Immobilization of Rh() precursor in a porphyrin metal-organic framework - turning on the catalytic activity

Two model porphyrin metal-organic frameworks were used for the incorporation of Rh( i ) species by a post-synthetic metallation under mild conditions. As a result, new rhodium MOFs (Rh/MOFs), Rh/PCN-222 and Rh/NU-1102 , were synthesized and structurally characterized. To illustrate the potential of this catalytic platform, we use Rh/MOFs as phosphine-free heterogeneous catalysts in the hydrogenation of unsaturated hydrocarbons under mild reaction conditions (30 °C and 1 atm H 2 ). We found that for our Rh/MOFs an activation step is required during the first run of the catalytic process. The presence of Rh-CO moieties allowed us to monitor the activation pathway of the catalyst under a H 2 atmosphere, by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). After activation, the catalyst remains highly active during the subsequent catalytic cycles. This simple post-synthetic modification approach presents new possibilities for the utilization of Rh-based catalytic systems with robust porphyrin-based MOFs as supports. Installation of rhodium centers in a stable porphyrin-based ZrMOF platform for catalytic hydrogenation of unsaturated hydrocarbons under mild conditions.