School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), 2 George Street, QLD, 4000, Brisbane, Australia.
Laboratory for Chemical Technology, Ghent University, Technologiepark 125, 9052, Ghent, Belgium.
Chemistry. 2020 Jan 7;26(2):478-484. doi: 10.1002/chem.201903641. Epub 2019 Dec 12.
The [4+4] photocycloaddition of anthracene is one of most relevant photoreactions and is widely applied in materials science, as it allows to remote-control soft matter material properties by irradiation. However, highly energetic UV irradiation is commonly applied, which limits its application. Herein, the wavelength dependence of the photodimerization of anthracene is assessed for the first time, revealing that the reaction is induced just as effectively with mild visible light (410 nm). To fully establish [4+4] cycloadditions within defined chemical environments, a conceptual framework for the solution kinetics of the photo-dimerization up to long reaction times is established by developing a novel photoreaction rate law that is dependent on individual rate coefficients of the key reaction steps. These coefficients can be determined based on low conversion photochemical experiments. Both differential and integral quantum yields can subsequently be predicted that are strongly time-dependent, highlighting the need for a detailed reaction pathway analysis. The presented approach simplifies a complex photochemical scenario, making the photochemical anthracene dimerization, or potentially any other photochemical dimerization, amenable to a time-dependent understanding at the elementary reaction level.
蒽的 [4+4] 光环加成是最相关的光反应之一，广泛应用于材料科学，因为它可以通过辐照远程控制软物质材料的性质。然而，通常应用高能量的紫外光照射，这限制了其应用。在此，首次评估了蒽的光二聚反应的波长依赖性，揭示了只需温和的可见光（410nm）即可有效地诱导反应。为了在确定的化学环境中完全建立[4+4]环加成，通过开发一种新的光反应速率定律，该定律取决于关键反应步骤的单个速率系数，为光二聚反应的溶液动力学建立了一个概念性框架。这些系数可以基于低转化率光化学实验来确定。随后可以预测微分和积分量子产率，它们具有强烈的时间依赖性，突出了需要进行详细的反应途径分析。所提出的方法简化了复杂的光化学情况，使得光化学蒽二聚化，或者可能是任何其他光化学二聚化，能够在基本反应水平上进行时间相关的理解。
