ESR STUDIES ON SOME SPIROPYRANS, SPIRONAPHTHOPYRANS, AND SPIROOXAZINES

Biradicals were double-trapped by bubbling NO through benzene solutions of some photochromic spirocompounds; it would however appear that these species do not directly participate in the photochromic process. The ESR spectra of the radical anions of some nitrosubstituted spirocompounds indicated that there is no electronic interaction between the two moieties of the spiromolecules; reducing the substrates in the absence or in the presence of light leads to different ESR signals, but it cannot be excluded that the observed differences are only due to the different reaction media.