Nile Red solvatochromy. TD-DFT calculations and experimental data

Abstract

The problem of theoretical (quantum chemical) description of electronic absorption spectra and, in particular, solvatochromism, for a well-known Nile Red dye has been investigated. In particular, we consider the use of the time-dependent density functional theory TD-DFT. A number of popular functionals have been investigated, including B3LYP, CAM-B3LYP, M06-L, M06-2X, PBE, BMK, and wB97XD. The standard AO basis set with polarization and diffusion functions 6-31+G(d,p) was used. To describe the effects of the media, three common models based on the polarization-continuum approach were considered. These models include the State Specific (SS) method, the Linear Response (LR) method, and the so-called universal solvation model (Solvation Model Density, SMD). It was found that, in general, the bulk of the functionals are able to qualitative description of the spectral properties of the dye. For the studied system, the best results of the solvation effects descriptions were achieved using the SMD method with the M06-L and B3LYP functionals.