Thermoresponsive Organic Inclusion Compounds: Modification of Thermal Expansion Behavior by Simple Guest Replacement
Thermoresponsive Organic Inclusion Compounds: Modification of Thermal Expansion Behavior by Simple Guest Replacement
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DOI：
10.1021/acs.chemmater.6b01916
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发表时间：
2016-07-26
影响因子：
8.6
通讯作者：
Barbour, Leonard J.
中科院分区：
文献类型：
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作者：
Engel, Emile R.;Smith, Vincent J.;Barbour, Leonard J.
研究表明，一系列等骨架有机包合物中的客体取代可以引起热膨胀行为的剧烈变化。化合物1、2和3分别以18-冠-6为主体分子，以硝基甲烷、乙腈和碘甲烷为客体。三种化合物都有不同程度的大体积热膨胀，其热膨胀系数分别为378(22)、226(3)和256(8)×10(-6)K-1。用晶体结构分析和计算方法阐明了该系列的热膨胀机理的一般特征。描述了几个因素的贡献，包括主客体相容、静电效应和空间效应。倾斜机制导致了1和2中热膨胀的负成分，但被3中大分子体积的客体抑制。此外，在2中观察到了热膨胀效应。据我们所知，这是第一个报道的包合物的热膨胀的例子。
It is demonstrated that guest replacement in a series of isoskeletal organic inclusion compounds can produce drastic changes in thermal expansion behavior. The compounds 1, 2, and 3 have 18-crown-6 as host molecule and nitromethane, acetonitrile, and iodomethane, respectively, as guests. Along the principal axis X1 the linear component of thermal expansion is negative for 1 and 2 but positive for 3. All three compounds have varying degrees of large volumetric thermal expansion, with coefficients of 378(22), 226(3), and 256(8) x 10(-6) K-1 for 1, 2, and 3, respectively. Crystal structure analysis and computational methods were used to elucidate general features of the underlying mechanism of thermal expansion for the series. The contributions of several factors are described, including host guest compatibility, electrostatic effects, and steric effects. A tilting mechanism gives rise to the negative components of thermal expansion in 1 and 2 but is inhibited by the large molecular volume of the guest in 3. In addition, the thermosalient effect was observed for 2. To our knowledge this is the first example of thermosalience reported for an inclusion compound.