This article reports on the new results on phase transitions, mesomorphic and electro-optical properties of new equimolecular mixture of calamitic and bent-core thiobenzoates. Two following liquid crystals were the components of the binary mixture: (S)-(+)-4-(1-methylheptyloxy)biphenyl 4 ′ -octylthiobenzoate (MHOBS8) having rode-like, calamitic-chiral molecules possessing among others ferroelectric smectic C (SmC * ) and bis [4-(4 ′ -octylphenylthiocarbonyl)phenyl] isophtalates from a homologous series of banana-shaped thioesters, referred to as IFOS8, where n = 8 denoted the number of carbon atoms in terminal alkyl chains in both mesogens, synthesized by us. The IFOS8 compound has two enantiotropic phases: B2 with antiferroelectric order and B6. The mesomorphic properties were investigated by means of three complementary methods: dierential scanning calorimetry, polarized light optical microscopy, and transmitted light intensity. Electro-optical measurements were also carried out.

Basing on the results of dierential scanning calorimetry and transmitted light intensity methods and texture observations in the temperature range from −50 • C to 90 • C phase diagram of 1-[3-uoro-4-(1-methylheptyloxycarbonyl)phenyl]-2-[4 ′-(2,2,3,3,4,4,4-heptauorobutoxybutoxy)biphenyl-4-yl]ethane was established. Monotropic system of thermodynamic phases was found. On cooling the isotropic phase transforms at 85 • C to ferroelectric SmC * phase and further two liquid crystalline phases, antiferroelectric SmC * A and SmI, and a metastable crystal Cr2 reveal. During heating exothermic anomaly in the wide temperature range was observed and ascribed to evolution of Cr2 to the stable crystal Cr1. On further heating both SmC * A and SmC * phases were observed. Thermodynamic parameters were calculated for all phase transitions. During rapid cooling (10 K/min) vitrication of metastable Cr2 crystal at Tg = −115 • C was registered.

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Bent-core compound, 4-chloro-1,3-phenylene bis{4-[(n-undecyloxybenzoyl)-sulfanyl]benzoate}, has been studied by dielectric spectroscopy, DSC calorimetry, and electro-optic methods. As found, the spontaneous polarization of the B phase is by one order of magnitude smaller than for B 2 phases of nOSOR series studied by us before. Its temperature dependence is characteristic for B 1 phase, observed for shorter homologues of nOSORs. Measurements of the complex electric permittivity were carried out in the frequency range from 40 to 15 MHz using gold-coated electrodes. Electro-optic studies have been done applying AWAT HG 1.9 mm cells with strongly rubbed polymer layers. Such cells facilitate inhomogeneous planar alignment, which under strong electric field transforms into a mono-domain exhibiting switching behavior. Dielectric and electro-optic data of bent-core compounds will be discussed taking into account molecular structure and phase structure as well.