Polar Pore Surface Guided Selective CO₂ Adsorption in a Prefunctionalized Metal–Organic Framework

Abstract

Selective CO2 adsorption over other small gases has been realized in an ultra-microporous metal-organic framework (MOF). In the quest of manifesting such selective carbon capture performance, the prefunctionalized linker strategy has been espoused. A new Zn(II)-based three-dimensional, 3-fold interpenetrated metal-organic framework material [Zn(PBDA)(DPNI)]n·xG (PBDA: 4,4′-((2-(tert-butyl)-1,4-phenylene)bis(oxy))dibenzoic acid; DPNI: N,N′-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide; xG: x number of guest species) with unusual rob topology is synthesized following a typical solvothermal synthesis protocol, which gleans a modest CO2-selective adsorption trend over its congener gases (saturation CO2 uptake capacity: 2.39 and 3.44 mmol g-1, at 298 and 273 K; volumetric single component isotherm based separation ratios at 0.2 bar: 189.4 (CO2/N2, 256.5 (CO2/H2), 12.3 (CO2/CH4); at 1 bar: 6.8 (CO2/N2, 17.1 (CO2/H2), 7.1 (CO2/CH4)). The compound also exhibits selective benzene sorption over its aliphatic C6-analogue cyclohexane. The structure-property correlation guided results supported by theoretical introspection further emphasize the omnipresent role of crystal engineering principles behind culmination of such targeted properties in the nanoporous MOF domain, to realize selective sorption facets.