Synthesis, spectroscopic characterization and in vitro antimicrobial studies of Schiff base ligand, H2L derived from glyoxalic acid and 1,8-diaminonaphthalene and its Co(II), Ni(II), Cu(II) and Zn(II) complexes

A novel Schiff base ligand, N,N′-bis (glyoxalicacidcarboxaldiimine)-1,8-diaminonaphthalene [H2L] obtained by the condensation of glyoxalic acid and 1,8-diaminonaphthalene and its mononuclear complexes of type, [ML] [M = Co(II), Ni(II), Cu(II), Zn(II)] have been synthesized and characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz., FT-IR, EPR, 1H NMR, FAB-Mass, UV–vis and magnetic moment data. A square planar geometry has been assigned on the basis of UV–vis and magnetic susceptibility around Co(II), Ni(II) and Cu(II) ions while conductivity data showed non electrolytic nature of all the complexes. The synthesized ligand, H2L and its complexes have been tested against Streptococcus mutans, Staphylococcus pyogenes, MRSA (Gram positive bacteria), Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli (Gram negative bacteria), Candida albicans, Candida krusei, Candida parapsilosis and Candida neroformans and results suggested that Cu(II) complex has significant antimicrobial activity.