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The visible spectra of a large panel of thioindigo dyes are evaluated with the polarizable continuum method (PCM) and time-dependent density functional theory (TD-DFT), using the PBE0 functional and extended atomic basis sets. It is found that the majority of the cis thioindigo dyes are planar and their hypso-character originates from repulsion of electron densities in the excited state, and the central C=O double bond length is a good indicator of the color of the substituted thioindigo

The structures and the properties of polyaminoborane oligomers by using ab initio computational tools including dynamic electron correlation effects are investigated. The variations of the properties upon conformation changes are studied.

An ab initio procedure relying on the combination of time-dependent density functional theory and polarizable continuum model is used for calculating the n -> [pi.sup.*] transitions in more than 100 thiocarbonyl dyes. The pros and cons of the most widely used hybrids, as well as the role of f polarization functions are discussed.

The ultraviolet absorption spectra of coumarins and chromones are investigated with the PCM-time-dependent-density functional theory (PCM-TD-DFT) theoretical scheme by using three hybrid functionals and taking into account methanol or ethanol solvation effects. The results have shown that there are at least two allowed excited states presenting strong oscillator strength in the UV region, where both involve a charge transfer from the benzenic cycle to the pyranone moiety.

The structure and visible spectra of a large panel of thioindigo dyes and derivatives have been evaluated using a TD-PBEO/6-31 1 +G(2d,p)//PBEO/6-31 1 G(d,p) approach explicitly taking bulk solvent effects into account by means of the polarizable continuum model. The influence of the solvent characteristics, the trans-cis isomerization, and the chemical substitution on the benzene rings have been investigated. In addition, hemi-thioindigo dyes, thiazine-indigo, chromophore-like molecules, and selenoindigo have been considered. Though the relative oscillator strengths of the two allowed visible transitions in the nonplanar cis isomers are not always correctly reproduced by theory, the agreement between theoretical and experimental results is far above expectations. For the 170 cases studied, we obtained a mean unsigned error on the predicted λmax limited to 6.9 nm or 0.03 eV, with only 6 (4) cases for which the difference exceeds 20 nm (0.10 eV). These errors are 1 order of magnitude smaller than what has previously been reported for indigoids. A linear correlation between the central double bond length and the λmaxhas been established, while the bond length and vibrational frequency of the carbonyl groups do not correlate with the thioindigo color. The higher excitation energies of the cis conformers, compared to the trans structures, result from a less stabilized LUMO in the former case. Indeed, for cis thioindigo, the two electron-rich (in the excited state) carbonyl units lie close to each other. [ABSTRACT FROM AUTHOR]