Superhydrophobic Photosensitizers. Mechanistic Studies of 1O2 Generation in the Plastron and Solid/Liquid Droplet Interface

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• 作者：David Aebisher ; Dorota Bartusik ; Yang Liu ; Yuanyuan Zhao ; Mark Barahman ; QianFeng Xu ; Alan M. Lyons ; Alexander Greer
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：December 18, 2013
• 年：2013
• 卷：135
• 期：50
• 页码：18990-18998
• 全文大小：511K
• 年卷期：v.135,no.50(December 18, 2013)
• ISSN：1520-5126

文摘

We describe here a physical-organic study of the first triphasic superhydrophobic sensitizer for photooxidations in water droplets. Control of synthetic parameters enables the mechanistic study of 鈥渂orderline鈥?two- and three-phase superhydrophobic sensitizer surfaces where ¹O₂ is generated in compartments that are wetted, partially wetted, or remain dry in the plastron (i.e., air layer beneath the droplet). The superhydrophobic surface is synthesized by partially embedding silicon phthalocyanine (Pc) sensitizing particles to specific locations on polydimethylsiloxane (PDMS) posts printed in a square array (1 mm tall posts on 0.5 mm pitch). In the presence of red light and oxygen, singlet oxygen is formed on the superhydrophobic surface and reacts with 9,10-anthracene dipropionate dianion (1) within a freestanding water droplet to produce an endoperoxide in 54鈥?2% yields. Control of the ¹O₂ chemistry was achieved by the synthesis of superhydrophobic surfaces enriched with Pc particles either at the PDMS end-tips or at PDMS post bases. Much of the ¹O₂ that reacts with anthracene 1 in the droplets was generated by the sensitizer 鈥渨etted鈥?at the Pc particle/water droplet interface and gave the highest endoperoxide yields. About 20% of the ¹O₂ can be introduced into the droplet from the plastron. The results indicate that the superhydrophobic sensitizer surface offers a unique system to study ¹O₂ transfer routes where a balance of gas and liquid contributions of ¹O₂ is tunable within the same superhydrophobic surface.