SUBSTITUENT EFFECT ON PHOTOCHROMISM OF INDOLINOSPIROOXAZINES

The photochromic reactions of five indolinospirooxazine derivatives (I I, III, IV, V and VII) were examined using nanosecond laser flash phot olysis techniques. Photolysis of II-V leads to the formation of long-l ived photomerocyanines (PMCs), whereas the only detectable product in the photolysis of CII is a short-lived, charge-separated, twisted spec ies (CT intermediate). The results show that the substituent in the 2' position of the oxazine ring has a decisive role on the photochromic reaction products and all of the substituents influence the absorption maxima of the photoproducts of indolinospirooxazines. A proposed pote ntial energy surface model has been established to explain these pheno mena. Moreover, the characteristics of the absorption spectra of the P MCs and CT intermediate are discussed.