Pulse radiolysis studies of open-formed diarylethenes in organic solvent: Does the radiochromism proceed in radical ions and triplet state?

Abstract

We performed pulse radiolysis of open-formed diarylethenes (o-DAEs) in organic solvents, and observed the transient absorption spectra. In dichloroethane and DMF, absorption spectra of the radical cations and anions, respectively, were obtained. They decayed in hundreds microsecond, and no residual absorption spectra were obtained. From these facts, the absence of the ring-closing reaction via the radical ions was inferred. Radiolysis of o-DAEs in benzene demonstrated occurrence of ring-closing reaction to the ring-closed DAEs (c-DAE), indicating that the triplets are reactive for ring-closing. The conformational relaxation processes in c-DAEs were observed, and the rates were determined.