Strong and reversible binding of carbon dioxide in a green metal-organic framework

Abstract

The efficient capture and storage of gaseous CO2 is a pressing environmental problem. Although porous metal-organic frameworks (MOFs) have been shown to be very effective at adsorbing CO2 selectively by dint of dipole-quadruple interactions and/or ligation to open metal sites, the gas is not usually trapped covalently. Furthermore, the vast majority of these MOFs are fabricated from nonrenewable materials, often in the presence of harmful solvents, most of which are derived from petrochemical sources. Herein we report the highly selective adsorption of CO2 by CD-MOF-2, a recently described green MOF consisting of the renewable cyclic oligosaccharide γ-cyclodextrin and RbOH, by what is believed to be reversible carbon fixation involving carbonate formation and decomposition at room temperature. The process was monitored by solid-state 13C NMR spectroscopy as well as colorimetrically after a pH indicator was incorporated into CD-MOF-2 to signal the formation of carbonic acid functions within the nanoporous extended framework. © 2011 American Chemical Society.