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 BBr(3) in dry dichloromethane gave the calix[5]arenes 6. Debutylation of both 5a-b and 6a-b with AlCl(3) 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.