Structure-activity relationships of simple molecules adsorbed on CPO-27-Ni metal-organic framework: In situ experiments vs. theory

In this work we review experimental XRPD, EXAFS, Raman, IR, microcalorimetric data on the adsorption of H ₂O, NO, CO, CO ₂, N ₂, C ₂H ₄ and H ₂ molecules on CPO-27-Ni material, a metal-organic framework (MOF) showing a coordination vacancy at the Ni ²⁺ site in its desolvated form. Literature data are complemented by few new experimental results. A systematic theoretical study performed at the B3LYP-D*/TZVP level of theory (using a periodic boundary conditions) allowed us to reach a complete understanding of the structural, vibrational and energetic features of the material in interaction with the different molecules obtained from the different experimental techniques. From both experimental and theoretical set of data, interesting trends have been obtained for the framework distances (Ni-O and Ni-Ni) and frequency shifts of the framework vibration modes as a function of the adsorption energy (enthalpy) of the different probe molecules. This multitechnical approach, already applied for UiO-66 MOF is of general validity and can be straightforwardly extended to all MOF materials.