Metal-organic frameworks (MOFs) have long been assumed to exist primarily as highly porous structures, an assumption that earned their discoverers the 2025 Nobel Prize in Chemistry. Researchers have now challenged this decades-old understanding by demonstrating that MOF thin films contain dense packing arrangements previously overlooked by conventional analysis.
The team discovered that when MOFs form as thin films rather than bulk crystals, they organize into unexpectedly compact structures alongside their traditionally porous regions. This finding emerged from detailed examination of MOF thin films using advanced characterization techniques that revealed density variations invisible to standard measurement methods.
The discovery carries practical implications across multiple industries relying on MOFs for gas storage, carbon dioxide capture, and pharmaceutical delivery systems. If thin films pack more densely than previously thought, their performance characteristics in these applications require reevaluation. Dense regions could either enhance certain properties like mechanical strength or reduce accessible surface area for adsorption.
The research reveals gaps in current understanding of how MOFs behave at different scales. Bulk MOFs and thin film versions apparently follow different organizational rules, suggesting that manufacturing processes and substrate interactions influence structure in ways the field has underestimated. This complexity means researchers cannot simply extrapolate bulk MOF properties to thin film applications.
The implications extend to materials design and optimization. If engineers can control when and where dense packing occurs within MOF films, they might engineer materials with tuned porosity gradients, creating devices that combine dense and porous regions for specific functions. Conversely, uncontrolled dense regions could represent inefficiencies limiting performance.
This work underscores how materials science repeatedly reveals that assumptions holding for one form of a material break down at different scales or geometries. The finding does not diminish MOFs' value for emerging technologies but rather indicates that their full potential remains untapped. Future research must systematically characterize how MOF structure varies