It was previously reported that azo compounds are vigorous and chemically stable compounds and well-known chromophores. Having different chromophores, the azo dyes act as probing units for capturing the charged particles either by electron transfer or deprotonation mechanisms. The probing efficiency usually exhibits in the magnitude of variations in UV absorbance, NMR peaks and visually observed color changes. The sensing application is a prerequisite for numerous analytical techniques involved in pharmaceutical as well as pathological discipline. In the last two decades, numerous azo based sensors have been developed, which render low cost and effective sensing approaches towards ionic diagnosis through instantaneous eye beaming chromogenic change. This sensing approach is simple, cost-effective, and precise and provides reliable quantitative and qualitative statistics of an analyte present in a complex environment. Our present study culminates the recent progress on the synthesis of azo compounds and their chromogenic sensing application towards various reactive analytes through reviewing spectral variations and colorimetric observations. This review article assesses the potential of azo dyes in chromogenic sensing for different analytes. We believe this review will be of interest and important for researchers working on designing azo-based chromogenic sensors.

中文翻译：

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偶氮基显色传感器：一种肉眼检测生物相关阴离子和金属阳离子的方法

此前有报道称，偶氮化合物是一种活泼且化学稳定的化合物，也是众所周知的发色团。偶氮染料具有不同的发色团，充当探测单元，通过电子转移或去质子化机制捕获带电粒子。探测效率通常表现为紫外吸光度、核磁共振峰和目视观察到的颜色变化的变化幅度。传感应用是制药和病理学领域众多分析技术的先决条件。在过去的二十年中，已经开发了许多基于偶氮的传感器，它们通过瞬时眼睛发光显色变化为离子诊断提供了低成本和有效的传感方法。这种传感方法简单、经济高效且精确，可为复杂环境中存在的分析物提供可靠的定量和定性统计数据。我们目前的研究通过回顾光谱变化和比色观察，总结了偶氮化合物的合成及其对各种反应性分析物的显色传感应用的最新进展。这篇综述文章评估了偶氮染料在不同分析物显色传感中的潜力。我们相信这篇综述对于致力于设计偶氮基显色传感器的研究人员来说将会是有趣且重要的。