Synthesis, spectroscopic, electrochemical, DNA binding and photocleavage studies on coordination compounds of bis(4-aminophenyl)methane based novel Schiff bases

Abstract

Two novel Schiff bases, 4,4′-methylenedianilidene-bis(3-methoxy-4-hydroxy-benzaldehyde) (L1) and 4,4′-methylenedianilidene-bis(3,4-dimethoxybenzaldehyde) (L2), have been prepared by condensing 4,4′-methylenedianiline (MDA) with vanillin and 3,4-dimethoxybenzaldehyde (DMB) respectively in ethanolic medium. Metal complexes of the above Schiff bases are prepared from salts of Cu(II), Zn(II), Co(II) and VO(IV). They are characterized by elemental analysis, molar conductivity, magnetic moment measurements, IR, 1H NMR, UV-Vis., FAB Mass, and EPR spectra. The elemental analysis data exhibit the formation of 1: 1 [M: L] ratio. The mode of bonding and the geometry of the complexes have been confirmed on the basis of IR, UV-Vis. and magnetic moment measurements. These data reveal a square-planar geometry for all the complexes except VO(IV) which has square-pyramidal geometry. The molar conductance measurements of the Schiff base complexes reveal the existence of non-electrolytic nature. The interactions of complexes with calf thymus DNA (CT-DNA) have been investigated by electronic absorption spectroscopy, viscosity measurements and cyclic voltammetry. The results indicate that the complex can bind to DNA by intercalation modes. The Schiff bases and their metal complexes have been evaluated for their antifungal and antibacterial activities against different species of pathogenic fungi and bacteria and their results are compared with standard drugs.