Theoretical study on ESIPT mechanism of 2-acetylindan-1,3-dione in hexane and acetonitrile solvents

The excited-state intramolecular proton transfer (ESIPT) mechanism of 2-acetylindan-1,3-dione (AID) in both non-polar (hexane) and polar (acetonitrile) solvents are theoretically investigated. Based on the calculation of electron density ρ(r) and Laplacian ∇2ρ(r) at the bond critical point using Atoms-In-Molecule (AIM) theory, the intramolecular hydrogen bond (O-H∙∙∙O) has been proved to be existent in the S0 state. Which has been proved to be strengthened in the S1 state, and facilitates the ESIPT process. Finally, solvent effect could play roles in controlling excited state behaviors of AID system, according to the scanned potential energy curves along the variational O-H coordinate.