Novel isoxazole derivatives useful as dopants for improving the properties of liquid crystal mixtures have the isoxazole ring linked in the three and/or five position to a thiophene or furane unit

摘要

Isoxazole derivatives have the isoxazole ring linked in the 3 and/or 5 position to a thiophene or furane unit. Isoxazole derivatives of formula (I) with the isoxazole ring linked in the 3 and/or 5 position to a thiophene or furane unit are new. T = an isoxazole ring of formula (II) or (III); X = S or O; R1 and R2 = H, F, CN or a 1-20C alkyl or 2-20C alkenyl (optionally with asymmetric C atoms) such that (a) 1-3 non-terminal CH2 groups can be replaced by -O-, -S- or -C(O)- with the proviso that the heteroatoms are not directly linked; (b) one -CH2- group can be replaced by -CH=CH-,-C equivalent to C-, -Si(Me)2, cyclopropane-1,2-diyl, oxirane-2,3-diyl, cyclobutane-1,3-diyl, cyclopentane-1,4-diyl, bicyclo(1.1.1)pentane-1,3-diyl and/or cyclohexane-1,4-diyl; (c) 1 or more H can be replaced by F or CN; (d) any asymmetric C atoms in the alk(en)yl groups can be substituted by Me, OMe, CF3, F, CN and/or Cl, with the proviso that only 1 of R1 and R2 can be H, F or CN; A1 and A2 = phenylene-1,3- or -1,4-diyl (optionally substituted once or twice by CN or F), cyclohexane-1,4-diyl (optionally with 1 or 2 H replaced by CN, Me or F), 1-cyclohexene-1,4-diyl (optionally with 1 H replaced by F), pyridine-2,5-diyl (optionally monosubstituted by F), thiophene-2,5-diyl (optionally monosubstituted by F), furane-2,5-diyl or naphthalene-2,6-diyl (optionally mono- or di-substituted by CN or F); M1 and M2 = -OC(O)-, -OCH2-, -SC(O)-, -SCH2-, -CH2CH2-, -OC(O)-CH2CH2-, -OCH2CH2CH2-, -C equivalent to C-, -(CH2)4- or a bond; and a and b = 0 or 1. Independent claims are also included for switching devices or displays based on such liquid crystal mixtures, especially those containing a chiral smectic mixture, with there being active matrix elements and the mixture forming a monostable switching mono-domain. Those with chiral smectic mixtures can be operated in inverse mode.