Spectroscopic studies on a ‘turn-on’ fluorescent sensor for transition metals with selective ‘turn-off’ for mercury(II) ions

Abstract

Spectroscopic studies on a dansyl-based fluorescent sensor N-(4-aminophenyl)-5-(dimethylamino)naphthalene-1-sulphonamide (1) and its interactions with transition metals are reported. The sensor's absorption and emission spectra exhibited different profiles at different polarities and pH values. Enhanced fluorescence was observed in the presence of chromium(III) ions in methanol, while the emission was quenched significantly in the presence of mercury(II) ions both in methanol and aqueous solution. The binding constants of 1 to chromium(III) in methanol and to mercury(II) ions in methanol and aqueous solution were calculated.

Keywords:

• fluorescent sensors
• dansyl fluorophores
• transition metals detection
• Cr(III) detection
• Hg(II) detection

Acknowledgements

This work was supported by the FRG07-002 grant of the American University of Sharjah, UAE. The authors are grateful for the help of Dr Bilal Kaafarani at AUB, Lebanon, and Dr Luke Leman at TSRI, USA.