A Highly Selective and High-Contrast Colorimetric "Off-On" Chemosensor for Cu2+ Based on Boron-Dipyrromethene (BODIPY) Derivatives

Based on the platform of boron-dipyrromethene (BODIPY) derivatives, a fluorescence turn-on probe BDP-2Z was rationally designed and synthesized with good water-solubility. With high sensitivity and selectivity for Cu2+ over other competitive ions, the reaction-based probe showed low detection limit and fast response in a wide pH range (pH=3.0 similar to 12.0). The contrast of color and fluorescence caused by Cu2+ was remarkable so much so that it was easily to distinguish Cu2+ from other ions with naked-eye detection. Along with adding of Cu2+, a blue shift of maximum absorption was observed from 548 nm to 496 nm, the corresponding solution color changed obviously from purple to light orange, and the fluorescence is enhanced by nearly 5-fold. Furthermore, the recognition mechanism was confirmed by UV-Vis, fluorescence spectra, and mass spectral analysis. The identified product of recognition process was even obtained by original silica gel column chromatography separation method. Also, the rapidly naked-eye application in real water samples provides an alternative to extension environmental detection.