Anisotropic Elastic Properties of Flexible Metal-Organic Frameworks: How Soft are Soft Porous Crystals?

作者：Ortiz, Aurelie U.^*; Boutin, Anne; Fuchs, Alain H.; Coudert, Francois-Xavier

来源：Physical Review Letters, 2012, 109(19): 195502.

DOI：10.1103/PhysRevLett.109.195502

• STRUCTURAL TRANSITIONS
• PRESSURE
• EXPLORATION
• MIL-53(AL)

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.

• 出版日期2012-11-7