氢化光开关光异构化量子产率的测定
Summary
光异构化量子产率是研究新开发的光开关时应准确确定的基本光物理性质。在这里，我们描述了一组测量光致变色腙的光异构化量子产率的程序，作为模型双稳态光开关。
Abstract
经历光驱动结构转变的光开关有机分子是构建适应性分子系统的关键成分，它们被用于各种应用。在大多数使用光开关的研究中，仔细测定了几种重要的光物理性质，例如吸收和发射的最长，摩尔衰减系数，荧光寿命和光异构化量子产率，以研究其电子态和过渡过程。然而，在典型的实验室环境中，光异构化量子产率的测量，光异构化相对于吸收光子的效率通常很复杂且容易出错，因为它需要基于适当的积分方法实施严格的光谱测量和计算。本文介绍了一组使用光致变色腙测量双稳态光开关的光异构化量子产率的程序。我们预计本文将成为研究日益开发的双稳态光开关的有用指南。
Introduction
光致变色有机分子在广泛的科学学科中引起了相当大的关注，因为光是一种独特的刺激，可以无创地使系统远离其热力学平衡1。以适当能量照射光允许以高时空精度2，3，4对光开关进行结构调制。由于这些优点，已经开发出基于双键（例如，二苯乙烯，偶氮苯，亚胺，富马酰胺，硫代金戈）和环开/闭合（例如，螺旋藻，二噻吩，黄酮，供体 – 受体Stenhouse加合物）的构型异构化的各种类型的光开关，并被用作各种长度尺度的自适应材料的核心成分。光开关的代表性应用涉及光致变色材料、药物递送、可切换受体和通道、信息或能量存储以及分子机器5、6、7、8、9、10、11、12。在大多数介绍新设计的光开关的研究中，它们的光物理性质，如吸收和发射的λ最大值 ，摩尔衰减系数（ε），荧光寿命和光异构化量子产率被彻底表征。对这些性质的研究提供了关于电子状态和转变的关键信息，这些信息对于理解光学性质和异构化机理至关重要。
然而，由于多种原因，光异构化量子产率的精确测量 – 发生的光异构化事件的数量除以反应物吸收的辐照波长处的光子数量 – 通常很复杂。光异构化量子产率的测定通常通过监测反应的进展和测量照射过程中吸收的光子的数量来实现。主要问题是，每单位时间的光子吸收量逐渐变化，因为随着光化学反应的进行，溶液的总吸收量随时间而变化。因此，每单位时间内消耗的反应物数量取决于在照射期间测量它的时间部分。因此，人们有义务估计以微分方式定义的光异构化量子产率。
当反应物和光产物都吸收照射波长的光时，会出现更麻烦的问题。在这种情况下，光化学异构化在两个方向上发生（即光可逆反应）。正向和反向反应的两个独立的量子产率不能直接从观察到的反应速率中获得。不准确的光强度也是导致误差的常见原因。例如，灯泡的老化逐渐改变其强度;14. 1000 h后，400 nm处的氙弧灯的辐照度降低30%。非准直光的扩散使得实际的入射辐照度明显小于光源的标称功率。因此，准确量化有效光子通量至关重要。值得注意的是，亚稳态形式在室温下的热弛豫应足够小，不容忽视。
本文介绍了一组确定双稳态光开关光异构化量子产率的程序。由该领域开创性研究团队Aprahamian小组开发的许多hydrazone光开关由于其选择性光异构化和其亚稳异构体15，16，17的显着稳定性而受到关注。它们的hydrazone光开关由两个由hydrazone基团连接的芳香环组成，并且C = N键在以适当的波长照射时经历选择性E / Z异构化（图1）。它们已被成功地纳入为动态分子系统的动力组分18，19，20，21。本文制备了一种新的含酰胺基团的腙衍生物，并研究了其光开关性能，以确定光异构化量子产率。
Protocol
Representative Results
Discussion
已经开发了各种策略来调整光开关的光谱和开关特性，并且光开关的寄存器正在迅速扩展28。因此，正确确定它们的光物理性质至关重要，我们预计本文中总结的方法将成为实验者的有用指南。前提是室温下的热弛豫速率非常慢，测量PSS组成在不同照射波长下、纯异构体的摩尔衰减系数、有效摩尔光子通量、沙伪量子产率可以估计单向光异构化量子产率。本研究提出的实验结果?…
Declarações
The authors have nothing to disclose.
Acknowledgements
这项工作得到了2019年中央大学研究补助金和韩国国家研究基金会（NRF-2020R1C1C1011134）的支持。
Materials
| 1,10-phenanthroline | Sigma-Aldrich | 131377-2.5G | |
| 340 nm bandpass filter, 25 mm diameter, 10 nm FWHM | Edmund Optics | #65-129 | |
| 436 nm bandpass filter, 25 mm diameter, 10 nm FWHM | Edmund Optics | #65-138 | |
| Anhydrous sodium acetate | Alfa aesar | A13184.30 | |
| Dimethyl sulfoxide | Samchun | D1138 | HPLC grade |
| Dimethyl sulfoxide-d6 | Sigma-Aldrich | 151874-25g | |
| Gemini 2000; 300 MHz NMR spectrometer | Varian | ||
| H2SO4 | Duksan | 235 | |
| Heating bath | JeioTech | CW-05G | |
| MestReNova 14.1.1 | Mestrelab Research S.L., https://mestrelab.com/ | ||
| Natural quartz NMR tube | Norell | S-5-200-QTZ-7 | |
| Potassium ferrioxalate trihydrate | Alfa aesar | 31124.06 | |
| Quartz absorption cell | Hellma | HE.110.QS10 | |
| UV-VIS spectrophotometer | Scinco | S-3100 | |
| Xenon arc lamp | Thorlabs | SLS205 | Fiber adapter was removed |
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