Exploring Ce(IV)-MOFs redox behavior for catalysis by spectroscopies

In the Metal-Organic Framework (MOF) panorama, Ce(IV)-based MOFs have emerged as potential candidates for heterogeneous catalysis, not only due to their intrinsic active species but also as a support of single metal sites. As the catalytic behavior of these materials is often associated to the redox properties of cerium, a large number of spectroscopic techniques have been employed to characterize them. Unfortunately, both data acquisition and interpretation are not always straightforward and sometimes the data are not well reported and discussed, limiting their impact in the literature. In this perspective review, we critically analyse the contributions provided by different spectroscopic techniques, sometime supported by molecular modelling approaches, to unravel the nature of Ce(IV)-MOFs at any stage of their preparation and along their use ( i.e. , post-synthesis treatments and under reaction conditions). A concise description of major results from the recent literature allows to provide basic insights associated to the applicability and limits of most used spectroscopic approaches, showing that more robust understanding of Ce(IV)-MOFs can be achieved when a broad spectrum of techniques are used in parallel, adopting similar conditions and following good practice rules.