In this work, we report that 2-cyano-2-phenylpropanoic acid and its p-Cl, p-CH3 and p-OCH3 derivatives can be used as chemical fuels to control the geometry of the calixarene scaffold in its cone conformation. It is shown that, under the action of the fuel, the cone calixarene 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 calixarene 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.
Time Programmable Locking/Unlocking of the Calixarene Scaffold by Means of Chemical Fuels / Del Giudice, D.; Spatola, E.; Cacciapaglia, R.; Casnati, A.; Baldini, L.; Ercolani, G.; DI STEFANO, Stefano. - In: CHEMISTRY-A EUROPEAN JOURNAL. - ISSN 0947-6539. - 26:(2020), pp. 14954-14962. [10.1002/chem.202002574]