Symmetry-Breaking in Cationic Polymethine Dyes: Part 2. Shape of Electronic Absorption Bands Explained by the Thermal Fluctuations of the Solvent Reaction Field.

摘要: The electronic absorption spectra of the symmetric cyanines exhibit dramatic dependence on conjugated chain length: whereas short-chain homologues are characterized by narrow and sharp bands high intensity, long-chain demonstrate very broad, structureless low intensity. Spectra intermediate combine both features. These broad often explained using spontaneous symmetry-breaking charge localization at one termini, combination features was interpreted as coexistence asymmetric species in solution. explanations were not supported first principle simulations until now. Here, we employ a time-dependent density functional theory, polarizable continuum model, Franck–Condon (FC) approximation to predict line shapes for series 2-azaazulene 1-methylpyridine-4-substituted polymethine dyes. To simulate inhomogeneous broadening the...