Highly Robust Tetranuclear Cobalt-Based 3D Framework for Efficient C2H2/CO2 and C2H2/C2H4Separations.

A novel noninterpenetrated tetranuclear cobalt(II)-based metal-organic framework, (NH4)2·[Co4(μ3-OH)2(ina)2(pip)3]·4EtOH·H2O (simplified as NbU-10·S), constructed by mix linkers was synthesized by a hydrothermal method. Interestingly, the presence of a hydrophobic benzene ring in the organic linker makes NbU-10·S exhibit high stability in high temperature and even in aqueous solution over a wide pH range of about 4-13. Magnetic studies showed that the tetranuclear cobalt(II) units in NbU-10·S show dominant antiferromangetic properties. However, in the absence of Lewis basic functional sites and open metal sites in the material, NbU-10 still displays high C2H2/CO2 and C2H2/C2H4 selectivity in ideal adsorbed solution theory calculations and dynamic breakthrough experiments. Moreover, density functional theory calculations were performed to identify the adsorption characteristics of different gas molecules.