Synthesis, Characterization and Theoretical Study of Some Transition Metal Complexes with New Schiff Base Derived from 1,2,4-triazole

Abstract

The present work involves, new Schiff base of (E)-2- (((3-mercapto-5-(3,4,5-trimethoxyphenyl)-4H-1,2,4-triazol-4yl)imino)methyl)phenol (L2) has been synthesized by condensation reaction of 4-amino-5-(3,4,5 trimethoxy phenyl)-4H-1,2,4triazole-3-thiol with 2-hydroxybenzaldehyde. The new Schiff base (L2) used as a ligand to synthesize a new complex with Co(II), Ni(II), Cu(II), Pd(II), and Cd(II) metal ions by 1:1 (Metal: ligand) ratio. New ligand and their complexes have been exanimated and confirmed by fourier-transform infrared (FT-IR), ultraviolet-visible (UV-visible), proton nuclear magnetic resonance ( 1 HNMR), carbon13 nuclear magnetic resonance ( 13 CNMR), microelement analysis (CHNS), thermal analysis (TG-DSC), atomic absorption flame (AAF), conductivity and magnetic susceptibility. The results obtained from spectra, elemental analyses and thermal analyses (TG-DSC) and compare by density functional theory (DFT) and TD-DFT calculations were screened for some selected complexes and the observed data indicated their stability and the expected chemical formula, Pd(II) were square planner, whereas the Cu(II), Co(II), Ni(II) octahedral, and Cd(II) were tetrahedral geometry . Furthermore, the antibacterial and antifungal activity was screened for the DMSO solution concerning the Schiff base (L2) and its complexes (20 µg/ml) against two kinds of gram; (Staphylococcus aureas and Bacillus subtilis) positive and two negative bacteria; (Esherichia coli and Burkholderia) and against (Candida albican) fungi. The results obtained from diffusion method confirmed the greater activity of Pd(II) and Cd(II) complexes whereas the Co(II),Cu(II) and Ni(II) complexes showed medium activity compared with the low inhibition zones of the free Schiff base of 1, 2, 4-triazole derivative.