title: Synthesis and characterization of thermally irreversible photochromic cholesteric liquid crystals.
abstract: Three thermally irreversible photochromic chiral liquid crystal dithienylcyclopentenes were found not only to be able to self-organize into a phototunable helical superstructure, i.e., cholesteric phase, but also to be able to induce a photoresponsive helical superstructure in an achiral liquid crystal host. The cholesteric phase in the three chiral compounds went into a glassy phase without crystallization upon cooling. All the materials exhibited reversible photochromism with thermal stability in both solution and thin film, and their fluorescence was shifted to longer wavelength upon UV irradiation while the shifted fluorescence was recovered upon visible light irradiation. The enhanced fluorescence emission with the addition of fluoride anions was observed, and its reverse process happened with the addition of an equivalent proton.
authors.affiliation: Liquid Crystal Institute, Kent State University, Kent, Ohio 44242, USA.
authors.forename: Krishnamurthy
authors.initials: K
authors.lastname: Rameshbabu
authors.forename: Augustine
authors.initials: A
authors.lastname: Urbas
authors.forename: Quan
authors.initials: Q
authors.lastname: Li