分子内敏化鎓盐的合成及光敏性研究

二芳基碘鎓盐和三芳基硫鎓盐是阳离子聚合的光引发剂和光敏产酸物,但他们在300nm以上的光吸收很低,限制了对紫外光的利用效率。为解决此问题,本文合成了一些新的碘鎓盐和硫鎓盐,并用凝胶时间方法考察了它们的光引发效率。实验结果表明,2-苯硫基甲基,2′,4′-二甲基二苯碘鎓盐和9-蒽丙基,二苯基硫鎓盐具有特别高的光引发效率,这归之于光照时这些鎓盐发生了分子内电荷转移反应,即发生了分子内敏化。9-蒽丙基二苯硫鎓盐分子中的蒽基(An)是电子给体也是敏化基团,光照时可发生如下反应:

STUDIES ON SYNTHESIS AND PHOTOACTIVITY OF SOME ONIUM SALTS WITH BUILT-IN PHOTOSENSITIZER

Triarylsulfonium Salts and diaryiodonium salts are photoinitiator for cationic polymerization as well as photo- acid generator. However, they exhibit low absorptivity above 300 nm, which limits the efficiency of light use for common UV sources. In order to overcome this limitation, a number of novel iodonium salts and sulfonium salts were prepared and their photoactivity for cationic polymerization were investigated by gel time studies. The results indicated that 2- phenylsulfur- methyl, 2',4'- dimethyl diphenyl iodonium salts and 9- anthryl- propyl, diphenyl sulfonium salts, which possess built- in sensitizer, show very high photoactivity. An intramolecular electron transfer mechanism has been proposed to explain this result. Thus, the anthryl group(An) is an electron donor and a built- in sensitizer group on the molecule of 9- anthryl- propyl, diphenyl sulfonium salts, and the photoreaction can be shown as following: