Proton phototransfer in a series of ortho-hydroxy derivatives of 2,5-diaryl-1,3-oxazole and 2,5-diaryl-1,3,4-oxadiazole in polystyrene films

Proton transfer in the lower excited singlet state has been examined for ortho-hydroxy derivatives of 2,5-diaryl-1,3-oxazole and 2,5-diaryl-1,3,4-oxadiazole in polystyrene films, as this largely determines the spectral characteristics. There is found to be a substantial reduction in the radiationless deactivation in the product from that reaction, namely the phototautomeric form, which is the basic reason for the low quantum yield in fluorescence in liquid solutions. These changes are explained from the viewpoint of a reduction in the probabilities of high-amplitude intramolecular motions in the excited phototautomeric forms of these ortho-hydroxy derivatives in a polymer. Chemical Research Institute, V. Karazin Kharkov National University, 4 pl. Svobody, Kharkov 310077, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 6, pp. 357–361, November–December, 1999.