Exploration of the mechanical behavior of metal organic frameworks UiO-66(Zr) and MIL-125(Ti) and their NH2 functionalized versions

The structural behaviour under mechanical stimuli of two metal organic frameworks, UiO-66(Zr) and MIL-125(Ti) and their amino-functionalized derivatives has been investigated by high-pressure powder X-ray diffraction up to 3.5 GPa. All these solids showed a gradual pressure-induced reversible decrease of their crystallinity and UiO-66(Zr)_NH2 material has been revealed as one of the most resilient MOFs reported so far corresponding to a very high bulk modulus. The mechanical behaviors of these MOFs have been correlated to their chemical and geometric features including the metal-oxygen coordination number, the nature of the organic linker, the porosity as well as their crystal density.