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Room Temperature Ferroelectric Mixture of Chiral and Achiral Thioesters

100%
Czerwiec J., Ossowska-Chruściel M., Chruściel J., Wróbel S.
Acta Physica Polonica A
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2010
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vol. 117
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issue 4
549-552
EN
Dielectric properties of the mixture of two thioester compounds: 4-8-alkoxy-benzoate-thio-carboxyl S-4-pentyl-phenyl (8OS5), (s)-4-(1-methyl-heptyloxy)biphenyl-4-thio-carboksyl 4-9-alkil-phenyl (MHOBS9) are presented. The chiral compound exhibits nematic (N*) and ferroelectric smectic C* phase (SmC*). The achiral compound shows N, SmA and monotropic SmC and SmB phases. the mixture of both compounds of 0.5 molar fraction shows SmC* in the wider temperature range than pure MHOBS9. The mixture was studied using frequency domain dielectric spectroscopy. Dielectric measurements for the SmC* phase of the mixture revealed Goldstone mode at higher frequencies and Maxwell-Wagner relaxation at low frequencies.
2
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Equimolecular Mixture of Calamitic and Bent-Core Thiobenzoates

100%
Chruściel J., Wantusiak B., Ossowska-Chruściel M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 2
375-377
EN
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: differential scanning calorimetry, polarized light optical microscopy, and transmitted light intensity. Electro-optical measurements were also carried out.
3
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Polymorphism and Initial Structure Modelling of a New Mesogen 9OSBch

100%
Kosyl M., Zając W., Ossowska-Chruściel M., Chruściel J.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
959-963
EN
We report the properties of a novel mesogen with high temperature cholesteric mesophase, which belongs to an unexplored as yet series of cholesteric esters. This compound is cholesteryl 4-(4-nonyloxybenzoylthio) benzoate (C_9H_{19}OC_6H_4COSC_6H_4COOch, where ch = cholesteryl), hereafter named 9OSBch. The chemical structure and purity of 9OSBch was established by ^1H NMR, ^{13}C NMR and FT-IR spectroscopy, and its mesomorphism was characterised by differential scanning calorimetry, polarizing optical microscopy, and transmitted light intensity. Differential scanning calorimetry measurements showed that substance is stable up to 270C and partially decomposes above this temperature. Observation under polarizing optical microscope revealed oily streak texture of cholesteric phase (Ch). The chemical structure of an isolated molecule was optimized by the density functional theory method. Energetically most favourable configuration is that of hockey stick geometry. At the same time this is the conformation best suited for the formation of highly ordered condensed phases.
4
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Dielectric and Conductivity Anisotropy in Liquid Crystalline Phases of Strongly Polar Thioesters

76%
Mikułko A., Fraś M., Marzec M., Wróbel S., Ossowska-Chruściel M., Chruściel J.
Acta Physica Polonica A
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2008
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vol. 113
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issue 4
1155-1160
EN
The main objective of this paper is to study dielectric properties of two compounds of acronyms 5OSCl and 6OSCl having strongly polar bond (C-Cl) at para position. Dielectric measurements were done in the frequency range from 40 Hz to 15 MHz. The dielectric spectra were measured for two principal alignments. For homeotropic alignment, the reorientation of molecule around the short molecular axis was observed. Both substances studied exhibit large positive dielectric anisotropy and the anisotropy of conductivity was obtained in smectic A as well as nematic phase.
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