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ENDOR studies of semiquinone radical ions in liquid crystalline solutions
Author(s) -
Kirste Burkhard
Publication year - 1987
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260250216
Subject(s) - chemistry , benzil , hyperfine structure , ion , semiquinone , photochemistry , radical ion , solubility , perchlorate , organic chemistry , quinone , physics , quantum mechanics , catalysis
Studies of a series of substituted benzo‐, naphtho‐, anthra‐ and phenanthrene‐semiquinones, benzil semidione and Wurster's blue perchlorate by ENDOR spectroscopy in liquid crystalline solutions are reported. Sufficient solubility of the radical anions is achieved by using lipophilic counter ions such as benzyltrimethylammonium. The effects of ion pairing were investigated, particularly in the case of benzil semidione, which can adopt cis or trans configurations. The anisotropic hyperfine shifts observed in nematic or smectic phases are interpreted by means of calculated dipolar hyperfine tensors. A detailed picture of the alignment of the radical ions in liquid crystalline solvents is obtained. The calculated hyperfine tensors are checked for consistency with experiment, and in some cases compared with measurements in solid solution.