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Larger Substituents on Amide Cavitands Induce Bigger Cavities.

Research paper by Safwan S Aroua, Andrew N AN Lowell, Ankita A Ray, Nils N Trapp, W Bernd WB Schweizer, Marc-Olivier MO Ebert, Yoko Y Yamakoshi

Indexed on: 20 Dec '18Published on: 20 Dec '18Published in: Organic Letters



Abstract

A series of quinoxaline cavitands bearing pendant amide groups with various substituent sizes (Et, Pr, Bu) were synthesized, and their cavity size/structure were investigated by X-ray and NMR analyses. In the case of the Et or Pr amide cavitand, the conformation of the molecule was in the vase form, while the bulky Bu amide cavitand gave the kite conformation at room temperature. X-ray crystal structures of Et and Pr cavitands clearly showed the intramolecular H-bondings to influence the conformation and the cavity sizes dependent on the bulkiness of functional groups. The H NMR spectrum revealed that the Et cavitand can encapsulate an adamantane guest compound with slow exchange.