Stress-Based Model for the Breathing of Metal−Organic Frameworks

Alexander V Neimark (1) , François-Xavier Coudert (2) , Anne Boutin (3) , Alain H. Fuchs (2)

1 RU - Rutgers, The State University of New Jersey [New Brunswick]
2 ENSCP - Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL
3 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)

Gas adsorption in pores of flexible metal−organic frameworks (MOF) induces elastic deformation and structural transitions associated with stepwise expansion and contraction of the material, known as breathing transitions between large pore (lp) and narrow pore (np) phases. We present here a simple yet instructive model for the physical mechanism of this enigmatic phenomenon considering the adsorption-induced stress exerted on the material as a stimulus that triggers breathing transitions. The proposed model implies that the structural transitions in MOFs occur when the stress reaches a certain critical threshold. We showcase this model by drawing on the example of Xe adsorption in MIL-53 (Al) at 220 K, which exhibits two consecutive hysteretic breathing transitions between lp and np phases. We also propose an explanation for the experimentally observed coexistence of np and lp phases in MIL-53 materials.

Mots clés: MOF; metal−organic frameworks; MIL-53; adsorption; structural flexibility; adsorption stress

Domaines: Chimie théorique et/ou physique

Alexander V Neimark, François-Xavier Coudert, Anne Boutin, Alain H. Fuchs. Stress-Based Model for the Breathing of Metal−Organic Frameworks. Journal of Physical Chemistry Letters, 2009, 1 (1), pp.445-449. ⟨10.1021/jz9003087⟩. ⟨hal-00548069⟩