water splitting catalysts for the catalytic splitting of water on the electrode surface driven by oxidizing agent (which can be a stable oxidizing agent or a transient oxidizing agent generated by light induction).

[0181] Specifically,

[0182] 1) The present invention utilizes rare earth ions, water or divalent manganese salts, permanganates, and simple organic carboxylic acids as starting materials to synthesize a cluster with a core structure of [Mn3XO2]. The cluster is liganded by nine carboxylate anions and three neutral carboxylic acid molecules. The three manganese ions have valences of +3, +3, and +4, respectively. This [Mn3XO2] cluster with mixed valences and ligands provided entirely by carboxylic acids has not been previously reported.

[0183] 2) The present invention utilizes rare earth ions, permanganate, divalent manganese ions (Mn 2+ ) and simple organic carboxylic acids as starting materials, and successfully realized the use of simple metal ions (Mn 2+ ,X 3+ ions), simple organic carboxylic acids and MnO4 - As the starting material, a cluster compound with a biomimetic core structure of [Mn4XO4] was obtained through a multi-step synthesis. In this [Mn4XO4] cluster compound, [Mn3XO4] cubane and an outer Mn ion are connected by a μ-O bridge to form a [Mn4XO4] core structure, and the peripheral ligands are composed of eight carboxylate anions R1CO2 - , ligands L1 and L2 and an exchangeable ligand L3. The valence states of the four manganese ions are +3, +3, +4, and +4 respectively.

[0184] 3) The present invention further reacts the aforementioned cluster compound having the structure of Formula II with water, successfully introducing a μ2-O bridge, i.e., a dicoordinated oxygen bridge, into the core, resulting in a cluster compound with a biomimetic core structure of [Mn4XO5]. Its peripheral ligands consist of eight carboxylate anions and two exchangeable ligands. The valence states of the four manganese ions are +3, +3, +4, and +4, respectively. This cluster compound not only successfully mimics the ten-atom core skeleton and coordination environment of biological OECs, but also their redox properties. In particular, this cluster compound can stably catalyze water splitting reactions, releasing oxygen. BRIEF DESCRIPTION OF THE DRAWINGS

[0185] Figure 1 This is a crystal structure diagram of cluster compound 1 prepared in Example 1 of the present invention.

[0186] Figure 2 This is a crystal structure diagram of cluster compound 2 prepared in Example 2 of the present invention.

[0187] Figure 3 This is a crystal structure diagram of cluster compound 3 prepared in Example 3 of the present invention.

[0188] Figure 4 This is a crystal structure diagram of cluster compound 4 prepared in Example 4 of the present invention.

[0189] Figure 5 Crystal structure of cluster 5 prepared for example 5 of the present invention.

[0190] Figure 6 Crystal structure of cluster 6 prepared for example 6 of the present invention.

[0191] Figure 7 Crystal structure of cluster 7 prepared for example 7 of the present invention.

[0192] Figure 8 Crystal structure of cluster 8 prepared for example 8 of the present invention.

[0193] Figure 9 Crystal structure of cluster 9 prepared for example 9 of the present invention.

[0194] Figure 10 Crystal structure of cluster 10 prepared for example 10 of the present invention.

[0195] Figure 11 Crystal structure of cluster 11 prepared for example 11 of the present invention.

[0196] Figure 12 UV-Vis absorption spectra of corresponding clusters 1, 2, 3, 4 and 5 in 1,2-dichloroethane for example 12 of the present invention.

[0197] Figure 13 UV-Vis absorption spectra of corresponding clusters 6 and 8 in 1,2-dichloroethane for example 12 of the present invention.

[0198] Figure 14 UV-Vis absorption spectra of corresponding clusters 9 and 11 in 1,2-dichloroethane for example 12 of the present invention.

[0199] Figure 15 Catalytic water splitting current curve generated by the working electrode adsorbed with cluster 6 for example 13 of the present invention.

[0200] Figure 16 Catalytic water splitting current curve generated by the working electrode adsorbed with cluster 8 for example 13 of the present invention.

[0201] Figure 17 Catalytic water splitting current curve generated by the working electrode adsorbed with cluster 9 for example 13 of the present invention.

[0202] Figure 18 Catalytic water splitting current curve generated by the working electrode adsorbed with cluster 11 for example 13 of the present invention.

[0203] Figure 19 Cluster 9 catalytic stability test graph for example 13 of the present invention.

