We report on the synthesis and characterization of trans N, N'-di-substituted macrocyclic "tet a" probe (L) for metal ion sensing. Both the colorimetric and fluorescent titration studies are performed with different metal ions. The results have suggested that the probe L is very selective and sensitive towards Zn2+ ions with significant changes in color. The pendant armed macrocyclic "tet a" probe has exhibited 1.28× 105 M-1 binding constant and virtuous selectivity for Zn2+ ion than other common metal ions. The detection limit of the probe towards Zn2+ ion is 0.027 nM. The selective sensing of Zn2+ ion is efficiently reversible with EDTA, which is demonstrated for five cycles without losing sensitivity. The time-resolved single-photon counting (TCSPC) studies have determined the average lifetime value for the probe L and L+ Zn2+ ion of 1.29 and 2.96 ns, respectively. The theoretical DFT studies have well supported the experimental outcomes. The practical application of the probe in visualizing intracellular Zn2+ ion distribution in live Artemia salina has proved the low cytotoxicity and cell membrane permeability of probe, which makes it capable of sensing Zn2+ ion in HeLa cells. Thus, the probe L can act as a selective recognition of Zn2+ ion in living cell applications.

中文翻译：

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Zn2 +离子的比色和荧光传感及其基于大环“ tet a”衍生物的生物成像应用。

我们报告了反式N，N'-二取代大环“ tet a”探针（L）的合成和表征，用于金属离子传感。比色和荧光滴定研究均使用不同的金属离子进行。结果表明，探针L对Zn2 +离子具有很高的选择性和敏感性，并且颜色显着变化。悬臂式大环“ tet a”探针与其他常见金属离子相比，具有1.28×105 M-1的结合常数和对Zn2 +离子的良好选择性。探针对Zn2 +离子的检出限为0.027 nM。EDTA可以有效地逆转Zn2 +离子的选择性感测，这在不降低灵敏度的情况下进行了五个周期的验证。时间分辨单光子计数（TCSPC）研究已确定探针L和L + Zn2 +离子的平均寿命值分别为1.29 ns和2.96 ns。DFT理论研究很好地支持了实验结果。该探针在可视化卤虫活细胞中细胞内Zn2 +离子分布中的实际应用已证明，该探针具有较低的细胞毒性和细胞膜通透性，使其能够感应HeLa细胞中的Zn2 +离子。因此，探针L可以在活细胞应用中充当Zn2 +离子的选择性识别。该探针在可视化卤虫活细胞中细胞内Zn2 +离子分布中的实际应用已证明，该探针具有较低的细胞毒性和细胞膜通透性，使其能够感应HeLa细胞中的Zn2 +离子。因此，探针L可以在活细胞应用中充当Zn2 +离子的选择性识别。该探针在可视化卤虫活细胞中细胞内Zn2 +离子分布中的实际应用已证明，该探针具有较低的细胞毒性和细胞膜通透性，使其能够感应HeLa细胞中的Zn2 +离子。因此，探针L可以在活细胞应用中充当Zn2 +离子的选择性识别。