Modifying a partial corn-sql layer-based (3,3,3,3,4,4)-c topological MOF by substitution of OH with Cl and its highly selective adsorption of C2 hydrocarbons over CH.

Modifying VNU-18 (a MOF with a partial cone-sql layer pillared by the chains of pillars decorated with OH) by substitution of OH with Cl, a new isoreticular structure, [Cu(L)·(Cl)·HO·4DMF]·4DMF·6(HO) (SNNU-Bai67, SNNU-Bai = Shaanxi Normal University Bai's group), has been successfully synthesized. Furthermore, we deeply investigated the selective C2 hydrocarbon separation properties of SNNU-Bai67 and VNU-18 by single-component gas adsorption experiments, breakthrough experiments and simulation studies. They exhibit highly selective adsorption for C2 hydrocarbons over CH compared to many reported MOFs for the separation of C2 hydrocarbons from CH, due to the suitable pore sizes of the partial corn sql-layer built from the isophthalic acid analogy and Cu-paddlewheel units. Interestingly, with the counterion of OH in VNU-18 tuned by Cl in SNNU-Bai67, the adsorption uptake values of C2 hydrocarbons were apparently improved by 15.0% for CH, 20.4% for CH and 25.3% for CH, respectively, while the IAST selectivities of C2 hydrocarbons/CH were still nearly the same, which may be because the synergistic effect of interactions of HO, HN/C, HC, ππ or HC between the gas molecules and the framework is enhanced by the weaker polarity of Cl decorating the framework.