聚环芳化合物分子对共振电子的捕获:阿扎替代的作用
Rustem V Khatymov1, Mars V Muftakhov2, Renat F Tuktarov2
1Mendeleev University of Chemical Technology of Russia, Miusskaya Square, 9, 125047 Moscow, Russia.
The Journal of chemical physics
|March 27, 2024
概括
亚萨替代的多环芳通过电子捕获形成稳定的负离子. 离子稳定性随着更多的原子和线性结构的增加而增加,与更高的电子亲和力相关.
科学领域:
- 物理化学 物理化学
- 化学物理 化学物理
- 分子光谱学 分子光谱学
背景情况:
- 多环芳 (PAH) 和它们含的类似物 (aza-PAH) 在各种化学和生物系统中起着至关重要的作用.
- 了解电子与这些分子的相互作用对于大气化学,材料科学和天体物理学至关重要.
- 之前的研究已经探索了对PAHs的电子附着,但对aza衍生物的系统研究较少见.
研究的目的:
- 为了研究由aza和diaza衍生物phenanthrene和anthracene的共振电子捕获.
- 为了确定由此产生的分子离子 (M-) 和它们的碎片的形成,稳定性和自脱离寿命.
- 为了将这些特性与分子结构,电子亲和力和气相酸度相关联.
主要方法:
- 电子捕获在发生电子能量 (0-15 eV) 的范围内的实验研究.
- 使用电子自离技术测量分子离子寿命 (τa).
- 理论分析包括赖斯-拉姆斯珀格-卡塞尔-马库斯 (RRKM) 理论,分子轨道计算和密度函数理论 (DFT) 以评估电子亲和力 (EAa).
主要成果:
- 所有研究的aza-PAHs,除了7,8-基诺林外,在热电子能量下形成长寿命的分子离子 (M-).
- 阿克里丁和也在表热能 (高达1.5-2.5 eV) 时形成M-离子.
- 离子寿命 (τa) 随着aza-substitution的程度的增加而增加,并且与增加的亚亚巴电子亲和力 (EAa) 相对应,有利于线性异构体 (azaanthracenes) 而不是曲的异构体 (azaphenanthrenes).
- M-离子的主要碎片化途径是原子抽象,形成[M-H]-离子.
- 从[M-H]-离子中观察到电子自离,并测量了寿命和外观能量.
- 分子的气相酸度和[M-H]·基的EAa与母分子的EAa成正比.
结论:
- 从aza-PAHs形成的负离子的稳定性受到分子结构和原子数量的强烈影响.
- 附带电子亲和度 (EAa) 是离子稳定性和电子捕获截面的关键决定因素.
- 观察到的趋势为含有的芳香系统中的电子分子相互作用提供了基本的理解.
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