Temperature-controlled changeable photooxygenation selectivity with a polymeric photosensitizer as a microreactor

ORGN 502

Hisao Koizumi, koizumi@cheng.es.osaka-u.ac.jp, Yumi Kimata, kimata@cheng.es.osaka-u.ac.jp, Yasuhiro Shiraishi, shiraish@cheng.es.osaka-u.ac.jp, and Takayuki Hirai. Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, 560-8531, Japan
Development of photoreaction systems promoting selective oxidation of molecules with molecular oxygen is one of the most important subjects in photochemistry. Substrate- and product-selective oxygenations have been achieved using several organized and constrained media. The selectivity is, however, basically not changeable. Some systems can change the selectivity by an addition of a third component; however, this results in an irreversible change. Here we report that a polymeric sensitizer, consisting of N-isopropylacrylamide and rose bengal units, demonstrates a temperature-controlled changeable oxygenation selectivity by singlet oxygen in water. We report here that this unprecedented activity is driven by a heat-induced self-assembly of the polymer, which promotes selective encapsulation/elimination of substrates.