Activation of fluorescence of lactone forms of rhodamine dyes by photodehydrogenation of aryl(hetaryl)pyrazolines

Aryl(hetaryl)pyrazolines are effective photogenerators of acid providing an irreversible photochemical activation of fluorescence of rhodamine group dyes. The effect of solvent on two consecutive reactions, photodehydrogenation of pyrazoline and lactone ring opening of the dye was studied. An increase in solvent polarity leads to an increase in the rate of both reactions by different degrees. The systems under study are believed to be promising for the formation of recording media for multilayer optical file type disks of ultrahigh data storage capacity with fluorescent readout.