A water-stable pyridine bisphosphonate-based metal–organic framework as a selective and sensitive luminescent probe for Cr(VI) ions and acetone

Abstract

A rare photoluminescent nitroxide pyridine bisphosphonate-based metal–organic framework, [Eu₄(L)₃(H₂O)₆]_n (1) [H₄L = 2,6-bis(phosphonomethyl)pyridine 1-oxide], was prepared under hydrothermal conditions and has a 3D supramolecular structure built from phosphonate linkers bridging Eu³⁺. It was characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), thermogravimetric analyses (TGAs), etc. The luminescence spectra of 1 show the strong characteristic luminescence of Eu³⁺ ions, and 1 shows high water stability, thermal stability, and chemical stability. Furthermore, luminescence studies have shown that 1 can be used as a fluorescent probe for detecting trace amounts of Cr(VI) ions and acetone in water samples with excellent sensitivity, great selectivity, and reproducibility. The detection limits are as low as 0.61 μM, 0.63 μM, and 0.0066 vol% for Cr₂O₇^2-, CrO₄^2-, and acetone, respectively. The fluorescence quenching of 1 by Cr(VI) ions and acetone may be due to spectral overlap and absorption competition. This is the first example of a Eu-based pyridine phosphonate fluorescence sensor for simultaneous detection of Cr(VI) ions and acetone.

Graphical Abstract

Keywords:

• Metal–organic framework
• Cr(VI) ions
• acetone
• fluorescence sensor

Supplementary data

CCDC 1969982 contains the supplementary crystallographic data for 1. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: [phone]; or E-mail: [email protected].

Acknowledgements

This work was supported by Two-Way Support Programs of Sichuan Agricultural University, China (Nos. 0351921993070 and 0352021993083).

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.