Chemical Synthesis and Characterization of Lanthanum(III) 2‑Hydroxybenzoate and Its Antibacterial Potential: In Vitro...

A novel lanthanum-(III) salicylate complex (La-(Sa)₃) with potential biomedical applications was chemically synthesized via the reaction of salicylic acid (SA) with lanthanum oxide nanoparticles (La₂O₃NPs). This two-step synthesis approach involved the initial preparation of La₂O₃NPs followed by their coordination with mixed SA ligands, after which the resulting complex and its precursors were comprehensively characterized. The structure of the La-(Sa)₃ complex was investigated using nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Molecular docking studies of the newly synthesized complex were conducted to elucidate the interactions between La-(Sa)₃ and the target microbial protein at the molecular level. Comparative evaluations of the bacteriostatic and bactericidal activities of the La-(Sa)₃ complex, its ligand (SA), and La₂O₃NPs were performed against Gram-positive and Gram-negative bacteria. These studies demonstrated that the La-(Sa)₃ complex exhibited significant antibacterial activity against the selected bacterial strains. The results further indicated that La-(Sa)₃ showed enhanced antibacterial properties due to a synergistic effect with La₂O₃NPs. The morphology of the La-(Sa)₃ complex revealed that the chemical synthesis of the La-(Sa)₃ complex in the presence of La₂O₃NPs resulted in notable differences in powder and particle morphology. Spectral analyses confirmed that the synthesized La₂O₃NPs successfully reacted with SA to form La-(Sa)₃ complex molecules. The data obtained from the in silico studies were consistent with the results of the experimentally conducted antibacterial assays. The experimental study results suggest that the La-(Sa)₃ complex may be developed as a promising antibacterial drug candidate.