  The metal organic framework (MOF) material UiO-66 has emerged as one of the
most promising MOF materials due to its thermal and chemical stability and its
potential for catalytic applications. Typically, as-synthesised UiO-66 has a
relatively high concentration of missing linker defects. The presence of these
defects has been correlated with catalytic activity but characterisation of
defect structure has proved elusive. We refine a recent experimental
determination of defect structure using static and dynamic first principles
approaches, which reveals a dynamic and labile acid centre that could be
tailored for functional applications in catalysis.
