Compound, photocatalyst containing the same, and method for producing hydrogen

Abstract

This invention provides a compound useful as a photocatalyst, possessing both light absorption and redox capabilities. [Solution] The compound is represented by the following general formula (1). R is an aryl group having 5 to 30 carbon atoms, which may have substituents. 1 is an alkyl group having 1 to 30 carbon atoms, and X is a specific group represented by general formula (2a) or (2b), a hydrogen atom, or R 1 In general formula (2a), M is Pt, Pd, or Ni, and L is -OH2, -NH3, or a halogen atom. In general formula (2b), M is Ni or Co, and L is -OH2, -NH3, or a halogen atom. TIFF2026099650000021.tif48142

Description

[Technical Field]

[0001] This invention relates to a compound, a photocatalyst containing the same, and a method for producing hydrogen. [Background technology]

[0002] The amount of solar energy that falls on Earth is enormous, and with concerns about the depletion of petroleum resources, the effective utilization of solar energy is being considered. As an example of such effective utilization methods, it is being considered to produce hydrogen by decomposing water by irradiating a photocatalyst with sunlight (see, for example, Patent Document 1). As photocatalysts used in this case, inorganic compounds that have absorption in the visible light region (wavelength: 400nm to 700nm) where the energy level of sunlight is at its peak are known, such as TiO2, LaTiO2, TaON, Y2Ti2O5S2, Rh-doped SrTiO3, ZnRh2O4, Sm2Ti2O2S5, CuAgZnSnS4, etc. These are called inorganic photocatalysts. When these inorganic photocatalysts are irradiated with light, they exhibit oxidation-reduction ability and decompose water into hydrogen and oxygen by oxidation-reduction.

[0003] Incidentally, while these inorganic photocatalysts exhibit redox potential when irradiated with light, as described above, their light absorption for exhibiting this redox potential is not necessarily more efficient than that of organic compounds. This is because most inorganic photocatalysts consist of compounds with electrons in the d-orbitals, and their visible light absorption is based on dd transitions, which inevitably results in a smaller molar extinction coefficient. For this reason, inorganic photocatalysts cannot be said to fully utilize the irradiated light. On the other hand, organic compounds mainly use π-π orbitals. * Transitions and n-π * Although it exhibits strong light absorption based on transitions, its excited form does not show enough redox activity to decompose water. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-050965

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a new compound useful as a photocatalyst having both efficient light absorption as an organic compound and redox ability by a metal element.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a compound in which metal complex units are bonded to both ends of a carbon-bridged p-phenylene vinylene, and have completed the present invention. Note that carbon-bridged p-phenylene vinylene is a compound in which a carbon bridge is formed between a vinylene group and a benzene ring in p-phenylene vinylene, and is a compound having higher rigidity than p-phenylene vinylene. Specifically, the present invention provides the following.

[0007] (1) The present invention is a compound represented by the following general formula (1).

Chemical formula

[0008] (2) The present invention also relates to the compound according to (1) represented by the following general formula (1a-1) or (1a-2). [Chemical formula] (In the above general formula (1a-1), each R is, independently of each other, a carbon chain having 1 to 30 carbon atoms which may contain a hetero atom in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have a substituent, an aryl group having 5 to 30 carbon atoms which may have a substituent, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs are linked to each other to form a cyclic structure, and each R 1 is, independently of each other, a carbazolyl group, -NR 2 2, an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have a substituent, and each R 2Each of the elements is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, M is Pt, Pd, or Ni, L is -OH2, -NH3, or a halogen atom, p is an integer from 1 to 10, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2. Furthermore, the compound represented by the above general formula (1a-1) contains the necessary counteranions according to its number of positive charges. In the above general formula (1a-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. C1-C30 alkyl group, C1-C30 alkyloxy group, and optionally substituted phenyl group, each R 2 Each of the following is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms; M is Pt, Pd, or Ni; each L is independently -OH2, -NH3, or a halogen atom; p is an integer from 1 to 10; each m is independently an integer from 0 to 2; and each n is independently an integer from 0 to 2. Furthermore, the compound represented by the above general formula (1a-2) contains the necessary counteranions according to its number of positive charges.

[0009] (3) The present invention also relates to the compound described in item (1) or (2), which is represented by the following general formula (1b-1) or (1b-2). [ka] (In the above general formula (1b-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, M is Pt, Pd or Ni, and L is -OH2, -NH3 or a halogen atom. Furthermore, the compound represented by the above general formula (1b-1) contains the necessary counteranions according to its number of positive charges. In the above general formula (1b-2), each R is independently a carbon chain having 1 to 30 carbon atoms, which may contain heteroatoms in the chain; a cycloalkyl group having 4 to 20 carbon atoms, which may have substituents; an aryl group having 5 to 30 carbon atoms, which may have substituents; a trialkylsilyl group; an arylalkyl group; an alkylarylalkyl group; or two adjacent Rs linked together to form a cyclic structure. M is Pt, Pd, or Ni, and each L is independently -OH2, -NH3, or a halogen atom. Furthermore, the compound represented by the above general formula (1b-2) contains the necessary counteranions according to its positive charge number.

