Twisted pentagonal prisms: AgnL2 metal-organic pillars

Summary

The structures of hierarchically assembled supramolecular architectures are dictated characteristically by the encoded symmetries and geometries of the corresponding building blocks. In literature, assorted Platonic molecular polyhedra have been built out of highly symmetric macrocycles. Nonetheless, the synthesis of pillararene-based molecular cages remains challenging owing to the underlying shape and limited derivatization strategies of this macrocyclic scaffold. Herein, we report the assembly of Ag_nL₂ metal-organic pillars from rim-differentiated pillar[5]arene-derived ligands, L_m and L_p, through [N···Ag⁺···N] coordinative bonds. These stereolabile macrocycles undergo chiral self-sorting during complexation. Although the meta-substituted L_m forms diastereoisomeric Ag₅L_m2 complexes without stereocontrol in solution, only a meso-Ag₄L_m2 complex with a Ag₄ kernel was observed in the solid state. In contrast, the narcissistic coassembly of the para-substituted L_p with AgPF₆ results in enantiomeric Ag₅L_p2 complexes resembling twisted pentagonal prisms. This research paves the way for the construction of deep-cavity metallocavitands and nanochannels with unique molecular recognition and transportation properties.