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Extreme Flexibility in a Zeolitic Imidazolate Framework: Porous to Dense Phase Transition in Desolvated ZIF‐4
Author(s) -
Wharmby Michael T.,
Henke Sebastian,
Bennett Thomas D.,
Bajpe Sneha R.,
Schwedler Inke,
Thompson Stephen P.,
Gozzo Fabia,
Simoncic Petra,
MellotDraznieks Caroline,
Tao Haizheng,
Yue Yuanzheng,
Cheetham Anthony K.
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201410167
Subject(s) - zeolitic imidazolate framework , porosity , phase transition , imidazolate , materials science , phase (matter) , crystallography , chemistry , chemical engineering , chemical physics , thermodynamics , metal organic framework , inorganic chemistry , composite material , organic chemistry , adsorption , physics , engineering
Desolvated zeolitic imidazolate framework ZIF‐4(Zn) undergoes a discontinuous porous to dense phase transition on cooling through 140 K, with a 23 % contraction in unit cell volume. The structure of the non‐porous, low temperature phase was determined from synchrotron X‐ray powder diffraction data and its density was found to be slightly less than that of the densest ZIF phase, ZIF‐zni. The mechanism of the phase transition involves a cooperative rotation of imidazolate linkers resulting in isotropic framework contraction and pore space minimization. DFT calculations established the energy of the new structure relative to those of the room temperature phase and ZIF‐zni, while DSC measurements indicate the entropic stabilization of the porous room temperature phase at temperatures above 140 K.