[0010] (4) The present invention is also a photocatalyst comprising any one of the compounds described in (1) to (3).

[0011] (5) The present invention also relates to a method for producing hydrogen from water by a photoreaction using ultraviolet or visible light in the presence of the photocatalyst described in item (4). [Effects of the Invention]

[0012] According to the present invention, a novel compound useful as a photocatalyst is provided, which possesses both efficient light absorption as an organic compound and redox ability due to a metal element. [Modes for carrying out the invention]

[0013] The following describes one embodiment of the compound and photocatalyst of the present invention, and one embodiment of a method for producing hydrogen. It should be noted that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

[0014] <Compound> First, the compound of the present invention will be described. The compound of the present invention is represented by the following general formula (1). This compound comprises a π-conjugated structure consisting of a carbon-bridged p-phenylenevinylene skeleton and two units consisting of metal complexes at both ends. The p-phenylenevinylene skeleton is bridged with carbon atoms so as to form a five-membered ring in the vinylene portion, and this bridge restricts the free rotation of the vinylene portion. As a result, twisting of the π-conjugated system is suppressed, and electron movement in the π-conjugated system becomes smooth. Furthermore, this p-phenylenevinylene skeleton can strongly absorb visible light, and when it enters an excited state due to this absorption, combined with the smooth electron movement as described above, it can transfer its excitation energy to the central metal contained in the metal complex present at one or both ends of the π-conjugated system. The central metal that receives the energy exhibits redox ability to decompose surrounding water molecules and produce hydrogen. Thus, the compound of the present invention is preferably used as a photocatalyst for hydrogen production.

[0015] [ka]

[0016] Both X in the above general formula (1) can become metal complexes for hydrogen production, but only one of them may become a metal complex, or both may become metal complexes. In either case, the compound of the present invention functions as a photocatalyst for hydrogen production. X will be described later.

[0017] In the general formula (1) above, each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked together to form a cyclic structure. These Rs are bonded to the carbon atoms forming the bridging described above, as can be understood from general formula (1), and are bulky substituents. These bulky substituents, Rs, protrude above and below the π-conjugated system of the compound, covering it and thus suppressing attack of chemical species on the π-conjugated system. As a result, the compounds of the present invention exhibit high thermal stability and chemical stability. Note that "each R is independently" means that the multiple Rs included in general formula (1) are determined independently, and they may be the same as or different from each other. The expression "each R is independently" is used frequently below, but in all cases it is interpreted in the same way.

[0018] A carbon chain having 1 to 30 carbon atoms that may contain heteroatoms is a linear or branched chain-like group containing 1 to 30 carbon atoms, and this chain-like group is a monovalent group that may or may not contain heteroatoms. Examples of heteroatoms include oxygen atoms, sulfur atoms, nitrogen atoms, etc. One or more of these heteroatoms may be present; for example, a polyoxyethylene group containing multiple oxygen atoms may be included.

[0019] A cycloalkyl group having 4 to 20 carbon atoms that may have substituents is a cycloalkyl group that may or may not have substituents, and in the case of substituents, the hydrogen atoms of the cycloalkyl group are replaced by substituents. Examples of such substituents include alkyl groups having 1 to 12 carbon atoms, arylalkyl groups, alkylarylalkyl groups, and the like.

[0020] An aryl group having 5 to 30 carbon atoms that may have substituents is an aryl group that may or may not have substituents, and in the case of substituents, the hydrogen atoms of the aryl group are replaced by substituents. Examples of such substituents include alkyl groups having 1 to 12 carbon atoms. Examples of aryl groups that may have substituents include phenyl groups, alkylphenyl groups, arylalkyl groups, and alkylarylalkyl groups, and among alkylphenyl groups, the 4-octylphenyl group is a preferred example.

[0021] Arylalkyl groups are groups that have an aromatic ring at the end of an alkylene chain, such as the benzyl group. The alkylene chain in this case can have approximately 1 to 20 carbon atoms. Examples of aromatic rings include phenyl, naphthyl, fluorenyl, and carbazolyl groups. Alkylarylalkyl groups are groups that have an aromatic ring sandwiched between two alkyl chains (an alkylene chain and an alkyl group). The alkyl chain in this case can have approximately 1 to 20 carbon atoms. Examples of aromatic rings include phenyl, naphthyl, fluorenyl, and carbazolyl groups.

