Ni(II)-tetrahedral complexes: Characterization, antimicrobial properties, theoretical studies and a new family of charge-transfer transitions

A new amine containing selenium and their five imine, (SeSchX)(X: -H, F, Cl, Br, CH3), and Ni (II) complexes, [Ni(SeSchnH(2)O)(2)]Cl/[Ni(SeSchCl)(H2O)Cl], were synthesized. The compounds were characterized by means of elemental analyses, C-13 and H-1 NMR (for imine), FT-IR, UV-Visible spectroscopy, TGA/DTA and elemental analyses. [Ni(SeSchCl)(H2O)Cl] complex from Ni(II) complexes changes color from yellow to orange in the range pH 5-7. [Ni(SeSchCl)(H2O)Cl] complex has ligand-to-metal charge-transfer (LMCT) transitions in the basic medium. Excitation characteristics and energetic of [Ni(SeSchCl)(H2O)Cl] complex, examined via TD-DFT calculations, reveals transitions of LMCT and pi -> pi* character that matches the experimental values. [Ni(SeSchCl)(H2O)Cl] complex showed the highest antibacterial activity when compared to other complexes reported in this work. (C) 2013 Elsevier B.V. All rights reserved.