Pre‐Cluster Controlled Assembly of Oriented Mesopores in MOF Crystals

Directional alignment of mesoporous channels in anisotropic crystals defines an unexplored paradigm, unlocking host-guest interactions, mass transport, and catalytic functions. Here, we report an in situ pre-cluster-controlled assembly strategy to construct hierarchically mesostructured MIL-53(Al) (HMMIL-53(Al)) with oriented mesopores precisely matched to crystallographic anisotropy. Pre-assembly of Al chain clusters lowers the nucleation barrier and guides the crystal growth around the micelles, yielding mesopore walls oriented along the [100] crystallographic axis of MIL-53(Al). Such orientation exposes adjacent Al-OH sites spaced by approximately 3.4 Å apart on the inner walls of the mesoporous channels, forming bimetallic active centers. Furthermore, the oriented mesopores allow for continuous tuning of their pore size, and can be integrated into diverse hierarchical architectures, forming ultrathin 2D mesoporous nanosheets (NSs), dendritic dual-mesoporous spheres, and mesoporous nanoparticles. The orderly arrangement of Al-OH active sites displays spatial configurations and chemical environments that closely resemble those of the bimetallic catalytic centers in natural nuclease. Compared with bulk MIL-53(Al) or ultrathin NSs dominated by the exposure of other crystal facets, HMMIL-53(Al) exhibits efficient nuclease-mimetic behavior, competently hydrolyzing DNA phosphodiester bonds and degrading extracellular DNA to achieve long-lasting inhibition of biofilm formation. Mechanistic studies confirm that DNA cleavage over HMMIL-53(Al) proceeds via a bimetallic cooperative catalytic pathway, analogous to natural nuclease. Overall, this work not only achieves precise control over mesopore size and unique mesostructure but also introduces a new perspective by coupling mesopore orientation with the crystallographic anisotropy of MOFs, thereby unlocking their capabilities inaccessible to traditional mesoporous architectures.