title: Trans-cis isomerization of arylether dendrimers with azobenzene core and terminal hydroxy groups.
abstract: Azobenzene-cored arylether dendrimers 2a-2c with polar hydroxy groups at the periphery have been prepared from hydroboration-oxidation reaction of azobenzene-cored arylether dendrimers 1a-1c with nonpolar vinyl groups at the periphery. Trans-->cis photoisomerization of central azo group has been investigated by UV-vis spectral changes after photolysis. The results show that dendrimers 1a-1c and 2a-2c in methanol/dichloromethane (1/1, v/v) have carried out trans-cis isomerization. Reaction rate for trans-->cis photoisomerization of 2a-2c with polar hydroxy groups increases with increasing generation upon irradiation of 350 nm. On the other hand, the reaction rate of cis-->trans thermal back isomerization for 2a-2c decreases with increasing the generation. This result is somewhat different from that for 1a-1c with nonpolar vinyl groups. Both the reaction rates of trans-->cis photoisomerization and cis-->trans thermal back isomerization for 1a-1c decrease in higher generation.
authors.affiliation: Department of Chemistry, Sunchon National University, Suncheon, Jeonnam 540-742, Republic of Korea.
authors.forename: Ji-hye
authors.initials: JH
authors.lastname: Lee
authors.forename: Daeock
authors.initials: D
authors.lastname: Choi
authors.forename: Eun Ju
authors.initials: EJ
authors.lastname: Shin
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D050091:Dendrimers / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular
chemical_list: D001391:Azo Compounds; D050091:Dendrimers; D004987:Ethers; C009850:azobenzene