HYPERFINE-STRUCTURE OBSERVED IN ELECTRON-PARAMAGNETIC-RES OF POLYPHENYLACETYLENE SOLUTIONS

In the reported study, the high-temperature ( greater than 120 degree C) electron paramagnetic resonance (EPR) spectrum of solutions of polyphenylacetylene have been deconvoluted into the spectra of two separate radicals, a delocalized pi radical, whose EPR spectrum consists of a single 15-G wide Gaussian line comprising about 90% of the total signal and a second, more localized pi radical exhibiting complex hyperfine structure in its EPR spectrum. Some possible structures for the minor component radical are suggested and their hyperfine splitting constants calculated using molecular orbital theory.