Solvent and substituent effects on the absorption spectra of
Brooker's merocyanine (BM) are investigated using the threedimensional
reference interaction site model self-consistent
field method and time-dependent density functional theory.
The π–π* excitation energies are computed for BM and its
derivative 2,6-di-tert-butyl (di-t-Bu) BM. The behaviors of the
computed excitation energies with increasing solvent polarity
are in good agreement with those of the corresponding experimental
measurements. In addition, analysis of the solute–solvent
interaction energies and spatial distribution functions
reveals that the effects of the solvent on the absorption spectra
are reduced by the steric hindrance of the t-Bu groups.
Furthermore, from the difference in the solute–solvent interaction
energies of BM and di-t-Bu BM, it is shown that the effect
of the t-Bu substituents on the absorption spectrum is
greater in high-polarity solvents.