A metal-based trisimidazolium cage that provides six C-H hydrogen-bond-donor fragments and includes anions

The rod-like N3– ion forms a water stable inclusion complex with a tris-imidazolium cage containing a FeII(bpy)32+ subunit as a cap, and establishes multipoint H bond interactions with the C–H fragments offered by the receptor. The N3– complex is 80-fold more stable than that formed by the spherical Cl– ion, which receives 6 H bonds from 6 C–H fragments.