[0204] Figure 20 Figure 1 is a test chart for oxygen testing of the water-splitting catalysis of cluster 9 in Example 13. DETAILED DESCRIPTION

[0205] The technical solutions of the present application will be further described in detail below in combination with specific examples. It should be understood that the following examples are only illustratively and explain the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope intended to be protected by the present application.

[0206] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0207] In Examples 1-11, in order to make the structural formula of clusters 1-11 clear, the core skeleton and ligand are shown in the form of a ball bat and a line respectively, and the hydrogen atoms have been omitted.

[0208] Example 1: Cluster 1, Mn3YO2(C5H9O2)9(C5H9O2H)3

[0209] The preparation method is selected from any one of the following:

[0210] Scheme 1: A 250 ml round-bottom flask was charged with tetrabutylammonium permanganate (Bu4NMnO4, 8 mmol), yttrium triflate (Y(CF3SO3)3, 2 mmol), water (2 mmol), and pivalic acid (BuCO2H, 80 mmol) in acetonitrile at 80°C. The reaction was continued for 25 minutes, then stopped, and a small amount of precipitate was removed by filtration. The resulting brown mother liquor was left to stand at 2°C. After several days, black crystals were precipitated. The resulting crystals were collected, washed with acetonitrile, and dried under vacuum, with a yield of about 15% (based on the number of moles of Y ions). n t After the reaction was continued for 25 minutes at 80°C, the reaction was stopped, and a small amount of precipitate was removed by filtration. The resulting brown mother liquor was left to stand at 2°C. After several days, black crystals were precipitated. The resulting crystals were collected, washed with acetonitrile, and dried under vacuum, with a yield of about 58% (based on the number of moles of Y ions).

[0211] Scheme 2: A 250 ml round-bottom flask was charged with tetrabutylammonium permanganate (Bu4NMnO4, 8 mmol), yttrium triflate (Y(CF3SO3)3, 2 mmol), manganese (II) acetylacetonate (2 mmol), and pivalic acid (BuCO2H, 80 mmol) in acetonitrile at 80°C. The reaction was continued for 25 minutes, then stopped, and a small amount of precipitate was removed by filtration. The resulting brown mother liquor was left to stand at 2°C. After several days, black crystals were precipitated. The resulting crystals were collected, washed with acetonitrile, and dried under vacuum, with a yield of about 58% (based on the number of moles of Y ions). n t After the reaction was continued for 25 minutes at 80°C, the reaction was stopped, and a small amount of precipitate was removed by filtration. The resulting brown mother liquor was left to stand at 2°C. After several days, black crystals were precipitated. The resulting crystals were collected, washed with acetonitrile, and dried under vacuum, with a yield of about 58% (based on the number of moles of Y ions).

[0212] ​​Cluster 1, with the chemical formula of Mn3YO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0213] Cluster 1, with the chemical formula of Mn3YO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl. 60 H 111 Mn3YO 26 Y. Elemental analysis theoretical value (%): C, 47.97; H, 7.45; experimental value (%): C, 47.83; H, 7.42. The single crystal of cluster 1 belongs to triclinic system, with space group P-1, cell parameters of α = 77.526 (3) °, β = 87.004 (2) °, γ = 65.818 (3) °, Z = 2, and volume of

[0214] The chemical structure of cluster 1 is shown in formula I-1 below, the specific parameters of the single crystal determination of cluster 1 are shown in Table 1, and the crystal space structure of cluster 1 is shown in Figure 1 .

[0215]

[0216] Example 2: Cluster 2, Mn3LaO2(C5H9O2)9(C5H9O2H)3

[0217] The preparation method of Example 2 is the same as the method 2 in Example 1, except that lanthanum triflate is used to replace yttrium triflate. The yield is about 31% (based on the number of moles of La ions).

[0218] Cluster 2, with the chemical formula of Mn3LaO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0219] Cluster 2, with the chemical formula of Mn3LaO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl. 60 H 111 LaMn3O 26 . Elemental analysis theoretical value (%): C, 46.43; H, 7.21; experimental value (%): C, 46.38; H, 7.14. The single crystal of cluster 2 belongs to monoclinic system, with space group P21 / n, cell parameters of α = 90 °, β = 107.516 (4) °, γ = 90 °, Z = 4, and volume of

[0220] The chemical structure of cluster 2 is shown in formula I-2 below, the specific parameters of the single crystal determination of cluster 2 are shown in Table 2, and the crystal space structure of cluster 2 is shown in Figure 2 .

