Investigating the structure and bioactivity of lanthanum coordination compounds

Lanthanum metal complexes were synthesized using a classical condensation method by reacting lanthanum nitrate salts with a bidentate ligand in a 1:2:1 molar ratio (M:L:L). The formation and structure of the resulting complexes were confirmed through a combination of analytical techniques, including Fourier transformation infrared spectroscopy, thermal gravimetric analysis, X-ray diffraction, elemental microanalysis, and scanning electron microscopy. The lanthanum complexes synthesized exhibited strong in vitro antimicrobial activity. Antibacterial screening showed inhibition zones of 18-26 mm against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>, surpassing those of the reference drug ciprofloxacin (16-20 mm). Antifungal studies demonstrated inhibition zones of 15-23 mm against <i>Candida albicans</i> and <i>Aspergillus niger</i>. The MIC values ranged from 25 to 50 μg/mL, indicating high potency. Additionally, moderate antimalarial activity was observed against <i>Plasmodium falciparum</i> (IC₅₀ = 12.4 μM). These findings confirm that lanthanum complexes possess potent antibacterial and antifungal properties, highlighting their promise as potential candidates for novel antimicrobial and antimalarial drug development.