TY - JOUR

T1 - Guest controlled rotational dynamics of terephthalate phenylenes in metal-organic framework MIL-53(Al)

T2 - Effect of different xylene loadings

AU - Kolokolov, Daniil I.

AU - Stepanov, Alexander G.

AU - Jobic, Hervé

PY - 2014/7/24

Y1 - 2014/7/24

N2 - MIL-53 is an interesting metal-organic framework (MOF) with a "breathing" framework which is envisioned for a number of potential applications. It is suggested that the processes of hydrocarbon adsorption, diffusion, and separation by this material are strongly influenced by flexibility of the framework and fastly moving terephthalate phenylene fragments, representing the array of molecular rotors. To govern the mentioned processes we need to learn how to monitor the flexibility of the framework and identify the specific effects of particular hydrocarbons on the rotational motion of phenylene fragments. Here we demonstrate that flexibility, i.e., large pore (LP) and narrow pore (NP) crystalline state interconversions of the framework, can be monitored by following the evolution of phenylene fragments dynamics with temperature by 2H solid-state nuclear magnetic resonance. We have established that the dynamics of phenylene fragments is very sensitive to the loading of xylene guests and the MOF structural state. The rotation rate is higher and the activation barrier lower for the LP state of the guest-free or loosely loaded material, whereas the NP and LP states with high loadings and dense guest packing show a decrease of the rotation rates and increase of the rotation energetic barrier.

AB - MIL-53 is an interesting metal-organic framework (MOF) with a "breathing" framework which is envisioned for a number of potential applications. It is suggested that the processes of hydrocarbon adsorption, diffusion, and separation by this material are strongly influenced by flexibility of the framework and fastly moving terephthalate phenylene fragments, representing the array of molecular rotors. To govern the mentioned processes we need to learn how to monitor the flexibility of the framework and identify the specific effects of particular hydrocarbons on the rotational motion of phenylene fragments. Here we demonstrate that flexibility, i.e., large pore (LP) and narrow pore (NP) crystalline state interconversions of the framework, can be monitored by following the evolution of phenylene fragments dynamics with temperature by 2H solid-state nuclear magnetic resonance. We have established that the dynamics of phenylene fragments is very sensitive to the loading of xylene guests and the MOF structural state. The rotation rate is higher and the activation barrier lower for the LP state of the guest-free or loosely loaded material, whereas the NP and LP states with high loadings and dense guest packing show a decrease of the rotation rates and increase of the rotation energetic barrier.

UR - http://www.scopus.com/inward/record.url?scp=84904977276&partnerID=8YFLogxK

U2 - 10.1021/jp506010p

DO - 10.1021/jp506010p

M3 - Article

AN - SCOPUS:84904977276

VL - 118

SP - 15978

EP - 15984

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 29

ER -