Synthesis of heterobimetallic complexes: in vitro DNA binding, cleavage and antimicrobial studies

The monometallic (1-3) and heterobimetallic (4-6) complexes, containing 1,10-phenanthroline and indole-3-acetic acid were synthesized and characterized by spectroscopic (IR, UV-vis, NMR, ESI-MS) and analytical methods. The in vitro DNA binding studies of 5 and 6 with CT DNA were carried out by employing various biophysical methods which reveal strong electrostatic binding via phosphate backbone of DNA helix. The binding constant (K) value as determined from fluorescence experiments of complexes 5 and 6 were calculated to be 4.09×10(4) and 2.51×10(4) M(-1), respectively revealing that complex 5 has greater binding propensity for DNA. To gain further insight into the molecular recognition at the target site, interaction studies of 5 with 5'-GMP were carried out by employing (1)H and (31)P NMR spectroscopy. Complex 5 exhibited preferential selectively towards the minor groove of pBR322 DNA and efficient cleavage activity via hydrolytic pathway. Furthermore complexes 4-6 exhibited significant antimicrobial activity.