Avdic Irma, Kempfer-Robertson Emily M, Thompson Lee M
Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, United States.
J Phys Chem A. 2021 Sep 23;125(37):8238-8248. doi: 10.1021/acs.jpca.1c06102. Epub 2021 Sep 8.
Azoheteroarenes are relatively new photoswitchable compounds, where one of the phenyl rings of an azobenzene molecule is replaced by a heteroaromatic five-membered ring. Recent findings on methylated azoheteroarenes show that these photoswitches have potential in various optically addressable applications. The thermal stability of molecular switches is one of the primary factors considered in the design process. For molecular memory or energy storage devices, long thermal relaxation times are required. However, inducing a short thermal isomerization lifetime is required to release stored energy or as an alternative to photoswitching to avoid overlapping absorption spectra that reduce switching fidelity. In this study, we investigate how oriented external electric fields can be used to tune the thermal isomerization properties of three unsubstituted heteroaryl azo compounds-azoimidazole, azopyrazole, and azopyrrole. We show that favorable electric field orientations can increase the thermal half-life of studied molecules by as much as 60 times or reduce it from tens of days to seconds, compared to their half-life values in the field-free environment. A deeper understanding of the relationship between structure and kinetic properties provides insight as to how molecular switches can be designed for their electric field response in switching applications.
氮杂芳烃是相对较新的光开关化合物，其中偶氮苯分子的一个苯环被一个杂芳族五元环取代。关于甲基化氮杂芳烃的最新研究结果表明，这些光开关在各种光学可寻址应用中具有潜力。分子开关的热稳定性是设计过程中考虑的主要因素之一。对于分子存储器或能量存储设备，需要较长的热弛豫时间。然而，为了释放存储的能量或作为光开关的替代方案以避免重叠的吸收光谱降低开关保真度，则需要诱导较短的热异构化寿命。在本研究中，我们研究了如何利用定向外部电场来调节三种未取代的杂芳基偶氮化合物——偶氮咪唑、偶氮吡唑和偶氮吡咯的热异构化性质。我们表明，与它们在无场环境中的半衰期值相比，有利的电场取向可以使所研究分子的热半衰期增加多达60倍，或者将其从数十天缩短至数秒。对结构与动力学性质之间关系的更深入理解为如何在开关应用中针对其电场响应设计分子开关提供了见解。
