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Molecular Mobility of Tert‐butyl Alcohol Confined in a Breathing MIL‐53 (Al) Metal‐Organic Framework
Author(s) -
Khudozhitkov Alexander E.,
Toktarev Alexander V.,
Arzumanov Sergei S.,
Gabrienko Anton A.,
Kolokolov Daniil I.,
Stepanov Alexander G.
Publication year - 2020
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000445
Subject(s) - chemistry , metal organic framework , molecule , diffusion , molecular dynamics , alcohol , adsorption , crystallography , solid state nuclear magnetic resonance , stereochemistry , computational chemistry , organic chemistry , nuclear magnetic resonance , thermodynamics , physics
We present a detailed solid‐state NMR characterization of the molecular dynamics of tert ‐butyl alcohol (TBA) confined inside breathing metal‐organic framework (MOF) MIL‐53(Al). 27 Al MAS NMR has demonstrated that TBA adsorption induces the iX phase of MIL‐53 material with partially shrunk channels. 2 H solid‐state NMR has shown that the adsorbed alcohol exhibits anisotropic rotations of the methyl groups around two C 3 axes and librations of the molecule as a whole about the axis passing through the TBA C−O bond. These librations are realized by two distinct ways: fast molecule orientation change during the translational jump diffusion along the channel with characteristic time τ D of about 10 −9 s at 300 K; slow local librations at a single coordination site, representing framework hydroxyl groups, with τ l ≈10 −6 s at 300 K. Self‐diffusion coefficient of the alcohol in the MOF has been estimated: D =3.4×10 −10 m 2 s −1 at 300 K. It has been inferred that both the framework flexibility and the interaction with framework hydroxyl groups define the dynamics of TBA confined in the channels of MIL‐53 (Al).