Computational design of metal-organic frameworks with triangular adsorbaphores for highly selective adsorption of -xylene.

Separation of xylene isomers, serving as indispensable feedstock in the petrochemical industry, is important but significantly challenging due to their similar physicochemical properties. With readily tunable network structures and chemical functionalities, metal-organic frameworks (MOFs) are promising for separation and many other potential applications. Here, we computationally design 150 lanthanide-based MOFs with one-dimensional triangular nanopores by varying metal compositions. Compared with -xylene (X) and -xylene (X), -xylene (X) exhibits the strongest interaction with these MOFs, as it can wedge at the vertices of triangular nanopores. Because of such shape-matching, highly selective adsorption of X is observed, with exceptional X/X and X/X selectivities. Remarkably, the nanopore size of these MOFs can be systematically adjusted through different metal combinations, achieving efficient xylene separation. The proposed design strategy would facilitate the development of new MOFs and other framework materials for highly selective xylene separation.