Structure and biological evaluation of pyridine-2-carboxamidine copper(II) complex resulting from N'-(4-nitrophenylsulfonyloxy)2-pyridine-carboxamidoxime.

The interaction of Cu(NO3)2·3H2O with the sulfonyl o-pyridine carboxamidoxime N'-(4-nitrophenylsulfonyloxy)picolinimidamide (L) resulted in the mononuclear complex [Cu(L1)2](L2)2 (1), where L1 = pyridine-2-carboxamidine ligand and (L2)- = 4-nitrobenzenesulfonate anion derived from the homolytic cleavage of the NO bond of L. The complex was characterized by diverse techniques including single-crystal X-ray crystallography. From the antimicrobial tests performed, complex 1 seems to be active against gram-negative bacterial strains. The complex binds tightly and reversibly to serum albumins and tightly to calf-thymus DNA via an intercalative mode and also via electrostatic interactions (as expected due to its cationic nature). Additionally, it interacts with (pBluescriptSK(+)) plasmid DNA in a concentration-dependent manner. The results from the present in silico molecular modeling simulations provide useful complementary insights for the elucidation of the mechanism of action of the studied complex at a molecular level. Molecular modeling calculations provide a molecular basis for the understanding of both the impairment of DNA by its binding with the studied complex and the ability of this compound to act as an antibacterial agent, most probably by its activity against DNA-gyrase, as well as for transportation through serum albumins and possible interaction with other protein targets involved in various diseases.