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Flexibility in a Metal–Organic Framework Material Controlled by Weak Dispersion Forces: The Bistability of MIL-53(Al)


  • A.M.W. and C.M.D. are supported by NERC and EPSRC (NE/E012922/2 and EP/E059392/1), respectively. SIESTA calculations were performed on the HECToR UK national computer facility (EPSRC EP/F067496/1) and on Legion, the UCL supercomputer. B.S. is grateful to Kleopatra Liourta for initial work on this topic. J.D.G. thanks the ARC for funding.


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Breathtaking MOFs: DFT calculations reveal that the exceptional, thermally induced density change of the metal–organic framework MIL53(Al) is controlled by a competition between short- and long-range interactions and entropic factors. As shown in the picture (C green, Al cyan, O red, H white), dispersive interactions between the phenyl rings are responsible for stabilizing a narrow-pore form at low temperature. At 325–375 K, vibrational entropy causes the structure to expand markedly, permitting large volumes of light gases to be adsorbed.

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