Spectral characteristics of monosubstituted phenoxyl radicals

The absorption spectrum of the 2-chlorophenoxyl radical is compared with those of its isomer radicals, with those of the bromo- and methylphenoxyl radicals, and also with that of the phenoxyl itself. Spectra of the monosubstituted phenoxyls are very similar. Substitution on the phenoxyl radical in 4-position causes a significant enhancement in the extinction coefficient. 2-substitution causes a little blue-shift of the spectrum, the 3-and 4-substitutions, however, more significant red-shifts. (author)