πl,π*-Absorption bands as a valuable source of information on the structure of tautomers and conformers

The presence of several πl,π*-absorption bands in the electronic spectrum of hydroxyanthraquinones indicates the occurrence of tautomeric and conformational equilibria. The structure of tautomers and conformers can be determined from the correlation between λmax and the sums of the constants σA of hydroxy and oxido groups, calculated for each isomer. © Pleiades Publishing, Inc., 2006.