Dynamic Characterization of Crystalline Supramolecular Rotors Assembled through Halogen Bonding

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• 作者：Luca Catalano ; Salvador P茅rez-Estrada ; Giancarlo Terraneo ; Tullio Pilati ; Giuseppe Resnati ; Pierangelo Metrangolo ; Miguel A. Garcia-Garibay
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：December 16, 2015
• 年：2015
• 卷：137
• 期：49
• 页码：15386-15389
• 全文大小：307K
• ISSN：1520-5126

文摘

A modular molecular kit for the preparation of crystalline molecular rotors was devised from a set of stators and rotators to gain simple access to a large number of structures with different dynamic performance and physical properties. In this work, we have accomplished this with crystalline molecular rotors self-assembled by halogen bonding of diazabicyclo[2.2.2]octane, acting as a rotator, and a set of five fluorine-substituted iodobenzenes that take the role of the stator. Using variable-temperature ¹H T₁ spin鈥搇attice relaxation measurements, we have shown that all structures display ultrafast Brownian rotation with activation energies of 2.4鈥?.9 kcal/mol and pre-exponential factors of the order of (1鈥?) 脳 10¹² s^鈥?. Line shape analysis of quadrupolar echo ²H NMR measurements in selected examples indicated rotational trajectories consistent with the 3-fold or 6-fold symmetric potential of the rotator.