Synthesis, Characterization and Biological Studies on Some Mixed Ligand La (III) Complexes

Synthesis of mixed ligand Lanthanum (III) complexes of the type [M (Q) (L) 2H2O] have been carried out by using 8-hydroxy quinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-proline, L-valine and L-serine as secondary ligands. The characterization of metal complexes has been done on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements specify that lanthanum (III) complexes are diamagnetic in nature. Electronic absorption spectra of the complexes show intra-ligand, charge transfer and d-d transitions respectively. The thermal analysis data of the complexes indicates the presence of coordinated water molecules. FTIR spectra show bonding of the metal ion through N- and O- donor atoms of the ligand molecules. Tube dilution and Agar cup methods were implemented for study of antibacterial activity of the complexes against S. aureus, C. diphtheriae, S. typhi and P. aeruginosa. The antibacterial study was carried out by using the tetracycline as a standard antibacterial compound and it was found that, the complexes show mild activity against selected strains of micro-organisms as compared to standard tetracycline.