Abstract
Liquid crystal compounds incorporating coumalic acid, 6-hydroxycoumarin, or 7-hydroxycoumarin at the terminal position were synthesized and their mesomorphic properties were examined. Compounds exhibit nematic (N) phase and/or smectic A (SmA) ones. 5- (4'-Alkoxybiphenyl-4-oxycarbonyl) pyran-2-one derivatives exhibit two kinds of SmA phases. For the mixture of 5- (4'-hexyloxybiphenyl-4-oxycarbonyl) pyran-2-one and 4'-octyloxybiphenyl-4-yl 4-cyanobenzoate, both SmA phases of the low temperature region are miscible, however, both SmA phases of the high temperature region are not miscible. As a result, a reentrant phenomenon involving N and SmA phases is observed in the 58-80 mol% of 5- (4'-hexyloxybiphenyl-4-oxycarbonyl) -pyran-2-one. The effect of the terminal lactone group on mesomorphic properties will be discussed in terms of molecular structure and electrostatic properties.
