Determination of the Hindered Rotation Degree of Chiral Molecules Around Their Long Molecular Axes in the Sc* Phase of 4-(2‘-Methylbutyl)-4‘-n-Octylbiphenyl-4-Carboxylate
作者:
Z. Raszewski,
J. Rutkowska,
J. Kedzierski,
P. Perkowski,
W. Piecek,
J. Zieliński,
J. Zmija,
R. Dabrowski,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 263,
issue 1
页码: 271-283
ISSN:1058-725X
年代: 1995
DOI:10.1080/10587259508033591
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Chiral 4-(2“-methylbutyl)-phenyl-4‘-octylbiphenyl-4-carboxylate (CE8) has been studied by dielectric, densytometric, refractic and X-ray measurements. On the basis of these measurements the effective value of the molecular dipole moment (μ), the angle between the vector of the molecular dipole moment and the long axis of molecule (γ) as well as the transverse (α1) and longitudinal (α1) molecular polarizabilities have been calculated8. In addition the sign and the magnitude of spontaneous polarization (Ps), the tilt angle (6) and the helical pitch (λ) have been measured for the same liquid crystal CE8. Knowing the molecular parameters μ, γ, α, α1and Θ from the experiment and the molecular structure from computer investigation, the spontaneous polarization Pshas been calculated as the vector sum of the components of molecular dipole moments μ perpendicular to the tilt direction. To do it the rotational potential given by B.Zeks2has been used. According to this approximation the measured spontaneous polarization Psis induced by hindered rotation of the molecules around their long axes and is expressed by molecular parameters μ, γ, α1, α1, tilt angle Θ and the hindered rotation parameter η The hindered rotation parameter for CE8 shows that dipolar ordering in this smectic C* phase is rather weak in the comparison with the strong orientational order of long molecular axes of the same phase.
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