Abstract A series of heteroaromatic azomethines containing phenyl, pyridine, thiophene or furan ring and ortho-catenated triphenylamine (TPA) core was synthesized and used to investigate the effect of the structural variation on opto-electronic and acid-sensing properties. The twisted structure induced by the TPA core enabled good solubility in organic solvents, including chloroform, acetone or ethyl acetate. Meanwhile, they preserved good thermal stability and showed high glass transition temperatures. The modulation of optical and electronic properties of azomethines was most likely due to two effects: the degree of coplanarity induced by the heterocyclic moiety and the electronic effect of the π-rich heterocycle that is electron-withdrawing (pyridine) or electron-acceptor (thiophene and furan). A detailed study was accomplished with respect to the acid recognition capability promoted by the electronic and basicity character of the azomethine center. The spectroscopic and electrochemical responses to acid environment were followed by cyclic voltammetry, FTIR, fluorescence and UV–vis spectroscopy. Different spectral changes occurred when doping was performed with hydrochloric and trifluoroacetic acids. The sensing properties toward the environmental pH modification were mostly accompanied by fluorescence quenching and driven by different recognition principles with respect to the acid dopant type.

中文翻译：

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含有三苯胺单元的新型杂环共轭偶氮甲碱对酸性环境具有光学和电化学响应

摘要 合成了一系列含有苯基、吡啶、噻吩或呋喃环和邻联三苯胺（TPA）核的杂芳族偶氮甲碱，并用于研究结构变化对光电和酸传感性能的影响。TPA 核诱导的扭曲结构使其在有机溶剂中具有良好的溶解性，包括氯仿、丙酮或乙酸乙酯。同时，它们保持良好的热稳定性并显示出高玻璃化转变温度。偶氮甲碱的光学和电子特性的调节最有可能是由于两种效应：杂环部分诱导的共面度和吸电子（吡啶）或电子受体（噻吩）的富 π 杂环的电子效应和呋喃）。对偶氮甲碱中心的电子和碱性特征促进的酸识别能力进行了详细研究。对酸性环境的光谱和电化学响应随后是循环伏安法、FTIR、荧光和紫外-可见光谱。用盐酸和三氟乙酸进行掺杂时发生了不同的光谱变化。对环境 pH 值改变的传感特性主要伴随着荧光猝灭，并由关于酸掺杂剂类型的不同识别原理驱动。荧光和紫外可见光谱。用盐酸和三氟乙酸进行掺杂时发生了不同的光谱变化。对环境 pH 值改变的传感特性主要伴随着荧光猝灭，并由关于酸掺杂剂类型的不同识别原理驱动。荧光和紫外可见光谱。用盐酸和三氟乙酸进行掺杂时发生了不同的光谱变化。对环境 pH 值改变的传感特性主要伴随着荧光猝灭，并由关于酸掺杂剂类型的不同识别原理驱动。