Synthesis, structural characterization, DFT studies, biological activity, and molecular docking of a cobalt(II) complex

The new coordination solid aqua-bis(benzoato)-(1,10-phenanthroline)‑cobalt(II) simplified as [Co(phen)(H2O) (Bz)(η2-Bz)] (C1) was synthesized and characterized using spectroscopic methods (IR, UV–vis) and single crystal X-ray diffraction. The complex adopts a geometry stabilized by a combination of strong O–H…O, weak C–H..O, C–H…C, and π-π stacking interactions. as well as nonconventional parallel intramolecular and antiparallel intermolecular interactions between chelate rings. DFT calculations on the optimized geometry and electronic properties using PBEPBE/LanL2DZ basis set found overall agreement with the experimental data. Hirshfeld surface analysis established intermolecular interactions, and the reactive sites in the complex were highlighted by the molecular electrostatic potential (MEP) maps. In addition, the antibacterial properties of the title complex were assessed against both Gram-positive and Gram-negative bacteria. It should be mentioned that (C1) exhibited a significantly antibacterial activity compared to the free ligand. Molecular docking studies indicated that (C1) has favorable predicted binding affinity for the dihydrofolate reductase (DHFR) receptor of Escherichia coli (PDB ID: 5E8Q), and holds promise as an antibacterial agent. This compound provides valuable insight into the structure–activity relationship of transition metal complexes, and demonstrated the potential for developing a new class of therapeutics to combat multidrug-resistant bacteria. For this study, trimethoprim was used as reference antibiotic for comparison. The cobalt complex demonstrated favorable binding affinity (MolDock score: 169.171) compared to trimethoprim ( 91.377), indicating that the cobalt complex may have better inhibitory potential against DHFR under the conditions investigated.