Tautomerism of Anthraquinones:IX.* Protonated 1,5- and 1,8-Dihydroxyanthraquinones

摘要

Fine structure of π1,π* absorption of mono- and dications derived from 1,5- and 1,8-dihydroxy-anthraquinones originates from their existence as dynamic equilibrium mixtures of isomers differing by position of the positive charge, double bond distribution, and number of intramolecular hydrogen bonds. Protonation is accompanied by displacement of isomeric equilibria. Isomeric transformations of protonated dihydroxyanthraquinones involve mainly excited states of their molecules.