ANDREEA CARAC, RICA BOSCENCU, GETA CARAC, SIMONA GABRIELA BUNGAU SPECTRAL STUDY OF SOME LANTHANIDES COMPLEXES WITH QUATERNARY PYRIDINIUM LIGANDS Some lanthanides complexes with two N-heterocyclic ligands derived from 4,4'-bipyridinium and 1,2-bis-(4-pyridinium) ethane (noted BP and BPE) were studied in presence of triethylamine and methanol in view of their application as cytotoxic agents. Absorption spectra have been recorded by UV-Vis spectroscopy during the complexation process in solution. The ligands demonstrate preferential arrangements in lanthanide’s electronic structure which is identified much clearly in ultraviolet range. La(III)-BP solution indicates absorption at lmax= 206 nm while La(III)-BPE at lmax of 208 nm. The solution from the Nd(III)-BPE complex synthesis shows the highest absorbance at lmax= 220 nm, compared with Nd(III)-BP at lmax= 212 nm. The bathochromic shifts of the spectral bands can be assigned to the physical interaction of Ln(III) ions with ligands. No major changes were observed in the absorption, hypsochromic and hyperchromic effects when varying the ligand. The complexes spectral properties were performed by dissolving them in methanol in three phases until a complete dissolution of the precipitates was achieved.