Surface Chemistry Regulation in Cu₄I₄-Triazolate Metal–Organic Frameworks for One-Step C₃H₆ Purification from Quaternary C₃ Mixtures

C₃H₆ is a crucial building block for many chemicals, yet separating it from other C₃ hydrocarbons presents a significant challenge. Herein, we report a hydrolytically stable Cu₄I₄-triazolate metal-organic framework (MOF) (JNU-9-CH₃) featuring 1D channels decorated with readily accessible iodine and nitrogen atoms from Cu₄I₄ clusters and triazolate linkers, respectively. The exposed iodine and nitrogen atoms allow for cooperative binding of C₃ hydrocarbons, as evidenced by <i>in situ</i> single-crystal crystallography and Raman spectroscopy studies. As a result, JNU-9-CH₃ exhibits substantially stronger binding affinity for C₃H₄, CH₂═C═CH₂, and C₃H₈ than that for C₃H₆. Breakthrough experiments confirm its ability to directly separate C₃H₆ (≥99.99%) from C₃H₄/CH₂═C═CH₂/C₃H₈/C₃H₆ mixtures at varying ratios and flow rates. Overall, we illustrate the cooperative binding of C₃ hydrocarbons in a Cu₄I₄-triazolate MOF and its highly efficient C₃H₆ purification from quaternary C₃ mixtures. The study highlights the potential of MOF adsorbents with metal-iodide clusters for cooperative bindings and hydrocarbon separations.