Multiple Hindered Rotators in a Gyroscope-Inspired Tribenzylamine Hemicryptophane

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• 作者：Najat S. Khan ; Jose Manuel Perez-Aguilar ; Tara Kaufmann ; P. Aru Hill ; Olena Taratula ; One-Sun Lee ; Patrick J. Carroll ; Jeffery G. Saven ; Ivan J. Dmochowski
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：March 4, 2011
• 年：2011
• 卷：76
• 期：5
• 页码：1418-1424
• 全文大小：969K
• 年卷期：v.76,no.5(March 4, 2011)
• ISSN：1520-6904

文摘

A gyroscope-inspired tribenzylamine hemicryptophane provides a vehicle for exploring the structure and properties of multiple p-phenylene rotators within one molecule. The hemicryptophane was synthesized in three steps in good overall yield using mild conditions. Three rotator-forming linkers were cyclized to form a rigid cyclotriveratrylene (CTV) stator framework, which was then closed with an amine. The gyroscope-like molecule was characterized by ¹H NMR and ¹³C NMR spectroscopy, and the structure was solved by X-ray crystallography. The rigidity of the two-component CTV-trismethylamine stator was investigated by ¹H variable-temperature (VT) NMR experiments and molecular dynamics simulations. These techniques identified gyration of the three p-phenylene rotators on the millisecond time scale at 鈭?3 掳C, with more dynamic but still hindered motion at room temperature (27 掳C). The activation energy for the p-phenylene rotation was determined to be 10 kcal mol^鈭?. Due to the propeller arrangement of the p-phenylenes, their rotation is hindered but not strongly correlated. The compact size, simple synthetic route, and molecular motions of this gyroscope-inspired tribenzylamine hemicryptophane make it an attractive starting point for controlling the direction and coupling of rotators within molecular systems.