Bond breakage under pressure in a metal organic framework.

ABSTRACT: The internal free volume of porous materials diminishes upon mechanical compression, and such volume collapse can have chemical consequences. We report here the endothermic bond breakage in a metal-organic framework (MOF) during compression-induced collapse. Upon bulk compression at 1.9 GPa, the effective number for Zr-O bonds between Zr(iv) ions and carboxylate groups in UiO-66 decreased from 4.0 to 1.9, as determined by EXAFS, and the internal free volume was synchronously collapsed. Consistent with the EXAFS data, IR spectra confirmed conversion of syn-syn bridging carboxylates to monodentate ligation, thus establishing mechanochemical reactions induced by external compression of MOFs. Substantial mechanical energy (∼4 kJ g^-1) was absorbed by UiO-66 nanocrystals

SUBMITTER: Su Z 

PROVIDER: S-EPMC5853553 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature