单体和二聚体4-氨基-1,8-萘二甲酰亚胺的溶剂依赖性光物理性质和反应性,The Journal of Physical Chemistry A

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单体和二聚体4-氨基-1,8-萘二甲酰亚胺的溶剂依赖性光物理性质和反应性
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2021-03-16 , DOI: 10.1021/acs.jpca.0c11639
Lisa A. Kelly ₁ , Melissa Roll ₁ , Jayan Joseph ₂ , Jeyaprakashnarayanan Seenisamy ₂ , Justin Barrett ₃ , Katalin Kauser ₃ , Kevin S. Warner ₃

Affiliation

使用荧光光谱和激光闪光光解法研究了两个4-氨基取代的1,8-萘酰亚胺（AIs）的溶剂依赖性光物理性质。将化合物用水溶性2,2'（亚乙基二氧基）二乙胺基团官能化，得到单体（AI3）和二聚体（AI4）。在10种溶剂中以及在不同的pH值下，对AI3和AI4的辐射和非辐射单重态失活过程进行了定量。水中的AI4二聚体的荧光量子产率比其他溶剂或单体AI3的荧光量子产率低100倍以上。二聚体AI4水溶液的增强的非辐射衰变伴随着双指数衰减动力学，暗示着与暗激发态的平衡。在水和正辛醇中均以416 nm激发时，生成了AI3的可氧淬灭的三重态（T ₁）。在水中，T ₁状态演变成长寿命的瞬态，对氧或几个电子供体没有反应。在正辛醇中未观察到该物种。在水中AI4的416 nm激发下观察到的瞬态非常弱。但是，在AI3和AI4中都产生T ₁通过光诱导的电子转移到甲基紫精中可以证明这一点，尽管量子产率很低（AI3和AI4分别为0.0503和0.00778 ）。光物理性质和反应性与在水中稳定的分子内电荷转移（ICT）状态的产生一致。显着地，这种稳定化增强了非辐射衰变途径，特别是在AI4二聚体中。结果表明，这些化合物的光化学可以被环境介导，从自由基引发过程转变为三重态引发过程。

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Solvent-Dependent Photophysics and Reactivity of Monomeric and Dimeric 4-Amino-1,8-Naphthalimides

The solvent-dependent photophysics of two 4-amino-substituted 1,8-naphthalene imides (AIs) were studied using fluorescence spectroscopy and laser flash photolysis. The compounds were functionalized with water-soluble 2,2′(ethylenedioxy) diethylamine groups, yielding a monomer (AI3) and a dimer (AI4). The radiative and nonradiative singlet-state deactivation processes of AI3 and AI4 were quantified in 10 solvents and at different pH values. The fluorescence quantum yield for the AI4 dimer in water was more than 100× lower than in other solvents, or for the monomeric AI3. The enhanced nonradiative decay of aqueous solutions of dimeric AI4 is accompanied by biexponential decay kinetics, suggesting equilibration with a dark excited state. An oxygen-quenchable triplet state (T₁) of AI3 was produced upon 416 nm excitation in both water and n-octanol. In water, the T₁ state evolved into a long-lived transient that was unreactive toward oxygen or several electron donors. This species was not observed in n-octanol. The transient observed upon 416 nm excitation of AI4 in water was extremely weak. However, production of T₁ in both AI3 and AI4 was evidenced by the photoinduced electron transfer to methyl viologen, albeit in low quantum yield (0.0503 and 0.00778 for AI3 and AI4, respectively). The photophysics and reactivity are consistent with the production of an intramolecular charge transfer (ICT) state that is stabilized in water. Significantly, this stabilization enhances nonradiative decay pathways, particularly in the AI4 dimer. The results indicate that the photochemistry of these compounds can be environmentally mediated, switching from radical- to triplet-initiated processes.

更新日期：2021-03-25

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