The strong light absorption behavior and high emission property of porphyrins and their derivatives permit the potential detection of various transition metal ions through binding to the porphyrin core. Here in we report the colorimetric and fluorescent enhancement and fluorescent turn-off detection of Sn²⁺, Zn²⁺ and Cu²⁺ by using a simple water-soluble porphyrin (TPPS) as molecular sensor. The porphyrin sensor displayed different electronic absorption pattern, fluorescent emission behavior and color change up on interacting with Sn²⁺, Zn²⁺ and Cu²⁺ in aqueous solution at room temperature. Interestingly, TPPS showed higher selectivity toward Cu²⁺ than Sn²⁺ and Zn²⁺ ions. Treating aqueous solution of TPPS with a mixture of Sn²⁺ and Zn²⁺ ions showed better selectivity for Sn²⁺ than Zn²⁺ ion. On the other hand, the electronic absorption pattern and emission behavior of TPPS showed no change at all up on addition of aqueous solution of the rest cations under study (Co²⁺, Ca²⁺, Na⁺, Ag⁺, Mn²⁺, Pb²⁺, Fe³⁺, Cd²⁺, Ni²⁺, NH₄⁺). This may be attributed to unique electronic behavior of the metal ion and ionic radius. The study shows the possibility of molecular based selective metal ion detection in aqueous solution. The selectivity and fluorescence on-off detection may be attributed to the size of metal ions to easily incorporate into porphyrin core, paramagnetic nature of metal ions, conformational rigidity after complexation and inhibition of PET (Photoinduced Electron Transfer) quenching pathways. The study has been successfully applied to effective detection of metal ion from discharged tannery effluent collected from Bahir Dar Tannery before treatment.

卟啉及其衍生物的强光吸收性能和高发射性质允许通过结合到卟啉核上而潜在地检测各种过渡金属离子。本文中，我们报告了使用简单的水溶性卟啉（TPPS）作为分子传感器对Sn 2 ⁺，Zn ²⁺和Cu ²⁺进行比色和荧光增强以及荧光关闭检测。卟啉传感器在室温下与水溶液中的Sn 2 ⁺，Zn ²⁺和Cu ²⁺相互作用时表现出不同的电子吸收模式，荧光发射行为和颜色变化。有趣的是，TPPS对Cu ^2+的选择性高于对Sn的选择性²⁺和Zn ²⁺离子。用Sn ²⁺和Zn ²⁺离子的混合物处理TPPS的水溶液显示对Sn ^2+的选择性比Zn ²⁺离子更好。另一方面，所研究的其余阳离子的水溶液（Co 2 ⁺，Ca 2 ⁺，Na ⁺，Ag ⁺，Mn ²⁺， Pb 2 ⁺，Fe ³⁺，Cd 2 ⁺，Ni 2 ⁺，NH ₄ ⁺）。这可能归因于金属离子和离子半径的独特电子行为。研究表明在水溶液中基于分子的选择性金属离子检测的可能性。选择性和荧光开-关检测可归因于易于掺入卟啉核中的金属离子的大小，金属离子的顺磁性，络合后的构象刚度以及抑制PET（光致电子转移）猝灭途径。该研究已成功地应用于有效地检测处理前从Bahir Dar制革厂收集的制革废水中的金属离子。