Tilting a Ground State Reactivity Landscape by Vibrational Strong Coupling

Site-selectivity is fundamental for steering chemical reactivity towards a given product and various efficient chemical methods have been developed for this purpose. Here we explore a very different approach by using vibrational strong coupling (VSC) between a reactant and the vacuum field of a microfluidic optical cavity. For this purpose, the reactivity of a compound bearing two possible silyl bond cleavage sites, at Si-C and Si-O, was studied as a function of VSC of its various vibrational modes in the dark. The results show that VSC can indeed tilt the reactivity landscape to favor one product over the other. Thermodynamic parameters reveal the presence of a large activation barrier and significant changes to the activation entropy, confirming the modified chemical landscape under strong coupling. This study shows for the first time that VSC can impart site-selectivity for chemical reactions without the need for chemical intervention.