The synthesis of networks based on the coordination of cucurbit[8]urils and alkali or alkaline earth ions in the presence of the polychloride transition-metal anions

Abstract

To extend the strategy for the induced formation of cucurbit[n]uril–metal by a third species, we introduced alkali or alkaline earth metal ions (M_{alkali or alkaline earth metal}) into cucurbit[8]uril (Q[8])–HCl systems in the presence of polychloride transition-metal anions. The polychloride transition-metal anions acted as structure inducers. A series of Q[8]–M_{alkali or alkaline earth metal} complexes and their corresponding two-dimensional (2D) supramolecular assemblies were first synthesized and characterized by single-crystal X-ray diffraction analysis. The crystal structural analysis revealed that the Q[8]-based trigonal-planar branches in the related compounds are the key building blocks for the construction of the novel 2D Q[8]–M_{alkali or alkaline earth metal} networks in which one or two alkali or alkaline earth metal ions link three Q[8] molecules through direct coordination. Moreover, the novel 2D Q[8]–M_{alkali or alkaline earth metal} networks have a honeycomb shape with hexagonal “nanoholes”. The superimposition of the 2D networks could create novel nanochannels which numerous water molecules and counter anions could occupy.