In order to study the in situ formation of UiO-66 family MOFs, we designed a series of experiments based on the conditions used in our lab syntheses of these materials, as summarised in Table . While UiO family MOFs are typically synthesised from zirconium salts, in this (as with our previous) work we have used hafnium chloride, due to the chemical similarity of Hf compared to Zr but greater scattering power. While a variety of solvents and conditions have been used across the literature, the majority of our work has focussed on reactions in DMF with formic acid and water. Our XPDF experiments, therefore, used these same reagents.