Complexes of Cu(II) and Ni(II) with Bis(Phenylthiosemicarbazone): Synthesis, Spectral, EPR and in Vitro ‐ Antibacterial and Antioxidant Activity

Abstract

AbstractThe synthesis of Cu(II) and Ni(II) complexes with 2,6‐diacetylpyridine bis(4‐phenyl‐3‐thiosemicarbazone) (L) ligand have been reported. The ligand was characterized by elemental analysis and spectral (IR and 1H NMR) studies and its complexes were characterized by electronic, UV/VIS, EPR and IR studies. The room‐temperature EPR spectrum of Cu(II) complex was recorded and the analysis of its spectrum gave {g} tensor with g1 = 2.25, g2 = 2.15, and g3 = 2.07 which were of distorted octahedral structure. The electronic spectrum of Ni(II) complex indicated the octahedral geometry around the Ni(II) ion. Their antibacterial activities were evaluated by the diameter of zone of inhibition (mm) against four bacteria such as B. subtilis, S. aureus, E. coli and K. pneumonia. The ligand and the 6‐coordinate Ni(II) complex did not inhibit the growth of the test organisms, while the Cu(II) complex showed good antibacterial activity than parent ligand against the same bacteria. The free ligand and its metal complexes have been tested for in vitro ‐ antioxidant activity by reduction of 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) and iron induced lipid peroxidation using rat brain homogenate. The ligand exhibited potent in vitro ‐ antioxidant activity than its Ni(II) and Cu(II)complexes.