Evaluation of Brønsted acidity and proton topology in Zr- and Hf-based metal–organic frameworks using potentiometric acid–base titration

Potentiometric acid–base titration is introduced as a method to evaluate p K a values (Brønsted acidity) of protons present in the nodes of water stable Zr 6 - and Hf 6 -based metal–organic frameworks (MOFs), including UiO-type MOFs, NU-1000, and MOF-808. p K a values were determined for the three typical types of protons present in these MOFs: μ 3 -OH, M–OH 2 , and M–OH (M = Zr, Hf). Additionally, the data was used to quantify defect sites resulting from either a surfeit or shortage of linkers in the MOFs and to provide information about the true proton topology of each material.