[0221]

[0222] Example 3: Cluster 3, Mn3GdO2(C5H9O2)9(C5H9O2H)3

[0223] The preparation method of Example 3 is the same as method 2 in Example 1, except that gadolinium triflate (Gd(CF3SO3)3) is used to replace yttrium triflate. The yield is about 48% (based on the number of moles of Gd ions).

[0224] Cluster 3, chemical formula: Mn3GdO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0225] That is, cluster 3, chemical formula: Mn3GdO2(C5H9O2)9(C5H9O2H)3, molecular formula: C 60 H 111 GdMn3O 26 Elemental analysis theoretical value (%): C, 45.88; H, 7.12; experimental value (%): C, 45.66; H, 7.23. The single crystal belongs to triclinic system, space group P-1, cell parameters are α = 77.898 (2) °, β = 87.087 (2) °, γ = 65.755 (2) °, Z = 2, volume is

[0226] The chemical structure of cluster 3 is as shown in formula I-3, the specific parameters of its single crystal determination are shown in Table 3, and its crystal space structure is shown in Figure 3 .

[0227]

[0228] Example 4: Cluster 4, Mn3DyO2(C5H9O2)9(C5H9O2H)3

[0229] The preparation method of Example 4 is the same as method 2 in Example 1, except that dysprosium triflate (Dy(CF3SO3)3) is used to replace yttrium triflate. The yield is about 43% (based on the number of moles of Dy ions).

[0230] Cluster 4, chemical formula: Mn3DyO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0231] That is, cluster 4, chemical formula: Mn3DyO2(C5H9O2)9(C5H9O2H)3, molecular formula: C 60 H 111 DyMn3O 26Elemental analysis: Theoretical value: C, 45.73; H, 7.10; Experimental value: C, 45.76; H, 6.98. The single crystal of the cluster belongs to triclinic system, space group P-1, cell parameters are a = 12. 858(3) A, b = 13. 858(3) A, c = 15. 858(3) A, α = 77. 790(2) °, β = 86. 995(2) °, γ = 65. 678(2) °, Z = 2, volume is 2 230. 6(1) A3. α = 77. 450(3) °, β = 87. 291(3) °, γ = 65. 954(3) °, Z = 2, volume is 2 230. 6(1) A3.

[0232] The chemical structure of the cluster 4 is as shown in the following formula I-4, the specific parameters of the single crystal determination of the cluster are shown in Table 4, and the crystal space structure is shown in Figure 4. Figure 4 .

[0233]

[0234] Example 5: Cluster 5, Mn3LuO2(C5H9O2)9(C5H9O2H)3

[0235] The preparation method of Example 5 is the same as the method 2 in Example 1, except that the yttrium triflate (Y (CF3SO3) 3) is replaced by lutetium triflate (Lu (CF3SO3) 3). The yield is about 48% (based on the number of moles of Lu ions).

[0236] The cluster 5 has a chemical formula of Mn3LuO2(R1CO2)9(R1CO2H)3, wherein R1 = tert-butyl.

[0237] That is, the cluster 5 has a chemical formula of Mn3LuO2(C5H9O2)9(C5H9O2H)3, a molecular formula of C 60 H 111 LuMn3O 26 . The single crystal of the cluster belongs to triclinic system, space group P-1, cell parameters are a = 12. 858(3) A, b = 13. 858(3) A, c = 15. 858(3) A, α = 77. 790(2) °, β = 86. 995(2) °, γ = 65. 678(2) °, Z = 2, volume is 2 230. 6(1) A3. α = 77. 450(3) °, β = 87. 291(3) °, γ = 65. 954(3) °, Z = 2, volume is 2 230. 6(1) A3.

[0238] The chemical structure of the cluster 5 is as shown in the following formula I-5, the specific parameters of the single crystal determination of the cluster are shown in Table 5, and the crystal space structure is shown in Figure 5. Figure 5 .

