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The kinetics of spiropyran photochromic systems in solution in a stirred batch reactor continuously irradiated with monochromatic light was studied by UV/visible spectrophotometry. The plots of absorbance vs time were analyzed, and the desired parameters (quantum yields, UV/visible spectrum of the unstable photomerocyanine, ...) were extracted from an iterative computation which fitted the calculated curves to the experimental ones on the basis of a representative model of the reaction mechanism. The method was applied to spiro[benzothiazoline-2‘,2-benzopyran] whose corresponding photomerocyanine has a lifetime of 100 s in toluene; the two quantum yields of the direct process of photocoloration and the reverse reaction of photobleaching could be determined along with the spectrum of the corresponding photomerocyanine. To demonstrate the general nature of the photokinetic method, it was applied to the reaction of spiro[indoline-2‘,2-benzopyran], where the main photochromic process is accompanied by a photodegradation. Despite this interfering phenomenon, the photokinetic method could be used to extract the parameters of the main photochromic process. It also showed that the photodegradation products catalyzed the thermal back-isomerization. The order of magnitude of the rate constant of this catalytic process and the quantum yields of photodegradation were estimated.

~~~~ ~New chromenes annulated with different six-membered azaheterocycles were prepared, i.e., the 3H-pyrano[3,2-Aquinolines 9/10 and 14, the 8H-pyrano[2,3-h]isoquinoline 11, the XH-pyrano[3,2-f]quinazoline 12, the XH-pyrano[3,2-flquinoxaline 13, and the 2H-pyrano[2,3-flisoquinoline 15. The synthesis was achieved using conveniently substituted a$-unsaturated aldehydes and organotitanium intermediates arising from azaheterocyclic phenols. Their photochromic behaviour (photocolouration yield, UVjVIS spectrum of photomerocyanines, rate constant of thermal bleaching) were studied besides those of corresponding naphthopyrans. The heterocycle effect and the role of substituents in the pyran moiety were investigated quantitatively through the study of the photochromic properties and the solvent effects. Diaryl-substituted azino-fused chromenes, especially isoquinoline derivatives, exhibit increased colourabilities and bathochromically shifted spectra for photomerocyanines which open up new prospects for photochromic applications.