Synthesis, characterization and biological evaluation of some novel hydrazide Schiff's bases and their metal complexes

Abstract

N'-(4-Hydroxy-3-methoxyphenyl)methylidene]formic hydrazide (L-1), N'-[-(4-hydroxy-3-methoxyphenyl)methylidene]-3'-hydroxynaphthalene-2'- carbohydrazide (L-2) N'-[-(5-methylfuran-2-yl)methylidene]-3'- hydroxynaphthalene-2'-carbohydrazide (L-3), N'-[-1''-(4-fluorophenyl)ethylidene] -3'-hydroxynaphthalene-2'-carbohydrazide (L-4) and N'-[(-1'-(4-chlorophenyl) ethylidene]formic hydrazide (L-5) were synthesized and tested for their antioxidant activity. All these newly synthesized Schiff's bases were treated with Cu(II), Co(II) and Zn(II) chlorides to form their respective complexes. Antioxidant activity of the synthesized ligands (L-1, L-2, L-3, L-4 and L-5), their corresponding metal(II) complexes, salts of the metal used in the complex formation and Trolox (as standard antioxidant) was measured in terms of their ability to scavenge the DPPH free radical. Ligand (L-4) was found to be the best antioxidant among all the ligands. As regards the activity of metal(II) complexes, Zn-L-4 exhibited the best antioxidant activity.