Synthesis, physicochemical characterizations and in vitro biological evaluations of amide based Zn(II) carboxylates

Carboxylate ligands are widely used in chemistry and pharmacy owing to their ability to form stable complexes with a large variety of metal ions. In that context, carboxylate complexes allow modulation of the pharmaceutical products. Herein, a series of six novel Zn(II) carboxylates: [Zn(L-1)(2)] (1), [Zn(L-1)(2) (bipy)] (2), [Zn(L-1)(2) (phen)] (3), [Zn(L-2)(2)] (4), [Zn(L-2)(2) (bipy)] (5) and [Zn(L-2)(2) (phen)] (6) (where L-1 = 4-(2-methoxy-5-nitrophenylamino)-4-oxobutanoic acid), L-2 = 4-(2-nitro-4-methoxyphenylamino)-4-oxobutanoic acid), phen = 1,10-phenanthroline and bipy = 2,2'-bipyridine) were synthesized in good yield and successfully characterized by H-1, C-13 NMR, FT-IR and single-crystal X-ray crystallography. The spectroscopic data reveal that the absence of OH peak in the spectra of complexes confirm their formation. Single-crystal X-ray crystallographic data for complexes 1 and 5 show a distorted octahedral environment around the Zn atom. The results of both FTIR and single-crystal X-ray crystallography confirm the bidentate nature of the carboxylate ligands. The DNA interaction study of the synthesized complexes was investigated using UV-visible spectroscopy and viscosity measurements suggesting an intercalative binding mode of interaction of the complexes with SS-DNA. The interaction between the synthesized complexes and CTAB was elaborately studied with a conductometric method. The conductivity method was used to find CMC, higher CMC values suggesting a stable complex-CTAB system. Results of in vitro antibacterial and antifungal activities indicate the biological potency of the synthesized compounds.