[0239]

[0240] Example 6: Cluster 6, Mn4YO4(C5H9O2)9(C9H7N)

[0241] The preparation method is as follows:

[0242] In the first step, 100 ml of round bottom flask is added with tetrabutylammonium permanganate (Bu n4NMnO4, 4 mmol), yttrium triflate (Y(CF3SO3)3, 1 mmol), manganese acetylacetonate (Mn(acac)2), 1 mmol) and pivalic acid ((CH3)3CCO2H, 40 mmol) in acetonitrile at 80°C for 25 minutes. The reaction was stopped and a small amount of precipitate was removed by filtration. The brown mother liquor was left to stand at 2°C. After several days, brown crystals of the synthetic intermediate were obtained.

[0243] Second step, the obtained intermediate was dissolved in dichloromethane and acetonitrile (1:2 by volume), and 1% of isoquinoline was added. After several days, brown crystals were obtained. The crystals were collected, washed with n-hexane and dried under vacuum. The yield was ~ 19% (based on the number of moles of Y ion).

[0244] Cluster 6, with the chemical formula Mn4YO4(R1CO2)9(L3), where R1 = t-butyl and L3 = isoquinoline.

[0245] Cluster 6, with the chemical formula Mn4YO4(C5H9O2)9(C9H7N), with the molecular formula C 54 H 88 Mn4NO 22 Y. Elemental analysis theoretical values (%): C, 45.94; H, 6.28; N, 0.99; experimental values (%): C, 46.19; H, 6.27; N, 1.01. Its single crystal belongs to the monoclinic system with space group P21 / n, with cell parameters of a = 14. 1 1 (3) A, b = 14. 1 1 (3) A, c = 22. 1 1 (4) A, a = 90.00°, b = 101.6590(10)°, g = 90.00°, Z = 4, and a volume of V = 3 1 1 1 (8) A3.

[0246] The chemical structure of cluster 6 is shown in formula II-1 below, and the specific parameters of its single crystal determination are shown in Table 6, and its crystal space structure is shown in Figure 2. Figure 6 .

[0247]

[0248] Example 7: Cluster 7, Mn4GdO4(C5H9O2)9(C9H7N)

[0249] The preparation method is as follows:

[0250] First step, add tetrabutylammonium permanganate (Bu4NMnO4, 4 mmol), yttrium triflate (Y(CF3SO3)3, 1 mmol), manganese acetylacetonate (Mn(acac)2), 1 mmol) and pivalic acid ((CH3)3CCO2H, 40 mmol) in a 100 ml round-bottom flask. n ​4NMn04, 8 mmol), gadolinium triflate (Gd(CF3S03)3, 2 mmol), manganese (II) acetylacetonate (Mn(acac)2), 2 mmol) and pivalic acid ((CH3)3CC02H, 80 mmol) in acetonitrile at 80 °C for 25 min. The reaction was stopped, a small amount of precipitate was removed by filtration, and the brown mother liquor was left to stand at 2 °C. After several days, brown crystals of the synthesis intermediate were obtained.

[0251] In the second step, the obtained intermediate was dissolved in dichloromethane and acetonitrile (volume ratio 1 :2), and ~1% isochinoline was added. After several days, brown crystals were obtained.

[0252] The cluster 7 has the chemical formula Mn4Gd04(R1C02)9(L3), wherein R1 = tert-butyl, L3 = isochinoline.

[0253] The cluster 7 has the chemical formula Mn4Gd04(C5H902)9(C9H7N), and the molecular formula is C 54 H 88 GdMn4NO 22 The single crystal thereof belongs to a monoclinic system, the space group is P21 / n, the cell parameters are a = 13. 119(3) A, b = 13. 119(3) A, c = 22. 657(5) A, a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and the volume is 3 1 1 1 1 A3. a = 90. 00°, b = 101. 799(2)°, g = 90. 00°, Z = 4, and the volume is 3 1 1 1 1 A3.

[0254] The chemical structure of the cluster 7 is shown in the following formula II-2, the specific parameters of the single crystal determination are shown in Table 7, and the crystal space structure is shown in Figure 7 .

[0255]

[0256] Example 8: Cluster 8, Mn4Lu04(C5H902)9(C9H7N)

[0257] The preparation method of the cluster 8 in Example 8 is the same as that in Example 6, except that lutetium triflate (Lu(CF3S03)) is used to replace yttrium triflate in Example 6.

[0258] The cluster 8 has the chemical formula Mn4Lu04(R1C02)9(L3), wherein R1 = tert-butyl, L3 = isochinoline.

