柔性四吡啶配体的钴(Ⅱ)配合物的合成及其结构和性质
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摘要
贵金属水氧化催化剂因价格昂贵而致其实际应用受限制,因此迫切需要开发非贵金属催化剂。为了寻找成本低廉、容易合成且具有理想的氧化还原电位等优势、水溶性良好的钴配合物催化剂,文中报道了柔性多吡啶基配体tpbn(N,N,N',N'-四(2-吡啶甲基)-1,4-丁二胺)的钴(Ⅱ)配合物[Co(tpbn)](ClO_4)_2(1)的合成及其结构和性质。X-射线单晶衍射分析表明,配合物(1)是单核配合物。在分子结构中,钴离子处于一个八面体配位环境中,每个钴中心金属离子的六个配位点全部被同一个tpbn的四个吡啶基上的氮和两个氨基上的氮所占据,两个高氯酸根作为抗衡离子存在。在0. 1 mol/L的磷酸缓冲溶液中,循环伏安图显示在0. 30 V出现一对氧化还原峰,归属为配合物的氧化还原过程CoⅢ/Ⅱ。紫外可见光谱测定表明,在500 nm左右有吸收峰,归属为d-d跃迁。
Since the practical application of the water oxidation catalysts based on noble metals is greatly limited,it is urgent to develop non-noble metal based molecular catalysts. Among them,cobalt complexes are low cost,easily synthesized and show ideal redox properties. Therefore,the development of cobalt complex-based catalysts with good water solubility has become one of the focuses of current research. Herein reported is the synthesis,structure and properties of complex[Co( tpbn)〗( ClO_4)_2(1) with the flexible tetrapyridyl ligand N,N,N',N'-tetrakis( 2-pyridylmethyl)-1,4-butanediamine( tpbn). X-ray single crystallography analysis reveals that complex(1)is a mononuclear complex. The cobalt( II) ion is located in an octahedron environment which is composed of six nitrogen atoms from the four pyridyl and two amino groups of a tpbn. Two perchlorate ions serve as counteranions. The cyclic voltammogram of complex(1) in 0. 1 mol/L phosphate buffer solutions shows a redox wave at 0.30 V,which is assigned to the process of CoⅢ/Ⅱ.The UV-visible spectrum of complex(1) displays one band centered at about 500 nm,attributed to the d-d transition.
Since the practical application of the water oxidation catalysts based on noble metals is greatly limited,it is urgent to develop non-noble metal based molecular catalysts. Among them,cobalt complexes are low cost,easily synthesized and show ideal redox properties. Therefore,the development of cobalt complex-based catalysts with good water solubility has become one of the focuses of current research. Herein reported is the synthesis,structure and properties of complex[Co( tpbn)〗( ClO_4)_2(1) with the flexible tetrapyridyl ligand N,N,N',N'-tetrakis( 2-pyridylmethyl)-1,4-butanediamine( tpbn). X-ray single crystallography analysis reveals that complex(1)is a mononuclear complex. The cobalt( II) ion is located in an octahedron environment which is composed of six nitrogen atoms from the four pyridyl and two amino groups of a tpbn. Two perchlorate ions serve as counteranions. The cyclic voltammogram of complex(1) in 0. 1 mol/L phosphate buffer solutions shows a redox wave at 0.30 V,which is assigned to the process of CoⅢ/Ⅱ.The UV-visible spectrum of complex(1) displays one band centered at about 500 nm,attributed to the d-d transition.
引文
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[2]ERICA C M,ORDING-WENKER M,PLAS V D,et al.Protonation of a biologically relevant CuⅡμ-thiolate complex:Ligand dissociation or formation of a protonated CuIdisulfide species?[J].Chemistry-A European Journal,2014,20(51):16913-16921.
[3]JIN H Y,IKARI S,KOBAYASHI K,et al.A pair of seven-coordinate oxorhenium complexes:[Re IVO(tpen)]2+and[Re VO(tpen)]3+[J].Bulletin of the Chemical Society of Japan,2004,77(6):1139-1146.
[4]GAGNE R R,KREH R P,DODGE J A,et al.Synthesis and structure of(N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine)dicopper(I)and its dicarbonyl adduct[J].Inorganic Chemistry,1982,21(1):254-261.
[5]MANDEL J B,MARICONDI C,DOUGLAS B E.Synthesis and spectroscopic characterization of cobalt(Ⅲ)and copper(Ⅱ)complexes of hexadentate and tetradentate ligands containing pyridyl arms[J].Inorganic Chemistry,1988,27(17):2990-2996.
[6]MAMBANDA A,JAGANYI D,HOCHREUTHER S,et al.Tuning the reactivity of chelated dinuclear Pt(Ⅱ)complexes through a flexible diamine linker.A detailed kinetic and mechanistic study[J].Dalton Transactions,2010,39(15):3595-3608.
[7]BLINDAUER C A,RAZI M T,PARSONS S,et al.Metal complexes of N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine(TPEN):Variable coordination numbers and geometries[J].Polyhedron,2006,25(2):513-520.
[8]BARTHOLOMA M,CHEUNG H,DARLING K,et al.[μ-N,N,N',N'-Tetrakis(2-pyridylmethyl)pentane-1,5-diamine]bis[dichloridocopper(Ⅱ)]sesquihydrate[J].Acta Crystallographica,Section E:Structure Reports Online,2010,66(10):1201-1202.
[9]BARTHOLOMA M,CHEUNG H,ZUBIETA J.[μ-N,N,N',N'-Tetrakis(2-pyridylmethyl)butane-1,4-diamine]bis[dibromidocopper(Ⅱ)][J].Acta Crystallographica,Section E:Structure Reports Online,2010,66(10):m1198.
[10]BARTHOLOMAE M,JONES S,ZUBIETA J.Construction of bimetallic oxide materials from molybdate building blocks and copper-ligand tethers with flexible spaces[J].Inorganic Chemistry Communications,2011,14(1):107-110.
[11]HUANG J F,CHEN W Y.A facile Pt catalyst regeneration process significantly improves the catalytic activity of Pt-organic composites for the O2reduction reaction[J].Chemical Communications,2015,51(60):12052-12055.
[12]JEFFREY B M,CHRIS M,BODIE E D.Synthesis and spectroscopic characterization of Cobalt(Ⅲ)and Copper(Ⅱ)complexes of hexadentate and tetradentate ligands containing pyridyl arms[J].Inorganic Chemistry,1988,27:2990-2996.
[13]KHULLAR S,MANDAL S K.Structural diversity of Mn(Ⅱ)complexes with acetylened-icarboxylate and hexadentate ancillary ligands under ambient conditions:effect of methylene chain length on coordination architectures[J].Crystal growth&design,2013,13:3116-3125.