Synthesis, characterization, crystal structure and antibacterial activity studies of cobalt(II) and zinc(II) complexes containing halogen quinoline Schiff base ligand

Abstract

This work presented the synthesis, characterization and biological activity of Co(II) and Zn(II) complexes derived from 4‑chloro-2-((quinolin-6-ylimino)methyl)phenol (HL), their structures were characterized using IR, NMR and single-crystal X-ray diffraction. The HL was crystallized in the orthorhombic crystal systems, space groups of Pccn, and two HL molecules contained its smallest asymmetric unit. The self-assembly of HL with metal (II) (M=Co, Zn) led to the formation of CoL2 (1) and ZnL2 (2) by solvothermal method in methanol-water system. The basis of spectroscopic techniques, single-crystal X-ray diffraction and powder X-ray diffraction analysis further revealed that 1 and 2 were isomorphous with similar coordination mode and similar structural features. The introduction of a chlorine atom and C=N group to the ligand facilitated the collaboration of electrostatic interaction, hydrogen bonding, π⋯π stacking interaction and the rare C—H⋯Cl interaction, which resulted in the formation of three-dimensional supramolecular architectures. The synthesized complexes exhibited significant antimicrobial activity when evaluated against six phytopathogenic fungi, 2 exhibited a wider range antimicrobial activity compared to HL and 1.