CHAPTER 4: Characterization of MOFs. 1. Combined Vibrational and Electronic Spectroscopies

This chapter provides an organic description of the basic theoretical background needed to understand the physical phenomena that are behind vibrational and electronic excitation of materials. Selected examples are then provided to underline the relevance of such spectroscopies in understanding porous MOF materials. As IR and UV‐Vis are the most widespread instruments for vibrational and electronic spectroscopies, respectively, most of the examples refer to these two techniques. Other laboratory techniques such as Raman, resonant Raman and XPS are also considered. Synchrotron radiation based techniques, such as X‐ray absorption (only XANES region) and X‐ray emission (XES and resonant‐XES) spectroscopies are reported as excellent techniques for investigating the occupied and non‐occupied electronic states, respectively. Inelastic neutron scattering (INS) is described as an ideal technique to characterize H₂ sitting inside MOF cavities. The chapter is organized in sub‐sections that describe how the abovementioned techniques, performed in controlled atmosphere, can be applied to follow: (i) solvent removal; (ii) presence of local defects; (iii) adsorption properties towards probe molecules; (iv) reactivity in respect to simple species. The role of computational techniques in both rational design of new materials and interpretation of experimental results is testified by some relevant examples. The ensemble of the examples hopes for a wider use of porous MOFs in catalysis.