Unidirectional Threading into a Bowl-Shaped Macrocyclic Trimer of Boron-Dipyrrin Complexes through Multipoint Recognition.

Bowl-shaped macrocycles have the distinctive feature that their two sides are differentiated, and thus can be developed into elaborate hosts that fix a target molecule in a controlled geometry through multipoint interactions. We now report the synthesis of a bowl-shaped macrocyclic trimer of the boron-dipyrrin (BODIPY) complex and its unidirectional threading of guest molecules. Six polarized B(δ+) -F(δ-) bonds are directed towards the center of the macrocycle, which enables strong recognition of cationic guests. Specifically, the benzylbutylammonium ion is bound in a manner in which the benzyl group is located at the convex face of the bowl and the butyl group at its concave face. Furthermore, adrenaline was strongly captured on the convex side of the bowl by hydrogen bonding, Coulomb forces, and C-H⋅⋅⋅π interactions.