Antimicrobial and antioxidant activities of new metal complexes derived from (E)-3-((5-phenyl-1,3,4-oxadiazol-2-ylimino)methyl)naphthalen-2-ol

Abstract

(E)-3-((5-phenyl-1,3,4-oxadiazol-2-ylimino)methyl)naphthalen-2-ol (LH) has been synthesized and used as a ligand for the formation of V(IV), Cr(III), Mn(II), Co(II), Ni(II), and Cu(II) complexes. The chemical structures were characterized using different spectroscopic methods. The elemental analyses revealed that the complexes have the general formula [ML2(H2O)2] [where M = Mn(II), Co(II), and Cu(II)], while the Cr(III) complex has the formula [CrL2(H2O)2]Cl, V(IV) complex has the formula [VO2L2], and Ni(II) complex has the formula [NiL2]. The molar conductance data revealed that all the metal chelates except the Cr(III) are non-electrolytes. From the magnetic susceptibility measurement and UV–Visible spectra, it is found that the structures of Cr(III), Mn(II), Co(II), and Cu(II) complexes are octahedral, V(IV), complex is square pyramid and Ni(II) complex is square planar. The stability of the prepared complexes was studied theoretically using density function theory. The total energy for the complexes was calculated and it was shown that the copper complex is the most stable. Complexes were tested against selected types of microbial organisms and showed significant activities. The free radical scavenging activity of metal complexes have been determined by their interaction with the stable DPPH-free radicals. All the compounds have shown encouraging antioxidant activities.