Chen Huan, Wang Ruijing, Xu Jinheng, Yuan Xu, Zhang Dongmei, Zhu Zhaoguo, Marshall Mary, Bowen Kit, Zhang Xinxing
College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Renewable Energy Conversion and Storage Centre, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Frontiers Science Centre for New Organic Matter, Nankai University, Tianjin 300071, China.
Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China.
J Am Chem Soc. 2023 Feb 1;145(4):2647-2652. doi: 10.1021/jacs.2c12731. Epub 2023 Jan 20.
Recent advances in microdroplet chemistry have shown that chemical reactions in water microdroplets can be accelerated by several orders of magnitude compared to the same reactions in bulk water. Among the large plethora of unique properties of microdroplets, an especially intriguing one is the strong reducing power that can be sometimes as high as alkali metals as a result of the spontaneously generated electrons. In this study, we design a catalyst-free strategy that takes advantage of the reducing ability of water microdroplets to reduce a certain molecule, and the reduced form of that molecule can convert CO into value-added products. By spraying the water solution of CFI into microdroplets, an exotic and fragile radical anion, CFI, is observed, where the excess electron counter-intuitively locates on the σ* antibonding orbital of the C-I bond as evidenced by anion photoelectron spectroscopy. This electron weakens the C-I bond and causes the formation of CF, and the latter attacks the carbon atom on CO, forming the pentafluorobenzoate product, CFCO. This study provides a good example of strategically making use of the spontaneous properties of water microdroplets, and we anticipate that microdroplet chemistry will be a green avenue rich in new opportunities in CO utilization.
微滴化学的最新进展表明，与在 bulk water 中的相同反应相比，水微滴中的化学反应可以加速几个数量级。在微滴众多独特性质中，一个特别引人入胜的性质是其强大的还原能力，由于自发产生的电子，这种还原能力有时可高达碱金属。在本研究中，我们设计了一种无催化剂策略，利用水微滴的还原能力来还原特定分子，且该分子的还原形式可将 CO 转化为增值产物。通过将 CFI 的水溶液喷入微滴中，观察到一种奇特且脆弱的自由基阴离子 CFI，阴离子光电子能谱表明，多余的电子反直觉地位于 C-I 键的σ*反键轨道上。这个电子削弱了 C-I 键并导致 CF 的形成，后者攻击 CO 上的碳原子，形成五氟苯甲酸盐产物 CFCO。本研究为战略性利用水微滴的自发性质提供了一个很好的例子，我们预计微滴化学将成为 CO 利用中充满新机遇的绿色途径。
