Synthesis of mono and hetero-bi nuclear lanthanum (III) and europium (III) complexes of 2-hydroxy-5-sulfobenzoic acid and 1,10-phenanthroline: luminescence and magnetic studies

The resurgence of interest in lanthanide coordination complexes due to their diverse applications has been increasing for past decade. These lanthanide complexes have found applications such as catalysts, sensors, optoelectronics, light sources, and modified semiconductors. The modifications in the lanthanide complex chemistry due to the use of different complexation agents enhanced the luminescence properties by varying the emission bands, stoke shifts, and lifetimes accordingly. This versatile nature of lanthanide complexes increased our interest to make a good contribution to the field. The complexes of lanthanum, europium, and novel binary complex of La and Eu metals with 1,10-phenanthroline (Phen) and 5-sulfosalicylic acid (SSA) were synthesized by co-precipitation method. Different physicochemical techniques like analytical and spectroscopic were used to characterize the ligands and complexes. The coordination of ligands with metals in complexes was confirmed by FTIR and UV spectroscopy. The surface morphology of nine coordinated La-complexes and seven coordinated Eu complexes was investigated by SEM micrographs. The X-ray crystallographic analysis revealed that all the complexes exhibit a triclinic crystal system. All the complexes were found to exhibit self-reversed magnetic hysteresis (SRMH). The luminescence and magnetic properties of mixed metal complexes are enhanced as compared to their mononuclear analogs.