Porous materials with pre-designed single-molecule traps for CO2 selective adsorption

Abstract

Despite tremendous efforts, precise control in the synthesis of porous materials with pre-designed pore properties for desired applications remains challenging. Newly emerged porous metal-organic materials, such as metal-organic polyhedra and metal-organic frameworks, are amenable to design and property tuning, enabling precise control of functionality by accurate design of structures at the molecular level. Here we propose and validate, both experimentally and computationally, a precisely designed cavity, termed a ‘single-molecule trap’, with the desired size and properties suitable for trapping target CO₂ molecules. Such a single-molecule trap can strengthen CO₂–host interactions without evoking chemical bonding, thus showing potential for CO₂ capture. Molecular single-molecule traps in the form of metal-organic polyhedra are designed, synthesised and tested for selective adsorption of CO₂ over N₂ and CH₄, demonstrating the trapping effect. Building these pre-designed single-molecule traps into extended frameworks yields metal-organic frameworks with efficient mass transfer, whereas the CO₂ selective adsorption nature of single-molecule traps is preserved.