Thiohydrazone copper(II) complexes. The relationship between redox properties and superoxide dismutase mimetic activity

The redox behaviour of copper(II) complexes with the open chain ligand, ben zilbisthiosemicarbazone, and the macrocyclic one [3,4,10,11-tetraphenyl-1,2 ,5,8,9,12,13-octaazacycyclotetradeca-7,14-dithione-2,4,9,11-tetraene] has b een explored by cyclic voltammetry. The half-wave potential values for the copper(II)/copper(I) redox couple and the spectral data obtained on dimethy lsulfoxide (DMSO) solution agree with the superoxide dismutase (SOD)-mimeti c activity of the complexes. The macrocyclic complexes show more positive r eduction potential and more activity than the open chain derivatives. From our results it follows that the structure and conformation of ligand has in fluence on the redox potential of central atom in coordination compound. Th e changes in the coordination sphere are connected with the change of biolo gical function of compounds represented by SOD-mimic activity. In addition, the (LH6)-H-1, derivatives show quasireversible waves associated to Cu(LI) /Cu(III) process. (C) 1999 Elsevier Science S.A. All rights reserved.