DYE RECYCLED PHOTOSENSITIZATION SYSTEM OF EOSIN ETHYL-ESTER IODONIUM SALT

A dye recycled photosensitization system has been designed. As a resul t of studies in the mechanism of electron transfer reaction of xanthen e iodonium salt, it is proposed that the dye-recycled process consists of three-step reactions during the photosensitization: The oxidative fading product (I) of dye is formed through electron transfer under ir radiation; In the presence of H-donor, product (I) changes into acidic leuco dye product (II); Product (II) undergoes deprotonization under action of base to regenerate initial dye. The roles of light, H-donor and base are three major factors in the process of dye regeneration. F or the efficiency of dye regeneration, it is critical to control the p roportion of acidic leuco dye product. For a dye regenerated system co mposed of eosin ethyl ester iodonium salt (EOEtIPh2) triethylamine (TE A), the efficiency of sensitization is 4 times higher than that of sin gle system EOEtIPh2, at mean time the number of active radicals is als o multiplicated and thus this system is of importance in practical app lication.