Protein Scaffold Activates Catalytic CO2 Hydrogenation by a Rhodium Bis(diphosphine) Complex

The utilization of CO2 to generate chemical fuels, such as formic acid, is a potentially beneficial route to balance carbon emissions and reduce dependence on fossil fuels. The development of efficient catalysts for CO2 hydrogenation is needed to implement this fuel generation. In the molecular catalyst design presented here, we covalently attached a rhodium complex, ([RhI(PNglyP)2]−, where PNglyP is defined as PEt2–CH2–N(CH2CO2–)–CH2–PEt2) to a protein scaffold, (lactococcal multidrug resistant regulator from Lactococcus lactis) to use the protein environment around the metal center to control substrate delivery and therefore enable and improve catalytic activity. The reactivities of the rhodium complex and the synthetic metalloenzyme were characterized by high-pressure operando NMR techniques. In solution, the rhodium complex alone is not a catalyst for CO2 hydrogenation. Incorporation of the rhodium complex into the protein scaffold resulted in a gain of function, turning on CO2 hydrogenation activity....