Unusual adsorption behaviours and responsive structural dynamics via selective gate effects of an hourglass porous metal–organic framework

Abstract

An hourglass porous metal–organic framework, LIFM-12, constructed on a T-shaped flexible ligand with Cu²⁺ paddle-wheel clusters, shows temperature and gas adsorption responsive structural dynamics upon reversible molecular guest binding. Temperature-dependent single crystal and powder X-ray diffraction experiments show that the open gate status of the framework with adaptive behaviours facilitates kinetic diffusion of gas molecules resulting in the sequential filling of pores of different sizes, thus creating a breathing behaviour reminiscent of the observation of several steps in adsorption isotherms. In addition, adsorption studies revealed that LIFM-12 performs exceptional adsorption selectivity of 10–25 for CO₂ versus light gases N₂, CH₄, and CO and up to 200 for C₃H₆ versus CH₄.