Indole core-based Copper (II), Cobalt (II), Nickel (II)and Zinc (II)complexes: Synthesis, spectral and biological study

In search of biologically active compounds, we have synthesized new Copper(II), Cobalt(II), Nickel(II)and Zinc(II)metal complexes by the reaction of N'-(4-(diethylamino)-2-hydroxybenzylid-ene)-5-methyl-3-phenyl-1H-indole-2-carbohydrazide (L)with the corresponding metal salts. The synthesized metal complexes are thoroughly characterized by various spectral techniques. The spectral data reveal the octahedral geometry for Copper(II), Cobalt(II)and Nickel(II)complexes and tetrahedral geometry for Zinc(II)complex. All the compounds have been screened for their antibacterial, antifungal, anti-tuberculosis and antioxidant activity. The complexes [Cu(L)(Cl)(H2O)2]and [Co(L)(Cl)(H2O)2]exhibited excellent activity against bacteria E. coli and B. subtilis with MIC-12.50 µg/mL and fungi A. flavus and A. niger with MIC-12.50 µg/mL. Among the screened compounds for anti-tuberculosis activity, the complexes [Cu(L)(Cl)(H2O)2], [Co(L)(Cl)(H2O)2]and [Zn(L)(Cl)] was found to be the most active against M. tuberculosis with a MIC of 3.125 µg/mL. Further, the ligand (L)and its [Cu(L)Cl(H2O)2]and [Co(L)Cl(H2O)2]complexes have shown good scavenging activity.