Abstract
New complexes of Cu(I,II), Zn(II) and Cd(II) of thiosemicarbazide ligand 1-(p-(methylanilinocetyl-4-phenyl-thiosemicarbazide)(H2LB) have been prepared and characterized by 1HNMR, Mass spectra, FT-IR, elemental analyses, molar conductance, UV-visible spectra, magnetic susceptibility measurements, thermogravimetric analysis (TGA/DTG) and X-ray diffraction pattern before and after irradiation. The results confirmed that gamma ray enhanced the stability of irradiated compounds as compared to non-irradiated compounds. XRD patterns proved that increasing the crystallinity of the samples and the particles in nano range after gamma irradiation. The obtained data indicated that the Cu(I) and Cd(II) ions coordinated to the ligand through the (C = O), N(2)H and (C = S), the ligand behaves as neutral tridentate. While in complexes Cu(II) and Zn(II)complexes (B2 and B3) the ligand behave as neutral tetradentate and coordination take place via (C = O) and two N(2)H. These studies revealed that, two kinds of stereochemical geometries; Cu(II) and Zn(II) complexes were predicted to be octahedral, Cu(I) and Cd(II)complexes were found to be tetrahedral. The theoretical conformational structure analyses were performed using density functional theory for ligand and complexes at B3LYP functional with 6-31G(++)d,p basis set for ligand and LANL2DZ basis set for complexes. The ligand and its metal complexes have been tested for their inhibitory effect on the growth of bacteria against gram-positive (Streptococcus pyogenes) and gram-negative (Escherichia coli). Results suggested that in case of 1µg/ml and 5µg/ml for Cu(II) and Zn(II) complexes have higher activity than other complexes. The chelation could facilitate the ability to cross the cell membrane of E. coli and can be explained by Tweedy’s chelation theory. Molecular docking investigation proved that; the Zn(II) complex had interesting interactions with active site amino acids of topoisomerase II DNA gyrase enzymes (code: 2XCT).
Molecular speciation and tissue compartmentation of zinc in durum wheat grains with contrasting nutritional status