Tridentate Bromo-Substituted Porphyrin-Based Metal–Organic Framework Nanoflowers for Alkene Cyclopropanation

Ultrathin two-dimensional (2D) metal–organic frameworks have exhibited powerful potential in heterogeneous catalysis due to their abundant exposed active sites. Herein, we report the one-pot synthesis of an ultrathin 2D porphyrinic metal–organic framework (Br–Cu–PPF-1(Cu)) based on the bromo-substituted asymmetric porphyrin and dinuclear copper cluster without any surfactant. The resultant Br–Cu–PPF-1(Cu) displayed a remarkable thickness of approximately 1 nm and exhibited strong stability in diverse organic solvents. With the introduction of Fe(III) atoms into porphyrin rings, the resultant Br–Fe–PPF-1(Cu) showed higher efficiency on catalytic alkene cyclopropanation compared with Br–Cu–PPF-1(Cu). Mechanistic studies revealed that in Br–Fe–PPF-1(Cu), Cu paddle-wheel units behaved as active sites for alkene cyclopropanation, and meanwhile, Fe-porphyrin adsorbed alkene molecules in its cavity and therefore increased the concentration of alkene substrates around Cu sites. The cooperative effect facilitated the catalytic cyclopropanation of alkenes.