Time Programmable Locking/Unlocking of the Calix[4]arene Scaffold by Means of Chemical Fuels
Daniele Del Giudice, Emanuele Spatola, Roberta Cacciapaglia, Alessandro Casnati, Laura Baldini, Gianfranco Ercolani, Stefano Di Stefano
Abstract
derivatives can be used as chemical fuels to control the geometry of the calix[4]arene scaffold in its cone conformation. It is shown that, under the action of the fuel, the cone calix[4]arene platform assumes a "locked" shape with two opposite aromatic rings strongly convergent and the other two strongly divergent ("pinched cone" conformation). Only when the fuel is exhausted, the cone calix[4]arene scaffold returns to its resting, "unlocked" shape. Remarkably, the duration of the "locked" state can be controlled at will by varying the fuel structure or amount. A kinetic study of the process shows that the consume of the fuel is catalyzed by the "unlocked" calixarene that behaves as an autocatalyst for its own production. A mechanism is proposed for the reaction of fuel consumption.