Co-operative Vibrational Strong Coupling: A New Route to Control Chemical Reactions

Recently, vibrational strong coupling was used to control chemical reactions very preciously by targeting a vibrational state.[1] However, this process is limited to molecules having very strong vibrational bands that can undergo strong coupling. Here, we show an efficient way of controlling chemical reactions by co-operative vibrational strong coupling (Co-VSC).[2] This is specifically achieved by choosing a solvent that has a matching vibrational band to the reactant molecule responsible for the reaction. Coupling the bulk solvent gives very high Rabi splitting that reshuffles the energy of the reacting species. We catalysed a simple ester hydrolysis process by Co-VSC of C=O band of the ester (reactant) and ethyl acetate (solvent) in a flow cell Fabry-Perot cavity. This results in the dropping of the enthalpy and entropy of activation of the hydrolysis reaction. In another attempt, large biomolecules such as alpha-chymotrypsin is coupled to the vacuum field via Co-VSC of water.[3] In this case, we improved the enzyme catalysis process and found that cavity coupling can bring a competitive enhancement in the reaction. High sensitivity with cavity tuning and increase in the reaction rate with increasing coupling strength are the two important features of cavity catalysis. This is purely an unconventional way of controlling chemical reactions, that will have direct application in chemistry.


References:
1. T. W. Ebbesen and co-workers, Angew. Chem. Int. Ed. 55 (38), 11462 (2016).
2. J. George and co-workers, Angew. Chem. Int. Ed. 58 (31), 10635 (2019).
3. J. George and co-workers, (unpublished results)