Extreme Carbon Dioxide Sorption Hysteresis in Open-Channel Rigid Metal-Organic Frameworks

A systematic study is presented of three closely related microporous metal-organic frameworks the pore dimensions of which vary according to the choice of 4,4'-bipyridyl linker. The tunable linker allows exploration of the effect of increasing pore dimensions on the sorption behavior of the frameworks. The MOFs described capture CO2 under supercritical conditions and continue to sequester the gas under ambient conditions. Gas sorption isotherms for CO2 are compared with thermogravimetric data, and the CO2 molecules in the channels of the frameworks could be modeled using single-crystal X-ray diffraction analysis. Crystallographic data were used to construct a theoretical model based on DFT methods to calculate framework electrostatic potential maps with a view to understanding the nature of the sorbate-sorbent interactions.