Two novel zinc(II) phosphonates for the selective luminescence sensing of 1,2,4-trichlorobenzene and Hg2+

Abstract

Two novel zinc(II) phosphonates, [Zn(H4L)]·2H2O (1) and [Zn(H4L)(2,2′-biim)] (2) (2,2′-biim = 2,2′-biimidazole), were synthesized based on (2,4,6-trimethylbenzene-1,3,5-triyl) tris(methylene) triphosphonic acid (H6L), via hydrothermal techniques. Structural characterization was conducted using single-crystal X-ray diffraction analyses, X-ray powder diffraction analyses (PXRD), FT–IR spectroscopy, thermogravimetric analyses (TGA) and elemental analyses (EA). Compound 1 was a 2D layered structure that exhibited high selectivity and sensitivity as a luminescent probe for the detection of polychlorinated benzene, with a very low detection limit of 8.20 × 10−7 M. Compound 2 possessed a one-dimensional chain structure that transformed into a 2D supramolecular structure through hydrogen bonding interactions. The excellent Lewis base recognition sites in 2 facilitated high sensitivity toward Hg2+ ions, with a low detection limit of 5.30 × 10−7 M. The test paper experiment showed that 2 could be made into the test paper to quickly detect Hg2+ by naked eye. Meanwhile, the probable sensing mechanisms were also discussed in this paper.