Department of Applied Chemistry, Cochin University of Science and Technology, Kochi, Kerala, 682022, India.
J Fluoresc. 2020 May;30(3):527-535. doi: 10.1007/s10895-020-02514-1. Epub 2020 Mar 17.
Porphyrins are highly conjugated molecules that perform wide variety of functions in biological systems. They absorb strongly in the visible region and they are excellent fluorophores that emit in the visible region. If the meso or β positions of porphyrins are properly substituted, emission in the NIR region is facilitated. The fluorescence property of porphyrins can be used in sensing applications. Here, we report the synthesis of a water soluble porphyrin that emits in the NIR region and this molecule is used in the fluorescent determination of cadmium ion, which is an environmental pollutant and affects the health of living organisms adversely. 5,10,15,20-tetrakis(4-hydroxy-3,5-dimethoxyphenyl)porphyrin (THMPP), which is water soluble was synthesised from 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl)porphyrin (TMPP) by partial demethylation, which in turn was synthesized by mixture acid method. The donor-acceptor interaction of THMPP-Cd system displays a dynamic fluorescence quenching through the electron transfer (ET) mechanism. Developed method showed a linear response toward Cd in the concentration range of 0.25 μM to 2 μM. The limit of detection was found to be 0.1499 μM. THMPP exhibited excellent selectivity towards Cd (II) in presence of other metal ions like Hg, Mn, Mg, Co in 1:100, Zn, Cu, Ni in 1:10 and Na, K in 1:1 M ratio.
卟啉是高度共轭的分子，在生物系统中执行多种功能。它们在可见光区域强烈吸收，是出色的荧光团，在可见光区域发射。如果卟啉的中卟啉或β位置得到适当取代，则有利于在近红外区域发射。卟啉的荧光性质可用于传感应用。在这里，我们报告了一种在近红外区域发射的水溶性卟啉的合成，该分子用于荧光测定镉离子，镉离子是一种环境污染物，会对生物体的健康产生不利影响。5,10,15,20-四（4-羟基-3,5-二甲氧基苯基）卟啉（THMPP）是一种水溶性卟啉，可通过部分脱甲基化从 5,10,15,20-四（3,4,5-三甲氧基苯基）卟啉（TMPP）合成，而 TMPP 则通过混合酸法合成。THMPP-Cd 体系的供体-受体相互作用通过电子转移（ET）机制显示出动态荧光猝灭。开发的方法在 0.25 μM 至 2 μM 的浓度范围内对 Cd 表现出线性响应。检测限为 0.1499 μM。THMPP 在存在其他金属离子如 Hg、Mn、Mg、Co（1:100）、Zn、Cu、Ni（1:10）和 Na、K（1:1）M 比时，对 Cd（II）表现出优异的选择性。
