Experimental assessment of the efficacy of sensitised emission in water from a europium ion, following intramolecular excitation by a phenanthridinyl group

Abstract

The overall quantum yields for phenanthridinium sensitised emission from a europium ion have been measured in H₂O and D₂O for a series of five structurally related, octadentate ligands in which the distance from the phenanthridinium chromophore to the Eu ion varies from 2.5 to ca. 8.2 Å. Overall quantum yields (pD⩽2) range from 0.25 to 0.012 suggesting that the experimental distance for 50% efficiency of intramolecular energy transfer lies close to 5.5 Å for this system.