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Photo-induced DNA cleavage activity of ternary (N-salicylidene-L-methioninato)copper(II) complexes of phenanthroline bases

Thomas, AM and Naik, AD and Nethaji, M and Chakravarty, AR (2004) Photo-induced DNA cleavage activity of ternary (N-salicylidene-L-methioninato)copper(II) complexes of phenanthroline bases. In: Indian Journal of Chemistry Sect. A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical, 43 (4). pp. 691-700.

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Abstract

Copper(II) complexes. [Cu(salmet)B] (1-3), where H(2)salmet is the Schiff base derived from salicylaldehyde and L-methionine and B is heterocyclic bases like 1,10-phenanthroline (phen, 1), dipyridoquinoxaline (dpq, 2) and dipyridophenazine (dppz, 3), are prepared and their DNA cleavage properties studied. Complex [Cu((t)Bu(2)salmet)(phen)].CHCl3 (4.CHCl3) has been prepared for structural characterization using single crystal X-ray crystallography. Complex 4 has a ternary structure in which the copper displays a distorted square pyramidal (4 + 1) geometry showing tri- and bidentate mode of bonding for the Schiff base and phen, respectively, in CuN3O2 coordination. The phen ligand exhibits axial-equatorial mode of bonding, while the dianionic Schiff base binds at the equatorial sites of the basal plane. The one-electron paramagnetic complexes show a d-d band in the electronic spectra in DMF at ca. 670 nm and axial EPR spectral features indicating {d(x2-y2)}(1) ground state in. a DMF glass at 77 K. The complexes are redox active displaying quasi-reversible cyclic voltammetric response near 0.1 V (vs. SCE) in DMF-0.1 M TBAP assignable to the Cu(II)/Cu(I) couple. The complexes bind to the calf thymus DNA but to a lesser extent in comparison to bis(phen)copper(II) species that has been used as a standard. The complexes. cleave supercoiled (SC) pUC19 DNA in dark under aerobic conditions by oxidative process in presence of mercaptopropionic acid as a reducing agent. They also show photo-induced DNA cleavage on irradiation with UV light of 312 nm or visible green light of 532 nm. The cleavage activity follows the order: 3 similar to 2 > 1. The mechanistic pathways for the DNA cleavage reactions are discussed.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to National Institute Science Communication.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 19 Dec 2008 12:46
Last Modified: 19 Dec 2008 12:46
URI: http://eprints.iisc.ernet.in/id/eprint/17219

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