Synthesis, Characterization and Biological Activity of Transition Metals Schiff Base Complexes Derived from 4,6-Diacetylresorcinol and 1,8-Naphthalenediamine

Abstract

The tridentate Schiff base ligand was prepared via condensation of 4,6-diacetylresorcinol and 1,8-naphthalenediamine in 1:1 molar ratio using conventional method. Additionally, a new series of transition metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions were prepared and fully characterized by elemental analysis, FT-IR, 1H NMR, UV–vis, conductivity and magnetic susceptibility measurements and theoretically through density function theory (DFT). Spectral studies suggested that, the Schiff base coordinated to the metal ions through the azomethine N, N-amine and phenolic oxygen atoms. From the elemental, magnetic susceptibility and spectroscopic data, the complexes were suggested to have octahedral geometry. The Schiff base and its metal complexes were screened for their in vitro antimicrobial activities and showed that Cd(II), Cu(II) and Cr(III) complexes have high activity against Escherichia coli, while Ni(II) and Cd(II) complexes have the highest activity against Bacillus Subtilis, Co(II) complex has the highest activity against Staphylococcus aureus and Cd(II) complex has the highest activity against Pseudomonas aeruginosa. In addition, the molecular docking study was performed to explore the possible ways for binding to crystal structure of Staphylococcus aureus nucleoside diphosphate kinase complexed with ADP (PDB ID: 3Q8U).