[0259] The cluster 8 has the chemical formula Mn4Lu04(C5H902)9(C9H7N), and the molecular formula is C 54 H 88 LuMn4NO 22Elemental analysis theoretical value (%): C, 43.30; H, 5.92; N, 0.94; experimental value (%): C, 43.69; H, 5.96; N, 0.90. The single crystal of the compound belongs to monoclinic system, space group P21 / n, cell parameters are a = 13. 8580 (10) A, b = 13. 8580 (10) A, c = 22. 4600 (10) A, a = 90. 00°, b = 101. 7670 (10) °, g = 90. 00°, Z = 4, volume is 3 809. 6 (4) A3. a = 90. 00°, b = 101. 7670 (10) °, g = 90. 00°, Z = 4, volume is 3 809. 6 (4) A3.

[0260] The chemical structure of the cluster compound 8 is shown as formula II-3, the specific parameters of the single crystal determination are shown in Table 8, and the crystal space structure is shown in Figure 8. Figure 8 .

[0261]

[0262] Example 9: Cluster compound 9, Mn4YO5H(C5H9O2)8(C4H9NO)2

[0263] The preparation method is as follows:

[0264] Mn4YO4(C5H9O2)9(C9H7N) shown as formula II-1 is dissolved in dichloromethane and ethyl acetate (volume ratio is 3:1), 5% N, N-dimethylacetamide (volume ratio) and water (molar ratio of water to Mn4YO4(C5H9O2)9(C9H7N) is 2:1) are added, and the reaction is carried out at 40°C for 5 min. The reaction product is filtered, a small amount of precipitate is removed, and the reaction solution is left to stand. Brown crystals are precipitated after several days. The obtained crystals are collected, washed with n-hexane, and vacuum dried, and the yield is about 52% (based on the number of moles of Y ions).

[0265] The cluster compound 9 has a chemical formula of [Mn4YO5]H(RCO2)8(L4)(L5), wherein R1 = tert-butyl; L4 and L5 are both N, N-dimethylacetamide.

[0266] That is, the cluster compound 9 has a chemical formula of Mn4YO5H(C5H9O2)8(C4H9NO)2, a molecular formula of H 91 C 48 N2O 23 Mn4Y. Elemental analysis theoretical value (%): C, 39.97; H, 6.41; N, 2.33; experimental value (%): C, 40.08; H, 6.39; N, 2.33. The single crystal thereof belongs to orthorhombic system, space group Pbca, cell parameters are a = 13. 8580 (10) A, b = 13. 8580 (10) A, c = 22. 4600 (10) A, a = 90°, b = 90°, g = 90°, Z = 8, volume is 3 809. 6 (4) A3. a = 90°, b = 90°, g = 90°, Z = 8, volume is 3 809. 6 (4) A3.

[0267] The chemical structure of cluster 9 is shown in formula III-1 below, and the specific parameters of its single crystal determination are shown in Table 9, and its crystal space structure is shown in Figure 9 .

[0268]

[0269] Example 10: Cluster 10, Mn4DyO5H(C5H9O2)8(C4H9NO)2

[0270] The preparation method is as follows:

[0271] The synthesis scheme of Mn4DyO5H(C5H9O2)8(C4H9NO)2 is similar to that of Mn4YO5H(C5H9O2)8(C4H9NO)2, except that yttrium triflate is replaced by dysprosium triflate (Dy(CF3SO3)3) in the synthesis raw materials.

[0272] Cluster 10, chemical formula is Mn4DyO5H(RCO2)8(L4)(L5), wherein R1 = tert-butyl; L4, L5 are both N,N-dimethylacetamide.

[0273] That is, cluster 10, chemical formula is Mn4DyO5H(C5H9O2)8(C4H9NO)2. Its single crystal is orthorhombic, space group is Pbca, unit cell parameters are a = 2. 1 1 1 1 (3) A, b = 2. 1 1 1 1 (3) A, c = 2. 1 1 1 1 (3) A, α = 90°, β = 90°, γ = 90°, Z = 8, volume is 2. 1 1 1 1 (3) A3. α = 90°, β = 90°, γ = 90°, Z = 8, volume is 2. 1 1 1 1 (3) A3.

[0274] The chemical structure of cluster 10 is shown in formula III-2 below, and the specific parameters of its single crystal determination are shown in Table 10, and its crystal space structure is shown in Figure 10 .

