Engineering Metal–Organic Frameworks for Selective Separation of Hexane Isomers Using 3-Dimensional Linkers
Courtney S. Smoljan, Zhao Li, Haomiao Xie, Caitlin J. Setter, Karam B. Idrees, Florencia A. Son, Filip Formalik, Saman Shafaie, Timur İslamoğlu, Lauren K. Macreadie, Randall Q. Snurr, Omar K. Farha
Abstract
Metal–organic frameworks (MOFs) are highly tunable materials with potential for use as porous media in non-thermal adsorption or membrane-based separations. However, many separations target molecules with sub-angstrom differences in size, requiring precise control over the pore size. Herein, we demonstrate that this precise control can be achieved by installing a three-dimensional linker in an MOF with one-dimensional channels. Specifically, we synthesized single crystals and bulk powder of NU-2002, an isostructural framework to MIL-53 with bicyclo[1.1.1]pentane-1,3-dicarboxylic acid as the organic linker component. Using variable-temperature X-ray diffraction studies, we show that increasing linker dimensionality limits structural breathing relative to MIL-53. Furthermore, single-component adsorption isotherms demonstrate the efficacy of this material for separating hexane isomers based on the different sizes and shapes of these isomers.