Synthesis, excited state properties, and dynamic structural change of photoresponsive dendrimers

This article reviews recent advances in research of the dendrimer synthesis in connection with the design, synthesis and reaction of photoresponsive dendrimers. Dendrimers with photoreversible stilbene cores undergo mutual cis–trans isomerization in organic solvents to give photostationary state mixture of cis and trans isomers. Even the fourth generation (G4) stilbene dendrimer with molecular weight as high as 6500 underwent cis–trans photoisomerization within the lifetime of the excited singlet state. The large dendron group surrounding the photoreactive core may affect the excited state properties of the core to increase the efficiency of photoisomerization and/or decrease the fluorescence efficiency. The photochemistry of stilbene dendrimers with various types of dendron groups, and azobenzene dendrimers is discussed. Furthermore, recent advance of dendrimer syntheses and the possibility of their application to construct photoresponsive large molecules are discussed.