[0275]

[0276] Example 11: Cluster 11, Mn4LuO5H(C5H9O2)8(C4H9NO)2

[0277] The preparation method is as follows:

[0278] The synthesis scheme of Mn4LuO5H(C5H9O2)8(C4H9NO)2 is similar to that of Mn4YO5H(C5H9O2)8(C4H9NO)2, except that yttrium triflate is replaced by lutetium triflate in the synthesis raw materials. Brown crystals are precipitated after a few days. The obtained crystals are collected, washed with n-hexane, and vacuum dried, with a yield of ~ 39% (based on the number of moles of Lu ions).

[0279] Cluster 11, with the formula of Mn4LuO5H(RCO2)8(L4)(L5), wherein R1is tert-butyl; L4, L5are both N,N-dimethylacetamide.

[0280] Cluster 11, with the formula of Mn4LuO5H(RCO2)8(L4)(L5), wherein R1is tert-butyl; L4, L5are both N,N-dimethylacetamide. 0.5 (Note: There are N,N-dimethylacetamide solvent molecules), with the formula of H 95.5 C 50 N 2.5 O 23.5 Mn4Lu. The theoretical elemental analysis (%): C, 39.99; H, 6.41; N, 2.33; the experimental elemental analysis (%): C, 40.08; H, 6.39; N, 2.33. Its single crystal is orthorhombic, with space group Pbca, cell parameters of α = 90°, β = 90°, γ = 90°, Z = 8, and a volume of

[0281]

[0282] The chemical structure of cluster 11 is shown as formula III-3, and its specific parameters of single crystal determination are shown in Table 11, and its crystal space structure is shown in Figure 11 .

[0283] Experimental Example 12: UV-Vis absorption spectra of clusters 1, 2, 3, 4, 5, 6, 8, 9 and 11

[0284] Into a 10 mm light path quartz cuvette, 20 μΜ of 1,2-dichloroethane solution of the corresponding cluster was added, and pure 1,2-dichloroethane was used as a reference, and the absorption spectrum of the corresponding cluster was measured on a Hitachi U-3900 UV-Vis spectrometer (as shown in Figure 12 、 13 and 14).

[0285] Experimental Example 13: Determination of clusters 6, 8, 9 and 11 catalyzing water splitting to release oxygen on the surface of the electrode

[0286] The catalytic water splitting on the electrode surface of the cluster compounds 6, 8, 9 and 11 was tracked by using Princeton Applied Research VersaSTAT 3 electrochemical workstation. The test used a three-electrode device, in which the working electrode was an ITO-nanoITO electrode adsorbed with the cluster compound, the counter electrode was a platinum mesh electrode, and the reference electrode was a silver / silver nitrate electrode (the reference liquid was an acetonitrile solution of 10 mM AgNO3 and 100 mM LiClO4). The electrolyte was a propylene carbonate solution containing 100 mM LiClO4 and 1.2 M water (H2O). The scanning speed was 10 mV / s. Figure 15 、 16 , 17 and 18 correspond to the catalytic water splitting current generated by the working electrode of the adsorbed cluster compounds 6, 8, 9 and 11, respectively, and no obvious catalytic current was observed when the above-mentioned cluster compounds were not adsorbed.

[0287] The cluster compounds were subjected to constant potential test. The electrolytic cell used was an H-type electrolytic cell, and the two chambers were separated by an anion exchange membrane. The working electrode and the reference electrode were placed in a propylene carbonate solution containing 100 mM LiClO4 and 1.2 M H2O, and the counter electrode was placed in an aqueous solution containing 10 mM Li2CO3 / HClO4 and 100 mM LiClO4 (pH = 6-7). The measured current-time curve is shown in Figure 19 , which shows that the cluster compound prepared in Example 9 with the core structure of [Mn4YO5] can stably catalyze for more than 10 hours in the above-mentioned electrolyte, and has excellent catalytic stability. At the same time, it was detected by Ocean Optics NeoFOX-GT oxygen sensing system that the process was accompanied by obvious oxygen release, as shown in Figure 20 . The above determination experiments show that the two cluster compounds with the core structures of [Mn4XO4] and [Mn4XO5] have the function of catalytically splitting water to release oxygen.

