Fe(III)‐Anchored Porphyrin‐Based Covalent Organic Framework as a Potent Catalyst for Biginelli Reaction

Covalent organic frameworks (COFs), characterized by their tunable porosity and abundance of functional moieties, offer an exceptional scaffold for the uniform dispersion and stable immobilization of metal species. Herein, we report the efficient immobilization of highly dispersed Fe(III) ions into a porphyrin-functionalized COF (AP-COF), synthesized via Schiff-base condensation between 4,4'-(ethyne-1,2-diyl)dibenzaldehyde and 5,10,15,20-tetrakis(4-aminophenyl)-21H, 23H-porphyrin. The resulting Fe@AP-COF was characterized by various techniques. High-resolution transmission electron microscopy and dark field imaging confirmed the homogeneous distribution of Fe(III) ions within the COF matrix. The Fe@AP-COF demonstrated excellent thermal robustness and high surface area, which facilitated the effective anchoring of active iron centers. This catalyst exhibited remarkable performance in promoting the one-pot synthesis of dihydropyrimidinones (DHPMs) via Biginelli multicomponent reaction under optimum conditions. Furthermore, the Fe@AP-COF showed outstanding structural integrity, minimal Fe leaching, and excellent recyclability over multiple catalytic cycles. Comparative analysis revealed its superior catalytic activity to both homogeneous and conventional heterogeneous Fe-based catalysts. These insights highlight the valuable prospects of metal-functionalized porphyrin-based COFs as adaptable and efficient platforms for advanced catalytic applications.