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摘要
2-{[4-(Thiazol-2-ylsulfamoyl)-phenyl]-hydrazono}-malonic acid diethyl ester (R1) and 2-{[4-(5-methyl-isoxazol-3-ylsulfamoyl)-phenyl]-hydrazono}-malonic acid diethyl ester (R2) were synthesized through diazocoupling of sulfathiazole and sulfamethoxazole, respectively, with diethyl malonate. They were characterized through various spectroscopic and mass spectral studies. R2 was also characterized through a single crystal X-ray diffraction (XRD) study. Only R1 selectively recognized Hg2+ from a wide range of metal ions through naked-eye change. A color change from orange to olive green was observed upon addition of 1.0 equivalent of Hg2+ as its chloride salt to the 1 x 10(-3) M DMSO solution of R1. The role of DMSO in the sensing process appears to be the crucial one, because the solvent-assisted band of R1 at 482 nm observed in its UV-Vis spectrum in DMSO did not appear in its spectra recorded in nujol or in a polar aprotic solvent. The UV-Vis and H-1 NMR titrations revealed that the formation of six-membered 1: 1 chelate between R1 and Hg2+ triggering the desolvation of R1 as the key step towards its sensing activity. The determination of binding stoichiometry between R1 and Hg2+ along with binding constant has also been discussed.
Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.
- 出版日期2011
