The integration of metal-organic frameworks (MOFs) into micro- and nanomotors promises advanced functionalities for environmental remediation and active matter research. However, the practical utility of MOF-based motors is constrained by their inherent water instability and the limited exploration of complex collective dynamics. Here, we address these challenges with a novel, fluorescent Zn-adeninate-based micromotor (ZABDC) engineered for exceptional aqueous stability. This stability is achieved through a coordination geometry featuring a large Zn-adenine vertex and a short-range linker, which provides steric shielding and enhances the hydrophobicity of the metal-linker bonds. The ZABDC micromotor exhibits a self-propulsion speed of ~7 µm s⁻1 in a low fuel concentration (0.3 wt.% H2O2). This speed is actively enhanced to ~15 µm s⁻1 under visible light illumination. Leveraging this robust platform, we demonstrate two key advances. First, its hierarchical porous structure, rich in nitrogen and oxygen chelating sites, enables highly efficient and selective uranium capture with a capacity of 406 mg g⁻1 and a distribution coefficient (Kd) of 1.0 × 104 mL g⁻1 in a complex brine matrix. Subsequently, under visible light, adsorbed uranyl ions are photocatalytically precipitated as studtite nanoparticles on the motor surface, achieving effective sequestration. Second, in binary mixtures of active MOFs with passive colloids, they exhibit mimic those of living organisms, such as chasing, escaping, and schooling, mediated by diffusiophoretic interactions driven by self-generated ionic gradients. This work establishes a versatile MOF-based micromotor system, bridging fundamental studies in complex active matter with practical applications in photocatalytic environmental decontamination.
Ikram et al. (Sun,) studied this question.