RESUMEN
An intramolecular tautomeric fluorescent BODIPY sensor has been designed and synthesized. The obtained BODIPY dye is a combination of the 4-bora- 3a, 4a-diaza- s-indacene core and a diketone fragment. The study of conformational equilibria in the ground and excited states has been completed for a broad range of solvent polarity by steady state and NMR methods as well as by DFT and TD-DFT calculations. The interpretation of the unique emission observed in hydrogen bond accepting solvents upon the excitation of the fluorescent dye in the S0-S2 transition has been accomplished. The Jablonski diagram has been analyzed for the observed processes in the BODIPY dye studied on the basis of DFT and TD-DFT calculations.
RESUMEN
A number of fluorescent dyes based on BODIPY (4,4'-difluoro-4-bora-3a,4a-diaza-s-indacene) have been studied theoretically. This paper presents the results of calculations of these BODIPY dyes in their ground and excited states, performed using DFT and TD-DFT methods, respectively. The influences of N,N-dimethylaminobenzyl, ortho-fluorophenol, and methyl substituents as well as the solvent polarity on the positions of the absorption and emission bands of the dyes were analyzed. The computational data obtained in this work were compared to the corresponding experimental data. The trends in the experimental data were found to agree with those shown by the computational data. Differences between the potential curves obtained when using linear-response (LR) and state-specific (SS) approaches for the ground and excited states are also reported. Graphical Abstract The article shows that the trends of the experimental dependencies λabs = f(Δf) and λem = f(Δf) well described by PBE0 (LR approach) and M06-2X (SS approach) calculations, respectively. The influence of substituents on the spectral characteristics of the BODIPY chromophore are analysed.