Luminescence Sensitization of Eu(III) Complexes with Aromatic Schiff Base and N,N'-Donor Heterocyclic Ligands: Synthesis, Luminescent Properties and Energy Transfer

Five luminescent Eu(III)-4-fluoro-N-salicylideneaniline (Fsa) complexes with different N,N- donor heterocyclic ligands (L) were synthesized (where L=2,2-bipyridine (bipy), 4,4-dimethoxy-2,2-bipyridine (dmbp), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neo) and 2,2-biquinoline (biq)) and characterized by structural, thermal and spectroscopic analyses. The photophysical studies of the complexes viz. UV-Vis absorption spectra, emission spectra, lifetime decay curve, radiative, non-radiative transition rates and quantum yields were investigated. The photophysical properties indicated that fluorine substituted salicylideneaniline acts as a better sensitizer for Eu3+ ion after involvement of ancillary ligands which leads to efficient energy transfer resulted in bright red emission due to (D0F2)-D-5-F-7 transition. The highest overall quantum yield (32.78%) and sensitization efficiency (75.30%) of [Eu(Fsa)(3)neo] showed that it is a potential candidate in optical field.