ortho-Fluoroazobenzenes: Visible Light Switches with Very Long-Lived Z Isomers
ortho-Fluoroazobenzenes: Visible Light Switches with Very Long-Lived Z Isomers
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DOI：
10.1002/chem.201404649
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发表时间：
2014-12-08
影响因子：
4.3
通讯作者：
Bleger, David
中科院分区：
文献类型：
--
作者：
Knie, Christopher;Utecht, Manuel;Bleger, David
提高分子光开关的光化学性能对于材料和生命科学中光响应系统的发展至关重要。邻氟偶氮苯是一类新的合理设计的光致变色偶氮化合物，具有优化的性质，例如仅在可见光下异构化的能力，高光转化率和前所未有的稳健的光致变色特性。在N=N单元的邻位引入σ-吸电子F原子，既能有效分离E和Z异构体的n -> pi* 带，从而提供了利用这两个跃迁选择性诱导E/Z异构化的可能性，又能大大提高Z异构体的热稳定性。额外的对位吸电子基团（EWG）与邻位-F原子协同工作，产生n -> pi* 跃迁的增强分离。本文报道了取代基对邻氟偶氮苯关键光化学性质影响的综合研究。特别是，EWG的位置，数量和性质已经改变，并且通过DFT计算测量和合理化了可见光光转换，异构化的量子产率和热稳定性。
Improving the photochemical properties of molecular photoswitches is crucial for the development of light-responsive systems in materials and life sciences. ortho-Fluoroazobenzenes are a new class of rationally designed photochromic azo compounds with optimized properties, such as the ability to isomerize with visible light only, high photoconversions, and unprecedented robust bistable character. Introducing sigma-electron-withdrawing F atoms ortho to the N=N unit leads to both an effective separation of the n -> pi* bands of the E and Z isomers, thus offering the possibility of using these two transitions for selectively inducing E/Z iso-merizations, and greatly enhanced thermal stability of the Z isomers. Additional para-electron-withdrawing groups (EWGs) work in concert with ortho-F atoms, giving rise to enhanced separation of the n -> pi* transitions. A comprehensive study of the effect of substitution on the key photochemical properties of ortho-fluoroazobenzenes is reported herein. In particular, the position, number, and nature of the EWGs have been varied, and the visible light photoconversions, quantum yields of isomerization, and thermal stabilities have been measured and rationalized by DFT calculations.