[0022] When two adjacent R atoms are linked to form a cyclic structure, this cyclic structure, together with the five-membered ring in general formula (1), forms a spirostructure. The cyclic structure may be an antilipid ring or an aromatic ring, may contain heteroatoms such as nitrogen, sulfur, or oxygen, or may form a fused ring. Examples of such cyclic structures include fluorene rings and cycloalkane rings with 4 to 20 carbon atoms. For example, if the cyclic structure is a fluorene ring, the two adjacent R atoms form a spirofluorenyl group, and if the cyclic structure is a cycloalkane ring such as a cyclopentane ring or a cyclohexane ring, the two adjacent R atoms become spirocycloalkyl groups such as a spirocyclopentyl group or a spirocyclohexyl group. When the cyclic structure is a fluorene ring, its fused five-membered ring and the five-membered ring in general formula (1) form a spirostructure. Furthermore, "two adjacent R atoms" means that the two R atoms are bonded to the same carbon atom.

[0023] In the above general formula (1), each R 1 These are, independently, a carbazolyl group and -NR. 2 2. C1-C30 alkyl groups, C1-C30 alkyloxy groups, and optionally substituted phenyl groups. These alkyl and alkyloxy groups may be linear or branched. The optionally substituted phenyl group may be a substituted phenyl group or an unsubstituted phenyl group. Examples of substituents include C1-C12 alkyl groups, arylalkyl groups, alkylarylalkyl groups, etc. -NR 2 R in 2 2 Each of these is independently either a hydrogen atom or an alkyl group having 1 to 30 carbon atoms.

[0024] In the above general formula (1), p is an integer between 1 and 10, preferably between 1 and 5, more preferably between 1 and 3, and particularly preferably 2. Each m is an independent integer between 0 and 2, and each n is an independent integer between 0 and 2.

[0025] In the above general formula (1), each X is independently a specific group represented by the following general formula (2a) or (2b), a hydrogen atom, or R 1 In this case, at least one X is a specific group. That is, of the two Xs included in the above general formula (1), only one may be a specific group represented by the following general formula (2a) or (2b), or both may be specific groups represented by the following general formula (2a) or (2b). Note that if only one X is a specific group, the remaining X may be a hydrogen atom or the above R 1 This is the result.

[0026] The specific group contains a metal atom as the central metal of the complex that receives energy from the carbon-bridged p-phenylenevinylene moiety and undergoes a redox reaction. When this central metal takes a planar four-coordinate configuration, the specific group is represented by the following general formula (2a), and when it takes a six-coordinate configuration (octahedral structure), the specific group is represented by the following general formula (2b). Among these, the specific group represented by the following general formula (2a) is preferred.

[0027] [ka]

[0028] In the above general formula (2a), M is Pt, Pd, or Ni. That is, when a specific group takes the structure of the above general formula (2a), the central metal M is Pt, Pd, or Ni, which has a planar four-coordinate structure. In this case, the terpyridine skeleton shown in general formula (2a) becomes a tridentate ligand for the central metal M. L is a monodentate ligand that coordinates to the remaining coordination sites of M, and is -OH2 (aqua ligand), -NH3 (ammine ligand), or a halogen atom. Among these, a halogen atom, particularly Cl, is preferred for L.

[0029] In the above general formula (2b), M is Ni or Co. That is, when a specific group takes the structure of the above general formula (2b), the central metal M is Ni or Co that takes a hexa-coordinate structure (octahedral structure). In this case, the terpyridine skeleton shown in general formula (2b) becomes a tridentate ligand for the central metal M. L is a monodentate ligand that coordinates to the remaining coordination sites of M, and is -OH2 (aqua ligand), -NH3 (ammine ligand), or a halogen atom. Among these, -OH2 and halogen atoms are preferred for L, and among halogen atoms, Cl is preferred.

[0030] Here, Pt, Pd, Ni, and Co, which are the central metals of the complex in the general formulas (2a) and (2b) above, are all known to be capable of generating hydrogen from water when their metal complexes are used as photocatalysts.

[0031] In addition, depending on the type of central metal and the combination of ligand L bonded to it, the entire compound represented by general formula (1) may be a cation. In that case, the compound represented by general formula (1) will contain an appropriate counteranion according to its number of positive charges. Although this counteranion is not shown in general formula (1) above, compounds containing such counteranions are of course included in the scope of the present invention. An example of such a counteranion is the hexafluorophosphate anion (PF6). - ) and others can be preferred examples. The same applies to the general formulas (1a-1), (1a-2), (1b-1), and (1b-2) described later.

[0032] Preferred examples of compounds represented by the above general formula (1) include those represented by the following general formulas (1a-1) and (1a-2). In the compound represented by the following general formula (1a-1), one of the two X groups in general formula (1) is a specific group, and in the compound represented by the following general formula (1a-2), both X groups in general formula (1) are specific groups.

