Exploring the Effect\nof Framework Flexibility on Water\nAdsorption in the Metal–Organic Framework NbOFFIVE-1-Ni Using\nMolecular Modeling

Many metal–organic frameworks (MOFs) are known\nto show complex\nstructural flexibility such as breathing, swelling, and linker rotations,\nand understanding the impact of these structural changes on their\nguest adsorption properties is important in developing MOFs for practical\napplications. In this study, we used a multiscale computational approach\nto provide a molecular-level understanding of how flexibility affects\nwater adsorption in the MOF, NbOFFIVE-1-Ni. This material has narrow\npores and good hydrothermal stability, which make it attractive for\nCO<sub>2</sub> capture. We utilized density functional theory (DFT)\ncalculations and grand canonical Monte Carlo (GCMC) simulations to\nstudy the impact of NbOFFIVE-1-Ni structural flexibility on its water\nadsorption at different humidity conditions. Studying the water adsorption\nin different configurations of NbOFFIVE-1-Ni demonstrated that DFT\noptimization in the presence of adsorbed water molecules and rotating\nthe linkers are useful strategies to mimic its structural flexibility.\nOur results illustrate the significance of taking structural flexibility\ninto account when designing MOFs for water adsorption and other relevant\napplications.