Syntheses, Crystal Structure, and Nuclease Activity of Oxalato-Bridged Dicopper(II) Complexes with Planar N-Donor Heterocyclic Bases

摘要: Oxalato-bridged dicopper(II) complexes $[{CuL(H_2O)}_2(\mu - ox)]-(ClO_4)_2 (1-4)$, where L is a bidentate chelating heterocyclic base such as 2,2'-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2), dipyridoquinoxaline (dpq, 3) and dipyridophenazine (dppz, 4), were prepared by treatment of copper(II) perchlorate hexahydrate with sodium oxalate in aqueous ethanol. Complex 3 has been structurally characterised. The coordination geometry the copper centres essentially square-pyramidal. ${CuL(H_2O)}$ units are bridged an moiety to form discrete dimeric core. Magnetic studies 20-300 K temperature range show presence antiferromagnetically coupled unit, giving -2J values $346-384 cm^{-1}$ range. redox-active retain core solution, two quasireversible $Cu^{II}/Cu^I$ couples observed potential from 0.2 -0.4 V vs. SCE DMF/tris-HCl/0.1 M KCl buffer system (1:1, v/v, pH = 7.2) glassy carbon working electrode. binding cleavage DNA have studied. intercalating ability planar bases, determined decrease fluorescence intensity ethidium bromide bound calf thymus on addition complex, gave order: > 4 2 >> 1. nuclease activity supercoiled pUC19 DMF/tris-HCl/NaCl (pH ascorbic acid follows dpq complex exhibits most efficient activity. dppz shows good but poor