The calculations are performed using seven porous materials belonging to three MOF families with different metal choice or local environment of the open-metal center. Two are the Hoffman-type family with formula Fe(pz)[M(CN)4] and Fe(bpac)[M(CN)4], where M = Fe(II), Mn(II) and Ni(II) exhibits a square planar coordination. The pz = pyrazine and the bpac = (bis(4-pyridyl)acetylene). The bpac ligand, being longer, results in a higher porosity in the MOF than the pz case and allows to adsorb two gas molecules onto the open-metal site, thus resulting in a stronger ligand field induced by the adsorbate. The third MOF is Fe2(tpt)2(NCS)4 with the Fe(II) sites in a square pyramidal coordination. We employ a novel Hubbard U density-corrected scheme within density-functional theory to compute the change in binding energy upon spin-state change and the adiabatic energy difference associated with the spin crossover, in presence of adsorbed gas. This method yields predictions of adiabatic energy differences with excellent accuracy when compared with experiments or higher quantum chemistry level calculations, and it is computationally very efficient even for periodic calculations. The importance of using this approach in the calculation of binding energies is demonstrated and discussed here for the first time. Our results show that for the two Hoffman-like families, the ligand field splitting upon adsorption is too weak for CO2 and too strong for CO to yield adiabatic energy differences consistent with a spin crossover near room temperature. A good candidate is N2 adsorption/desorption on Fe(pz)[M(CN)4] and the case of H2 adsorption in bpac Fe and Mn MOF represents the most original and promising result. The strong adsorption in LS as expected from a Kubas mechanism results in a large uptake even at non-cryogenic conditions and the adiabatic energy difference may be consistent with a T-induced spin crossover. The potential of employing such a mechanism for an efficient H2 capture and release is further confirmed for the case of Fe2(tpt)2(NCS)4.