Chiral valerolactone derivs. - useful as dopants for liq. crystal media, to give high spontaneous polarisation with compensated pitch

摘要

Chiral valerolactone derivs. of formula (I) are new: R1 is 1-18C alkyl, opt. with 1 or 2 non-adjacent CH2 gps. replaced by O, COO, OCO or S; A is -CH2-, -CMe2- or -CH2CH2-; Sp is a spacer gp., opt. contg. a chiral C atom; Zo is -COO-, -CH2O-, -CH2CH2-, -CC- or -CH=CH-; MG is mesogenic gp.; n is 0 or 1; p is 0 or 1. USE/ADVANTAGE - Used as optically active dopants for liq. crystal (LC) compsns.. Cpds. (I) induce high spontaneous polarisation in achiral base mixts., combined with almost compensated pitch, with little or no effect on the Sc phase range. (I) can also be used to prevent reverse twist in nematic LC phases. In an example, a mixt. of 6 mmoles 1-r-cyano-1-heptyl-cis-4- (4'-hydroxybiphenyl-4-yl)- cyclohexane, 6 mmoles pyridine and 10ml toluene was mixed with a suspension of 6 mmoles camphanic acid chloride in 6ml toluene, heated for 1 hr. at 100 deg.C, cooled and poured into 50ml water; this mixt. was worked up by extn. with methyl tert.-butyl ether, evapn. and recrystallisation from EtOH/EtOAc (1:2) to give cpd. (I), where R1 is Me; A is CMe2; p is 1; Zo is COO; n is 0; MG is 4-(4'-cyano-4'-heptyl- cyclohexyl)-biphenylyl. The prod. had phase transitions, K 153 Ch 151 I. A 9-component LC base mixt. with K below 0 Sc 87 S(A) 80 N 96 I was doped with 10% (I) to give a ferroelectric medium with K below -10 Sc 73 S(A) 79 Ch 99 I (where K is cryst. solid, Ch is cholesteric, S is smectic, N is nematic, I is isotropic phase). This medium had Ps, 30.8 nC/cm2; tau, 115 micro-s (at 15 V/micron); helical pitch in cholesteric phase, greater than 40 microns; angle of tilt, 30 deg. (all at 20 deg.C).