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The Effects of Conjugation Path Variation on Electron Delocalization in Phenoxyl-Based Systems.
Department of Chemistry, University of Massachusetts, Amherst, MA 01003 USA
* Author to whom correspondence should be addressed.
Received: 23 April 2004; Accepted: 2 June 2004 / Published: 31 August 2004
Abstract: A number of persistent 2,6-di-tert-butylphenoxyl based radicals were synthesized as models for unpaired spin delocalization as a function of conjugation pathway, and were investigated by ESR and UV-vis spectroscopy. Phenoxyl spin delocalizes significantly onto a para-phenyl ring, but further delocalization through a meta-vinyl or meta-carbonyl linkage is not detectable by ESR hyperfine coupling. UV- vis spectra do show a red shift of the longest wavelength transition for a carbonyl-type substituent by comparison to a vinyl substituent in the meta-position of a para-phenyl group. By comparison, a para-styryl substituent on the phenoxyl causes very large spin delocalization from the phenoxyl unit, with the largest hyperfine coupling being found on the ethenyl unit of the assemblage. This large delocalization accounts for the reactivity of radicals that incorporate such units.
Keywords: 2; 6-Di-tert-butylphenoxyl; conjugated polyradicals; spin delocalization; exchange; molecular magnetism; electron spin resonance; hyperfine coupling.
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MDPI and ACS Style
Liu, Y.; Lahti, P.M. The Effects of Conjugation Path Variation on Electron Delocalization in Phenoxyl-Based Systems.. Molecules 2004, 9, 725-745.
Liu Y, Lahti PM. The Effects of Conjugation Path Variation on Electron Delocalization in Phenoxyl-Based Systems.. Molecules. 2004; 9(9):725-745.
Liu, Yanbing; Lahti, Paul M. 2004. "The Effects of Conjugation Path Variation on Electron Delocalization in Phenoxyl-Based Systems.." Molecules 9, no. 9: 725-745.