Synthesis, crystal structures, DNA binding and cleavage studies of two oxovanadium(IV) complexes of 1,10-phenanthroline and Schiff bases derived from tryptophan

Two new V(IV) complexes, [VO(Naph-trp)(phen)]center dot CH3OH (1) and [VO(o-Van-trp)(phen)]center dot CH3OH center dot H2O (2) (Naph-Trp = Schiff base derived from 2-hydroxy-1-naphthaldehyde and l-tryptophan, o-Van-trp = Schiff base derived from o-vanillin and l-tryptophan, phen = 1,10-phenanthroline), have been synthesized and characterized by physicochemical methods. The V(IV) atoms in both complexes are six-coordinated in a distorted octahedral environment. In the crystals of complex 1, the C-H center dot center dot center dot pi and pi-pi stacking interactions form a 1D chain structure, whereas for complex 2, hydrogen bonds connect the molecular units into a 2D plane structure. The DNA binding properties and cleavage efficiencies of the complexes have been investigated by spectroscopic methods, viscosity measurements and agarose gel electrophoresis. The results suggest that both complexes can bind to CT-DNA in an intercalative mode and can also cleave pBR322 DNA.