Yuchen Xiao, Anh N. Hong, Ziyang Jia, Xianhui Bu, Pingyun Feng
One tenet of isoreticular chemistry is the use of longer framework-building units to increase unit-cell and pore volume. While this belief has led to tremendous success as shown by isoreticular series such as IRMOF-1 to IRMOF-16 and MOF-74-I to MOF-74-XI, it can nevertheless be flawed as we move to multimodule systems, for which the quantitative analysis on the correlation between cell volume and ligand dimension can offer guidance on the rational formulation of MOF components. Here, through the synthesis of 60 new pacs materials, we report a broad expansion of pacs -type MOFs by extensively varying metal-trimer compositions, framework-forming ligands (L1), and pore-partitioning ligands (L2). This expanded structural library provides the experimental basis to highlight a nonmonotonic trend between unit-cell volumes and ligand lengths as an intrinsic property of the pacs platform. We further reveal an amplification of the stability-enhancing effect by the NiV trimer over other trimers as we transition to a greater pore-size regime, showing that the nickel–vanadium combination provides a crucial stabilizing factor for large pacs materials. The new structural family includes members with record-setting properties, including ultrahigh BET surface areas (>4400 m 2 /g) which is likely the highest among high-connected (>6) frameworks based on low-valent (≤3) metals. Multiple members of this family are believed to have the all-time-high propane uptake capacity (e.g., 15.6 mmol/g or 350.1 cm 3 /g at 298 K and 1 bar; 6.72 mmol/g or 150.7 cm 3 /g at 298 K and 0.1 bar), especially among C 3 H 8 -selective MOFs. The exceptional uptake capacity, coupled with inverse propane/propylene selectivity, enables efficient separation.