Impact of Ni(II) coordinatively unsaturated sites and coordinated water molecules on SO₂ adsorption by a MOF with octanuclear metal clusters

A Ni-based pyrazolate MOF (NiBDP) is studied for SO(2 )adsorption under static conditions, demonstrating a high SO2 uptake of 8.48 mmol g(-1) at 298 K and 1 bar while maintaining a high chemical stability. The influence of Ni(II) coordinatively unsaturated metal sites and coordinated water on the SO2 adsorption performance of this MOF is investigated by using a combination of experimental techniques, including FTIR and in situ DRIFTS measurements, along with Density Functional Theory calculations. The pore-filling of the SO2 adsorbates within the material, at the molecular level, is further unravelled through grand Canonical Monte Carlo simulations employing a newly DFT-derived accurate set of force field parameters.