An off-on chemosensor for Hg2+ based on the excimer emission of anthracene

Abstract A quinazoline derivative 6-anthracenyl-5,6-2H-benzimidazo[1,2- c ]quinazoline (L) was obtained and characterized by elemental analysis, IR spectroscopy, 1 H NMR and single-crystal X-ray diffraction. L shows very weak emission in DMSO, but can respond to Hg 2+ ion intensively in off-on mode. Job's plot and titration experiments show that Hg 2+ ion binds L in 1:1 stoichiometry. The detection limit for Hg 2+ is 6.34 μM. 1 H NMR titration experiments indicate that only one benzimidazo nitrogen atom coordinates with Hg 2+ . And the fluorescence emission spectra imply that an excimer formed in the Hg 2+ -L system, and the detection of Hg 2+ was realized by excimer emission of anthracene moiety.