Herein, a novel notion is used to reuse an expired drug namely Telmisartan (Sensor 2) to optically sense the Fe³⁺ metal ion. Direct re-usage of the drug avoided wearisome procedures of synthesis, hence proved the method as simple and economic. Sensor 2 found highly stable in the temperature range 25–75 °C. Relative fluorescence was almost the same even after 35 days of observation. There were no significant changes in wavelength even after adding different concentrations of FeCl₃, which shows the high stability of the compound. The value of Limit of Detection (LOD) observed was 34.2 nM. FTIR studies confirmed the presence of carboxylic group. The method of fluorescence quenching was used to detect the Fe³⁺ ion. The association between Sensor 2 and Fe³⁺ was analyzed using Benesi-Hildebrand relation. Positive deviation from the linearity of S-V plots suggested that the quenching was not purely dynamic. Further, this deviation was analyzed by the sphere of action quenching model. To investigate whether the quenching is diffusion limited, we applied the finite sink approximation model and deduced that quenching is due to both static and dynamic processes. Due to the high fluorescence property of the molecule, it was successfully tested to be used as fluorescent ink.

中文翻译：

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废药的再利用作为 Fe3+ 离子的分子化学传感器：在荧光墨水中的应用。

在此，一个新的概念被用于重复使用过期药物即替米沙坦（传感器 2）来光学检测 Fe ³⁺金属离子。该药物直接重复使用，避免了繁琐的合成程序，证明该方法简单、经济。发现传感器 2 在 25–75 °C 的温度范围内高度稳定。即使在观察 35 天后，相对荧光也几乎相同。_{即使加入不同浓度的FeCl 3} ，波长也没有明显变化，说明该化合物具有较高的稳定性。观察到的检测限 (LOD) 值为 34.2 nM。FTIR 研究证实了羧基的存在。采用荧光猝灭法检测Fe ³⁺离子。传感器 2 和 Fe 之间的关联³⁺使用 Benesi-Hildebrand 关系进行分析。与 SV 图线性的正偏差表明淬火不是纯粹动态的。此外，通过作用淬火模型的球体分析了这种偏差。为了研究淬火是否受扩散限制，我们应用了有限汇近似模型并推断淬火是由于静态和动态过程引起的。由于该分子具有高荧光性，被成功测试用作荧光油墨。