Naked-eye fluorescent sensor for Cu(II) based on indole conjugate BODIPY dye

Abstract

A novel on/off fluorescent indole/BODIPY-based Cu2+ chemosensor (3) was synthesized by Knoevenagel condensation of BODIPY derivative 1 with 2-methyl-indole-3-carbaldehyde 2. The identity of compound 3 was confirmed by H-1 NMR, C-13 NMR, FT-IR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and single crystal X-ray diffraction techniques. Fluorescent chemosensor (3) is found to be highly selective and sensitive for detection of Cu2+ with a color change from purple to yellow. The optical sensor features for the Cu2+ complex of 3 were investigated by UV-Vis and fluorescence spectroscopy. The addition of Cu2+ caused quenching of fluorescence intensity and the detection limit was calculated to be 0.124 mu M. Also, the stoichiometry ratio of 3+Cu2+ was obtained 2:1 by Job's plot. Live cell image, flow cytometry and cytotoxic properties of compound 3 were examined. (C) 2016 Elsevier Ltd. All rights reserved.