Ferroelectric liquid crystals for nonlinear optics applications

摘要

This invention provides chiral, non-racemic compounds and liquid crystal compositions comprising such compounds. The compounds of this invention include those having the formula: ##STR1## wherein k=0 or 1 and when k=1, B=COO, OOC, --C.tbd.C--, or --C.tbd.C--C.tbd.C--; X.sub.1, X. sub.2, X.sub.3 and X.sub.4 are either H, an electron donor or an electron acceptor where at least one of the groups X.sub.1, X.sub.2, X. sub.3 or X. sub.4 is an electron acceptor and at least one of these groups is an electron donor or H and when one of X.sub.1 or X.sub.3 is an electron donor or H, the other is an electron acceptor and when one of X. sub.2 or X.sub.4 is an electron donor or H, the other is an electron acceptor; and R.sub.1 and R.sub.2 can be various substituted and unsubstituted alkanes and monoalkenes. Compounds provided include those where one of R.sub.1 or R.sub.2 is a chiral non-racemic tail group, particularly a group selected from --O--C*H(CH.sub.3)R.sub.c, --O--C*H(CH. sub.3)COOR.sub.d, and --O--CH. sub.2 C*HF--C*HF--R.sub.e in which the * indicates an asymmetric carbon enriched in one stereoconfiguration where R.sub.c, R.sub.d, and R.sub.e can be various substituted and unsubstituted alkanes and monoalkenes. The compounds of this invention are useful in the preparation of FLC mixtures and as non-linear optical materials.