Synthesis, Structural Analysis, Theoretical Calculations, In Silico Prediction of Antibacterial Efficacy, Toxicity Assessment, In Vitro Antioxidant Evaluation and Polymerization Activity of Cobalt(II) Coordination Complexes of Para-biphenylol

In this study, we report synthesis of novel cobalt(II) para-biphenyloxides (complexes 1 and 2 ) by reacting cobalt(II) chloride hexa-hydrate with sodium salt of para-biphenylol under reflux. The formation of synthesized complexes has been substantiated by physicochemical methods and spectral techniques. Spectroscopic data have confirmed the coordination of phenolate oxygen to cobalt(II) centre thereby creating an octahedral environment around the cobalt metal. Theoretical studies were performed for all the complexes to calculate global reactivity descriptors using the Density Functional Theory (DFT) B3LYP/6–311 + + G (d, p) basis set for calculations on the ligand atoms and for the cobalt(II) complexes. Molecular docking studies were used to reveal the mode of interaction between cobalt(II) complexes and various receptor proteins of Gram-positive bacterial strains viz. Bacillus cereus and Staphylococcus aureus . 1 has shown highest binding affinity corresponding to – 9.7 kcal/mol with Tyrosine 56 residue of B. cereus. The in vitro assessment of antibacterial effectiveness was conducted employing the Minimum Inhibitory Concentration ( MIC ) method, involving six bacterial pathogens comprising two Gram-positive and four Gram-negative strains sourced from MTCC -Chandigarh. 2 has demonstrated remarkable efficacy against Pseudomonas aeruginosa bacterium, displaying an MIC value of 3.905 µg/mL (100% efficacy), outperforming the standard antibacterial drug, chloramphenicol, which exhibited a value of 7.81 µg/mL (87.5%). Furthermore, the in vitro assessment of antioxidant activity was performed utilizing ferric reduction, ferrous chelating and hydroxyl radical scavenging assay for the newly synthesized complexes. 2 has displayed significant reducing power, showcasing a 92.02% efficacy, comparable to the standard value utilized in the study (93.66%). Catalytic evaluation has indicated the complexes to be both selective and effective towards polymerization of isoprene monomer with conversion rate of 99.39% at room temperature in 3 h. Graphical Abstract