The absorption and emission spectra of DMAC-TRZ and its five derivates were measured in different polarity solvents (Figure ). The absorption spectra are mostly unaffected by the solvent polarity, presumably because of the low ground-state dipole moment of these compounds, while the emission spectra follow the expected bathochromic shift with increasing solvent polarity that is associated with excited states of CT character. Indeed, toluene, THF, and DCM solutions show broad and unstructured spectra, typical of a CT-type emission, while methyl-cyclohexane shows a narrower and more structured LE-type emission, in all cases.