Rational Design of Noncovalent Diamondoid Microporous Materials for Low-Energy Separation of C6-Hydrocarbons

Selective separation of gases/vapors with similar physicochemical properties involves energetically costly distillation processes. Alternative separation processes based on shape-selective molecular sieving, taking place on porous frameworks (or membranes), are less energy demanding but require an optimal balance between selectivity and diffusion kinetics (permeability). Herein, we report a rational strategy to select an optimal soft noncovalent microporous material (NPM) suitable for the low-energy separation of C6-hydrocarbons with kinetic diameters in the range of 4.3–6.3 A. This strategy is based on a Cambridge Structural Database search of diamondoid NPMs with a low packing factor, leading to the selection of an oxidotetrazinc cluster based diamondoid NPM network named DiaMM-1 containing tetrahedral voids of 336 A3 (tetrahedron insphere diameter of 5.8 A accessible through 8.2 A triangular windows) suitable for this separation. Based on this result the fluorinated analogue DiaMM-2 was designed and sy...