Photoisomerisation and fluorescence behaviour of polyphenylene-based stilbene dendrimers

Abstract

The photoinduced structural changes of three polyphenylene-based stilbene dendrimers, G1, G2, and G3, has been studied. They all exhibit fluorescence emission with considerably higher quantum efficiency and longer fluorescence lifetimes compared with the parent stilbene. These dendrimers undergo mutual cis → trans isomerisation on direct irradiation with 310 nm light at room temperature. In a solvent glass at 77 K, one-way cis → trans isomerisation was observed for G2. A volume-conserving isomerisation mechanism is presumed to be operating in the cis-to-trans isomerisation of G2 at 77 K.