Department of Physics, University of Ioannina, 451 10 Ioannina, Greece.
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
J Phys Chem B. 2021 Apr 15;125(14):3700-3709. doi: 10.1021/acs.jpcb.1c00100. Epub 2021 Apr 5.
The polarity of all--multifluorinated cyclohexanes can be fine-tuned by the number and relative orientation of fluoro substituents, giving rise to a series of compounds with strong dipole moments. Simulations provided the energetics, the dipole moments, and the respective molecular polarizabilities, while dielectric spectroscopy gave information on the dielectric permittivities and the molecular dynamics. In special cases, dipole moments in excess of 6 D and dielectric permittivities of over 300 were obtained by simulation and experiment. Melting temperatures within a given family of multifluorinated cyclohexanes were found to scale with the molecular volume. The less-symmetric all--octafluorotetrahydronaphthalene did not readily crystallize, permitting an investigation of the molecular dynamics in an energetically unfavorable yet rigid and facially polarized isomer. The resulting dynamics above the glass temperature conform to the structural α-relaxation and to the celebrated Johari-Goldstein β-relaxation.
所有多氟环己烷的极性都可以通过氟取代基的数量和相对取向来微调，从而产生一系列具有强偶极矩的化合物。模拟提供了能量学、偶极矩和各自的分子极化率，而介电光谱则提供了介电常数和分子动力学的信息。在特殊情况下，通过模拟和实验获得了超过 6 D 的偶极矩和超过 300 的介电常数。在给定的多氟环己烷家族中，发现熔融温度与分子体积成比例。不对称的全-八氟四氢化萘不易结晶，允许在能量不利但刚性和面向极化的异构体中研究分子动力学。在玻璃化温度以上的这些动力学符合结构 α-松弛和著名的 Johari-Goldstein β-松弛。
