Engineering Carbonic Anhydrase Mimics via Metal Ion Doping: Tailoring the Structure and Catalytic Properties of a 2-Aminoimidazole-Based MOF

Metal-organic frameworks (MOFs) show great promise as carbonic anhydrase (CA) mimics due to their high surface area, tunable porosity, and abundant active sites. This study enhances a reported 2-aminoimidazole-based Zn-MOF by incorporating Co²⁺, Ni²⁺, or Cu²⁺ via in situ doping, systematically investigating how metal doping regulates morphology, crystal structure, and catalytic performance. The results reveal that the type and ratio of doped metal ions critically influence the framework: Co²⁺ demonstrated the highest compatibility, while Ni²⁺ and Cu²⁺ induced structural distortion at higher levels. All doped samples exhibited reversible catalytic kinetics akin to natural CA, with improved maximum reaction rates (<i>V</i>_max) and substrate affinity. Specifically, Co_75%/Zn-MOF, Ni_50%/Zn-MOF, and Cu_25%/Zn-MOF achieved optimal performance, showing esterase activities of 0.47 ± 0.02, 0.56 ± 0.02, and 0.39 ± 0.02 U/mg─increases of 67.9%, 100.0%, and 40.0% over pristine Zn-MOF, respectively. These materials also displayed exceptional high-temperature (80 °C) activity, hydrothermal stability, pH tolerance, and recyclability, retaining 67-79% activity after six cycles. This work provides a theoretical and experimental basis for designing efficient and stable MOF-based CA mimics, highlighting their potential for carbon capture, utilization, and storage (CCUS) applications.