Photoacids offer a controlled method to study the mechanisms of excited state proton transfer (ESPT). Our lab has previously demonstrated that the ESPT mechanism of the diprotic photoacid, 8-amino-2-naphthol (8N2OH), is dependent on the solvent. Proton transfer can also occur in solvent mixtures, and it is important to understand the effect of solvent composition on the process. Using a combination of absorption and time-resolved emission spectroscopy, we investigated the proton dynamics of 8N2OH in binary mixtures. Acetonitrile, water, and methanol were chosen as solvents for their different hydrogen bonding capabilities. Emission spectra and lifetimes were analyzed to elucidate the effect of the mixture’s composition on the energy stabilization and ESPT mechanisms. Preliminary findings of acetonitrile-water mixtures indicate a non-linear relationship between the water composition and emission lifetimes. We will employ time-dependent density functional theory to explore the effect of explicit and implicit solvent models on the 8N2OH excited state energies. The combined experimental and theoretical approach will lead to greater understanding of the solvents’ role in the ESPT mechanism of 8N2OH.

Excited state proton transfer mechanisms of 8-amino-2-naphthol in binary mixtures

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.