Accurate H2 Sorption Modeling in the rht-MOF NOTT-112 Using Explicit Polarization

Abstract

Hydrogen sorption was characterized theoretically in NOTT-112, an rht-metal–organic framework (MOF) that consists of Cu2+ ions coordinated to 1,3,5-tris(3′,5′-dicarboxy[1,1′-biphenyl]-4-yl)benzene ligands. Grand canonical Monte Carlo (GCMC) simulations of H2 sorption were performed using three different sorbate potentials of increasing complexity to elucidate the mechanism of interaction in NOTT-112. Reasonable agreement with the experimental H2 sorption isotherms, isosteric heats of adsorption (Qst), and H2–Cu2+ distances was obtained with the model that includes explicit many-body polarization. This highlights the physical importance of induction in H2 sorption in MOFs with open-metal sites. The two Cu2+ ions within the paddlewheels in NOTT-112 have distinct electrostatic profiles and sorption characteristics. The Cu2+ ions projecting into the cuboctahedral (cub–Oh) cage of the MOF are more electropositive than the Cu2+ ions projecting toward the organic linker, and therefore serve as the initial loadin...