Excited state intramolecular proton transfer in hydroxyanthraquinones: Toward predicting fading of organic red colorants in art
Excited state intramolecular proton transfer in hydroxyanthraquinones: Toward predicting fading of organic red colorants in art
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DOI：
10.1126/sciadv.aaw5227
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发表时间：
2019-09-01
期刊：
影响因子：
13.6
通讯作者：
de Vries, M. S.
中科院分区：
文献类型：
--
作者：
Berenbeim, J. A.;Boldissar, S.;de Vries, M. S.
在组成相似的有机红色着色剂中，其光降解可以引起不可逆转的颜色和稳定性变化，长期以来一直被用于艺术品中。不同的有机红及其多个发色团受到不同程度的降解。因此，了解这些分子降解的细节为了解它们在艺术品中的行为提供了一个窗口，并可能有助于改进保护方法的发展。根据一个提出的光降解动力学模型，分子内质子转移在一些光激发的发色团中提供了一条动力学上有利的衰变途径，阻止了降解促进电子转移(ET)。为了进一步验证这一模型，我们用高能级理论测量了取代气相蒽醌的激发态寿命，并对实验结果进行了解释。数据显示了一个总的结构趋势：具有1，4-OH取代的蒽醌是长寿的，容易破坏ET，而激发态分子内质子转移促进了对缺乏这个基序的羟基蒽醌的有效猝灭。
Compositionally similar organic red colorants in the anthraquinone family, whose photodegradation can cause irreversible color and stability changes, have long been used in works of art. Different organic reds, and their multiple chromophores, suffer degradation disparately. Understanding the details of these molecules' degradation therefore provides a window into their behavior in works of art and may assist the development of improved conservation methods. According to one proposed model of photodegradation dynamics, intramolecular proton transfer provides a kinetically favored decay pathway in some photoexcited chromophores, preventing degradation-promoting electron transfer (ET). To further test this model, we measured excited state lifetimes of substituted gas-phase anthraquinones using high-level theory to explain the experimental results. The data show a general structural trend: Anthraquinones with 1,4-OH substitution are long-lived and prone to damaging ET, while excited state intramolecular proton transfers promote efficient quenching for hydroxyanthraquinones that lack this motif.