Photophysical Exploration of Two Isomers of Octaethyltrioxopyrrocorphin
Photophysical Exploration of Two Isomers of Octaethyltrioxopyrrocorphin
复制标题
DOI：
10.1021/acs.jpca.3c03184
复制
发表时间：
2023-09-10
影响因子：
2.9
通讯作者：
Nemykin，Victor N.
中科院分区：
文献类型：
--
作者：
Bhattacharya，Sayantan;Nevonen，Dustin E.;Nemykin，Victor N.
通过氧化/重排反应将三个β-氧取代基引入辛乙基卟啉，生成三氧卟啉发色团。pyrorocorphins（六氢卟啉）通常是非芳香的，但我们最近证明了trioxoprocorphins具有相当大的芳香特征。这篇文章探讨了这些不寻常的发色团的光物理特性。与密度泛函理论模型一致，所研究的四种可能的三酮区域异构体中的两种（其中两种）的紫外-可见光谱和磁圆二色性符合类卟啉光谱的guouterman模型，与其芳香性一致。它们的激发态动力学进一步揭示了β-氧取代对卟啉类化合物光物理性质的调节程度。β-氧官能团的引入提高了体系间杂交的速率和产率，缩短了三重态寿命。出乎意料的是，这两种pyrocorphin的单线态产氧率仍然相对较高，这可能是由于平面性的扭曲模式增强了三重态能量传递。这项工作扩大了我们对一类罕见的卟啉类化合物的认识，并进一步将它们定性为维持芳香卟啉π系统。我们的研究结果表明，三重β-氧取代是开发新型高单线态氧产率卟啉光敏剂的可行途径。
The introduction of three β-oxosubstituents to octaethylporphyrin by means of an oxidation/rearrangement reaction generates the trioxopyrrocorphin chromophore. Pyrrocorphins (hexahydroporphyrins) are generally nonaromatic, but we recently demonstrated trioxopyrrocorphins to possess considerable aromatic character. This contribution explores the photophysical characteristics of these unusual chromophores. In agreement with density functional theory modeling, the UV–vis and magnetic circular dichroism spectra of the two─out of the four possible─triketone regioisomers investigated conform to the Gouterman model of porphyrinoid optical spectra, in alignment with their aromaticity. Their excited-state dynamics shed further light on the degree to which β-oxo substitutions tune the photophysical properties of porphyrinoids. Introduction of β-oxo functionalities increases the rate and yield of intersystem crossing and shortens the triplet state lifetime. Unexpectedly, the singlet oxygen generation yield of both pyrrocorphins remains relatively high, with modes of distortion from planarity likely enhancing triplet energy transfer. This work thus expands our understanding of a rare class of porphyrinoids and further characterizes them as sustaining aromatic porphyrinic π-systems. Our findings suggest triple β-oxo substitution as a viable route toward the development of novel, high-singlet oxygen yield porphyrinic photosensitizers.