title: Stilbene analogs in Hula-twist photoisomerization.
abstract: Photoisomerization of several cis- or Z-stilbene analogs and two E-analogs in low temperature organic glasses was examined. From a mechanistic view-point, the compounds can be divided into three types: (i) those giving identical Hula-twist (HT) and one-bond-flip (OBF) products, (ii) those giving a single HT product that is different (hence distinguishable) from the OBF product and (iii) those showing two distinct HT processes but only one OBF process. Examples for all three types of analogs are provided emphasizing the most informative Type-II (stilbene analogs with identical but unsymmetrically substituted phenyl rings), including linear as well as conformationally constrained compounds. Conditions necessary for establishing HT and OBF processes are defined. Proper choice and design of model systems are essential for establishing or eliminating HT mechanism(s) of isomerization.
authors.affiliation: Department of Chemistry, University of Hawaii, 2545 The Mall, Honolulu, HI 96822, USA.
authors.forename: Lan-Ying
authors.initials: LY
authors.lastname: Yang
authors.forename: Miki
authors.initials: M
authors.lastname: Harigai
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Imamoto
authors.forename: Mikio
authors.initials: M
authors.lastname: Kataoka
authors.forename: Tong-Ing
authors.initials: TI
authors.lastname: Ho
authors.forename: Elena
authors.initials: E
authors.lastname: Andrioukhina
authors.forename: Olga
authors.initials: O
authors.lastname: Federova
authors.forename: Sergei
authors.initials: S
authors.lastname: Shevyakov
authors.forename: Robert S H
authors.initials: RS
authors.lastname: Liu