Tj. Dingemans et al., FERROELECTRIC LIQUID-CRYSTALS DERIVED FROM ISOLEUCINE I - SYNTHESIS AND CHARACTERIZATION, Liquid crystals, 24(2), 1998, pp. 247-253
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.