Synthesis, structural characterisation, bio-potential efficiency and DNA cleavage applications of nicotinamide metal complexes

Mixed ligand complexes were synthesised using nicotinamide as the primary ligand and nitrite as the secondary ligand were characterised by FT-IR, UV–Vis, 1H NMR, TG–DTA–DTG, X-ray powder diffraction and physical analytical studies. From the molar conductance, magnetic moment and electronic spectral data of the synthesised complexes a general formula of [M(ONO)2(NA)2] where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) and [Cr2(ONO)6(NA)2] with a distorted octahedral structure were proposed. Thermal analyses show that the complexes lose molecules of hydration initially and subsequently expel anionic and organic ligands in continuous steps. The kinetic parameter values, such as, E*, ΔH*, ΔS* and ΔG* illustrate the spontaneous association of the metal and ligands in the formation of the complexes. The antimicrobial efficacy of the ligand and its complexes were examined by in vitro method against various pathogenic bacterial and fungal strains. The metal complexes were found to posses efficient antimicrobial properties compared to nicotinamide and a few of these complexes could turn out to be excellent models for the design of effective antibiotic drug substances. The intercalating interaction of Cu(II) complex with CT-DNA was inspected by absorption spectral and viscosity studies, thermal denaturation and electro-analytical experiments.

► Nicotinamide; nitrite ion mixed ligand complexes are prepared by microwave methodology.
► The ligand field parameters support the distorted octahedral geometry.
► TG, DTA analysis shows spontaneous association of the ions to form complexes.
► Complexes are more toxic towards gram positive strains than gram negative strains of bacteria.
► Cu(II) complex binds to CT-DNA through intercalative mode.