Design and creation of reaction active multinuclear metal complex

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(1)Phosphotriesterase-like hydrolytic functionBis(μ-carboxylato)-μ-phenolatocomplexes, [M_2(L)(AcO)_2]^+(M=Mn,Co,Ni,Zn), based on ‘end-off' type dinucleating compartment ligand have been prepared as phosphotriesterase-model compounds which catalyze the hydrolysis of tris(p-nitrophenyl)phosphate (TNP)→bis(p-nitrophenyl)phosphate (BNP^-). The hydrolysis was traced by means of UV-vis and ESI mass spectra. The ability of hydrolysis depends on the metal combination of dinuclear core and decreased in the order, MnMn〜ZnZn>CoCo>>NiNi. This tendency is well explained by the order of nucleophilicity of water molecules binding to the metal centers. Actual phosphotriesterase has not MnMn but ZnZn dinuclear core as active sites, because natural abundance of Zn in the sea is more than that of Mn.(2)Phosphodiesterase-like hydrolytic functionHydrolysis of bis(p-nitrophenyl) phosphate (BNP^-) has been studied by using of dinuclear complexes, [M_2(L)(AcO)_2]^+ (M=Mn,Co,Ni,Zn). It was revealed that the hydrolysis progresses via [M_2(L)(AcO)(BNP)]^+ which was generated from an equilibrium [M_2(L)(AcO)_2]^++BNP^-= [M_2(L)(AcO)(BNP)]^++AcO^- and the ability of hydrolysis decreased in the order, MnMn〜CoCo>>NiNi>>ZnZn. The hydrolysis ability of ZnZn compound, [Zn_2(L)(AcO)_2]^+, is very low, because it forms ‘rigid' μ-acetato-μ-BNP core structure with BNP-, which is inconvenient to take water molecules on ZnZn core. In natural, phosphodiesterase has not CoCo but MnMn core as active sites, because natural abundance of Co in the sea is much less than that of Mn. Furthermore, the first function-model of purple acid phophatase which has FeZn core structure has been prepared successfully.