Highly Selective Separation of Benzene and Cyclohexane in a Spatially Confined Carborane Metallacage

Separation of light hydrocarbons (C1-C9) represents one of theseven chemical separations to change the world.Boron clusters can potentially play an important role in chemical separation, due to their unique three-dimensional structures andtheir ability to promote a potentially rich array of weak noncovalent interactions. Herein, we report the rational design ofmetallacages with carborane functionality and cooperative dihydrogen binding sites for the highly selective capture of cyclohexanemolecules. The metallacage1, bearing the ligand 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT), can produce cyclohexane with a purity of98.5% in a single adsorption-desorption cycle from an equimolar mixture of benzene and cyclohexane. In addition, cyclohexenemolecules can be also encapsulated inside the metallacage1. This selective encapsulation was attributed to spatial confinementeffects, C-Hmiddotmiddotmiddot pi interactions, and particularly dihydrogen-bond interactions. This work suggests exciting future applications ofcarborane cages in supramolecular chemistry for the selective adsorption and separation of alkane molecules and may open up a newresearch direction in host-guest chemistry.

Automated summary

This study reports the rational design of a metallacage with carborane functionality and cooperative dihydrogen binding sites for the highly selective capture of cyclohexane molecules, which could potentially have exciting future applications in supramolecular chemistry for the selective adsorption and separation of alkane molecules.