Assembling Magneto-Responsive Metal-Organic Framework Long-Range Chains

Template-assisted strategies provide control over the spatial arrangement, shape, and orientation of metal-organic frameworks (MOFs). However, conventional approaches often rely on rigid templates or a soft polymer matrix to stabilize materials by adhering or wrapping MOF microparticles, which compromises the accessible porosity of MOFs and yields a random spatial organization. Here, we introduce a novel magnetic template method that produces freestanding, chain-like clusters of a 2D MOF, magnetically active zeolitic imidazolate framework (MZIF-L), on a large macroscopic scale. Preassembled magnetic nanoparticle (MNP) chains, formed under the influence of an external magnetic field, act as field-aligned nucleation centers, directing the interfacial growth of similarly oriented leaf-shaped ZIF-L platelets. Concurrent, confined growth drives interpenetration of neighboring leaves orthogonal to the chain axis while preserving consistent one-dimensional order to the macroscale. The resulting unique spiky anisotropic architectures exhibit enhanced magnetic torque and remain structurally coherent after the field removal. Embedding these chains in polyacrylamide (PAAm) hydrogels preserves their geometry in a mechanically robust matrix while maintaining long-range chain assembly and magneto-responsive actuation. Under rotating magnetic field, the MZIF-L chains exhibit synchronized rotation and helical translation, enabling rapid fluid mixing and capture of polymer microbeads through their spiky surface, which facilitates localized microplastic remediation and field-programmable materials' micromanipulation.