RING-OPENING PROCESS OF SOME SPIROCHROMENES BY PHOTOPRODUCED HCL IN POLY(N-VINYL CARBAZOLE)

The coloration reaction of some spirochromenes (SP) has been investiga ted in the case of a free radical photosensitive system composed of a poly(N-vinylcarbazole) matrix (PVCz) in dichloromethane containing car bon tetrachloride as an activator at average ratios of 5:1:0.1 for PVC z, CCl4 and SP, respectively In this system, photoproduced HCl leads t o the formation of the colored forms of SP. Acidification and irradiat ion of the variety of spirochromene solutions in the presence and abse nce of PVCz were also investigated and compared with the effect of pho toproduced HCl on the reversibility of the ring opening process. The o pened forms of the compounds were characterized by UV-visible spectra, pH and conductivity measurements. The effect of solvent and the subst ituent of SP were investigated. Decoloration reactions of the opened f orms of SP at 50 degrees C were followed using UV-visible spectroscopy , pH and conductivity measurements. (C) 1997 by John Wiley & Sons, Ltd .