Syntheses and structural characterization of metal complexes of 4-(naphthalen-1-yl)-1-(quinolin-2-yl)methylene)thiosemicarbazide: their in-vitro screening studies for antitubercular activity

Abstract

The ligand 4-(naphthalen-1-yl)-1-((quinolin-2-yl)methylene)thiosemicarbazide (HL) and its cobalt(III), nickel(II) and copper(II) complexes of type [CoIIIL2]Cl (1), [NiIIL2] (2), [CuIILCl] (3) were synthesized and structurally characterized by various spectral techniques. The structure of 2 was confirmed through single-crystal X-ray structure determination. Complex 2 crystallized in the triclinic system with the P-1 space group. HL acts as tridentate chelate with N,N,S-donor sites. The spectrochemical analysis of all the complexes showed that, in the case of 1 and 2, the metal-to-L ratio is 1:2, while in the case of 3, the copper-to-ligand ratio is 1:1. The antitubercular studies of the complexes were explored in vitro against the Mycobacterium strain, M. H37Rv. Complex 3 has better activity compared to the standard drug pyrazinamide. Cytotoxicity studies were carried out on human embryonic kidney cell lines (HEK293). Inhibition of tuberculosis bacteria has increased upon complexation compared to the free ligand.