Immobilization of Rh(I) 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 degrees 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.

Automated summary

Two model porphyrin metal-organic frameworks were utilized for the incorporation of Rh(I) species through post-synthetic metallation, resulting in the synthesis and structural characterization of new rhodium MOFs (Rh/MOFs), Rh/PCN-222 and Rh/NU-1102. These Rh/MOFs were demonstrated to be active heterogeneous catalysts for the hydrogenation of unsaturated hydrocarbons at mild reaction conditions, with an activation step required during the initial run of the catalytic process. In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) was utilized to monitor the activation pathway of the catalyst under a H-2 atmosphere.