Synthesis, Structures, and Conformational Characteristics of Triptycene-Derived Calix[5]arenes

A series of novel calix[5]arenes 5 containing one 1,8-dimethoxytriptycene moiety were synthesized through an efficient fragment coupling strategy. The subsequent demethylation of 5 with BBr3 in dry dichloromethane gave the calix[5]arenes 6. Debutylation of both 5a∼b and 6a∼b with AlCl3 resulted in the same products 7a∼7b. The structural studies revealed that all of the macrocyclic compounds have well-defined structures with fixed cone conformations in both solution and solid state. Moreover, it was also found that the triptycene-derived calix[5]arenes could encapsulate small neutral molecules in the solid state.