New homodi- and heterotrinuclear metal complexes of Schiff base compartmental ligand: interaction studies of copper complexes with calf thymus DNA

The new homodinuclear complexes 1-4 of the type [(LM2Cl2)-Cl-II], heterotrinuclear complexes 5 and 6 of the type [(LM2SnCl6)-Sn-II-Cl-IV] where M = Cu-II, Mn-II, Co-II, Ni-II and Cu-II and Ni-II, respectively have been synthesized and characterized by elemental analysis and various spectroscopic techniques. The homodinuclear complexes possess two different environments (N-2 and N(2)O(2)donor sets) for holding the metal ions. The metal ion in N-2 set exhibits square planar geometry with two chloride ions in the inner sphere but rhombic structure is found in tetradentate N2O2 Schiff base cavity while in heterotrinuclear complexes Sn-IV atom is in the octahedral environment. The interaction of complexes 1 and 5 with calf thymus DNA was carried out by absorption spectroscopy and cyclic voltammetry. The intrinsic binding constants (K-b) of complex 1 and 5 were determined as 3.2 x 10(3) M-1 and 9.6 x 10(3) M-1, respectively suggesting that complex 5 binds more strongly to CT-DNA than complex 1. Fluorescence studies along with viscosity measurements have also been checked to authenticate the binding of metal complexes with DNA. (C) Versita Warsaw and Springer-Verlag Berlin Heidelberg. All rights reserved.