During the formation of some metal organic frameworks, the metal centers coordinate with both linker and solvent molecules. Subsequent activation removes the solvent molecules and creates unsaturated 'open-metal' sites, which have strong affinity for CO2. Current force fields in the literature underestimate the adsorption of CO2 in these open-metal site cases (e.g. Mg-MOF-74) by as much as two orders of magnitude. In order to accurately model the strong interaction of CO2 at the metal site, we require a more subtle description of the interaction potential than what is offered by a standard Lennard-Jones type potential. Here we present a systematic procedure to develop force fields for Mg-MOF-74 and similar systems using high-level quantum chemical calculations. This force field accurately takes into account the chemistry of the open metal sites. Monte Carlo simulations based on this force field shed some light on the interpretation of thermodynamic data of this system.

Ab initio carbon capture in open-site metal organic frameworks

244th National Meeting (2012)

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