Anisotropic elastic properties of flexible metal-organic frameworks: how soft are soft porous crystals?

We performed ab initio calculations of the elastic constants of five flexible metal-organic frameworks (MOFs): MIL-53(Al), MIL-53(Ga), MIL-47, and the square and lozenge structures of DMOF-1. Tensorial analysis of the elastic constants reveals a highly anisotropic elastic behavior, some deformation...

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Bibliographic Details
Published in:Physical review letters 2012-11, Vol.109 (19), p.195502-195502, Article 195502
Main Authors: Ortiz, Aurélie U, Boutin, Anne, Fuchs, Alain H, Coudert, François-Xavier
Format: Article
Language:English
Subjects:
Chemical Sciences
Material chemistry
or physical chemistry
Theoretical and
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Summary:We performed ab initio calculations of the elastic constants of five flexible metal-organic frameworks (MOFs): MIL-53(Al), MIL-53(Ga), MIL-47, and the square and lozenge structures of DMOF-1. Tensorial analysis of the elastic constants reveals a highly anisotropic elastic behavior, some deformation directions exhibiting very low Young's modulus and shear modulus. This anisotropy can reach a 400:1 ratio between the most rigid and weakest directions, in stark contrast to the case of nonflexible MOFs such as MOF-5 and ZIF-8. In addition, we show that flexible MOFs can display extremely large negative linear compressibility. These results uncover the microscopic roots of stimuli-induced structural transitions in flexible MOFs, by linking the local elastic behavior of the material and its multistability.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.109.195502