Chemosensors Research Papers - Academia.edu (original) (raw)

A novel, optical rhodamine-2-chloronicotinaldehyde-type chemosensor (R6CN) was designed, synthesized and characterized as a reversible switch. R6CN displayed high selectivity toward Al 3+ from various metal ions, including Al 3+ , Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , Hg 2+ , Pb 2+ and the resultant complex [R6CN-Al 3+ ]. The ring-opening mechanism of the rhodamine spirolactam was induced by Al 3+ binding, and the 1:1 stoichiometric structure between R6CN and Al 3+ was adequately supported by the Job-plot evaluation, optical titration, FT-IR and 1 H NMR results. Theoretical calculations and modeling simulations were performed using Material Studio 4.3 suite (VAMP), and the results supported the formation of a 1:1 complex between R6CN and Al 3+. The fluorescence quantum yield of R6CN-Al 3+ (˚ f = 92.33%) was very high compared to that of the bare ligand. The detection limit for Al 3+ was 4.28 × 10 −9 M, and a significant color change from almost colorless to pale-pink occurred in the presence of Al 3+. In turn, the R6CN-Al 3+ complex acted as a selective chemosensor toward N 3 − among various anions, including F − , Cl − , Br − , I − , NO 3 − , CH 3 COO − , ClO 4 − , CN − , SCN − , HSO 4 − , HPO 4 − and PF 6 − , in acetonitrile media. Moreover, the R6CN-Al 3+ complex also exhibited a high selectivity and sensitivity toward the azide anion upon the addition of Al 3+ , and the color reversed back to colorless when the two ions were present together in solution. At last, R6CN was productively applied to the PEGDMA polymer to sense Al 3+ ions, which was analyzed using FT-IR, fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.