Phosphorescence lifetime of naphthalene and phenanthrene in aggregated aromatic molecule-beta-cyclodextrin-precipitant complexes

Aggregated aromatic molecule-beta-cyclodextrin-precipitant complexes exhibit long-lived phosphorescence at room temperature in water after the chemical binding of oxygen. The temperature dependences of the phosphorescence lifetimes of naphthalene-h(g), naphthalene-d(g), and phenanthrene in the aggregates were measured. For example, the phosphorescence lifetimes of naphthalene-d(g) aggregated with beta-cyclodextrin and cyclohexane are equal to 25.1, 17.6, and 6.8 s at 77, 276, and 347 K, respectively, and that of phenanthrene aggregated with isooctane and beta-cyclodextrin are 3.24, 3.06, and 1.26 s at 268, 274, and 335 K, respectively. The temperature dependences of the phosphorescence lifetimes at room temperature are determined by the rate constants of the radiative and nonradiative transitions from the triplet state of an aromatic molecule.