Research Projects

Polaritonic chemistry provides a new handle to control and modify molecular properties, including chemical reactivity, without any chemical or structural modification to the molecules involved. It involves strongly coupling the electronic or vibrational transitions of molecules and materials with a quantized radiation field inside a photonic cavity. The holy grail in physically perturbed chemical reactivity is the vibrational mode selectivity. Vibrational strong coupling (VSC) offers the control of chemical properties using non-invasive physical perturbation, the possibility of catalysing or hindering chemical reactions, and control of the branching ratio of products with a vibrational mode selectivity. However, it has been challenging for theorists to explain the effects of light-matter strong coupling on chemical reactivity. So it is highly desirable to understand the mechanism of VSC-catalysed or hindered reactions. On the other hand, it is unknown whether VSC or ESC can result in a new reactive landscape, or their effect is only to suppress or catalyse an existing pathway. Interestingly, intermolecular interactions and molecular assembly are significant areas in which strong coupling has a profound impact. The proposal aims to bridge the gap between experiments and theorists and understand the polaritonic chemistry mechanism. We propose experiments and a theoretical model to understand the role of polaritonic chemistry emerging from the light-matter strong coupling in controlling (i) chemical reactivity, (ii) intermolecular interactions, and (iii) energy flow and excited state photochemistry in spatially separated donor-acceptor molecules. With the above objective, we combine experiments and theory to understand the modification to intermolecular interaction and vibrational energy flow under VSC to develop a mechanistic model for polaritonic chemistry. To achieve the objective, we investigate whether VSC can act as a reagentless catalyst to enhance the reactivity of a group of molecules undergoing the industrially relevant cyanosilylation reaction. We propose using non-optical and non-biased techniques, such as NMR, to probe the reactivity to provide direct evidence. Motivated by the preliminary results, we check whether VSC can create a new reactivity landscape and if it is related to any post-transition state bifurcation process. Additionally, we study a class of molecules that undergo chemical reactions to produce chemiluminescence to understand how VSC affects the subsequent light emission. Then we explore how electronic and vibrational strong coupling affect intermolecular interactions, resulting in modified self-assembly patterns and excited state characteristics. Further, we probe whether VSC can impart energy, electron, or charge transport across spatially separated donor-acceptor systems. The results of this objective will benefit the next generation of quantum communication devices. We combine all these experimental results and try to develop a theoretical model that can explain the mechanistic aspects of how light-matter strong coupling imparts these modifications to molecular properties. The PI and the Co-PIs are leaders in the field of polaritonic chemistry. Therefore, the proposal's outcome will be a crucial stepping stone towards understanding the mechanisms of polaritonic chemistry. While the mechanistic part of the proposal will improve the fundamental understanding of the emerging field of polaritonic chemistry, the experimental outcomes will have a technology readiness level (TRL) of 4, as evidenced by a recent patent by the PI (Patent No: 560361). The PI of the proposal has already worked with multinational companies such as BASF and Novartis on projects related to polaritonic chemistry. The results from the experiments, together with the predictive power of the proposed theory model, will therefore be highly suitable for translation into industrial use.