The Metal-Organic Framework Collapse Continuum: Insights from Two-Dimensional Powder X-ray Diffraction

The process of activation, an essential step to reveal the porosity of metal-organic frameworks (MOFs), was examined for materials that produce surface areas in accord with prediction as well as for those failing to meet expectations. In situ two-dimensional powder X-ray diffraction, in combination with surface area measurements, was used to classify the structural outcomes of a variety of MOF activations. By modulation of activation solvent as well as linker length and flexibility, a variety of structural outcomes were obtained. In addition to pristine and amorphous products, MOFs that exhibit intermediate activation success were observed. Such MOFs were found to undergo reductions in crystallite size while varying in total amorphous content, which leads to vastly different product surface areas. Models to explain different activation outcomes are presented.