Decoupling the Effect of Crystal Morphology and Pore Microenvironment in Metal–Organic Frameworks for High-Resolution Separation

Crystal morphology and pore microenvironment in metal-organic frameworks (MOFs) are intrinsically coupled factors governing separation resolution in gas chromatography (GC), yet their individual roles remain difficult to disentangle. Here, using PCN-608 as a model system, we systematically decoupled the effects of crystal morphology and pore microenvironment on chromatographic performance. Three distinct morphologies, nanodisks, nanosheets, and interpenetrated nanosheets, were constructed to elucidate morphology-dependent transport behavior, while pore microenvironments were independently tuned by alkoxy functionalization with methoxy, ethoxy, and propoxy groups. We showed that crystal morphology dominantly regulated mass transfer and peak retention through changing the diffusion path length and morphology-dependent stacking voids. Among three morphologies, the nanosheets exhibited the highest column efficiency. With morphology fixed as nanosheets, pore microenvironment modulation revealed that excessive functionalization introduced steric hindrance and deteriorated separation resolution despite enhanced retention. These results establish a general design principle for MOF-based GC stationary phases through coordinated optimization of transport pathways and pore environments.