State-specific solvation models applied to proton transfer benchmark systems

BURNIC S.; BRASCA R.; CULZONI M. J.; THEILER A.; KELTERER A-M.; STRAUSS M. K.

Congreso; 51st Symposium on Theoretical Chemistry; 2015

The theoretical description of the absorption and fluorescence emission processes in solution within the continuum solution model contains the separation of the fast and slow response to the vertical excitation. Standard linear response (LR) does not take into account the dynamic relaxation of the solute charge in excited state, which is important for the emission. Recently, a few available state-specific approaches have been tested with respect to the solvatochromic shift of organic molecules [1-4].In this presentation, three state-specific approaches of the continuum solvation models (SS [3] cLR [4], VEM [2]) were compared to each other and to the LR approach for 2-naphthol, 3- hydroxypyridine and salicylic acid. In water, these benchmark molecules can perform proton transfer in the ground and excited state, either intramolecular or to the solvent water. Therefore, all protonation forms were included in the study, with and without the first solvation shell. Additionally, the ground state pKa and excited state pKa* values were computed for the investigated molecules.Time-dependent density functional theory was used throughout this study. The calculated data of the neutral and anionic structures will be compared to experimental data recorded at different pH with a spectrophotometer and spectrofluorimeter.References:[1] A.-M. Kelterer, G. Uray, W.M.F. Fabian, Comp. Theor. Chem. 2015, 1055, 25.32.[2] A.V. Marenich, C.J. Cramer, D.G. Truhlar, B. Mennucci, G. Scalmain, M.J. Frisch,Chem. Science 2001, 2,2143-2161.[3] R. Cammi, S. Corni, B. Mennucci, J. Tomasi, J. Chem. Phys. 2005, 122, 104513.[4] R. Improta, V. Barone, G. Scalmani, M.J. Frisch, J. Chem. Phys. 2006, 125, 054103.