Interaction between CO2 and Organic-Metal Frameworks

We study trends in the binding between CO2 and MIL-47(V) (see bottom figure) as an open-metal site (OMS) metal-organic framework (MOF) using van der Waals-corrected density functional theory. The latter method is same Grimme s functional including dispersion on periodic boundary DFT that call usually DFT-D2. We find that the OMS-MOF based on vanadium (V) with terephthalic acid as its linker has large CO2 binding energies and show that for these cation, the CO2 binding energies are twice the value expected based on pure electrostatics. We associate this adsorption behavior with the specific electronic configuration of the divalent cations and symmetry of the Zn and Fe site in same organic linker upon CO2 binding. In the last investigations, the grand canonical Monte-Carlo (GCMC) and molecular dynamics (MD) simulations based on REPEAT electrostatic charges are presented to demonstrate that physical bond and electrostatic interactions can be used to predict trends of CO2 binding affinities to OMS-MOFs with transition-metal cations which are filing their d orbitals.