Synthesis of Manganese(II), Iron(III), and Vanadium(IV) Complexes with New Schiff Bases and their Spectroscopic and Thermal Studies and Evaluation of their Antimicrobial Activity

Heterocyclic 3-acetyl coumarin with hydrazide derivatives and their metal complexes are a substantial family of pharmaceutical drugs used to treat infection, anti-inflammatory issues, diabetes, and neurological disorders in the field of medicinal chemistry. Cyclization of 5- floro-2-furaldehyde, ethyl acetoacetate, and urea or thiourea by LaCl3.7H2O, addition of hydrazine to form amine derivatives were performed, and respective Schiff base derivatives (L1, L2) were produced by adding acetyl coumarin in an ethanolic solution at ambient temperature. New ligands and its complexes of the V (IV), Fe (III) and Mn (II) ions were characterized using (FT-IR, UV, MS) and nuclear magnetic resonance (1H-NMR) as well as elemental analysis (CHN). The synthesized complexes chelate with ligands L1, L2 via (N, O2) atoms. The structural geometry of the complexes was illustrated in the solid phase using FT-IR and UV-VIS spectroscopy, elemental analysis (CHNS), and flame atomic absorption, in addition to magnetic susceptibility and conductivity measurement. The antibacterial activity of the newly prepared ligands and their metal complexes was evaluated against Pseudonomous aerugionosa as a gram negative and Bacillus subtilis as a gram positive microorganism. Moreover, the antifungal activity against two fungi Aspergillus flavus, and Saccharomyces cerevisiae was studied for all compounds. The coordinated ligands significantly increased their bactericidal and fungicidal action compared to the free ligands, which did not exhibit any activity against the selected fungal and bacterial strains. The results focused on the synergetic relationship between the metal ion and the ligand, in addition to the structural variation.