A Synthetic Receptor Which Uses Multiple Edge−Face Interactions To Bind Aromatic Guests

Host 1 binds bicyclic aromatic guests such as 6-nitro-2-naphthol 2, serotonin mimic 3, and stilbene-derivative 4 with high affinity. Competition studies were performed to determine the association constants for complexation of 2-4 by 1. Lower-affinity host 14 lacked the structural requirements to form edge-face contacts with guests 2-4 and served as the competitive host. For each guest, evaluation of the geometry of the host-guest interaction by low-temperature NMR experiments revealed two edge-face interactions between the face of the anthracene bridge of 1 and the edge of the guest. The results reported in this paper suggest that the observed edge-face interactions stabilize the complexes formed by host 1. The synthesis of host 1 and the complexation of 2-4 by this host are described.