Three metal complexes[Re(bpy)(CO)3(CN-t-Bu)]Cl (1) (where bpy = 2,2-bipyridine), Bu4N[Ir(ppy)2(CN)2] (2), and Ir(ppy)3 (3) (where ppy = 2-phenylpyridine and Bu4N = tetrabutylammonium cation)were evaluated as oxygen sensors in poly((n-butylamino)thionylphosphazene) (nBuPTP) matrixes. The
phosphorescent dyes 2 and 3 exhibit long lifetimes and high quantum yields in degassed dichloromethane
and toluene solutions and when dissolved in the polymer matrix. These two dyes exhibited exponential
decays both in solution and in the polymer films, with somewhat longer lifetimes (for 2, τ0 = 4.78 μs;
for 3, τ0 = 1.40 μs) in the polymer film. All three dyes gave linear Stern−Volmer plots, but 1 was rather
sensitive to photodecomposition. The slopes of the Stern−Volmer plots for these dyes were compared to
those measured previously for platinum octaethyl porphine (PtOEP) and ruthenium tris-diphenylphenanthroline chloride ([Ru(dpp)3]Cl2. Attempts to explain the differences in slope using τ0 as the sole scaling
parameter were unsuccessful. To explain these results, we calculated the effective capture radius for
quenching by oxygen, which was 1.7 nm for 2 and 2.7 nm for 3, relative to a value of 1.0 nm for PtOEP.
Thus, dye 3 is 2.7 times more sensitive to quenching by oxygen than PtOEP and more than 5 times more
sensitive than [Ru(dpp)3]Cl2.
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