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

An hourglass porous metal-organic framework, LIFM-12, constructed on a T-shaped flexible ligand with Cu 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 CO light gases N, CH, and CO and up to 200 for CH CH.