Studies of de Vries SmA* type phase in chiral thiobenzoates

The nature of the SmA*-SmC* phase transition was studied in three chiral liquid crystal compounds, in two belonging to the same homologous series, (S)-1-methylheptyl-4-(4 '-alkoxybiphenylthiocarboxy)-benzoates, (S)-MHPSBOn, where n = 7 and 8 is the number of carbon atoms in the alkyl chain and (S)-4-[(4-{1-methylheptylcarboxyl} phenyl) carbonylthio] phenyl-4 '-decyloxy-1-benzenecarboxylate (10OPOSMH). Compounds (S)-MHPSBO7 and (S)-MHPSBO8 show different behavior in the SmA*-SmC* phase transition, in MHPSBO7 the SmA* phase is the de Vries phase, while in MHPSBO8 it is the classic SmA* phase. The aim of the study is to demonstrate the presence of the de Vries type SmA * phase in three chiral thiobenzoates. The electro-optical method and SAXS were used to analyze the SmA*-SmC* transition.