Microwave-assisted synthesis of N-carbamoyyl-2-hydroxybenzamide and its Co(II), Co(II), and Zn(II) complexs with antibacterial activity studies

A green and efficient method for the synthesis of a ligand, N-carbamoyl-2-hydroxybenzamide (SU), was developed using microwave assisted solid state reaction of urea (carbonylamide) and calicylic acid (2-hydroxybenxoic acid). The ligand was subsequently coordinated with Co(II), Cu(II), and Zn(II) ions to form complexes of the general formula [M(SU)2Cl2] (M= Co, Cu, Zn). The synthesized metal complexes were characterized by elemental (C, H, N) analysis, metal content estimation, molar conductance measurements, FTIR spectroscopy, UV-Visible electronic spectroscopy, and magnetic susceptibility studies. The synthesized ligand was investigated using FTIR, UV-Visible, and 1H-CNMR and 13C-NMR spectroscopies as well as CHN elemental analysis. The low molar conductance values of the complexes indicate their non-electrolytic nature, while spectroscopic and magnetic data support an octahedral coordination geometry around the metal ions. The antibacterial activities of the ligand and its complexes were evaluated in vitro against Gram-positive Staphylococcus epidermidis, and Gram-negative Escherichia coli using the agar diffusion method. The free ligand exhibited weak antibacterial activity, whereas metal coordination resulted in enhanced efficacy. In particular, the Co(II) and Zn(II) complexes showed appreciable activity against both bacterial strains. This study demonstrates the microwave-assisted green synthesis provides an environmentally friendly, rapid, and effective route for the preparsation of transition-metal complexes with potential antibacterial applications. KEY WORDS: Salicylic acid, First transition metal(II), Microwave irradiation, Antimicrobiology Bull. Chem. Soc. Ethiop. 2026, 40(1), 135-145. DOI: https://dx.doi.org/10.4314/bcse.v40i1.11