Substituent Effect of 1,4-Benzenedicarbonitriles as Sensitizers on the Photoinduced Electron Transfer Reactions in Alcohol
作者:Masanori Suzuki、Taketo Ikeno、Kazuhiko Osoda、Koichi Narasaka、Tomoyoshi Suenobu、Shunichi Fukuzumi、Akito Ishida
DOI:10.1246/bcsj.70.2269
日期:1997.9
In the photosensitized electron transfer reaction of 6,6-diphenyl-1,4-dioxaspiro[4.5]decane in methanol (MeOH), the quantum yield is increased by the use of 2-methylbenzene-1,4-dicarbonitrile (2-methyl-BDC) or 2,5-dimethylbenzene-1,4-dicarbonitrile (2,5-dimethyl-BDC) as compared to that by the use of 1,4-benzenedicarbonitrile (BDC), though the excited methyl-substituted BDCs have lower reduction potentials than the excited BDC. Detailed study on this substituent effect reveals that the electron transfer between MeOH and the excited BDC occurs to some extent. By the use of methylated BDCs, electron transfer between the excited sensitizers and MeOH is suppressed enough due to its lower reduction potential. Some typical photoinduced electron transfer reactions in alcohol proceed more efficiently by the use of 2-methyl-BDC or 2,5-dimethyl-BDC instead of BDC.
在甲醇(MeOH)中,6,6-二苯基-1,4-二氧杂螺[4.5]癸烷的光敏电子转移反应中,与使用1,4-苯二甲腈(BDC)相比,使用2-甲基苯-1,4-二甲腈(2-甲基-BDC)或2,5-二甲基苯-1,4-二甲腈(2,5-二甲基-BDC)能够提高量子产率,尽管甲基取代的BDC的激发态具有比BDC更低的还原电位。对这种取代基效应的详细研究表明,MeOH与激发态BDC之间存在一定程度的电子转移。由于其较低的还原电位,使用甲基化的BDC能够充分抑制激发态敏化剂与MeOH之间的电子转移。在醇类中,一些典型的光诱导电子转移反应通过使用2-甲基-BDC或2,5-二甲基-BDC而不是BDC来更有效地进行。