Synthesis and Antimicrobial Activity of Nitrobenzaldehyde Schiff base and Complexes

Abstract

The Schiff base (NL) was synthesized by the reaction between ethanolamine and 3-nitrobenzaldehyde. The metal complexes with Mn(II), Co(II), Ni(II), and Cu(II) were obtained in an alcoholic KOH medium. The diagnostic H-C=N proton shift at 8.48 δ ppm confirmed the formation of the Schiff base ligand. The stoichiometry of the metal complexes was determined through the percentage metal content by EDTA titration. The infrared spectra suggested the chelation of the ligand through the ethanolamine oxygen as a monodentate ligand. The O-H band of the hydroxide ion was observed between 3650 and 3450 cm^–1. The shift in n ® p* transition from 327 nm in the ligand spectrum to 337-347 nm in the complexes was ascribed to delocalisation of lone electrons to the aromatic ring upon coordination, while the metal ions were assigned to the octahedral geometry as shown by their visible bands. The in vitro antimicrobial potency of the compounds was investigated against ten microbial strains using the agar well diffusion method. The compounds were generally active against the bacterial and fungal cells, demonstrating a broad-spectrum while the Cu(II) complex has the largest inhibition zone against Staphylococcus aure