DNA binding and cleavage properties of certain ethylenediamine cobalt(III) complexes of modified 1,10-phenanthrolines

摘要

Two complexes of the type [Co(en)(2)IP](3+) (IP=imidazo[4,5-q[1,10]-phenanthroline) and [Co(en)(2)PIP](3+) (PIP = 2-phenylimidazo [4,5-a[1,10]-phenanthroline) have been synthesized and characterized by UV-VIS, IR and H-1 NMR spectral methods. Absorption spectroscopy, emission spectroscopy, viscosity measurements and DNA melting techniques have been used to investigate the binding of these two complexes with calf thymus DNA and photocleavage studies have been used to investigate the binding of these complexes with plasmid DNA. The spectroscopic studies together with viscosity measurements and DNA melting studies support that complexes 1 and 2 bind to CT DNA(=calf thymus DNA) by an intercalation mode via IP or PIP into the base pairs of DNA. Complex 2 binds more avidly to CT DNA than 1, which is consistent with the extended planar ring pi system of PIP. Noticeably, the two complexes have been found to be efficient photosensitisers for strand scissions in plasmid DNA. (c) 2006 Elsevier Ltd. All rights reserved.