Motivated by the previous studies reported by Benali-Cherif et al. “Comprehensive study of a novel cobalt(II) complex: Synthesis, X-ray crystal structure, Hirshfeld surface analysis, computational quantum investigations, and molecular docking insights“ (Polyhedron 271 (2025) 117,445), we synthesized heteroleptic cobalt(II)-based complexes from CoX2·6H2O (X = NO3–, Cl–), benzoic acid (bzH) and 1,10-phenathroline (phen) or 2,2′-bipyridine (bpy). It was established that using Co(NO3)2·6H2O and phen yielded complex [Co(phen)2bz]NO3·2bzH (1). Using CoCl2·6H2O and phen allowed to produce complex [Co(phen)bz2(H2O)] (2), while using CoX2·6H2O (X = NO3–, Cl–) and bpy produced the same complex [Co(bpy)bz2] (X = NO3–, 3-I; Cl–, 3-II) regardless of the nature of the anion in the parent cobalt salt. Elemental analysis and powder X-ray diffraction confirmed the composition and purity of the isolated complexes. Diffuse reflectance and UV–Vis spectroscopy revealed optical properties of complexes 1–3, with the bands assigned to intraligand, MLCT and d-d transitions. Bidentate coordination of the bz anions was established in the crystal structures of 1 and 3, while monodentate coordination of the bz anions was established in the crystal structure of 2. Structures of 1 and 2 were stabilized by O–H···O hydrogen bonds and π···π interactions. The RDG and combined QTAIM/NCI analyses supported the described bonding interactions. Molecular docking predicted similar potential inhibition against a Klebsiella pneumoniae protein for all complexes, with favorable ligand efficiency scores and distinct interaction profiles stabilizing the complexes.
