Arrays of Molecular Rotors with Triptycene Stoppers: Surface Inclusion in Hexagonal Tris(o-phenylenedioxy)cyclotriphosphazene

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• 作者：Ji艡铆 Kaleta ; Paul I. Dron ; Ke Zhao ; Yongqiang Shen ; Ivana C铆sa艡ov谩 ; Charles T. Rogers ; Josef Michl
• 刊名：Journal of Organic Chemistry
• 出版年：2015
• 出版时间：June 19, 2015
• 年：2015
• 卷：80
• 期：12
• 页码：6173-6192
• 全文大小：1040K
• ISSN：1520-6904

文摘

A new generation of rod-shaped dipolar molecular rotors designed for controlled insertion into channel arrays in the surface of hexagonal tris(o-phenylenedioxy)cyclotriphosphazene (TPP) has been designed and synthesized. Triptycene is used as a stopper intended to prevent complete insertion, forcing the formation of a surface inclusion. Two widely separated ¹³C NMR markers are present in the shaft for monitoring the degree of insertion. The structure of the two-dimensional rotor arrays contained in these surface inclusions was examined by solid-state NMR and X-ray powder diffraction. The NMR markers and the triptycene stopper functioned as designed, but half of the guest molecules were not inserted as deeply into the TPP channels as the other half. As a result, the dipolar rotators were distributed equally in two planes parallel to the crystal surface instead of being located in a single plane as would be required for ferroelectricity. Dielectric spectroscopy revealed rotational barriers of 鈭? kcal/mol but no ferroelectric behavior.