Mesomorphic properties of (S)-MHPSBOn series

This article reports new results on synthesis and mesomorphic properties of the homologous series of (S)-1-methylheptyl-4-(4'-alkyloxybiphenylthiocarboxy)-benzoates, referred to as (S)-MHPSBOn, where n varies from 7 to 10 and denotes the number of carbon atoms in the alkyl chain. These compounds are sulphur analogous to a liquid crystal known as MHPOBC, where the central ester bridge was replaced with the -COS- connecting group. The (S)-MHPSBOn homologous series possesses enantiotropic SmA*, SmC*, SmCA* and monotropic SmI* phases for n = 7-10. The (S)-MHPSBO7 compound has also smectic chiral subphases: SmCα* and SmCγ*. Their mesomorphic properties were investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), transmittance light intensity (TLI), X-ray diffraction and electro-optic (EO) measurements.