Sulfonamide-imines as selective fluorescent chemosensors for the fluoride anion.
Two new sulfonamide-type fluorescent chemosensors in organic media are reported. The two receptors, [N,N'-bis(2-tosylaminobenzylidene)-1,2-diaminoethane and N,N'-bis(2-tosylaminobenzylidene)-1,3-diamino-2-propanol], display marked changes in the fluorescence emission intensities as a result of deprotonation by basic anions, and show high selectivity for fluoride over other inorganic anions, such as acetate or dihydrogenphosphate. These results suggest that the presence of the imine group as an intramolecular H-bond acceptor enhances the selectivity of these sensors compared to previous examples in the literature. The deprotonation mechanism has been demonstrated by spectrophotometric and spectrofluorimetric titrations as well as by NMR spectroscopy. The X-ray structures of both receptors are also discussed.
López
Miguel Vázquez
MV
Departamento de Química Inorgánica, Facultad de Química, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain. miguel.vazquez.lopez@usc.es
Bermejo
Manuel R
MR
Vázquez
M Eugenio
ME
Taglietti
Angelo
A
Zaragoza
Guillermo
G
Pedrido
Rosa
R
Martínez-Calvo
Miguel
M
D000097:Acetonitriles / Q000737:chemistry; D018360:Crystallography, X-Ray; D005456:Fluorescent Dyes / Q000737:chemistry*; D005459:Fluorides / Q000032:analysis* / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D013379:Substrate Specificity; D013449:Sulfonamides / Q000737:chemistry*
D000097:Acetonitriles; D005456:Fluorescent Dyes; D007097:Imines; D013449:Sulfonamides; D005459:Fluorides; C032159:acetonitrile