Double structural transition in hybrid material MIL-53 upon hydrocarbon adsorption: the thermodynamics behind the scenes.

We rationalize the thermodynamics behind the guest-induced structural transitions of hybrid material MIL-53, showing that the existence of a double transition depends on the relative guest affinities for the two phases, rather than absolute adsorption enthalpies. Based on a simple model, we interpret recent experimental data on alkane adsorption and predict transition pressures.