Experimental and theoretical study on photochromism of triphenylvinyl-naphthopyrans

A novel class of dual photo-responsive triphenylvinyl-naphthopyrans (TNPs) have been designed and synthesized by linking a triphenylvinyl fluorophore with the skeleton of 2H-naphthopyran. UV–vis absorption spectral experiments show that TNPs exhibit very rapid color changes and tunable thermal fading rates, which are controlled greatly by the electronic and steric effect of the triphenylene moiety and the 2-aryl rings. In addition, TNPs can emit strong blue fluorescence in aggregate state due to the restriction of intramolecular rotations. Theoretical calculation unveiled that the triphenylethylene moiety can regulate dynamically the photochromic and discoloration rates of TNPs. These findings will greatly promote the rational design and further development of new organic functional materials.