Dinuclear Complexes Comprising a d-Transition Metal Ion and a Lanthanide Ion as Model Compounds with Nuclease-like Functions

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The purpose of this work is to synthesize heterodinuclear complexes comprising a d-transition metal and a lanthanide (f-transition metal) ions effectively hydrolyzing various phosphate diesters and to give useful informations for the development of the artificial restriction enzymes.In this year, dinuclear CuLn and CuCu and mononuclear Ln and Cu complexes (Ln= lanthanide(III)) were synthesized using dinucleating macrocycles obtained by the condensation of 2,6-diformyl-4-methylphenol and 1,3-diaminopropane in the 2 : 1 molar ratio, 2,6-diformyl-4-methylphenol, ethylenediamine and diethylenetriamine in the 2 : 1 : 1 molar ratio, and 2,6-diformyl-4-methylphenol, ethylenediamine and 1,3-diamino-2-propanol in the 2 : 1 : 1 molar ratio, and their hydrolytic properties toward 4-nitrophenylphosphate (NPP) were investigated. Dinuclear CuLn and mononuclear Ln complexes were active for the hydrolysis. The activitiy of the former was higher than that of the latter. On the other hand, hydrolysis by the dinuclear CuCu and mononuclear Cu complexes was not significantly recognized. These observations suggest that the heterometal CuLn core takes part in the hydrolysis (cooperation effect of a d-transition metal and a f-metal ions). Here, only a HPLC peak due to 4-nitrophenolate as a product was observed, indicating that the reaction is only hydrolytic and the redox reaction does not occur. The-NH-and-OH groups on the lateral chain of macrocyles were found to play an important role in the hydrolysis. Furthermore, the hydrolysis of bis(4-nitrophenyl)phosphate was also investigated using some d-f heteronuclear complexes.