We show that metal-organic frameworks (MOFs) can incorporate a large number of different functionalities on linking groups in a way that mixes the linker, rather than forming separate domains. We made complex MOFs from 1,4-benzenedicarboxylate (denoted by "A" in this work) and its derivatives -NH2, -Br, -(Cl)2, -NO2, -(CH3)2, -C4H4, -(OC3H5)2, and -(OC7H7)2 (denoted by "B" to "I," respectively) to synthesize 18 multivariate (MTV) MOF-5 type structures that contain up to eight distinct functionalities in one phase. The backbone (zinc oxide and phenylene units) of these structures is ordered, but the distribution of functional groups is disordered. The complex arrangements of several functional groups within the pores can lead to properties that are not simply linear sums of those of the pure components. For example, a member of this series, MTV-MOF-5-EHI, exhibits up to 400% better selectivity for carbon dioxide over carbon monoxide compared with its best same-link counterparts.

Thermodynamic models that explicitly account for association have become essential tools for correlating and predicting multiphase equilibria. These models have many adjustable parameters, which create difficulties for uniquely fitting experimental data. Reducing the number of adjustable parameters is an important pathway to increase the reliability and extrapolation power of thermodynamic models for practical applications. In this work, we revisit the relationship between the chemical and perturbation theories of association. This relationship creates a pathway for estimating association parameters using quantum chemistry calculations and statistical mechanics. Estimated parameters are applied to pure-component calculations, which demonstrate that they can be used to reduce the number of adjustable model parameters for the cubic plus association and perturbed-chain statistical associating fluid theory equations of state.

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