Spectroscopic properties of an amphiphilic naphthalimide derivative with high surface activity and detection of trace salt in the water as a fluorescent sensor

Abstract

A novel amphiphilic fluorescent sensor bearing high surface activity, 4-(3-Dimethyl-benzyl propylamine ammonium)-N-dodecyl-1,8-naphthalimide chloride (DADNC), has been designed and used to rapidly detect trace salt in the pure water as an “on-off” fluorescent sensor. The surface activity and high sensitivity to trace salt ions and organic contaminants were measured. The average particle sizes of the molecular micelles of DADNC were 31–55nm in diameter. The fluorescence of DADNC is highly sensitive to trace salt ions and ionic organic contaminants. The aggregation and disintegration of DADNC in the presence of ionic micelles showed sensitive “on-off-on” fluorescence switching. There were good linear relationships between its fluorescence intensities and the salt concentrations at very low salt concentrations from 1×10^−8 to 1×10^−5mol/L. This system could be used as an “on-off” fluorescence sensor for the detection and the quantitative determination of ionic substrate or anionic organic compounds at ultralow ion concentration. It has potential applications in the recognition and detection of the trace amounts of the salt ions and organic contaminants in the drinking water and pure water.