On the synthesis and performance of a simple colorimetric and fluorescent chemosensor for Cu2+ with good reversibility.

ABSTRACT

A colorimetric and fluorescent chemosensor (CS1) for Cu2+ based on the mechanism of internal charge transfer (ICT) has been successfully designed and prepared by simple condensation of 4_(diethylamino)salicylaldehyde and oxalyl dihydrazide. Cu2+ in solution (DMSO/H2O = 73, v/v) by 5 mM NaAc-HAc at pH 7.0 was determined through dual channels (1) "naked-eye" observation, a visually dramatic color change from light green to orange, which can be used for qualitative determination of Cu2+; (2) spectrofluorometry, which can quantificationally assay Cu2+. It provides a simple-to-use platform for reliable detection of Cu2+ at concentrations ranging from 5.0 × 10-7 to 1.1 × 10-5 M with detection limit of 1.2 × 10-7 M, which is nearly 2 × 102 times lower than the maximum allowable level of inorganic Cu2+ in drinking water (1.3 ppm, ∼20 µM) permitted by the EPA (Environmental Protection Agency), and the sensing detection of Cu2+ ions was reversible.