Synthesis and photochemical properties of polyphenylene dendrimers with photoreactive stilbene core

Photoresponsive polyphenylene dendrimers trans-1 and 2 were synthesized for the first time, and their photochemical reaction as well as excited state properties were studied. trans-1 and 2 exhibited fluorescence emission with considerably high quantum efficiency. Furthermore, they underwent photochemical isomerization to the cis-isomers. Thus, polyphenylene dendrimer trans-2 with the molecular weight as high as 4700 and with weak conjugation throughout the molecule was found to undergo trans–cis photoisomerization within its excited state lifetime.