Fluorescence characteristics of complex formation of europium(III)-salicylate

The complexation of salicylate with EU(3+) was studied by means of time-resolved laser-induced fluorescence spectroscopy (TRLFS) using ultra-short pulses at a concentration of sodium salicylate of 1.00 x 10(-4) M. Ionic media was kept constant at 0.1M NaClO(4). pH was adjusted to 4.00. The concentration of Eu(3+) was varied from 1.98 x 10(-3) M to 1.31 X 10(-2) M. From the fluorescence lifetime analysis of the salicylate, we confirmed that a dynamic quenching process did not take place, while static quenching proceeded under the experimental conditions. The Stern Volmer plots indicated only the formation of a I : I complex, and the stability constant was assigned to be log beta(1.1) = 2.08 +/- 0.02. This agrees with reported values, which have been determined by other techniques. This result shows that the Studies on complex formation can be safely investigated quantitatively by means of TRLFS from not only the luminescence of Eu(3+) but the fluorescence of salicylate.