ESR STUDIES ON SOME SPIROPYRANS, SPIRONAPHTHOPYRANS, AND SPIROOXAZINES

Biradicals were double-trapped by bubbling NO through benzene solution s of some photochromic spirocompounds; it would however appear that th ese species do not directly participate in the photochromic process. T he ESR spectra of the radical anions of some nitrosubstituted spirocom pounds indicated that there is no electronic interaction between the t wo moieties of the spiromolecules; reducing the substrates in the abse nce 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.