A Unique Nickel System having Versatile Catalytic Activity of Biological Significance

Chattopadhyay, T and Mukherjee, M and Mondal, A and Maiti, P and Banerjee, A and Banu, KS and Bhattacharya, S and Roy, B and Chattopadhyay, DJ and Mondal, TK and Nethaji, M and Zangrando, E and Das, D (2010) A Unique Nickel System having Versatile Catalytic Activity of Biological Significance. In: Inorganic Chemistry, 49 (7). pp. 3121-3129.

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Abstract

A new dinuclear nickel(II) complex, [Ni-2(LH2)(H2O)(2)(OH)(NO3)](NO3)(3) (1), of an "end-off" compartmental ligand 2,6-bis(N-ethylpiperazine-iminomethyl)-4-methyl-phenolato, has been synthesized and structurally characterized. The X-ray single crystal structure analysis shows that the piperazine moieties assume the expected chair conformation and are protonated. The complex 1 exhibits versatile catalytic activities of biological significance, viz. catecholase, phosphatase, and DNA cleavage activities, etc. The catecholase activity of the complex observed is very dependent on the nature of the solvent. In acetonitrile medium, the complex is inactive to exhibit catecholase activity. On the other hand, in methanol, it catalyzes not only the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) but also tetrachlorocatechol (TCC), a catechol which is very difficult to oxidize, under aerobic conditions. UV vis spectroscopic investigation shows that TCC oxidation proceeds through the formation of an intermediate. The intermediate has been characterized by an electron spray ionizaton-mass spectrometry study, which suggests a bidentate rather than a monodentate mode of TCC coordination in that intermediate, and this proposition have been verified by density functional theory calculation. The complex also exhibits phosphatase (with substrate p-nitrophenylphosphate) and DNA cleavage activities. The DNA cleavage activity exhibited by complex 1 most probably proceeds through a hydroxyl radical pathway. The bioactivity study suggests the possible applications of complex 1 as a site specific recognition of DNA and/or as an anticancer agent.

Item Type:	Journal Article
Publication:	Inorganic Chemistry
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Keywords:	zinc superoxide-dismutase; density-functional theory; catechol oxidase; copper(ii) complexes; excitation-energies; crystal-structure; metal-complexes; molecules; exchange; adducts.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	22 Apr 2010 08:41
Last Modified:	04 Jan 2013 07:12
URI:	http://eprints.iisc.ac.in/id/eprint/27176

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