Synthesis, structure and DNA binding studies of a mononuclear cobalt(III) complex with a NNO donor Schiff base derived from 4-methyl-2,6-dibenzoylphenol and ethane-1,2-diamine

摘要

The mononuclear cationic cobalt(III) complex 1 [Co(L)(2)](+) [where HL is H2N(CH2)(2)NC(Ph)C6H2(Me)(OH)COPh] has been obtained by the condensation of 4-methyl-2,6-dibenzoylphenol and ethane - 1,2-diamine in the presence of CoCl2 center dot 6H(2)O and isolated as the chloride solvate {1 center dot Cl center dot 2H(2)O center dot EtOH}. The water and ethanol do not form part of the cobalt(III) pseudo-octahedral [Co(L)(2)](+) coordination sphere, which is cis-CoN4O2 with the NNO-ligands mer. Compound 1 has been characterised by mass spectrometry, IR, electronic, H-1 and C-13 NMR spectroscopy, conductivity measurements, elemental analysis, TGA, cyclic voltammetry and an X-ray structural determination. The average Co-N and Co-O distances are, respectively, 1.929(4) and 1.882(3) angstrom. The N center dot center dot center dot N intraligand bite distance is 2.73(4) angstrom and the N-Co-N and O-Co-O angles are, respectively, 86.2(15)degrees and 93.3(13)degrees. Cyclic voltammetric studies of complex 1 indicate an irreversible cathodic peak (E-pc, ca. -0.61 V) corresponding to the reduction of cobalt(III) to cobalt(II). Absorption titration experiments gave a binding constant for DNA interaction of 1.4 x 10(4) M-1 and a binding site size 0.16 base pairs. (c) 2007 Elsevier B.V. All rights reserved.