Synthesis, spectral and structural studies on some new isonicotinic thiosemicarbazide complexes and its biological activity

Complexes of Co(II), Ni(II) and Cu(II) with the new N-ethyl-2-isonicotinoylhydrazine carbothioamide (HEITsc) have been prepared. The complexes have been characterized by elemental analysis, molar conductance, spectral (IR, UV-Vis, ESR and mass), thermal (TG) and magnetic measurements. The IR spectra showed that HEITsc behaves as mononegative bidentate. According to the spectral data (UV-Vis and ESR) and magnetic measurements, different stereochemistries were proposed where both of Ni(II) and Co(II) complexes have octahedral while the Cu(II) has square planar geometry. The DFT calculation was used to optimize the geometric structure of the ligand its metal complexes. The minimum energy optimized structures were coincided with the proposed structures. The comparison of DFT calculated spectral data (IR and UV-Vis) with the experimental data showed a good agreement. Also, the ligand and metal complexes were examined as antimicrobial agents and the effect of these compounds on DNA degradation was studied. (C) 2015 Elsevier Ltd. All rights reserved.