Stabilizing an scu-topology Zr-MOF via linker installation for enhanced gas chromatographic separation

Flexible metal-organic frameworks (MOFs) with dynamic adaptability offered exciting opportunities for advanced separation, yet their tendency to undergo void collapse severely limited their application as gas chromatography (GC) stationary phases. Here, we overcame this challenge by stabilizing the scu-topology Zr-MOF NU-903 through a linker installation strategy. By incorporating biphenyl-4,4'-dicarboxylic acid (BPDC) into the vacant coordination pockets along the c-axis, the resulting material, NU-903-BPDC, exhibited markedly enhanced stability and structural rigidity, retaining its porosity even at 250 °C. Comprehensive characterization confirmed that the original structure was preserved, while framework flexibility was effectively suppressed. Fluorescence spectroscopy further revealed restricted ligand dynamics, corroborating the rigidified framework environment. When employed as a GC stationary phase, NU-903-BPDC delivered significantly improved resolution for C₇ hydrocarbons and dichlorobenzene isomers, benefitting from stronger thermodynamic interactions and reduced band broadening. Crucially, NU-903-BPDC maintained stable separation performance after thermal treatment, in sharp contrast to the pronounced degradation observed for pristine NU-903. This work demonstrated linker installation as an effective strategy to modulate framework flexibility, opening a general pathway toward robust, high-performance MOF-based stationary phases for chromatographic separations.