Remote-Controlled Exchange Rates by Photoswitchable Internal Catalysis of Dynamic Covalent Bonds
Remote-Controlled Exchange Rates by Photoswitchable Internal Catalysis of Dynamic Covalent Bonds
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DOI：
10.1021/jacs.2c04658
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发表时间：
2022-06-15
影响因子：
15
通讯作者：
Kalow, Julia A.
中科院分区：
文献类型：
--
作者：
Barsoum, David N.;Kirinda, Viraj C.;Kalow, Julia A.
硼酸酯与二醇的酯交换反应速率在14个数量级以上是可调的。速率加速是通过内部碱催化实现的，这降低了质子转移的障碍。在这里，我们报告了一种可光切换的内部催化剂，其调节硼酸酯/二醇交换的速率超过4个数量级。我们采用了酰腙分子光开关，它形成了一个热稳定的，但光可逆的分子内氢键，门在8-喹啉硼酸酯的内部碱催化剂的活性。光电开关是双向的，可以反复循环。分子内的H-键被发现是必不可少的设计，这种光开关的内部催化剂，作为质子化的喹啉与外部来源的酸的交换率几乎没有影响。
The transesterification rate of boronate esters with diols is tunable over 14 orders of magnitude. Rate acceleration is achieved by internal base catalysis, which lowers the barrier for proton transfer. Here we report a photoswitchable internal catalyst that tunes the rate of boronic ester/diol exchange over 4 orders of magnitude. We employed an acylhydrazone molecular photoswitch, which forms a thermally stable but photoreversible intramolecular H-bond, to gate the activity of the internal base catalyst in 8-quinoline boronic ester. The photoswitch is bidirectional and can be cycled repeatedly. The intramolecular H-bond is found to be essential to the design of this photoswitchable internal catalyst, as protonating the quinoline with external sources of acid has little effect on the exchange rate.