[0033] [ka]

[0034] In the above general formula (1a-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R 1 These are, independently, a carbazolyl group and -NR. 2 2. C1-C30 alkyl group, C1-C30 alkyloxy group, and optionally substituted phenyl group, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, M is Pt, Pd, or Ni, L is -OH2, -NH3, or a halogen atom, p is an integer from 1 to 10, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2. These are the same as those in the general formula (1) above, so a detailed explanation will be omitted.

[0035] The compound represented by the above general formula (1a-1) is one in which one of the two X in the above general formula (1) is identified as a specific group, and that specific group is identified as the one in the above general formula (2a). Similar to the case in the above general formula (1), p is preferably an integer from 1 to 5, more preferably an integer from 1 to 3, and particularly preferably 2.

[0036] In the above general formula (1a-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R 1 These are, independently, a carbazolyl group and -NR. 22. C1-C30 alkyl group, C1-C30 alkyloxy group, and optionally substituted phenyl group, each R 2 Each of these is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, M is Pt, Pd, or Ni, each L is independently -OH2, -NH3, or a halogen atom, p is an integer from 1 to 10, each m is independently an integer from 0 to 2, and each n is independently an integer from 0 to 2. These are the same as those in the general formula (1) above, so a detailed explanation will be omitted.

[0037] The compound represented by the above general formula (1a-2) is one in which both X in the above general formula (1) are identified as specific groups, and those specific groups are identified as those in the above general formula (2a). As in the case of the above general formula (1), p is preferably an integer from 1 to 5, more preferably an integer from 1 to 3, and particularly preferably 2.

[0038] More preferred examples of compounds represented by the above general formulas (1a-1) and (1a-2) include those represented by the following general formulas (1b-1) and (1b-2), respectively.

[0039] [ka]

[0040] In the above general formula (1b-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked together to form a cyclic structure, M is Pt, Pd or Ni, and L is -OH2, -NH3 or a halogen atom. These are the same as those in the above general formulas (1) and (1a-1), so a detailed explanation is omitted.

[0041] The compounds represented by the above general formula (1b-1) are those specified by the above general formula (1a-1) where p is 2 and n and m are 0.

[0042] In the above general formula (1b-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked together to form a cyclic structure. M is Pt, Pd, or Ni, and each L is independently -OH2, -NH3, or a halogen atom. These are the same as those in the above general formulas (1) and (1a-2), so a detailed explanation is omitted.

[0043] The compounds represented by the above general formula (1b-2) are those specified by the above general formula (1b-1) where p is 2 and n and m are 0.

[0044] More specific examples of compounds represented by the above general formulas (1b-1) and (1b-2) include those represented by the following chemical formulas (1c-1) and (1c-2), respectively. However, the present invention is not limited to those represented by the following chemical formulas (1c-1) and (1c-2).

[0045] [ka]

[0046] Next, an example of a synthesis method for the compounds of the present invention will be described. This description will focus on the synthesis routes of the chemical formulas (1c-1) and (1c-2) above, but the present invention is not limited to the compounds represented by these chemical formulas, and the compounds of the present invention may be synthesized by other synthesis routes. The compound 10 that serves as the starting material for the following synthesis route can be one synthesized according to the method described in Japanese Patent Application Publication No. 2011-32197. In the following synthesis route, Ph means an unsubstituted phenyl group, Ar means a 4-octylphenyl group, and B2pin2 means bis(pinacolate)diborone.

[0047] First, we will show the synthesis route of the compound represented by chemical formula (1c-2), in which both X groups in the above general formula (1) are specific groups. As shown in the synthesis scheme below, starting with compound 10 synthesized according to the description in Japanese Patent Publication No. 2011-32197, compound 11 with both ends brominated is obtained, and compound 12 is obtained by introducing a pinacol-protected boronic acid group to this compound. Compounds 11 and 12 are both intermediates for obtaining the compound of the present invention. Subsequently, compound 13 is obtained by cross-coupling compound 12 with 4'-bromo-2,2':6',2''-terpyridine, and compound 14 corresponding to the above chemical formula (1c-2) is obtained by anion exchange of compound 13 as a Pt complex.

[0048] [ka]

[0049] Next, we will show the synthesis route of the compound represented by chemical formula (1c-1), in which only one X in the above general formula (1) is a specific group. As shown in the synthesis scheme below, starting with compound 10 synthesized according to the description in Japanese Patent Publication No. 2011-32197, bromination is performed under relaxed bromination conditions compared to when obtaining compound 14, to obtain a mixture of compound 21 with one end brominated and compound 11 with both ends brominated. To perform bromination under relaxed bromination conditions, the amount of the brominating agent CuBr2 and the reaction conditions can be adjusted as appropriate. Subsequently, following the same procedure as when obtaining compound 13, a mixture of compound 23 with a terpyridine ligand introduced at only one end and compound 13 with terpyridine ligands introduced at both ends is obtained. Then, compound 23 is isolated by column chromatography, and compound 23 is then converted into a Pt complex and subjected to anion exchange to obtain compound 24 corresponding to the above chemical formula (1c-1).

