FERROELECTRIC LIQUID-CRYSTALS DERIVED FROM ISOLEUCINE I - SYNTHESIS AND CHARACTERIZATION

A series of ferroelectric liquid crystals (FLCs), '(3-methyl-2-halopen tanoyloxy)-4-hexyloxybiphenyls (3M2XPHOB, X = F for fluorine, C for ch lorine, B for bromine) and their racemates (3M2XPHOB-R), were synthesi zed and characterized. The FLCs contain a chiral tail comprised of cc- halo acids which are derived from L-isoleucine (DL-isoleucine for the racemates). The mesogens were characterized by high-resolution H-1 and C-13 NMR and their phase behaviour was studied by optical microscopy and differential scanning calorimetry. The chloro and bromo derivative s show both chiral smectic C (SmC) phases and smectic A (SmA) phases, while the fluoro derivatives exhibit only a SmA phase. The spontaneou s polarization of 3M2CPHOB and 3M2BPHOB were measured in the respectiv e SmC: phases; that of the fluoro derivative was inferred by extrapol ating its concentration dependent polarization in an achiral SmC solve nt, a racemic mixture of 3M2BPHOB.