DNA binding of metal complexes with mixed recognition motifs : photophysical and biophysical studies

New rhodium complexes containing tripodal ligands have been synthesised and their physical properties have been investigated. [Rh(tpm*)C13] has been synthesised and its reaction with pyridyl-based ligands has been studied. These complexes may be convenient building blocks for construction of dinuclear complexes, as they are achiral and coordinative saturated they offer facile routes of synthesis. Several ruthenium (II)-dppz complexes have been synthesised which have been designed to show mixed motif binding to DNA (e. g. hydrogen-bond and intercalation). The binding of these complexes with different DNA sequences has been studied using a variety of techniques, including melting points, viscometry, UV-Vis, luminescence, CD, ITC and SPR. In most of the cases, the metal complexes stabilised DNA, bind via intercalation and their affinity with CT-DNA are in the micromolar range. We have observed a remarkable modulation of the binding of our complexes to DNA by changing the R-subsistent of the pyridine ring. DNA binding properties of some monomeric and bimetallic Ru(II)-azo(bpy)s complexes synthesised in the Otsuki's group were explored. These metal complexes stabilise DNA and viscosity measurements shows no intercalation between base pairs. It has been observed that the shape of the bridging ligand is an important factor for the interaction of the complexes with DNA.