[0050] [ka]

[0051] <Photocatalyst> A photocatalyst comprising the compound of the present invention described above is also a part of the present invention. The compound of the present invention has an absorption band in the visible light region, and as already mentioned, the energy of the absorbed visible light is transferred to the central metal contained in the metal complex at both ends of the molecule through the π-conjugated system of carbon-bridged p-phenylenevinylene. The central metal that receives the energy then exhibits redox ability to decompose surrounding water molecules and generate hydrogen. In other words, the compound of the present invention functions as a photocatalyst that decomposes water and generates hydrogen. Notably, compound 14, one of the compounds of the present invention, exhibits hydrogen generation activity with light irradiation at 1 / 1000th the intensity of PtCl(tpy), which is the elemental metal complex at both ends of its molecule. From this, it can be inferred that the carbon-bridged p-phenylenevinylene skeleton efficiently performs light absorption and energy transfer to the metal complex.

[0052] The light source used to exert the photocatalytic effect is not particularly limited, as long as it includes light of wavelengths that the compound of the present invention can absorb. Examples of such light sources include sunlight and xenon lamps.

[0053] The form of the photocatalyst of the present invention is not particularly limited. Examples of such forms include an aqueous solution of the compound of the present invention, or the compound of the present invention supported on a carrier such as silica.

[0054] Furthermore, when hydrogen is produced using the photocatalyst of the present invention, it is preferable to add an appropriate sacrificial reagent. In this case, any known sacrificial reagent used in hydrogen production reactions can be listed without particular limitation, but among these, amine compounds such as triethylamine are preferred.

[0055] <Methods for generating hydrogen> Another method of producing hydrogen, characterized by generating hydrogen from water through a photoreaction using ultraviolet or visible light in the presence of the above-mentioned photocatalyst, is also part of the present invention. As this has already been explained, a further explanation will be omitted here. [Examples]

[0056] • Synthesis of compound 11 [ka]

[0057] A carbon tetrachloride mixture (14 mL) of compound 10 (0.282 g, 0.203 mmol), synthesized according to the method described in Japanese Patent Publication No. 2011-32197, and CuBr2 / Al2O3 (0.82 g, 1.22 mmol) was heated at 85°C for 12 hours. After cooling to room temperature, an aqueous solution of sodium bisulfate was added and the mixture was rapidly cooled. The mixture was then passed through a short-path silica gel column using dichloromethane. The solvent was removed by distillation, and the residue was washed with methanol and n-hexane to obtain compound 11 as a yellow solid (yield 0.281 g, yield 90%).

[0058] 1 H-NMR(500MHz, CDCl3):δ(ppm) 0.88(t,J=6.3Hz,12H),1.27-1.30(m,40H),1.50-1.55(m,8H),2.49(t,J=8.0Hz,8H),6.95(d,J=8.0Hz, 8H),6.99(d,J=8.0Hz,2H),7.06(d,J=8.6Hz,8H),7.15-7.23(m,22H),7.25(s,2H),7.50(d,J=1.8Hz,2H) MS(APCI + ):1542.9

[0059] Synthesis of compound 12 [ka]

[0060] A 1,4-dioxane solution (16 mL) containing compound 11 (1.36 g, 0.80 mmol), bis(pinacolate)diborone (1.03 g, 4.1 mmol), PdCl2(dppf)·CH2Cl2 (72.3 mg, 0.089 mmol), and potassium acetate (813 mg, 8.3 mmol) was stirred at 80°C for 22 hours. Distilled water was added to the reaction mixture and extracted with dichloromethane. The organic phase was dried over magnesium sulfate, and the solvent was removed by distillation. The residue was purified by silica gel column chromatography (hexane:dichloromethane = 9:1, 4:1, then 2:1), and reprecipitation with dichloromethane and methanol yielded compound 12 as a yellow solid (yield 671 mg, 41%).

[0061] 1 H-NMR(500MHz, CDCl3):δ(ppm) 7.82(s,2H),7.59(d,J=8.0Hz,2H),7.27(s,2H),7.20-7.14(m,22H),7.10(d,J=8.6Hz,8H),6.92(d ,J=8.0Hz,8H),2.48(t,J=7.7Hz,8H),1.55-1.52(m,8H),1.31-1.25(m,64H),0.88(t,J=6.9Hz,12H) TOF HRMS (APCI + ):1641.0798

[0062] • Synthesis of compound 13 [ka]

[0063] A mixture of compound 13 (164 mg), 4'-bromo-2,2':6',2''-terpyridine (78 mg), dioxane (3 mL), and 2M potassium carbonate aqueous solution (0.15 mL) was degassed by argon bubbling. Then, Pd2(dba)3 (9.0 mg) and XPhos (2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl; 9.5 mg) were added, and the mixture was heated at 100°C for 15 hours. To this, 4'-bromo-2,2':6',2''-terpyridine (38 mg), Pd2(dba)3 (9.0 mg), and XPhos (9.5 mg) were added, and the mixture was heated at 120°C for 3 days. After cooling, sodium carbonate aqueous solution was added, and the mixture was extracted three times with chloroform. The organic layer was then dried over calcium chloride and filtered through activated alumina. After concentrating the organic layer, compound 13 was purified by GPC to obtain 158 mg (yield 84%).

