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This article has been retracted as it is essentially identical in title and technical content with a previously published paper in Polyhedron. The earlier publication is “DNA binding and cleavage properties of certain ethylenediamin cobalt(III) of modified 1,10-phenanthrolines,” Penumaka Nagababu and S. Satyanarayana, Polyhedron, Volume 26, Issue 8, Pages 1686–1692.

Bioinorganic Chemistry and Applications
Volume 2007, Article ID 54562, 8 pages
Research Article

DNA Binding and Photocleavage Studies of Cobalt(III) Polypyridine Complexes: [Co(en)2PIP]3+, [Co(en)2IP]3+, and [Co(en)2phen-dione]3+

Department of Chemistry, Osmania University, Hyderabad 500 007, Andhra Pradesh, India

Received 18 October 2006; Revised 25 January 2007; Accepted 21 March 2007

Academic Editor: Nick Katsaros

Copyright © 2007 Penumaka Nagababu and S. Satyanarayana. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In this paper, three complexes of type [Co(en)2PIP]3+(PIP=2-phenylimidazo[4,5-f][1,10,] phenanthroline)(1), [Co(en)2IP]3+ (IP=imidazo[4,5-f][1,10,] phenanthroline)(2), and [Co(en)2phen-dione]3+(1,10 phenanthroline 5,6,dione)(3) have been synthesized and characterized by UV/VIS, IR, 1H NMR spectral methods. Absorption spectroscopy, emission spectroscopy, viscosity measurements, and DNA melting techniques have been used for investigating the binding of these two complexes with calf thymus DNA, and photocleavage studies were used for investigating these 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 intercalation mode via IP or PIP into the base pairs of DNA, and complex 3 is binding as groove mode. Complex 1 binds more avidly to CT DNA than 2 and 3 which is consistent with the extended planar ring π system of PIP. Noticeably, the two complexes have been found to be efficient photosensitisers for strand scissions in plasmid DNA.