Remarkably, the photoinduced changes in aromaticity of [5]helicene as a central ethene bridge along with the relative smaller activation energy and higher frequency factor facilitated the thermal bleaching rates of diarylethene switches 2 and 3 in solution.  This research provides a new insight for designing aromatic diarylethene photoswitches for reversible fluorescence switching behaviour, photoinduced changes in aromaticity and further fast thermal back reaction.
THERM