[0064] 1 H-NMR(400MHz, CDCl3):δ(ppm) 0.86(t,J=7.4Hz,12H),1.2-1.4(m,48H),2.51(t,J=8.0Hz,12H),6.98(d,J=8.4Hz,8H),7.20(d,J=8.4Hz,8H),7.22-7.36(m,28H),7 .70(dd,J=1.2,7.6Hz,2H),7.84(dt,J=2.0,8.0Hz,4H),7.91(s,2H),8.59(s,4H),8.60(brd,J=4.4Hz,4H),8.69(brd,J=5.2Hz,4H). 13C-NMR (125MHz, CDCl3): δ (ppm) 14.2,22.8,29.6,29.7,31.0,31.4,32.0,35.7,62.8,63.0,118.3,118.8,120.9,121.4,123.6,123.8,126.9,128.2,128.4,12 8.5,128.7,132.4,135.8,136.7,136.9,139.8,140.0,141.6,143.4,149.2,150.6,153.8,155.9,156.3,156.4,157.6,158.2. TOF HRMS: 1849.0602 (C 136 H 132 N6)

[0065] ·Synthesis of compound 14

change

[0066] Compound 13 (0.0769 g, 41.6 μmol) was dissolved in N,N-dimethylformamide (DMF; 30 mL), and separately synthesized cis-[PtCl2(dmso)2] (0.0700 g, 166 μmol, 4.0 equivalents) was added as a metal source. The mixture was stirred at room temperature for 2.5 days under an argon atmosphere in the dark. The solvent was removed from the resulting deep red reaction solution under reduced pressure at 50°C to obtain a purple crude product. This crude product was dissolved in acetonitrile (700 mL), and sodium tetraphenylborate (0.5706 g, 1.67 mmol, 40 equivalents) was added. The mixture was stirred at room temperature for 2.5 days under the dark, resulting in a dark red suspension. The suspension was concentrated to approximately 50 mL under reduced pressure at 30°C, the purple solid was filtered, washed with 5 × 10 mL of acetonitrile, and dried under reduced pressure (crude yield: 0.0782 g). The entire purple solid was dissolved in 10 mL of DMF, then 5 mL of a DMF solution of ammonium hexafluorophosphate (1.0719 g, 6.58 mmol, 158 equivalents) was added, and the mixture was stirred at room temperature under light protection for 1 day. The solvent was then removed by distillation under reduced pressure at 50°C. The resulting crude product was dissolved in 2 mL of DMF, and then reprecipitation was performed by adding 20 mL of methanol. The resulting solid was filtered, washed three times with 3 mL of methanol, and dried under reduced pressure to obtain compound 14, a dark purple powder (yield 0.0609 g, yield 56.3%).

[0067] 1 1H-NMR (600MHz, DMF-d7):δ (ppm) 0.84(t,J=7.0Hz,12H),1.19-1.37(m,40H),1.49-1.59(m,8H),2.59(t,J=7.5H z,8H),7.24(d,J=8.4Hz,8H),7.31-7.43(m,28H),7.52(s,2H),7.58(d,J=7.7H z,2H),7.99(dd,J=7.1,5.1Hz,4H),8.21(d,J=7.7Hz,2H),8.54(dd,J=7.7,7.1 Hz,4H),8.56(s,2H),8.89(d,J=7.7Hz,4H),8.97(d,J=5.1Hz,4H),9.07(s,4H). 13C-NMR(151MHz,DMF-d7):δ(ppm) 14.3,23.1,29.7,30.0,30.0,32.0,32.4,35.9,63.6,63.7,119.4,121.9,125.0,126.8,128.0,128.8,129.0,129.0,129.3,12 9.5,129.5,129.8,133.3,137.5,140.0,142.5,142.7,143.1,143.4,151.9,153.6,154.7,155.1,157.8,159.2,159.5,160.0. 19 F-NMR(565MHz,DMF-d7):δ(ppm) -72.0(d,J FP (=710Hz, 12F). CHN elem. anal. Calcd for C 136 H 132 Cl2F 12 N6P2Pt2:C,62.79;H,5.11;N,3.23. Found:C,62.88;H,5.37;N,3.16. UV-vis(DMF) λ max (ε M / M -1 cm -1 ) 516(52917),404(26340),390(25885),351(26068),336(31798),288(64273)nm.

