Abstract: Photoacid generators (PAGs) and photohydride generators (PHGs) are specific photolabile protecting groups that release acid and hydride, respectively. Over the past decade, great efforts have been devoted to developing novel PAGs and PHGs with advanced efficiency, and among which, one of the promising candidates is the diarylethylene (DAE)-based PAGs and PHGs, which release acids/hydrides accompanying photochromic electrocyclization. The release quantum yield for PAG is acceptable, while that of PHG is only 4.2% even after molecular structure modification. In this work, time-resolved transient absorption spectroscopies with femtosecond and nanosecond resolutions along with DFT/TD-DFT calculations were utilized to unravel the detailed photochemical reaction mechanisms of DAE-based PAG (1o) and PHG (2o), respectively. The results show that the different photorelaxation mechanism is the key that leading to distinctive release quantum yield between 1o and 2o. The factors affecting the release quantum yield are discussed in details and several key design principles are proposed, to facilitate future rational design of DAE-based PAGs and PHGs.

中文翻译：

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获得基于光化学反应机理的高效二芳烯烃光酸和光氢化物发生器的分子设计原理


摘要：光酸发生剂 （PAG） 和光氢化物发生剂 （PHG） 是特异性的光不稳定保护基团，分别释放酸和氢化物。在过去的十年中，人们投入了大量精力开发具有先进效率的新型 PAGs 和 PHG，其中，其中一个有前途的候选者是基于二芳乙烯 （DAE） 的 PAGs 和 PHG，它们会随着光致变色电环化释放酸/氢化物。PAG 的释放量子产率是可以接受的，而即使在分子结构修饰后，PHG 的释放量子产率也仅为 4.2%。在这项工作中，利用飞秒和纳秒分辨率的时间分辨瞬态吸收光谱以及 DFT/TD-DFT 计算来分别揭示基于 DAE 的 PAG （1o） 和 PHG （2o） 的详细光化学反应机制。结果表明，不同的光弛豫机制是导致 1o 和 2o 之间独特释放量子产率的关键。详细讨论了影响释放量子产率的因素，并提出了几个关键设计原则，以促进未来基于 DAE 的 PAGs 和 PHG 的合理设计。