The Phosphorescence Spectra of 9,10-Anthraquinone β- and β,β′-Sulfonates in an Aqueous Solution at 77 K

The nπ* phosphorescence spectra, and their excitation spectra and lifetimes of 9,10-anthraquinone-2-sulfonate, and -2,6- and -2,7-disulfonates in water–ethylene glycol 1:1 mixture at 77 K have been obtained. These phosphorescence spectra shift to the red with increases in the concentration of the solutions, and show an excitation-wavelength dependence. From the results obtained it is concluded that in the glassy solutions at 77 K an association of these quinones occurs, and that the phosphorescence state of the associates corresponds to the nπ* triplet excimer state, similar to that of the p-quinone aggregates in polycrystalline solutions at 77 K, previously studied.