E. Sabatani et al., EMISSION-SPECTROSCOPY OF RU(BPY)(2)DPPZ(2- PROBING THE CHEMICAL ENVIRONMENT IN CAST FILMS() IN NAFION ), Journal of the American Chemical Society, 118(5), 1996, pp. 1158-1163
The incorporation of Ru(bpy)(2)dppz(2+) (dppz = dipyrido[3,2-a:2',3'-c
]phenazine) into Nafion coatings was monitored in situ by electronic a
bsorption, steady-state emission, and lifetime measurements. Whereas t
he aqueous loading solution does not show any luminescence (the emissi
on of Ru(bpy)(2)dppz(2+) in nonaqueous solvents is completely quenched
by water), strong emission was detected immediately after immersion o
f the Nafion coating. The emission decay is triexponential, with two l
ong-lived components (tau = 900 and 300 ns) dominating a fast decay (t
au = 50 ns). Emission intensities, lifetimes, and lifetime distributio
ns depend strongly on the loading level, owing both to self-quenching
and environmental changes brought about by increases in the concentrat
ion of the complex in the film. Owing to the remarkable efficiency of
excited-state deactivation attributable to dppz-H2O hydrogen bonding,
Ru(bpy)(2)dppz(2+) is an extremely sensitive probe of accessible water
structures in Nafion.