Tuning the Wettability of Hydrophobic Metal-Organic Frameworks by Linker-Doping

The wetting behavior of hydrophobic nanoporous materials plays a pivotal role in advanced technologies such as energy storage, molecular separations, catalysis, and biomimetic systems. A central challenge in employing these materials is the precise control of wetting (intrusion) and dewetting (extrusion) pressures. To address this, we investigated how varying the concentration of organic linkers in ZIF-7-8 (composed of Zn-methylimidazole and benzimidazole) influences the intrusion-extrusion behavior of water within its micropores. Remarkably, we noticed that even a minor substitution of organic linkers (below 3%) led to significant and systematic changes in the wetting properties. Owing to the small fraction of substituted linkers, such effect could not be explained by classical models that consider individual cages. To elucidate this phenomenon, we combined experiments with molecular dynamics simulations and stochastic modeling of the crystallites. Our results reveal that the introduction of alien linkers perturbs the hydrogen-bond network, thereby disrupting the cooperative effects fundamental to the intrusion-extrusion process.