Twisted pentagonal prisms: AgnL2 metal-organic pillars

Abstract

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 AgnL2 metal-organic pillars from rim-differentiated pillar[5]arene-derived ligands, Lm and Lp, through [N···Ag+···N] coordinative bonds. These stereolabile macrocycles undergo chiral self-sorting during complexation. Although the meta-substituted Lm forms diastereoisomeric Ag5Lm2 complexes without stereocontrol in solution, only a meso-Ag4Lm2 complex with a Ag4 kernel was observed in the solid state. In contrast, the narcissistic coassembly of the para-substituted Lp with AgPF6 results in enantiomeric Ag5Lp2 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.