Synthesis, Characterization and Antibacterial Activity of Nanocrystalline Ni(II)-6-methyl-4-oxo-4H-chromene-3-carbaldehyde Complex

Abstract

The methyl substituted 3-formyl chromones was synthesized by Vilsmeier-Haack reaction. Nickel(II) complex was synthesized by refluxing the mixture of ligand solution taken into ethanol:acetic acid as 1:1 ratio and Ni(II) salt solution. The nature of bonding and geometry of the Ni(II) complex have been characterized from elemental analysis, FTIR, UV-visible spectral studies, thermal methods like TGA, the magnetic susceptibility, XRD, SEM, ESI-MS and molar conductance measurement, etc. Nickel(II) chloride is forming 1:2 (M:L) complex. The FTIR spectrum shows characteristic frequency band at 1614 cm^-1 and 1695 cm^-1, which belongs to carbonyl of pyron ring and neighboring aldehyde carbonyl in ligand respectively. The Ni(II)-ligand complex shows characteristic frequency of M-O- bonding in 545-466 cm^-1 region. The electronic spectrum shows three absorption bands and confirmed complex has octahedral geometry. The formation of nanocrystalline complex and their bird feather like morphology was identified by powder XRD and SEM. Finally, NiO residue was obtained in thermogravimetric study of the complex. The ligand and its Ni(II) complex were screened for antimicrobial activities by the agar well diffusion technique.