EPR and MO calculation studies on α-aminoanthraquinone anion radicals in aprotic solvents

Abstract

The EPR spectra of electrolytically produced anion radicals of 1,4-diamino-9,10-anthraquinone, 1,4-bis-(methylamino)-9,10-anthraquinone, 1-amino-4-hydroxy-9,10-anthraquinone, 1,5-diamino-9,10-anthraquinone and 1,8-diamino-4,5-dihydroxy-9,10-anthraquinone were measured in N,N-dimethylamine (DMF) and dimethylsulfoxide (DMSO). The isotropic hyperfine coupling constants (hcc) are assigned according to dihydroxy-substituted anthraquinones and molecular orbital (MO) calculations made in this study. The results are compared with the radical anions of 1,4-diamino- and 1,5-diamino-9,10-anthraquinone made in protic solvents by chemical reduction. A tentative assignment of the hcc is made for 1-amino-4-hydroxy-9,10-anthraquinone by MO calculations. The result show that the self-consistent isodensity polarised continuum model (SCI-PCM) gives hcc constants with good accuracy compared to the experimental hcc values. Copyright © 1999 John Wiley & Sons, Ltd.