Bioinspired Zinc Macrocycles Confined in UiO-67: A Heterogeneous Synzyme for Sustainable CO₂ Valorization

Nature relies on multifunctional microenvironments to combine substrate recognition, activation, and catalysis with remarkable efficiency. Inspired by this principle, we report heterogeneous synzymes generated by the supramolecular immobilization of pseudopeptidic zinc macrocyclic complexes onto UiO-67 for CO₂ activation and valorization. The zinc chiral pseudopeptidic macrocycles can be selectively prepared through solvent-directed macrocyclization, exploiting the conformational preorganization of the precursors to create enzyme-inspired catalytic motifs. Comprehensive structural and computational studies of hybrid materials reveal a defect-driven encapsulation mechanism. The bulky macrocycles partially perturb the UiO-67 framework and reduce porosity, but also markedly improve the thermal stability of the hybrid materials. Despite this porosity loss, the hybrids display enhanced catalytic activity in the additive-free cycloaddition of CO₂ to epoxides at ambient pressure. C3@UiO-67 outperforms both the pristine MOF and the molecular zinc complex, revealing a cooperative microenvironment where hydrogen-bond-stabilized "naked" iodides promote epoxide ring opening and secondary amines assist CO₂ activation. Overall, this work shows that looking to nature for catalytic design principles can deliver bioinspired MOF-macrocycle synzymes as robust platforms for mild and sustainable CO₂ coactivation and valorization.