Nano-dimensions for the pyrogallol[4]arene cavity

The cup-like cavity of pyrogallol[4]arenes has been deepened by the addition of four hydrogen bonded bipyridine molecules to the upper-rim of the calixarene, enabling the extended cup-like molecules to stack inside one another and consequently trap and completely enshroud a single guest molecule within the 250 (angstrom)^3 cavitand formed between two of these stacked "nano-cups".