Thermally activated adsorption in metal-organic frameworks with a temperature-tunable diffusion barrier layer.

Modification of the external surfaces of metal organic frameworks offers a new level of control over their adsorption behavior. We have previously shown that capping of MOFs with ethylenediamine (EDA) can effectively retain small gaseous molecules [Nat. Comm. 2016, 7, 13871] at room temperature. Here, we report a temperature-induced variation in the capping-layer gate opening mechanism through a combination of in situ IR experiments and ab initio simulations of the capping layer. We find an atypical acceleration and increase in the loading of weakly adsorbed molecules upon raising the temperature above room temperature. Our findings show the discovery of a novel temperature-dependent kinetics that goes beyond standard kinetics and suggest a new avenue for tailoring selective adsorption by thermally tuning the surface barrier.