Liu Xiao-Mei, Jin Xing-Yi, Zhang Zhi-Xiang, Wang Jian, Bai Fu-Quan
Institute of Theoretical Chemistry, Laboratory of Theoretical and Computational Chemistry, International Joint Research Laboratory of Nano-Micro Architecture Chemistry, Jilin University Changchun 130023 People's Republic of China
1st Department of Neurosurgery, China-Japan Union Hospital, Jilin University Xiantai Street No. 126 Changchun 130033 People's Republic of China.
RSC Adv. 2018 Mar 23;8(21):11580-11588. doi: 10.1039/c8ra01132j. eCollection 2018 Mar 21.
This research was based on the quantum chemical calculations of a set of valid photoswitches of azobenzene compounds, with the aim of describing their thermal isomerization. The influences of familiar fluorine substitution and additional electron-donating groups (EDGs) and electron-withdrawing groups (EWGs) on the -position were also systematically studied. The results show that the presence of fluorine in different -positions has a distinct effect on the molecular orbital distribution of the isomer, which realizes the purpose of splitting the n → π* transition between the and isomers. On this basis, further -substitution can allow tunability on the order of the energy level to the molecular orbitals through their influence on the conjugation pattern of the compound. It is the modification of the substituent on these positions that allows the photoisomerization to proceed under visible wavelength light surroundings. The thermal → isomerization mechanism has also been analyzed, and a detailed comparison of these compounds has been made with respect to the thermal half-life , and the rate constants . The results reveal that isomerization is thought to be a process of globally structural change, during which the effect of the substituents is determined by the extent of their influence on the conjugated system.
本研究基于一组有效的偶氮苯化合物光开关的量子化学计算，旨在描述它们的热异构化过程。还系统地研究了常见的氟取代以及对位上额外的供电子基团（EDG）和吸电子基团（EWG）的影响。结果表明，不同位置的氟的存在对反式异构体的分子轨道分布有明显影响，实现了分离反式和顺式异构体之间n→π*跃迁的目的。在此基础上，进一步的对位取代可以通过其对化合物共轭模式的影响，实现分子轨道能级顺序的可调性。正是这些位置上取代基的修饰使得光异构化能够在可见光波长环境下进行。还分析了热反式→顺式异构化机理，并对这些化合物的热半衰期t1/2和速率常数k进行了详细比较。结果表明，异构化被认为是一个全局结构变化的过程，在此过程中，取代基的作用取决于它们对共轭体系影响的程度。
