Efficient Light‐Induced pKa Modulation Coupled to Base‐Catalyzed Photochromism,Angewandte Chemie International Edition

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Efficient Light‐Induced pKa Modulation Coupled to Base‐Catalyzed Photochromism
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2018-03-23 , DOI: 10.1002/anie.201801270
Johannes Gurke ₁ , Šimon Budzák _{2,

3} , Bernd M. Schmidt _{1,

4} , Denis Jacquemin ₂ , Stefan Hecht ₁

Affiliation

Photoswitchable acid–base pairs, whose pK_a values can be reversibly altered, are attractive molecular tools to control chemical and biological processes with light. A significant, light‐induced pK_a change of three units in aqueous medium has been realized for two thermally stable states, which can be interconverted using UV and green light. The light‐induced pK_a modulation is based on incorporating a 3‐H‐thiazol‐2‐one moiety into the framework of a diarylethene photoswitch, which loses the heteroaromatic stabilization of the negatively charged conjugate base upon photochemical ring closure, and hence becomes significantly less acidic. In addition, the efficiency of the photoreactions is drastically increased in the deprotonated state, giving rise to catalytically enhanced photochromism. It appears that protonation has a significant influence on the shape of the ground‐ and excited‐state potential energy surfaces, as indicated by quantum‐chemical calculations.

中文翻译：

高效的光诱导pKa调制与碱催化的光致变色反应

光交换酸碱对，其p K _a值可逆地改变，是用光控制化学和生物过程的有吸引力的分子工具。对于两个热稳定状态，已经实现了水介质中三个单位的显着光致p K _a变化，可以使用紫外线和绿光将其相互转换。光诱导的p K _a调制是基于将3-H-噻唑-2-酮部分掺入二芳基乙烯光开关的框架中，该光开关闭环后，该基团失去了带负电荷的共轭物的杂芳族稳定作用，因此其酸性显着降低。另外，在去质子化状态下，光反应的效率大大提高，从而引起催化增强的光致变色。量子化学计算表明，质子化似乎对基态和激发态势能表面的形状具有重大影响。

更新日期：2018-03-23

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