Synthesis and antibacterial evaluation of Co(II) and Ni(II) metal-organic frameworks derived from a Schiff base linker

Abstract This study reports the successful synthesis of two novel metal-organic frameworks (MOFs), Co-L MOF and Ni-L MOF, using a custom-designed Schiff base linker, 4-(((2E,3Z)-4-hydroxy-4-phenylbut-3-en-2-ylidene)amino)benzoic acid (LH). The frameworks were thoroughly characterized using a suite of techniques, including FTIR, XPS, PXRD, FESEM-EDX, BET, and TGA, which confirmed their porous structures, specific coordination geometries (square planar for Co(II) and octahedral for Ni(II)), and thermal stability. The antibacterial efficacy of both MOFs was evaluated against clinical strains of Escherichia coli and Staphylococcus aureus. Results demonstrated that both MOFs exhibited significant antibacterial activity, with Co-L MOF showing superior performance, as evidenced by larger inhibition zones (20 mm for both strains) and lower minimum inhibitory concentrations (MICs: 0.64 mg/ml for E. coli and 0.32 mg/ml for S. aureus). This enhanced activity is attributed to its geometry and higher surface-to-volume ratio, which facilitates better bacterial interactions. The proposed antibacterial mechanism involves the generation of reactive oxygen species (ROS) and electrostatic interactions, leading to damage to the bacterial cell membrane. These findings underscore the potential of Schiff base-derived MOFs as promising antibacterial agents.