Blurring the Lines between Host and Guest: A Chimeric Receptor Derived from Cucurbituril and Triptycene

We report the synthesis and X-ray crystal structure of a cucurbituril-triptycene chimeric receptor (1). Host 1 binds to guests typical of CB[6]-CB[8], but also binds to larger guests such as blue box (20) and the Fujita square (22). Intriguingly, the geometries of the 1.20 and 1.22 complexes blur the lines between host and guest in that both components fulfill both roles within each complex. The fluorescence output of 1 is fully quenched by the formation of complexes with pyridinium-derived guests.