Bile Salt-Derived Eu3+ Organogel and Hydrogel: Water-Enhanced Luminescence of Eu3+ in a Gel Matrix

Eu3+ was found to form gel with cholate in methanol and comparative study was done with the hydrogel. Water is a well known quencher of Eu3+ luminescence, and its quenching rate constant is higher than that of MeOH. In a Eu3+ derived luminescent material, therefore, the replacement of water by methanol should lead to enhanced Eu3+ luminescence. However, significant pyrene-mediated sensitizatized luminescence of Eu3+ was observed in a Eu3+ cholate hydrogel, but not in the methanolic gel. We provide experimental data that rationalize this apparent paradox.