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首页> 外文会议> >~(13)C-NMR Observed Conformations and Motions of Neat Liquid and Crystalline M-Hexatriacontane and as a Guest in the Narrow Channels of Its Inclusion Compound Formed with α-Cyclodextrin
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~(13)C-NMR Observed Conformations and Motions of Neat Liquid and Crystalline M-Hexatriacontane and as a Guest in the Narrow Channels of Its Inclusion Compound Formed with α-Cyclodextrin

机译：〜（13）C-NMR观察到纯净的液体和结晶M-六方十六烷的构象和运动，以及在其与α-环糊精形成的包合物的窄通道中作为客体

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摘要

A non-covalently bonded inclusion compound (IC) was formed between a 36 carbon guest n-alkane, hexatriacontane (HTC), and the host a-cyclodextrin (a-CD) and observed by solid-state ~(13)C-NMR, as were neat HTC in both its liquid melt and in its crystallline solid. Based on the number and frequencies of observed ~(13)C resonances, HTC in its neat crystals is restricted to the fully extended all trans conformation, while in the melt HTC chains are experiencing rapid inter-conversions between all possible conformations containing trans and gauche bonds. The spin-lattice relax-ation times, T_1(~(13)C), observed for interior CH2 carbons in crystalline HTC are ～500 s and for the molten liquid are 1-3 s. In the crystal HTC chains experience virtually no ～100 MHz motions, while molten HTC chains are efficiently moving at both this and much higher frequencies, leading to an over two orders of magnitude decrease in HTC spin-lattice relaxation times. While the narrow channels (～0.5 nm) of its α-CD-IC largely restrict the HTC chains to the all-trans conformation, the T_1(~(13)C) relaxation times of its interior CH_2 carbons range from 1-4 s at temperatures from -30 to 85℃. In other words, even though the conformations of HTC chains in the narrow a-CD-IC channels are severely restricted compared to those of neat molten HTC chains, they are also experiencing efficient -100 MHz motions that lead to virtually identical T_1(~(13)C)s in both environments. Here we attempt to identify similarities and differences between the types, length-scales, and cooperativities' of the motions experienced by HTC chains in the neat melt and in the narrow crystalline channels of its a-CD-IC.
机译：在36个碳的客体正构烷烃，六金刚烷（HTC）和主体α-环糊精（a-CD）之间形成了非共价键合的包含化合物（IC），并通过固态〜（13）C-NMR进行了观察就像HTC的液态熔体和结晶固体一样。根据观察到的〜（13）C共振的次数和频率，其纯净晶体中的HTC限于完全扩展的所有反式构象，而在熔融状态下，HTC链正经历所有可能的含有反式和薄纱构象的快速相互转化。债券。晶体HTC中内部CH2碳的自旋晶格弛豫时间T_1（〜（13）C）为〜500 s，熔融液体为1-3 s。在晶体中，HTC链实际上没有约100 MHz的运动，而熔融的HTC链则以该频率和更高的频率有效地运动，从而导致HTC自旋晶格弛豫时间减少了两个数量级以上。虽然其α-CD-IC的狭窄通道（〜0.5 nm）在很大程度上将HTC链限制为全反式构象，但其内部CH_2碳的T_1（〜（13）C）弛豫时间为1-4 s在-30至85℃的温度下。换句话说，尽管与纯净的熔融HTC链相比，狭窄的a-CD-IC通道中的HTC链构象受到严格限制，但它们也正在经历有效的-100 MHz运动，从而导致几乎相同的T_1（〜（在两种环境下都是13）C）s。在这里，我们试图确定HTC链在纯熔体及其a-CD-IC的狭窄晶体通道中经历的运动的类型，长度尺度和合作性之间的相似性和差异。

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  • 来源
    《》|2010年|p.265-277|共13页
  • 会议地点 Honolulu HI(US);Honolulu HI(US)
  • 作者

    M. A. Hunt; S. Villar-Rodil; M. A. Gomez-Fatou; I. D. Shin; F.C. Schilling; A. E. Tonelli;

  • 作者单位

    Oak Ridge National Laboratory, Oak Ridge, TN 37831;

    National Institute of Coal (INCAR), CSIC, Oviedo, Spain;

    Department of Polymer Physics and Engineering, Institute of Science and Technology of Polymers (ICTP), C.S.I.C., Madrid, Spain;

    College of Pharmacy Health Sciences, Campbell University,Buies Creek, NC 27506;

    37433 South Ocotillo Canyon Dr., Tucson, AZ 85739;

    Fiber Polymer Science, North Carolina State University,Campus Box 8301, Raleigh, NC 27695-8301;

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  • 正文语种 eng
  • 中图分类 聚合反应过程;
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