Pore Space Partition in Indolo[3,2-b]carbazole-based Zr-MOF via Post-Synthetic Linker Installation for Enhanced Ethane/Ethylene Separation.

The separation of ethane (C2H6)/ethylene (C2H4) by metal-organic frameworks (MOFs) depends largely on the pore environment. Here we construct a C2H6-selective mesoporous Zr-MOF, NUT-77, using indolo[3,2-b]carbazole-based tetracarboxylate ligands, and then apply post-synthetic linker installation of dicarboxylate linkers for pore space partition (PSP). The resulting NUT-77-Me2BPDC and NUT-77-BPDC-NH2 show increased pore volumes and reduced pore sizes, leading to higher C2H6 uptake and selectivity. At 273 K and 1 bar, the C2H6/C2H4 separation potential (Δq) of NUT-77-Me2BPDC is 122% higher than that of parent NUT-77. Breakthrough experiments confirm the improved dynamic separation. Density functional theory calculations indicate that the installed linkers introduce more C-H···π and hydrogen-bonding sites, strengthening C2H6 affinity. The PSP strategy provides a route for tailoring MOF pore environments to enhance C2H6-selective adsorption in C2H6/C2H4 separation.