A grand challenge for chemistry is to exhibit selectivity and control over a chemical transformation at any stage in the synthesis process. However, what makes this task so difficult is that for a given set of molecular catalysts, substrates and reaction conditions, synthesis outcomes generally follow a set of established rules of reactivity. Chemical synthesis relies upon the creative manipulation of these rules fundamentally established by ground and excited-state potential energy surfaces and frontier molecular orbitals. However, within this established framework, the tools a synthetic chemist can use to alter reactivity (photochemistry, catalysis, temperature) are limited. The guiding principle of QuEST is to develop a new way to alter the frontier orbitals of organic molecules by taking advantage of the principle of quantum superposition found for light-matter interactions, which is historically described by quantum electrodynamic theory. While the physics of light-matter coupling is well understood, the consequences for chemistry remain almost completely underexplored. Understanding and controlling quantum light-matter interactions inside the cavity has great promise to manipulate chemical reactivities in a general and transformative way.

Despite tantalizing experiments indicating that molecules coupled to a cavity show modified chemical reaction outcomes, the fundamental question of how and whether polaritons can substantially alter chemical reactions in broad and transformative ways remains unclear. From a synthetic chemistry perspective, a major challenge is that the rules of reactivity of this hybridized molecular/photonic state are completely unknown. Thus, our primary goal is to characterize the physical properties of cavity polariton states relevant for chemistry so that chemical reaction outcomes can be accurately predicted. This characterization will be demonstrated using simple, model chemical reactions that can illuminate the “catalytic” properties of polaritons for selective syntheses.

One of the primary goal of QuEST is to investigate the fundamental mechanisms by which cavity polaritons alter reaction selectivity, and thus enable chemical transformations that are not currently possible. Synthetic chemists have a suite of tools to control reaction outcomes (catalysis, photochemistry, pressure, temperature). Quantum light-matter interactions will provide a brand-new, orthogonal tool to change established synthetic “rules” and control selectivity. QuEST will explore the possibilities to control the relative distribution of products, break selective bonds in a single molecule, and deliver an electron to a specific substrate regardless of the relative redox potentials. These achievements will represent a true paradigm shift in synthesis, with a broad transformative impact.