C₆₀‐Mediated Molecular Shape Sorting: Separation and Purification of Geometrical Isomers

Abstract

A supramolecular crystallization-based approach has been developed for the shape-dependent separation of geometrical isomers under near-ambient conditions. Difficulties to separate such isomers arise because of their very similar physical properties. The present approach relies on the ability of C 60 to preferentially form solvate crystals with molecules of a specific geometry. Subsequently, these molecules are released upon mild heating to regenerate pure C 60 . By taking isomers of xylene and trimethylbenzene (TMB) as examples, we show that one of the isomers can be extracted from the rest with very high purity. To separate TMB isomers, a new C 60 -1,3,5-TMB solvate was developed, which led to the isolation of isomer purities greater than 99.6 %. Versatility, a low operating temperature of approximately 100 8C, a separation efficiency of more than 10 weight % of C 60 per cycle, and reagent recyclability makes this a promising molecular shape-sorting approach.

Silica bound co-pillar[4+1]arene as a novel supramolecular stationary phase

“…1 Chromatographic techniques are therefore often adopted to facilitate their separation; however, normal and reverse stationary phases require extensive method development in order to attempt even separation of the simplest of isomers. 2 Supramolecular host-guest interactions between functional groups, together with size complementarity, have been widely utilised to selectively bind specific geometric isomers. 3 While this approach to separation via stepwise complexation and crystallisation is viable for selective isomers, it is inherently restricted to single geometric isomers and therefore has limited application for in situ separation of multiple sets of isomers.…”