A Cyclam-Based Fluorescent Ligand as a Molecular Beacon for Cu2+ and H2 S Detection (original) (raw)

A pentadentate cage-like cyclam-based fluorescent ligand has been designed, synthesized and characterized by monodimensional and bidimensional NMR analysis. To further characterize the title ligand ESI-MS, Uv-vis and fluorescence experiments have been also performed. Its suitability as a chemosensor for the detection of Cu 2+ ions has been successfully explored via a variety of spectroscopic techniques (i.e. ESI-MS, Uv-vis and fluorescence). The Job's plot experiment together with the ESI-MS experiments indicate a 1:1 stoichiometry for the binding of Cu 2+ to the cyclam-based ligand. Fluorescence experiments corroborate this hypothesis. The system resulted selective in the recognition of copper and stable for a week, as assessed via fluorescence spectroscopy. The Cu(II) complex has been isolated and tested as a fluorescent probe for the detection of H 2 S. NMR and ESI-MS investigation provided evidence that H 2 S recognition occurs via a copper displacement mechanism, as reported in the literature for different copper complexes. The system functions with a selective response to HSharnessing a concentration-dependent 'turnon' of the initial fluorescence intensity.