1. Bis(2-pyridylmethyl)amine-functionalized alizarin: an efficient and simple colorimetric sensor for fluoride and a fluorescence turn-on sensor for Al3+ in an organic solution.
- Author
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Zhu, Ling, Bai, Yue-Ling, Zhao, Yongmei, Xing, Feifei, Li, Ming-Xing, and Zhu, Shourong
- Subjects
ALKALINE earth metals ,ALIZARIN ,FLUORESCENCE ,MANNICH reaction ,NUCLEAR magnetic resonance spectroscopy ,DETECTORS - Abstract
A complexone analog chemosensor, H
2 L, bearing chelating bis(2-pyridylmethyl) amine and alizarin groups was synthesized via the Mannich reaction. H2 L chromically responds to OH− , F− , CH3 COO− , and H2 PO4 − in DMF, CH3 CN, and acetone, but not in CH3 OH or H2 O. The addition of F− ions to H2 L selectively induces a significant and visible color change in acetonitrile and shifts both methylene proton signals upfield. H2 L also exhibits visible responses to Mg2+ , Sr2+ , Ba2+ , Tb3+ , Cu2+ , Co2+ , Ni2+ , Zn2+ , Mn2+ , Cd2+ , and Fe3+ in solution. AlCl3 can form an Al : L = 2 : 3 complex that not only changes the color of the DMF solution, but also significantly increases its fluorescence intensity. The limit of fluorescence turn-on detection for AlCl3 in DMF is 2.7 × 10−8 M, which is an order higher than those of other anthraquinone sensors reported in the literature. NMR spectroscopy shows that hydroxyl is not deprotonated upon interacting with Al3+ , but will be partially deprotonated in the presence of Zn2+ . Contrary to the complexone, the H2 L–Ce(iii) complex does not react chromically to F− . However, the H2 L–NiCl2 complex responds chromically to F− , with higher sensitivity (LOD = 1.3 × 10−6 M F− in acetonitrile) than free H2 L. The spectral changes in the presence of F− are similar to that of OH− ; however, the spectrum shifts slightly to a longer wavelength and is more sensitive to both H2 L and the H2 L–NiCl2 complex. Moreover, 4% or less H2 O in the solvent essentially has no influence on the F− sensitivity; however, high water content significantly decreases the F− sensitivity. The spectral changes of the Zn2+ , Cu2+ , Fe3+ , Ce3+ , and Ni2+ complexes in the presence of different NaOH concentrations were also investigated. [ABSTRACT FROM AUTHOR]- Published
- 2019
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