[0068] Synthesis of Compound 24 [ka]

[0069] In the synthesis procedure for compound 11 described above, the amount of the brominating agent CuBr2 / Al2O3 was adjusted to obtain a mixture of compound 21, in which only one Br group was introduced, and compound 11, in which two Br groups were introduced. Then, the procedure up to the synthesis of compound 14 described above was performed on this mixture to obtain a mixture of compound 23, in which one terpyridine ligand was introduced, and compound 13, in which two terpyridine ligands were introduced. This mixture was then separated and purified by column chromatography to obtain compound 23, in which one terpyridine ligand was introduced.

[0070] Compound 23 (0.00131 g, 8.07 μmol), separately synthesized cis-[PtCl2(dmso)2] (0.000686 g, 16.2 μmol, 2.0 equivalents), and ammonium hexafluorophosphate (0.132 g, 0.810 mmol, 100 equivalents) were dissolved in N,N-dimethylformamide (DMF; 10 mL) and stirred at 80°C for 2 days under an argon atmosphere in the dark. The solvent was removed from the resulting red reaction solution under reduced pressure at 40°C to obtain a deep reddish-purple slurry, to which methanol (5 mL) was added, and a deep purple precipitate was collected. This precipitate was further washed four times with 2 mL of methanol, and thoroughly vacuum-dried to obtain compound 24 (yield 0.0152 g, yield 94.4%) as a deep reddish-purple powder. 1 H-NMR(600MHz,DMF-d7):δ(ppm) 0.84(t,J=7.0Hz,6H),0.87(t,J=7.0Hz,6H),1.23-1.32(m,40H),1.49-1.58(m,8H),2.55(t,J=8.0Hz,4 H),2.57(t,J=8.2Hz,4H),7.16(d,J=8.3Hz,4H),7.22(d,J=8.3Hz,8H),7.22(1H),7.27-7.39(m,26H),7. 46(s,1H),7.47(s,1H),7.54(d,J=8.2Hz,1H),7.57(dd,J=6.6and0.9Hz,1H),8.01,8.19(d,J=8.2Hz,1H ),8.54(s,1H),8.55(dd,J=7.7and7.6Hz,2H),8.89(d,J=7.7Hz,2H),9.01(d,J=4.5Hz,2H),9.06(s,2H). 13C-NMR(151MHz,DMF-d7):δ(ppm) 14.3,14.3,23.1,23.1,29.7,29.7,29.9,30.0,30.0,30.9,32.0,32.3,32.4,35.8,35.9,36.1,63.1,63.6,63 .7,118.8,119.3,121.5,121.8,121.8,124.9,126.0,126.7,126.8,126.8,127.8,127.9,128.0,128.7,128.8, 128.8, 128.9, 129.0, 129.2, 129.3, 129.4, 129.5, 129.8, 133.1, 136.5, 138.1, 139.0, 140.1, 140.8, 142.2, 142.6, 143.1, 143.5, 143.6, 152.0, 153.6, 154.0, 155.1, 156.0, 156.3, 157.2, 157.6, 158.1, 159.3, 159.4, 160.2. 19 F-NMR(565MHz,DMF-d7):δ(ppm) -72.1(d,J FP =710Hz, 6F). CHN elem. anal. Calcd for C 121 H 123 ClF6N3PPt:C,72.85;H,6.22;N,2.11. Found:C,73.14;H,6.44;N,2.32. UV-vis(DMF) λ max (ε M / M -1 cm -1 ) 498(27287),412(31622),396(29749),353(16634),336(17423),275(44998)nm.

[0071] [Hydrogen generation from water using compound 14 as a photocatalyst] Compound 14 (10 μM), triethylamine (5 vol%), and ultrapure water (5 vol%) were added to DMF to prepare a total volume of 10 mL of sample solution. The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was then attached to a closed circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.), and the headspace was depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 513.8 Torr. Subsequently, the reaction was allowed to proceed for 24 hours at room temperature (25°C) by irradiating the sample solution with light using a xenon lamp (500 W) while stirring the sample solution with a magnetic stirrer. The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automated gas sampler, into a gas chromatograph (Shimadzu Corporation, GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector, every hour from the start of light irradiation. As a result, the amount of hydrogen generated after 24 hours was 11 μmol. Furthermore, the turnover speed (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained in this way. As a result, the turnover speed (TON) after 24 hours was 102, and the maximum turnover frequency (TOF) was 6.4 h at 8 hours after the start of the experiment. -1 That was the case. Furthermore, as is well known to those skilled in the art, the above "μM" means "μmol / L". This is also true hereafter.

