Relaxation, de Vries behavior, and layer contraction in chiral liquid crystal by dielectric spectroscopy

Fluorenone imidazolium salts as novel de Vries materials

“…These materials show no or only very low layer contraction upon the SmA to SmC phase transition, enabling ferroelectric displays without zig-zag defects caused by the chevron-like arrangement of the molecules in the mesophase. With regard to the design of calamitic liquid crystals displaying SmA and SmC phases and de Vries behaviour most previous work has focused on 5-phenylpyrimidines, 39,41,43,[48][49][50][51][52][53] 2phenylpyrimidines, [54][55][56][57][58] biphenyls, 40,44,[59][60][61][62][63][64] thiadiazoles, 54,65 aroylhydrazones 66 and bent-core mesogens. 37,[67][68][69][70][71][72][73][74] Lemieux and Ivanov have reported independently for non-charged liquid crystals 3-5 that a rigid uorenone core promotes formation of the SmC phase.…”