Helical chirality in hexamethylene triperoxide diamine.
Helical chirality in hexamethylene triperoxide diamine.
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六亚甲基三过氧化二胺的螺旋手性。
DOI：
10.1002/mrc.1853
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Harbison,GerardS
中科院分区：
文献类型：
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作者：
Guo,Chunlei;Persons,John;Harbison,GerardS
六亚甲基三过氧二胺以前被发现以螺旋手性、三重对称对映体的外消旋混合物的形式存在于固体中；预测了另一对低能构象对映体，但从未观察到。我们通过14T的2DNMR溶液、非手性溶液和添加手性位移试剂，证明了在室温下，所有四种光学异构体在核磁共振时间标度上以缓慢平衡的方式共存，并且可以观察到。用规范-包括原子轨道方法计算~1H和~(13)C核磁共振化学位移与实验符合得很好；对溶液中自由能的热化学计算的一致性稍差，但正确地预测了构象的相对稳定性。手性位移试剂对核磁共振谱影响的分析表明，手性异构体之间的区别主要在分子赤道附近，在分子赤道周围排列着对映异构体O--O键。版权所有©2006 John Wiley&Sons，Ltd.
The primary explosive hexamethylenetriperoxide diamine has previously been found to exist in the solid state as a racemic mixture of helically chiral, threefold symmetric enantiomers; another enantiomeric pair of low‐energy conformers has been predicted, but has never been observed. We show by solution 2D NMR at 14 T, in achiral solution and by addition of chiral shift reagents, that all four optically isomeric conformers coexist at slow equilibrium on the NMR timescale at room temperature, and can be observed. Calculations of the1H and13C NMR chemical shifts using gauge‐including atomic orbital methods are in excellent agreement with experiment; thermochemical calculation of the free energies in solution are in somewhat worse agreement, but correctly predict the relative stability of the conformers. Analysis of the effects of chiral shift reagents on the NMR spectra suggests that discrimination between chiral isomers is primarily around the molecular equator, around which the enantiomericgaucheOO linkages are arrayed. Copyright © 2006 John Wiley & Sons, Ltd.