Synthesis of Carborane-Backbone Metallacycles for Highly Selective Capture of n -Pentane.

The specific recognition and separation of alkanes with similar molecular structures and close boiling points face significant scientific challenges and industrial demands. Here, rectangular carborane-based metallacycles were designed to selectively encapsulate n -pentane from n -pentane, iso -pentane, and cyclo -pentane mixtures in a simple-to-operate and more energy-efficient way. Metallacycle 1 , bearing 1,2-di(4-pyridyl) ethylene, can selectively separate n -pentane from these three-component mixtures with a purity of 97%. The selectivity is ascribed to the capture of the preferred guest with matching size, C-H···π interactions, and potential B-H δ- ···H δ+ -C interactions. Besides, the removal of n -pentane gives rise to original guest-free carborane-based metallacycles, which can be recycled without losing performance. Considering the variety of substituted carborane derivatives, metal ions, and organic linkers, these new carborane-based supramolecular coordination complexes (SCCs) may be broadly applicable to other challenging recognition and separation systems with good performance.