KINETIC MODELING OF THE PHOTOCHROMISM OF DIHYDROINDOLIZINES

Dihydroindolizines (DHI) are photochromic compounds, which on irradiat ion with long wavelength UV or visible light afford a colored open pho toisomer, the betaine. Light induces breaking of the azacyclopentene r ing. In the dark, there is only one thermal back reaction (ring closur e) The determination of photochromic parameters of these systems such as the quantum yields and the UV/visible spectra of the unstable photo isomers is not a trivial problem and requires appropriated methods. In this paper, we show that kinetic modelling and inverse treatment of e xperimental (Abs vs t) plots recorded under continuous irradiation can help to solve this problem (dynamic method).