Mechanism of the Pyrene-Sensitized Photolysis of N-(1-Naphthoyl)-O-(p-toluoyl)-N-phenylhydroxylainine

Abstract

The title hydroxylamine (NT) undergoes pyrene-sensitized photodecomposition to give rearrangement and fragmentation products. An analysis of linear Stern–Volmer plots, both for the sensitized photolysis of NT and for the fluorescence quenching of pyrene by NT, indicates the involvement of singlet pyrene in this photolysis. The observation of negligible effects of 1,3-cyclohexadiene and trans-stilbene as a triplet quencher on the reaction provides further supporting evidence for a singlet-pathway mechanism. A comparison of the relative state energies of NT and the sensitizer suggests the existence of a reactive singlet-exciplex intermediate formed between the singlet-state sensitizer and the ground-state NT. The results of solvent and micellar effects on the sensitized photolysis establish that electron transfer in the exciplex predominates in a polar solvent, and that in a nonpolar solvent energy transfer in this exciplex plays a major role in the reaction.

Photoinduced Organic Reactions by Employing Pyrene Catalysts

“…Okubo and co-workers reported the photolysis of N -(1-naphthoyl)- O -( p -toluoyl)- N -phenylhydroxylamine ( 1 ) catalyzed by pyrene ( Py1 ) (Scheme 2 ). 9 N -Hydroxylamine derivative 1 underwent decomposition in the presence of Py1 as a singlet-sensitizer upon irradiation at 366 nm to give the different products 2 – 6 . The yield of each of these products was not reported.…”