[0288] The above has exemplarily described the embodiments of the present application. However, the protection scope of the present application is not limited to the above-mentioned embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rare earth manganese heteronuclear metal cluster compound, characterized in that, which is selected from any one of the following cluster compounds 6-8: Cluster compound 6, chemical formula: Mn4YO4(R1CO2)8(L1)(L2)(L3), wherein R1= tert-butyl, L1 and L2 are connected to form a pivalate, i.e. R2 is tert-butyl in formula II-1, and L3= isoquinoline; The cluster compound 6 is a single crystal; its structure is shown in formula II-1: Formula II-1 The single crystal thereof belongs to a monoclinic system, and a space group is P 21 / n, the unit cell parameters are a = 12.3400(2) Å, b = 25.2611(3) Å, c = 21.9652(3) Å, α = 90.00º, β = 101.6590(10)º, γ = 90.00º, Z = 4, and the volume is 6705.76(16) Å 3 ; Cluster compound 7, chemical formula: Mn4GdO4(R1CO2)8(L1)(L2)(L3), wherein R1= tert-butyl, L1 and L2 are connected to form a pivalate, i.e. R2 is tert-butyl in formula II-2, and L3= isoquinoline; The cluster compound 7 is a single crystal; its structure is shown in formula II-2: Formula II-2 The single crystal thereof belongs to monoclinic system, and the space group is P 21 / n, the cell parameters are a = 12.3194(3) Å, b = 25.2435(5) Å, c = 21.9729(4) Å, α = 90.00º, β = 101.799(2)º, γ = 90.00º, Z = 4, and the volume is 6688.9(2) Å 3 ; Cluster compound 8, chemical formula: Mn4LuO4(R1CO2)8(L1)(L2)(L3), wherein R1= tert-butyl, L1 and L2 are connected to form a pivalate, i.e. R1 is tert-butyl in formula II-3, and L3= isoquinoline; The cluster compound 8 is a single crystal; its structure is shown in formula II-3: Formula II-3 The single crystal thereof belongs to a monoclinic system, and the space group is P 21 / n, the cell parameters are a = 12.3098(2) Å, b = 25.1930(3) Å, c = 22.0248(3) Å, α = 90.00º, β = 101.7670(10)º, γ = 90.00º, Z = 4, and the volume is 6686.81(16) Å 3 .

2. A rare earth manganese heteronuclear metal cluster, characterized in that: which is selected from any one of the following cluster compounds 9-11: Cluster compound 9, chemical formula: Mn4YO5H(RCO2)8(L4)(L5), wherein R1= tert-butyl; L4, L5 are both N,N-dimethylacetamide; The cluster compound 9 is a single crystal; its structure is shown in formula III-1: Formula III-1 The single crystal thereof belongs to the orthorhombic system, and the space group is Pnma P bca, with a cell parameter of a = 24.6725(7) Å, b = 20.9179(7) Å, c = 24.7495(9) Å, α = 90º, β = 90º, γ = 90º, Z = 8, and a volume of 12773.1(7) Å 3 Cluster compound 10, chemical formula: Mn4DyO5H(RCO2)8(L4)(L5), wherein R1= tert-butyl; L4, L5 are both N,N-dimethylacetamide; The cluster compound 10 is a single crystal; its structure is shown in formula III-2: Formula III-2 The single crystal thereof belongs to the orthorhombic system, and the space group is Pnma P bca, with a unit cell parameter of a = 24.6127(3) A, b = 20.9300(3) A, c = 24.7718(3) A, a = 90°, b = 90°, g = 90°, Z = 8, and a volume of 12761.0(3) A 3 ; Cluster compound 11, chemical formula: Mn4LuO5H(RCO2)8(L4)(L5), wherein R1= tert-butyl; L4, L5 are both N,N-dimethylacetamide; The cluster compound 11 is a single crystal; its structure is shown in formula III-3: Formula III-3 The single crystal thereof belongs to the orthorhombic system, and the space group is Pnma P bca, with a cell parameter of a = 24.5313(6) Å, b = 20.8348(3) Å, c = 24.6806(4) Å, α = 90º, β = 90º, γ = 90º, Z = 8, and a volume of 12614.4(4) Å 3 .

3. A biomimetic water-splitting catalyst characterized in that, The catalyst contains the cluster compound according to claim 1 or 2.

4. Use of the biomimetic water-splitting catalyst according to claim 3, characterized in that The catalyst is applied to catalyze the cracking of water.

5. Use according to claim 4, characterized in that, The catalytic process is carried out on the surface of an electrode, or in the presence of an oxidizing agent.

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