[0072] [Hydrogen generation from water using compound 24 as a photocatalyst] Compound 24 (10 μM), triethylamine (5 vol%), and ultrapure water (5 vol%) were added to DMF to prepare a total volume of 10 mL of sample solution. The sample solution was frozen and degassed using a Schlenk tube, and then transferred to a photoreaction cell (manufactured by Makuhari Chemical Glass Co., Ltd.) containing a stirring bar in a glove box filled with argon. The photoreaction cell containing the sample solution was then attached to a closed circulation system for photocatalytic reactions with a single automated gas sampler (manufactured by Makuhari Chemical Glass Co., Ltd.), and the headspace was depressurized and filled with argon four times until the headspace was finally subjected to an argon atmosphere of 527.3 Torr. Subsequently, the reaction was allowed to proceed for 24 hours at room temperature (25°C) by irradiating the sample solution with light using a xenon lamp (500 W) while stirring the sample solution with a magnetic stirrer. The generated hydrogen was quantified using a calibration curve method by directly introducing the headspace gas, separated via an automated gas sampler, into a gas chromatograph (Shimadzu Corporation, GC-8A, mobile phase: argon) equipped with a stainless steel packed column (Shinwa Chemical Co., Ltd., stationary phase: molecular sieve 5A, 3.0 mm I.D. × 3.0 m × 2) and a thermal conductivity detector, every hour from the start of light irradiation. As a result, the amount of hydrogen generated after 24 hours was 9.8 μmol. Furthermore, the turnover speed (TON) and turnover frequency (TOF) were calculated based on the hydrogen generation data obtained in this way. As a result, the turnover speed (TON) after 24 hours was 95, and the maximum turnover frequency (TOF) was 10h at 2 hours after the start of the experiment. -1 That was it.

[0073] As described above, it can be understood that the compounds of the present invention, regardless of whether they have one or two specific groups (metal complex sites), can decompose water and generate hydrogen upon light irradiation.

Claims

1. A compound represented by the following general formula (1). 【Chemistry 1】 (In the above general formula (1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, and each X is independently a specific group represented by the following general formula (2a) or (2b), a hydrogen atom, or R １ In this case, at least one X is a specific group, p is an integer from 1 to 10, each m is an integer from 0 to 2 independently, and each n is an integer from 0 to 2 independently. Furthermore, the compound represented by the above general formula (1) contains the necessary counteranions according to its number of positive charges. 【Chemistry 2】 (In the above general formula (2a), M is Pt, Pd or Ni, and L is -OH ２ , -NH ３ or a halogen atom. In the above general formula (2b), M is Ni or Co, and each L is independently -OH ２ , -NH ３ or a halogen atom.)

2. The compound according to claim 1, represented by the following general formula (1a-1) or (1a-2). 【Transformation 3】 (In the above general formula (1a-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, M is Pt, Pd, or Ni, and L is -OH ２ , -NH ３ Alternatively, it is a halogen atom, where p is an integer from 1 to 10, each m is an independent integer from 0 to 2, and each n is an independent integer from 0 to 2. Furthermore, the compound represented by the above general formula (1a-1) contains the necessary counteranions according to its number of positive charges. In the above general formula (1a-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, and each R １ These are, independently, a carbazolyl group and an -NR ２ ２ , an alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, or a phenyl group which may have substituents, each R ２ Each is independently a hydrogen atom or an alkyl group having 1 to 30 carbon atoms, M is Pt, Pd, or Ni, and each L is independently -OH ２ , -NH ３ Alternatively, it is a halogen atom, where p is an integer from 1 to 10, each m is an independent integer from 0 to 2, and each n is an independent integer from 0 to 2. Furthermore, the compound represented by the above general formula (1a-2) contains the necessary counteranions according to its number of positive charges.

3. The compound according to claim 2, represented by the following general formula (1b-1) or (1b-2). 【Chemistry 4】 (In the above general formula (1b-1), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, M is Pt, Pd or Ni, and L is -OH ２ , -NH ３ Alternatively, it may be a halogen atom. Furthermore, the compound represented by the above general formula (1b-1) contains the necessary counteranions according to its number of positive charges. In the above general formula (1b-2), each R is independently a carbon chain having 1 to 30 carbon atoms which may contain heteroatoms in the chain, a cycloalkyl group having 4 to 20 carbon atoms which may have substituents, an aryl group having 5 to 30 carbon atoms which may have substituents, a trialkylsilyl group, an arylalkyl group, an alkylarylalkyl group, or two adjacent Rs linked to each other to form a cyclic structure, M is Pt, Pd or Ni, and each L is independently -OH ２ , -NH ３ Alternatively, it may be a halogen atom. Furthermore, the compound represented by the general formula (1b-2) above contains the necessary counteranions according to its number of positive charges.

4. A photocatalyst comprising the compound according to any one of claims 1 to 3.

5. A method for producing hydrogen, characterized by generating hydrogen from water by a photoreaction using ultraviolet or visible light in the presence of the photocatalyst described in claim 4.

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