The introduction of the concept of surface properties can help us to better analyze the basic physicochemical property changes of metal−organic framework (MOF) materials before and after fluorine functional group treatment. In this study, several polar and nonpolar probes were selected to determine the surface properties, including surface-dispersive free energy, Lewis acid−base constants of Ni-MOF-74, and perfluoro carboxylic acid-modified Ni-MOF-74-Fn (n = 3, 5, and 7) in the range of 343.15−383.15 K by inverse gas chromatography (IGC). It was observed that the surface energy of the treated Ni-MOF-74-Fn showed a substantial decrease with the growth of the perfluorocarbon alkyl chains and the increase in surface roughness. In addition, Lewis acidic sites exposed by the Ni-MOF-74 material after adopting modification with fluorine functional groups increased with the increase of perfluorinated carboxylic acid chains, and their surface properties changed from amphiphilic acidic to strongly acidic. These results not only enrich the basic physical property data of Ni-MOF-74 but also provide more theoretical basis for the fluorinated functionalized custom-designed MOFs and enrich their applications in the fields of multiphase catalysis, gas adsorption, and chromatographic separation.

Inverse gas chromatography (IGC) was used to determine a series of thermodynamic parameters for a deep eutectic solvent (DES) composed of choline chloride (CHCl) and oxalic acid (OA) in a 1:1 molar ratio at temperatures ranging between 303.15 and 343.15 K. The infinite dilution activity coefficients (γ12 ∞) and Flory–Huggins interaction parameters (χ12 ∞) of 31 organic solutes with different chemical properties in the DES were determined to predict the separation ability of the DES and the miscibility between the DES and solutes, respectively. The results show that alcohols and acetonitrile are good solvents for the DES. The selectivity (S 12 ∞) and capacity (k 2 ∞) of DES were determined for azeotropic mixtures of acetone (1)/ethanol (2), cyclohexane (1)/ethanol (2), n-heptane (1)/thiophene (2), benzene (1)/methanol (2), and tetrachloromethane (1)/methanol (2), showing that the DES is an effective separation agent for the tetrachloromethane (1)/methanol (2) and acetone (1)/ethanol (2) systems compared with the reported solvents. Furthermore, the Hildebrand solubility parameters (δ2) of the examined DES were determined at different temperatures using the Guillet method and provide a theoretical basis for solute selection.