Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira 19, Ekaterinburg 620002, Russian Federation.
Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira 19, Ekaterinburg 620002, Russian Federation; Institute of Organic Synthesis, Ural Branch of the Russian Academy of Sciences, Kovalevskoy 22, Ekaterinburg 620219, Russian Federation.
Spectrochim Acta A Mol Biomol Spectrosc. 2022 Feb 15;267(Pt 2):120499. doi: 10.1016/j.saa.2021.120499. Epub 2021 Oct 19.
A series of coumarin-pyridine-based push-pull fluorophores were prepared starting from 1,2,4-triazines by using direct C-H functionalization (S-reaction)-Diels-Alder-retro Diels-Alder domino reaction sequence. This efficient synthetic strategy allowed to obtain a series of 19 coumarin-pyridine fluorophores. Their photophysical properties were studied. While pyridine-substituted derivatives of 4-alkylcoumarins may be considered as alternative to coumarin dyes characterized by emission maxima mainly in a visible region with wavelengths of 402-415 nm, absorption in the UV range at 210-307 nm, and good photoluminescence quantum yields of 6-19%, all the derivatives of 4-phenylcoumarin did not exhibit any noticeable fluorescence. More detailed photophysical studies were carried out for two the most representative derivatives of 4-alkyl-coumarin-pyridines to demonstrate their positive solvatochromism, and the collected data were analyzed by using Lippert-Mataga equation, as well as Kosower and Dimroth/Reichardt scales. The obtained results demonstrate that the combining two chromophore systems, such as 2,5-diarylpyridine and coumarin ones, is promising in terms of improving the photophysical properties of the new coumarin-pyridine hybrid compounds.
一系列基于香豆素-吡啶的推拉型荧光染料是通过直接 C-H 功能化（S 反应）-Diels-Alder-反 Diels-Alder 级联反应序列，从 1,2,4-三嗪出发制备的。这种高效的合成策略允许获得一系列 19 个香豆素-吡啶荧光染料。研究了它们的光物理性质。虽然吡啶取代的 4-烷基香豆素衍生物可以作为发射最大值主要在可见光区域的香豆素染料的替代物，其波长为 402-415nm，在 210-307nm 的紫外范围内吸收，并且具有 6-19%的良好光致发光量子产率，但所有 4-苯基香豆素的衍生物都没有表现出任何明显的荧光。对两种最具代表性的 4-烷基香豆素-吡啶衍生物进行了更详细的光物理研究，以证明它们具有正溶剂化变色性，并通过 Lippert-Mataga 方程以及 Kosower 和 Dimroth/Reichardt 标度对收集到的数据进行了分析。所得结果表明，将两种生色团体系（如 2,5-二芳基吡啶和香豆素体系）结合起来，在改善新的香豆素-吡啶杂化化合物的光物理性质方面具有很大的前景。
