FROM MOLECULES TO MATERIALS: SCALABLE SYNERGISTIC EFFECTS FOR ENHANCED CATALYSIS

To change the paradigm of molecular catalytic processes for fine chemical synthesis and green fuel production, we introduced recently the concept of solid porous macroligand for heterogenized molecular catalysis. Having molecularly-defined active sites, porous macroligands have been found to drive the activity of heterogenized catalytic processes on a similar way as molecular ligands but with the advantage of the structuration in a three-dimensional framework and the confinement within a porous nanospace. We first demonstrated that a parameter defined at the molecular level, like the Hammett constant, can be applied at the scale of a porous materials to tune the productivity of heterogeneous catalyst. Following this principle, organometallic Rh molecular complexes embedded within porous organic polymer (POP) and metal-organic frameworks (MOF) used as macroligand showed a high productivity for the photoreduction of carbon dioxide into formic acid using visible light as sole energy source. Another generation of these heterogenous photocatalysts has been then designed to combine both the Rh catalytic site and a photosensitizer in a unique network. The superior productivity of this all-in-one catalytic system originated from a perfect interplay between the photosensitizer to the catalytic unit. Finally we applied our strategy to more complex Rh-based metal organic polyhedral (Rh-MOP) as catalytic building units. Rh-MOP gels showed the highest activity reported so far for CO2 to formic acid photoreduction using visible light, with a productivity of 3 g(formic acid)/g(catalyst)/h. The MOP gel assembly has been furthermore evidenced to have enhanced activity compared to the parent molecular MOP due to electronic effect of bridging linker.