Synthesis, characterization, superoxide dismutase, and antimicrobial activities of Co (II) complexes with Schiff base ligand and their hybrid proteins

Metal complexes have been reported to possess excellent free radical scavenging and antimicrobial properties. In the present study, seven linear trinuclear complexes were synthesized based on bis Schiff base ligand and complexes 1 , 3 – 7 are reported for the first time. Their structure was characterized by IR spectroscopy and single crystal diffraction. BSA was used as carrier to hybridize the synthesized complexes to construct hybrid proteins. The interaction between metal complex and BSA was studied by UV–Vis spectrophotometry and fluorescence spectroscopy. Static quenching was the main mechanism identified for the interaction between metal complex and BSA. In the superoxide dismutase (SOD) activity test, IC 50 values of complexes and hybrid proteins range between 2.89 and 26.53 μM, with hybrid proteins demonstrating a stronger activity than the complexes. Among all the complexes studied, complex 5 exhibited the strongest inhibition against Candida albicans (MIC 12.5 μg ml −1 ) and Cryptococcus neoformans (MIC 6.5 μg ml −1 ).