was proposed. The free nature of the hydroxide results from the dissociation of the K-OH bond due to significant hydrogen bonding from the cyclodextrin sugar framework. However, ambiguity remains in the adsorption mechanism with IR, C NMR and heats of adsorption data unable to fully discard the possibility of carbonate formation (eq. 3). Thus, distinguishing between these two mechanisms is vital for understanding and improving not only CD-MOF capture materials, but also hydroxide-based CO 2 capture systems more generally.