Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India.
Dalton Trans. 2018 Oct 23;47(41):14696-14705. doi: 10.1039/c8dt03058h.
A Zr(iv) based luminescent metal-organic framework (MOF; 1) was synthesized by a solvothermal method using a mixture of ZrCl4, quinoline-2,6-dicarboxylic acid (H2QDA) ligand and trifluoroacetic acid (modulator) having a 1 : 1 : 10 molar ratio in N,N-dimethylformamide (DMF). For activation, the methanol-exchanged sample was heated under high vacuum at 120 °C for 1 day. Different techniques like X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy and energy dispersive X-ray (EDX) analysis were applied to fully characterize 1. The activated form of 1 (called 1') has the formula [Zr6O6(OH)2(CF3COO)2(C11H5NO4)4(H2O)4]. It exhibited quick response and great selectivity for the fluorimetric sensing of 4-nitrophenol (4-NP) in acetonitrile and Fe3+ ions in water. The probe maintained its high selectivity for 4-NP and Fe3+ ions even in the presence of potentially intrusive nitroaromatics and metal ions, respectively. The detection limits for 4-NP and Fe3+ were found to be 1.40 ppt and 0.71 ppb, respectively. These values are the lowest among the existing MOF probes for Fe3+ and 4-NP. The electron and energy transfer processes along with the electrostatic interactions of 4-NP with the MOF can be the possible reasons for the selectivity for 4-NP. The fluorescence resonance energy transfer (FRET) process can be the major reason behind the quenching mechanism for Fe3+ ions. The recyclability test indicates that 1' is a promising probe for the long-term detection of 4-NP and Fe3+ ions.
一种基于 Zr(iv) 的发光金属-有机骨架（MOF；1）通过溶剂热法合成，使用 ZrCl4、喹啉-2,6-二羧酸（H2QDA）配体和三氟乙酸（调节剂）的混合物，摩尔比为 1:1:10，在 N,N-二甲基甲酰胺（DMF）中。为了活化，将甲醇交换的样品在 120°C 下在高真空下加热 1 天。应用了不同的技术，如 X 射线粉末衍射（XRPD）、热重分析（TGA）、傅里叶变换红外（FT-IR）光谱和能量色散 X 射线（EDX）分析，以充分表征 1。1 的活化形式（称为 1'）的化学式为[Zr6O6(OH)2(CF3COO)2(C11H5NO4)4(H2O)4]。它在乙腈中对 4-硝基苯酚（4-NP）的荧光传感和水中的 Fe3+离子表现出快速响应和高选择性。即使存在潜在干扰的硝基芳烃和金属离子，探针也能保持对 4-NP 和 Fe3+离子的高选择性。4-NP 和 Fe3+的检测限分别为 1.40 ppt 和 0.71 ppb，这是现有 MOF 探针中对 Fe3+和 4-NP 的最低检测限。电子和能量转移过程以及 4-NP 与 MOF 的静电相互作用可能是对 4-NP 选择性的原因。荧光共振能量转移（FRET）过程可能是 Fe3+离子猝灭机制的主要原因。可重复使用性测试表明，1'是一种有前途的探针，可用于长期检测 4-NP 和 Fe3+离子。
