Diverse host-guest recognition of terphen[3]arene carboxylate in water.

We report the water-soluble macrocycle ExBP3C, which binds 20 guests to form well-defined 1 : 1 complexes, with association constants in the range of 102-105 M-1. NMR studies, titration experiments and theoretical calculations clearly uncovered the binding stoichiometry, affinities, and complexation modes. This host holds promise for applications in neurotransmitter regulation, photosensitizer delivery, and antibacterial systems.