Oriented Self-assembly of Flexible MOFs Nanocrystals into Anisotropic Superstructures with Homogeneous Hydrogels Behaviors

Building of metal-organic frameworks (MOFs) homogeneous hydrogels made by spontaneous crystallization remains a significant challenge. Inspired by anisotropically structured materials in nature, an oriented super-assembly strategy to construct micro-scale MOFs superstructure is reported, in which the strong intermolecular interactions between zirconium-oxygen (ZrO) cluster and glutamic acid are utilized to drive the self-assembly of flexible nanoribbons into pumpkin-like microspheres. The confined effect between water-flexible building blocks and crosslinked hydrogen networks of superstructures achieved a mismatch transformation of MOFs powders into homogeneous hydrogels. Importantly, the elastic and rigid properties of hydrogels can be simply controlled by precise modulation of coordination and self-assembly for anisotropic superstructure. Experimental results and theoretical calculations demonstrates that MOFs anisotropic superstructure exhibits dynamic double networks with a superior water harvesting capacity (119.73 g g-1) accompanied with heavy metal removal (1331.67 mg g-1) and strong mechanical strength (Young's modulus of 0.3 GPa). The study highlights the unique possibility of tailoring MOFs superstructure with homogeneous hydrogel behavior for application in diverse fields. Oriented construction of nanocrystals into MOFs anisotropic superstructure is achieved by molecular self-assembly strategy. Confined interaction between flexible building blocks and hydrogen networks of superstructure realized mismatch transformation of homogeneous hydrogels, possessing superior water adsorption ability (119.73 g g-1) and strong mechanical strength (Young's modulus of 0.3 GPa).image