Aryl(hetaryl)pyrazolines as new photoacid generators for optical information recording

On the Mechanism of Photodehydrogenation of Aryl(hetaryl)pyrazolines in the Presence of Perchloroalkanes

“…For comparison, electronic absorption spectra of pyrazoline 1 in the same solvent compositions are also given in Fig. 4 (right) as an illustration of its keto-enol transitions (12,13). The similar effect in spectral properties of 3-(pyrazolinyl)-4-hydroxycoumarins has been noted by D.-Y.…”

“…In these conditions pyrazolines behave themselves as effective photogenerators of H + ‐acidity. Thus, photodehydrogenation of pyrazolines in the presence of CCl 4 is able to generate via proton formation highly fluorescent Rhodamine dye open form from its lactone form, providing a new effective way for optical information recording (Scheme 2) .…”

“…However, (1,5‐diaryl‐3‐pyrazolinyl)‐4‐hydroxycoumarins can effectively operate as acid photogenerators being only in the enol‐form . Since acidity photogenerators have recently received many significant applications in polymeric materials and in the control of biochemical reactions , search of new pyrazolines as acidity photogenerators and study of their phototransformation mechanistic pattern are in an obvious demand.…”

Media with photoinduced irreversible fluorescence

“…New PAGs are of interest to diminish subside processes of dye destruction upon irradiation and, therefore, to increase resolution and information capacity of the WORM materials. One possible solution is the photodehydrogenation of aryl(hetaryl)pyrazolines under illumination in carbon tetrachloride [16][17][18]. The following mechanism of the phototransformation of aryl(hetaryl) pyrazolines has been proposed (Scheme 7) [18].…”

“…It is important to note the ability of aryl(hetaryl)pyrazolines to photogenerate acidity and thus to activate the rhodamine dye fluorescence in polymer films as well [17]. The changes in the electronic absorption and emission spectra during the irradiation of a poly(methyl methacrylate) film (PMMA film) containing rhodamine B in lactone form and pyrazoline 11 are shown in Figure 2.…”