Disorder in crystalline phases of chiral glass formers 5∗CB and 8∗OCB evidenced by the low temperature heat capacity

Inaba, Akira; Suzuki, Hal; Krawczyk, J.; Massalska-Arodź, Maria

doi:10.1016/j.cplett.2008.08.016

Cited by 6 publications

(2 citation statements)

References 24 publications

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“…Its chiral (right-handed) counterpart, 4-(2-methylbutyl) 4′-cyanobiphenyl (or isopentylcyanobiphenyl, 5*CB; see Figure ), was synthesized in 1976 by the same group . At room temperature, 5*CB exists in the isotropic phase, with an interesting polymorphism revealed by various experiments, − as summarized in the phase diagram (Figure ) showing schematically the temperature dependence of the free energy of various phases: (i) a monotropic system of phases with stable isotropic and crystalline phase I, (ii) a metastable cholesteric phase and its glass, and (iii) a metastable disordered crystalline phase II and its glass. Both glassy phases can be attained with slow cooling (1 K/min).…”

Section: Introductionmentioning

confidence: 99%

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Phase Diagram and Dynamics of the Liquid Crystal Isopentylcyanobiphenyl (5*CB)

et al. 2011

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From measurements of the specific volume as a function of temperature and pressure, the phase diagram for the liquid crystal forming isopentylcyanobiphenyl (5*CB) was determined. There are a number of phases (isotropic liquid, glass, cholesteric, and crystalline), and we show that the phase boundaries differ from previous reports, reflecting the slow crystallization kinetics of the system. Using dielectric spectroscopy at ambient and elevated pressure, we identify the relaxation processes in the isotropic and cholesteric phases. From application of density scaling to the dynamics, we obtain scaling exponents, which were found to vary with the type of motion. Moreover, unlike previous results for many other liquid crystals, the scaling exponent for the isotropic state differs from the thermodynamic potential parameter, and hence the relaxation time along the clearing line varies significantly with pressure. The distinctive properties of 5*CB reflect the very different volume dependences of the thermodynamics and the dynamics.

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Section: Introductionmentioning

confidence: 99%

“…Schematic phase diagram of Gibbs energy versus temperature for isopentylcyanobiphenyl (5*CB, structure shown), based on adiabatic calorimetry studies at ambient pressure. , Solid lines are for stable phases, dashed are for metastable phases, and dotted are for glasses. The observed transition temperatures are noted.…”

Section: Introductionmentioning

confidence: 99%

Phase Diagram and Dynamics of the Liquid Crystal Isopentylcyanobiphenyl (5*CB)

et al. 2011

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Two polymorphic forms of 10,12-pentacosadiyn-1-ol molecular layers on graphite transferred from an aqueous surface

2014

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Isotopic localization of the partially deuterated methyl group in solid methanol and methyl iodide

Suzuki

Inaba

2017

The Journal of Chemical Physics

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Heat capacity measurements were made down to 0.35 K for the isotopic modifications of methanol, CHDOH, and methyl iodide, CHDI, (n = 0, 1, 2, 3) to determine the orientation of the partially deuterated methyl group in the solid phase. The mono-deuterated modifications favor the symmetric conformation, whereas the di-deuterated ones favor the asymmetric conformation. Infrared spectroscopy demonstrates that some vibrational modes change in intensity depending on temperature, which supports the energy scheme obtained by calorimetry. Zero-point kinetic energies were obtained by single molecule density functional theory calculations. Although the favorable conformations of CHDOH and CHDOH were confirmed, the energy difference between symmetric and asymmetric conformations was twice as large as that determined experimentally, which indicates that intermolecular forces significantly decrease the energy difference. For CHDOH, the conversion between the two asymmetric conformations becomes very slow at low temperature and results in a residual entropy of R ln 2.

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Disorder in crystalline phases of chiral glass formers 5∗CB and 8∗OCB evidenced by the low temperature heat capacity

Cited by 6 publications

References 24 publications

Phase Diagram and Dynamics of the Liquid Crystal Isopentylcyanobiphenyl (5*CB)

Phase Diagram and Dynamics of the Liquid Crystal Isopentylcyanobiphenyl (5*CB)

Two polymorphic forms of 10,12-pentacosadiyn-1-ol molecular layers on graphite transferred from an aqueous surface

Isotopic localization of the partially deuterated methyl group in solid methanol and methyl iodide

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