Preparation and Characterization of Novel Mixed-Ligand Compounds of Mn(II), Fe(II), Co(II), Cu(II), and Zn(II) Derived from Schiff Bases and Nitrogenous Bases with Biological Activity Evaluation

Abstract

This Schiff base ligand (ScB) was synthesized by the condensation reaction of (2-hydroxybenzaldehyde) with (O-tolidine). Coordination complexes of Schiff bases and Nitrogenous bases were prepared by reacting the Schiff base and Nitrogenous bases with metal(II) chlorides, yielding five new chelating complexes with manganese, iron, cobalt, copper, and zinc ions using ethanol as the solvent. The prepared ligand and its complexes were characterized by various chemical and physical methods, including melting point determination, elemental analysis (C.H.N), atomic absorption spectroscopy, thermogravimetric analysis (TGA), proton nuclear magnetic resonance (H-NMR,¹³C-NMR), mass spectrometry, UV-visible spectroscopy (UV-Vis), infrared spectroscopy (FT-IR), measuring magnetic sensitivity, and molar electrical conductivity, where the study proved that (1-5) the resulting complexes are non-conductive and (6-15) complexes are conductive in ratio 1:2. The results suggested an octahedral geometry for the complexes. In addition, the biological activity of the prepared ligand and its complexes were measured against two types of bacteria, namely (E.coli) negative gram and (Staphylococcus aureus) positive gram. These bacteria were chosen due to their importance in the medical field, and the results confirmed that most of the prepared compounds have high inhibitory activity against the bacteria used.