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1,4-Bis(2-(pyridin-4-yl)vinyl)naphthalene and Its Zinc(II) Coordination Polymers: Synthesis, Structural Characterization, and Selective Luminescent Sensing of Mercury(II) Ion

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journal contribution
posted on 2017-05-19, 00:00 authored by Wu-Xiang Li, Hong-Xi Li, Hai-Yan Li, Min-Min Chen, Yi-Xiang Shi, Jian-Ping Lang
Solvothermal reactions of Zn­(NO3)2­·6H2O with 1,4-bis­(2-(pyridin-4-yl)­vinyl)­naphthalene (1,4-bpyvna) and 1,3,5-benzenetricarboxylic acid (1,3,5-H3BTC) (molar ratio = 1:1:1) at 120 °C in CH3CN/H2O (v/v = 1:2) afforded one three-dimensional (3D) coordination polymer [Zn2(1,4-bpyvna)­(1,3,5-HBTC)2­(H2O)]n (1). Similar reactions with the same three components at 140 °C in dimethylformamide (DMF)/CH3CN/H2O produced another 3D coordination polymer {[Zn2(1,4-bpyvna)­(1,3,5-BTC)­(OH)]·H2O}n (2) in 72% yield. When the molar ratio of Zn­(NO3)2­·6H2O, 1,4-bpyvna, and 1,3,5-H3BTC was changed to 1:1:2, the analogous treatment at 140 °C yielded one one-dimensional coordination polymer {[Zn­(1,3,5-HBTC)2­(H2O)]­[1,4-bpyvna-H2]­·CH3CN}n (3, 1,4-bpyvna-H2 = 4,4′-((1,1′)-naphthalene-1,4-diylbis­(ethene-2,1-diyl))­bis­(pyridin-1-ium)). Solvothermal reactions of Zn­(NO3)2·6H2O with equimolar 1,4-bpyvna and 1 or 2 equiv of 4,4′-oxidibenzoic acid (4,4′-H2OBA) at 120 °C in DMF/CH3CN/hexane resulted in the formation of {[Zn2(1,4-bpyvna)­(4,4′-OBA)2]­·0.5DMF­·2.25H2O}n (4) and {[Zn2(1,4-bpyvna)­(4,4′-OBA)2]­·3DMF}n (5), respectively. Compounds 15 were characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, single-crystal X-ray diffraction, and thermogravimetric analysis. Upon addition of Hg2+ ions to the DMF solution of 1,4-bpyvna, remarkable changes in the absorbance and emissive spectra were observed, associated with color changes, which were easily identified by the naked eye. This ligand could serve as a chemoprobe with the detection limit of Hg2+ being 0.060 ppm. When solid 2 was added in the DMF solution containing Hg­(NO3)2, the emission color of 2 was also changed from blue to yellow, and its detection limit of Hg2+ was as low as 0.057 ppm. This compound can be reused for several cycles without evident efficiency decay. Compound 2 would be a promising sensitive naked-eye indicator for low-concentration Hg2+ with high sensitivity and selectivity.