Photophysical and photochemical properties of anthraquinones: A DFT study

In the present work, we investigated the photophysical and photosensitive properties and further explored the substituent effects on these properties of a series of anthraquinones by means of theoretical calculations. It is revealed that comparing with the parent 9,10-anthraquinone (AQ), the substitutents red-shifted the absorption spectra and lowered the ET1 of anthraquinones considerably. Moreover, the present results also provide some deeper insights into the photosensitization mechanisms of anthraquinones, that is, although anthraquinones can photo-generate 1O2 through direct energy transfer in both non-polar and polar solvents, they give birth to O2- through electron transfer only in polar solvents, and it is the anthraquinones anions (generated from autoionization) that are responsible for the O2--generation.