Bridge-Disubstituted Calix[4]arenes in the Rare 1,2-Alternate Conformation: Control of the Inclusion Behavior Depending on the Bridge Substituents

X-ray crystal structures of several novel diametrically bridge-disubstituted calix[4]­arenes are presented, revealing the calixarene core in the rare 1,2-alternate conformation. Structural comparisons suggest a tunable inclusion behavior depending on the bridge substituents, which is a promising tool for supramolecular host guest design in terms of “synthon engineering”.