Ground and excited state properties of naphthazarin: Absorption spectroscopy and theoretical modeling study

In this study, ground and excited state properties of naphthazarin were investigated within the frame of static and time dependent density functional theory. Solvent effects on vertical electronic transitions of different ionic and tautomeric forms of naphthazarin were studied by polarized continuum model. The calculated transition energies were compared with the absorption spectroscopy data obtained in cyclohexane, DMSO and water solution at different pH. In aqueous solution, the spectral characteristics of distinct ionic naphthazarin forms were determined by factor analysis. Inclusion of solvent effects improved quantitative agreement between theoretical predictions and experimental data for both neutral and anionic forms. Mean absolute deviation between calculated and observed transitions energies for all considered forms was less than 0.15 eV. The lowest observable transitions were predicted with the accuracy better than 0.1 eV.