Highly selective colorimetric and fluorescent detection for Hg2+ in aqueous solutions using a dipeptide-based chemosensor†
Abstract
A peptidyl chemosensor (1) showed sensitive colorimetric and fluorescent responses to Hg2+ and Ag+ among 16 metal ions in aqueous solutions. 1 detected sensitively Hg2+ and Ag+ by color change with a red shift of the maximum absorbance band at 452 nm; a red color for Hg2+ and an orange color for Ag+. Furthermore, 1 showed a highly selective colorimetric response to Hg2+ among 16 metal ions in aqueous solutions containing NaCl. The selective colorimetric detection of Hg2+ was not interfered by other metal ions. About 2 equiv. of Hg2+ was enough for the saturation of color and fluorescent change of 1 in aqueous solutions. The dissociation constant for Hg2+ was 2.4 × 10−10 M2 (R2 = 0.993) and the detection limit for Hg2+ was 25.6 nM (R2 = 0.994). The binding mode of 1 with Hg2+ ions was proposed on the basis of the results of pH titration experiment, NMR titration experiment, and mass spectrometry.