Abstract Coumarin and its derivatives have potential applications in sensing, laser dyes, fluorescent probes, and dye sensitized solar cells due to their unique photophysical properties. However, synthesis and studies of linear pyridine-fused-π-extended coumarins remained unexplored. Here, we synthesised two π-expanded coumarin derivatives (PC1, PC2) in which molecular backbone is linearly extended with pyridyl ring where 5,7-positions are substituted with aryl groups. Single crystal X-ray structure analysis confirmed the molecular geometry. We found in spectroscopic studies that both coumarins in solutions show fluorescence via predominant radiative decay of charge transfer (CT) state due to rotational motion associated with the molecules. In addition, detailed spectroscopic analysis of both coumarins in presence of acid and base revealed the acidochromic property in solutions. Based on the acid-base sensing property of PC1, we could show its use as solid-state acid-base vapor sensor and anti-counterfeiting agent.

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新型π-延伸吡啶稠合香豆素的合成、光学性质、酸碱气相变色及防伪

摘要 香豆素及其衍生物由于其独特的光物理性质，在传感、激光染料、荧光探针和染料敏化太阳能电池等方面具有潜在的应用价值。然而，线性吡啶稠合-π-扩展香豆素的合成和研究仍未得到探索。在这里，我们合成了两种 π 扩展的香豆素衍生物（PC1、PC2），其中分子主链线性延伸并带有吡啶环，其中 5,7 位被芳基取代。单晶 X 射线结构分析证实了分子几何结构。我们在光谱研究中发现，由于与分子相关的旋转运动，溶液中的两种香豆素都通过电荷转移 (CT) 状态的主要辐射衰减显示出荧光。此外，在酸和碱存在下，香豆素的详细光谱分析揭示了溶液中的酸致变色特性。基于PC1的酸碱传感特性，我们可以展示其作为固态酸碱蒸汽传感器和防伪剂的用途。