Impact of Internal Charge Transfer on the Photophysical Properties of Pyridine‐Fused Phosphorus‐Nitrogen Heterocycles
Impact of Internal Charge Transfer on the Photophysical Properties of Pyridine‐Fused Phosphorus‐Nitrogen Heterocycles
复制标题
内部电荷转移对吡啶-熔融磷-氮杂环光物理性质的影响
DOI：
10.1002/chem.202203918
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Haley, Michael M.
中科院分区：
文献类型：
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作者：
McNeill, J. N.;Kascoutas, Melanie A.;Karas, Lucas J.;Zakharov, Lev N.;Wu, Judy I.;Johnson, Darren W.;Haley, Michael M.
磷喹啉酮支架先前已被研究为多种荧光物质的模块化核心，其中取代基效应的使用集中于增加或减少核心环中的电子密度。我们现在报告了几种含吡啶的磷喹啉酮物质的合成和分析，这些物质表现出从芳基取代基到吸电子吡啶基氮的显着线性共轭。将芳基取代基的性质从吸电子变为给电子会导致吸收光谱中产生内部电荷转移（ICT）带，该带在最富电子的-NMe2示例中成为强度方面的主要吸光度。与该组中的其他杂环相比，该杂环表现出改进的光物理性质，包括高量子产率和相当大的红移发射。增强的 ICT 可以在 X 射线数据中观察到，其中观察到分子共面性的罕见例子。计算数据显示，随着芳基取代基的给电子特性的增加，吡啶基氮上负电荷的定位增加。
The phosphaquinolinone scaffold has been previously studied as a modular core for a variety of fluorescent species where use of substituent effects has focused on increasing or decreasing electron density in the core rings. We now report the synthesis and analysis of several pyridine‐containing phosphaquinolinone species exhibiting notable linear conjugation from the aryl‐substituent to electron‐withdrawing pyridyl nitrogen. Varying the nature of the aryl substituent from electron‐withdrawing to electron‐donating leads to the generation of an internal charge‐transfer (ICT) band in the absorbance spectrum, which becomes the dominant absorbance in terms of intensity in the most electron‐rich ‐NMe2example. This heterocycle exhibits improved photophysical properties compared to others in the set including high quantum yield and considerably red‐shifted emission. The enhanced ICT can be observed in the X‐ray data where a rare example of molecule co‐planarity is observed. Computational data show increased localization of negative charge on the pyridyl nitrogen as the electron‐donating character of the aryl‐substituent increases.