Understanding adsorption-induced structural transitions in metal-organic frameworks: From the unit cell to the crystal

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

1 LECIME - Laboratoire d'Electrochimie, Chimie des Interfaces et Modélisation pour l'Energie (LECIME - UMR 7575)
2 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)
3 Rutgers University [Newark]

Breathing transitions represent recently discovered adsorption-induced structural transformations between large-pore and narrow-pore conformations in bi-stable metal-organic frameworks such as MIL-53. We present a multiscale physical mechanism of the dynamics of breathing transitions. We show that due to interplay between host framework elasticity and guest molecule adsorption, these transformations on the crystal level occur via layer-by-layer shear. We construct a simple Hamiltonian that describes the physics of host-host and host-guest interactions on the level of unit cells and reduces to one effective dimension due to the long-range elastic cell-cell interactions. We then use this Hamiltonian in Monte Carlo simulations of adsorption-desorption cycles to study how the behavior of unit cells is linked to the transition mechanism at the crystal level through three key physical parameters: the transition energy barrier, the cell-cell elastic coupling, and the system size.

Domaines: Chimie; Chimie théorique et/ou physique; Matériaux

Carles Triguero, François-Xavier Coudert, Anne Boutin, Alain Fuchs, Alexander V Neimark. Understanding adsorption-induced structural transitions in metal-organic frameworks: From the unit cell to the crystal. Journal of Chemical Physics, 2012, 137 (18), pp.184702. ⟨10.1063/1.4765369⟩. ⟨hal-02310171⟩