A Coupled Potential QM/MM Simulation of 2-(2-fury)-3-hydroxychromone: Insights into the ESIPT Process

Hybrid quantum mechanics/molecular mechanics (QM/MM) simulations are a powerful method for studying chemical reactions in condensed phases. This approach combines two levels of modeling: regions involved in chemical processes are treated using quantum mechanics, while the remaining parts of the system are modeled with molecular mechanics. This method allows for the analysis of chemical reactivity, such as the Excited-State Intramolecular Proton Transfer (ESIPT) process. In this study, two simulations were performed to examine the behavior of 2-(2-fury)-3-hydroxychromone (FHC) in a periodic box with a polar protic solvent. The first simulation uses classical molecular dynamics (MD), while the second applies the semi-empirical PM3 Hamiltonian to the FHC molecules. The goal was to compare the results of both simulations to better understand the system's dynamics. A key feature of this approach is the abrupt change in the description of the molecule when it crosses a given cutoff, leading to sudden changes in the energy and forces involved. This study provides new insights into the use of QM/MM hybrid simulations to analyze proton transfer processes like ESIPT and their application in complex molecular systems where interactions between molecules play a crucial role. In summary, the study highlights the potential of hybrid simulations to understand the dynamics of chemical processes at the molecular scale, particularly for complex phenomena like ESIPT.