A series of novel donor–acceptor pyrid-2-ones was synthesized. The influence of the donor group on the photophysical properties of chromophores in solution was shown by varying the methoxy group position in the electron-rich aromatic ring. The effect of the π-linker was also demonstrated by the comparison of the D–π–A pyridone with its spacer-free analogue (D–A) and with the chromophore bearing an additional thiophene bridge (D–π–π–A). It was found that the presence of a π-linker plays a crucial role in the implementation of an intramolecular charge transfer (ICT) from the donor aryl moiety to the pyridone acceptor. Thus, for the synthesized D–A, D–π–A and D–π–π–A derivatives, the photoluminescence quantum yield in DMSO solution decreases from 56.8 to 4.3 and 3.5%, respectively, along with a strong bathochromic shift both for absorption (66 nm) and emission (162 nm) bands. Also, the possibility of shifting the equilibrium in DMSO solution towards either the pyridone form or the anionic form by the addition of a strong acid (TFA) and base (DBN) respectively was shown. Drastic changes in the photoluminescence of the solutions showed prospects for the application of the synthesized donor–acceptor pyridone derivatives as naked-eye acid–base indicators in organic media.

中文翻译：

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新型2-吡啶酮供体-受体染料：供体基团位置、π-连接体类型和介质酸碱特性对光物理性质的影响

合成了一系列新型供体-受体吡啶-2-酮。通过改变富电子芳环中的甲氧基位置来显示供体基团对溶液中发色团的光物理性质的影响。通过比较 D-π-A 吡啶酮与其无间隔类似物 (D-A) 以及带有额外噻吩桥的发色团 (D-π-π-A)，也证明了 π-连接体的作用。研究发现，π-连接体的存在在实现从供体芳基部分到吡啶酮受体的分子内电荷转移（ICT）中起着至关重要的作用。因此，对于合成的 D–A、D–π–A 和 D–π–π–A 衍生物，DMSO 溶液中的光致发光量子产率分别从 56.8 下降到 4.3 和 3.5%，同时出现强烈的红移。吸收（66 nm）和发射（162 nm）波段。此外，还显示了通过分别添加强酸（TFA）和强碱（DBN）将DMSO溶液中的平衡向吡啶酮形式或阴离子形式移动的可能性。溶液光致发光的剧烈变化显示了合成的供体-受体吡啶酮衍生物作为有机介质中肉眼酸碱指示剂的应用前景。