ESR, ENDOR and TRIPLE resonance study on substituted 9,10-anthraquinone radicals in solution

Abstract

ESR, ENDOR and TRIPLE resonance spectra were recorded for 9,10-anthraquinone (I), 1,2-dihydroxy-9,10-anthraquinone (II), 1,4-dihydroxy-9,10-anthraquinone (III), 1,5-dihydroxy-9,10-anthraquinone (IV), 1,8-dihydroxy-9,10-anthraquinone (V), l,2,5,8-tetrahydroxy-9,10-anthraquinone (VI), 2,6-dihydroxy-9,10-anthraquinone (VII), 9,10-anthraquinone-l-sodium sulfonate (VIII), 9,10-anthraquinone-1,5-disodium sulfonate (IX), 9, 1 0-anthraquinone-2-sodium sulfonate (X), 9,10-anthraquinone-2,6-disodium sulfonate (XI), 1,2-dihydroxy-9,10-anthraquinone-3-sodium sulfonate (XII) and 2-methyl-9,10-anthraquinone (XIII) anion radicals and for 9,10-anthraquinol, 9,10-anthraquinol-1-sodium sulfonate, 9, 10-anthraquinol-l ,5-disodium sulfonate, 9, 10-anthraquinol-2-sodium sulfonate, 9,10-anthraquinol-2,6-disodium sulfonate and 2-methyl-9,10-anthraquinol cation radicals under various chemical conditions. The hyperfine coupling constants and g-factors are given. Use of deuterated compounds and an additivity relationship allowed assignment of hyperfine coupling constants. New methods of radical generation and new solvent systems for ENDOR measurements are presented.