Photoluminescence enhancement of Sm3+ in the Sm3+-salicylic acid-o-phenanthroline ternary composite

There has been growing interest in the study of the enhancement effect of fluorescence of the lanthanides, generally achieved through ligand sensitization. In this process, an organic ligand is first excited by light absorption, followed by energy transfer from the ligand to the excited levels of a lanthanide. The photons are then emitted by the decay from the excited levls to its ground level. The ternary Sm(III) complex with the salicylic acid (HSal) and o-phenanthroline (Phen) has been prepared. The photoluminescence intensity of the complex Sm(Sal)3(Phen) is enhanced by more than two hundred times with respect to that of the binary complex Sm(Sal)3(H2O)2. It is confirmed by Sm(III) content titration and the spectra of IR, UV-vis and fluorescence that the second ligand, Phen, also coordinates with the Sm3+ ion. The second ligand Phen shows enhancement effect on the fluorescence of the complex. These observations are discussed in detail and the results are rationalized.