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首页> 外文期刊>Journal of Inclusion Phenomena and Macrocyclic Chemistry >Dielectric Relaxation of the bveta-Cyclodextrin Complexes with Tridecanoic Acid and 1,13-Tridecanedioic Acid
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Dielectric Relaxation of the bveta-Cyclodextrin Complexes with Tridecanoic Acid and 1,13-Tridecanedioic Acid

机译：bveta-环糊精与十三烷酸和1,13-十三癸二酸的介电弛豫

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摘要

The frequency and temperature dependence of the real (implied by') and imaginary (implied by") parts of the dielectric permittivity of the polycrystalline complex beta-cyclodextrin-tridencanoic acid in two hydration forms (with 16.2 and 10.7 water molecules) and beta-cyclodextrin-1,13-tridecanedioic acid with 16.4 and 10.5 water molecules have been investigated, in the frequency range 0.1-100kHz and temperature range 120-310 K. The dielectric behavior is described wel by Debvye-type relaxation alpha dispersion. All systems except for the complex of partially dehydrated monocarboxylic acid, exhibit an additional OMEGA-dispersion, at low frequencies (f<1000 Hz). Only one-step was found in the implied' vs. T plots of both complexes in the two hydration forms, a fact indicating that the water molecules cannot be divided into strrongly bound and easily movable molecules. The implied"vs. T plots, at a fixed frequency (200 Hz), show the characteristic peak attributed to a transition bvetaween ordered and disordered bveta-CD hydroxyl groups and water molecules. The transition temperature was 202.7 K for all systems examined process was unaffected by the dehydration process in the case of the dicarboxylic acid complex, whereas in the case of the monocarboxylic acid, it was unexpectedly facilitated. The relaxation time varies with temperature, in a LAMBDA like curve (in the range 8-14 mus), with maximum values located at the corresponding order-disorder transition temperatures. The activation energies of the fully hydrated complexes have absolute values of approx 5 kJ/mol in the range 1.98-3.82 K_BT_transition which are higher than the corresponding values of approx 2 kJ/mol of the dehydrated comploexes. A thermal hysteresis observed in all complexes is a result of the order-disorder transformation.
机译：两种水合形式（含16.2和10.7水分子）和β-已经研究了具有16.4和10.5水分子的环糊精1,13-十三烷二酸，在0.1-100kHz的频率和120-310K的温度范围内，介电性能由Debvye型弛豫α分散体描述。对于部分脱水的一元羧酸的配合物，在低频（f <1000 Hz）下表现出额外的OMEGA分散性，两种水合形式的两种配合物的隐含'-T图仅显示了一步。事实表明水分子不能分为束缚结合的分子和易于移动的分子。在固定频率（200 Hz）上的T图显示了归因于有序和无序bveta-CD羟基与水分子之间过渡的特征峰。对于二羧酸络合物而言，对于所考察的所有体系，转变温度为202.7K，该过程不受脱水过程的影响，而对于单羧酸而言，出乎意料地促进了该过程。弛豫时间随温度变化，呈类似LAMBDA的曲线（在8-14亩范围内），最大值位于相应的有序-无序转变温度。完全水合的配合物的活化能在1.98-3.82 K_BT_transition范围内具有约5 kJ / mol的绝对值，该绝对值高于脱水化合物的约2 kJ / mol的对应值。在所有配合物中观察到的热滞是有序-无序转换的结果。

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