Tetraimidazolium macrocycle: a versatile building block and precursor for box-type coordination cages

Abstract

This study describes a facile synthesis of the imidazolium-based cyclophane H₄-1(PF₆)₄ from 1-(1H-imidazol-1-ylmethyl)-1H-imidazole and 1,4-bis(bromomethyl)benzene, followed by anion exchange. Slipped π–π stacking interactions between the flexible cyclophane and aromatic sulfonate anions—including the 1,5-naphthalenedisulfonate dianion (1,5-nds), 2,6-naphthalenedisulfonate dianion (2,6-nds), and 2,7-naphthalenedisulfonate dianion (2,7-nds)—induce one-dimensional (1D) self-assembly, forming nanochannels. Significantly, a metallocage, Ag₄(1)₂(PF₆)₄ is derived from the corresponding tetraimidazolium salt via reaction with Ag₂O and subsequent transmetalation. This cyclophane-based metallocage possesses an optimal size for binding acetonitrile and exhibits excellent selectivity for acetonitrile encapsulation, mediated by weak N⋯Ag interactions.