Y. Nabeshima et al., SYNTHESIS OF NOVEL LIQUID-CRYSTALLINE THIOPHENE DERIVATIVES AND EVALUATION OF THEIR PHOTORESPONSIVE BEHAVIOR, Chemistry of materials, 9(6), 1997, pp. 1480-1487
Novel liquid-crystalline (LC) thiophene derivatives were synthesized,
and their LC behavior and photoresponsive behavior were explored. Amon
g the thiophene derivatives synthesized, 4-(4-alkylphenylazo)phenyl 2-
thienylacrylates (TAn, n = 4, 5, 6, and 7) were found to show nematic
(N) phase. TAn exhibited the N phase only when the azobenzene moiety i
n the molecule was in the trans form while no LC phase when the azoben
zene was in the cis form. Photoirradiation of TA6 in a cell to bring a
bout the trans-cis isomerization of the azobenzene moiety resulted in
disappearance of the N phase. The N phase was restored when the irradi
ated sample was kept in the dark. Time-resolved measurements by means
of a laser pulse (355 nm; 10 ns fwhm) revealed that in transmission-mo
de analysis the N-isotropic phase transition was completed in 8 ms, wh
ile in reflection-mode analysis it occurred in 100 mu s.