A TD-DFT investigation of the visible spectra of fluoro-anthraquinones

With ab initio computational chemistry techniques explicitly taking into account electron correlation and solvent effects, we investigate the chemical substitution impact on the λmax of absorption, of 1,2,3,4-tetrafluoro-9,10-anthraquinone. Increasing the electron-donating strength of the auxochromic groups leads to bathochromic displacements. The largest bathochromic effect has been observed when four built-up hydrogen bonds interact with the CO chromophores. For each substitution, the results are rationalized in terms of HOMO and LUMO energy levels, as well as in hydrogen bond effects on the charge separation and bond length in the chromophoric unit.