Efficient energy transfer of cationic iridium(III) complexes on the surface of a colloidal clay

In order to investigate energy transfer on a clay surface, blue- and red- emitting cationic iridium(III) complexes, [Ir(dfppy)2L]+ (dfppyH = 2-(4′,6′-difluorophenyl)pyridine, L = 4,4′-dimethyl-2,2′-bipyridine) and [Ir(piq)2L]+ (piqH = 1-phenyisoquinoline) , respectively, were co-adsorbed by colloidally dispersed synthetic saponite in 1:3 (v/v) methanol/water. The stationary and transient emission results were analyzed on the basis of the Förster-type energy transfer mechanism. It was concluded that energy transfer took place from the excited blue emitter to the red one efficiently. The accumulation of the reactants on a clay particle was essential, since no energy transfer occurred in the absence of a clay in the similar concentration ranges.