In this paper, a novel Schiff base ligand NaHL (NaHL = sodium (S,E)-2-((4-chloro-2-hydroxybenzylidene) amino) propanoate) was designed and synthesized, and three novel complexes with Zn(II) were obtained by a solvent evaporation technique. Single crystal X-ray diffraction indicated that [Zn(L)(H₂O)]_n 1 and [Zn(L)(H₂O)]_n 2 were one-dimensional coordination polymers (CPs) with a helix structure, while [Zn₂(L)₂(bipy)] 3 was a two-dimensional CP with the participation of an auxiliary ligand. Fluorescence spectra exhibited that 1 and 2 had good fluorescence properties in both solution and solid states, but 3 was basically quenched due to the addition of ancillary ligands in the solid state. Density functional theory (DFT) calculations have been performed to further reveal the intrinsic fluorescence properties and mechanisms of 1 and 2, which demonstrated the chelate fluorescence enhancement effect (CHEF). Moreover, 1 and 2 show selective recognition of NH₄⁺ and HPO₄²⁻ accompanied by an efficient fluorescence “turn off” phenomenon, and a series of related experiments demonstrate that 1 and 2 were fully quenched through the removal of Zn²⁺ from the complex and the protonation of the ligand.

中文翻译：

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锌 (II) 席夫碱配合物作为双探针检测 NH4+ 和 HPO42- 离子

本文设计合成了一种新型席夫碱配体NaHL（NaHL =( S , E )-2-((4-氯-2-羟基亚苄基)氨基)丙酸酯),并与Zn( II )形成了三种新型配合物。通过溶剂蒸发技术获得。单晶X射线衍射表明[Zn(L)(H ₂ O)] _n 1和[Zn(L)(H ₂ O)] _n 2是具有螺旋结构的一维配位聚合物(CPs)，而[Zn ₂ (L) ₂ (bipy)] 3是一个有辅助配体参与的二维 CP。荧光光谱显示，1和2在溶液和固态都具有良好的荧光特性，但3由于固态辅助配体的加入而基本猝灭。密度泛函理论 (DFT) 计算进一步揭示了1和2的内在荧光特性和机制，证明了螯合荧光增强效应 (CHEF)。此外，1和2显示选择性识别NH ₄ ⁺和HPO ₄ ^2-伴随着有效的荧光“关闭”现象，一系列相关实验表明，通过从配合物中去除 Zn ²⁺和配体的质子化， 1和2被完全淬灭。