de la Hoz Tomás Mario, Yamaguchi Mao, Cohen Boiko, Hisaki Ichiro, Douhal Abderrazzak
Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, and INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, S/N, 45071 Toledo, Spain.
Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan.
Phys Chem Chem Phys. 2023 Jul 19;25(28):18874-18888. doi: 10.1039/d3cp01295f.
Tetraphenylethylene (TPE) derivatives are ones of the most versatile building blocks showing aggregation-induced emission (AIE). However, their applications are limited by the photophysical and photochemical processes that occur in their excited state. Herein, we report a detailed study of the photochemical behaviour of a new TPE derivative with bulky terphenyl groups (TTECOOBu) in solvents of different viscosities and in a PMMA film. UV light irradiation shows an efficient photocyclization reaction, which produces a 9,10-diphenylphenanthrene (DPP) derivative photoproduct. The emission spectra of the irradiated samples show intermediate (∼420 nm) and final (∼380 nm) species. The photocyclization events are more efficient in environments of higher viscosities or rigidity. We show that in a photoirradiated PMMA film containing TTECOOBu, it is possible to etch a message for more than 1 year. The kinetics is dictated by the motions of the phenyl rings and is faster when their motions are precluded or inhibited. We also elucidated the femto- to millisecond photodynamics of the intermediate and final photoproducts and provide a full picture of their relaxation, with the latter in ∼1 ns at S and ∼1 μs at T. We also demonstrate that the kinetics of the bulky TTECOOBu is much slower than that of the TPE core. Our results also show that both photoevents are not reversible contrary to the case of TPE kinetics. We believe that these results will shed more light on the photochemical behaviour of TPE derivatives and should help in the development of novel TPE-based materials with improved photostability and photo-properties.
四苯乙烯（TPE）衍生物是最具多功能性的显示聚集诱导发光（AIE）的结构单元之一。然而，它们的应用受到其激发态发生的光物理和光化学过程的限制。在此，我们报告了一种带有庞大三联苯基团的新型TPE衍生物（TTECOOBu）在不同粘度溶剂和聚甲基丙烯酸甲酯（PMMA）薄膜中的光化学行为的详细研究。紫外光照射显示出高效的光环化反应，生成一种9,10 - 二苯基菲（DPP）衍生物光产物。辐照样品的发射光谱显示出中间态（约420 nm）和终态（约380 nm）物种。光环化事件在更高粘度或刚性的环境中更有效。我们表明，在含有TTECOOBu的光辐照PMMA薄膜中，可以蚀刻一条信息长达一年多。动力学由苯环的运动决定，当苯环的运动被阻止或抑制时更快。我们还阐明了中间态和终态光产物从飞秒到毫秒的光动力学，并提供了它们弛豫的全貌，终态在单重态约1 ns，在三重态约1 μs。我们还证明，庞大的TTECOOBu的动力学比TPE核心的动力学慢得多。我们的结果还表明，与TPE动力学情况相反，这两个光事件都不可逆。我们相信这些结果将为TPE衍生物的光化学行为提供更多启示，并有助于开发具有改善的光稳定性和光性能的新型TPE基材料。
