Spectral studies on the interaction of yttrium ion with the ligands of phenolic groups: N,N'-Ethylenebis[2-(o-hydroxyphenolic)glycine] and N,N'-di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid.

The interactions of yttrium with N,N′-ethylenebis[2-(o-hydroxyphenolic)glycine] (EHPG) and N,N′-di(2-hydroxybenzyl)ethylenediamine-N,N′-diacetic acid (HBED) are investigated by using UV difference and fluorescence spectra methods in 0.1M N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid (Hepes) at pH 7.4. Yttrium binding produces two UV difference peaks near 240 and 294nm, respectively, that both are the characteristic of phenolic groups binding to yttrium. The molar extinction coefficient of Y-EHPG and Y-HBED are (15.7±0.40)×103, (15.8±0.80)×103cm−1M−1 at 240nm, respectively. Using EDTA as a competitor the obtained conditional equilibrium constants of the complexes are logKY-EHPG=15.07±0.32 and logKY-HBED=15.18±0.26, respectively. However, the effects of yttrium binding on the fluorescence intensity of EHPG and HBED are quite different, the former showing a decrease but the latter an increase.