Synthesis, characterization and biological activity of nano-sized Co(II), Ni(II), Cu(II), Pd(II) and Ru(III) complexes of tetradentate hydrazone ligand

Furo-(phenyldimethine)-carbohydrazone (H2L) has been prepared via the condensation reaction of 2-furoic acid hydrazide with terephthaldehyde by (2:1) molar ratio. Octahedral and square planar complexes were synthesized from the reaction of (H2L) ligand with chloride salts of Co(II), Ni(II), Cu(II), Ru(III) and Pd(II) ions. All the chelates were structurally characterized by various analytical and spectral techniques. The stoichiometry of chelates was found to be 1:1, 1:2 and 1:3 (L:M) molar ratios to form sandwich, binuclear and trinuclear complexes, respectively. All complexes were found to be non-electrolytic in nature on the basis of molar conductance values. The IR data showed that the ligand served as tetradentate in a neutral keto form. The ligand coordinated with all metal ions via oxygen atoms of carbonyl group and furan ring. The thermal properties of the ligand and its chelates were investigated utilizing thermogravimetry and reflected that Ru(III) complex has lower thermal stability than other complexes. X-ray diffraction spectra established nano-size for Ni(II) and Ru(III) complexes. The ESR result revealed axial symmetry with hyperfine structure for Cu(II) complex indicative of (B-2(1g)) as a ground state. Some quantum parameters were reported in order to compare the reactivity of the compounds. The biological data indicated that all complexes have cytotoxic and antioxidant activity rather than the native ligand. Among all complexes, Ru(III) complex had excellent cytotoxic and antioxidant activity. This was due to its chemical structure and its nano-size. (C) 2020 Elsevier B.V. All rights reserved.