Benchmark C H /CO Separation in an Ultra-Microporous Metal-Organic Framework via Copper(I)-Alkynyl Chemistry.

Separation of acetylene from carbon dioxide remains a daunting challenge because of their very similar molecular sizes and physical properties. We herein report the first example of using copper(I)-alkynyl chemistry within an ultra-microporous MOF (Cu @UiO-66-(COOH) ) to achieve ultrahigh C H /CO separation selectivity. The anchored Cu ions on the pore surfaces can specifically and strongly interact with C H molecule through copper(I)-alkynyl π-complexation and thus rapidly adsorb large amount of C H at low-pressure region, while effectively reduce CO uptake due to the small pore sizes. This material thus exhibits the record high C H /CO selectivity of 185 at ambient conditions, significantly higher than the previous benchmark ZJU-74a (36.5) and ATC-Cu (53.6). Theoretical calculations reveal that the unique π-complexation between Cu and C H mainly contributes to the ultra-strong C H binding affinity and record selectivity. The exceptional separation performance was evidenced by breakthrough experiments for C H /CO gas mixtures. This work suggests a new perspective to functionalizing MOFs with copper(I)-alkynyl chemistry for highly selective separation of C H over CO .