ESR Spectrum of the 4,4′-Dipyridyl Radical

Abstract

The high‐resolution ESR spectrum of the radical of 4,4′‐dipyridyl (Tony blue) is observed and analyzed. Dipyridyl in alcoholic solution is converted into Tony blue upon irradiation with sunlight. The spectrum consists of 153 lines, each of less than 0.1 gauss width. The measurements were also extended to a partially deuterated compound of Tony blue, and the analysis was found to be in agreement with the former within the limits of observation.