Ring opening process of some spirochromenes by photoproduced HCl in poly(N-vinyl carbazole)

The coloration reaction of some spirochromenes (SP) has been investigated in the case of a free radical photosensitive system composed of a poly(N-vinylcarbazole) matrix (PVCz) in dichloromethane containing carbon tetrachloride as an activator at average ratios of 5:1:0.1 for PVCz, CCl₄ and SP, respectively. In this system, photoproduced HCl leads to the formation of the colored forms of SP. Acidification and irradiation of the variety of spirochromene solutions in the presence and absence of PVCz were also investigated and compared with the effect of photoproduced HCl on the reversibility of the ring opening process. The opened forms of the compounds were characterized by UV-visible spectra, pH and conductivity measurements. The effect of solvent and the substituent of SP were investigated. Decoloration reactions of the opened forms of SP at 50°C were followed using UV-visible spectroscopy, pH and conductivity measurements.