Solvent‐controlled Novel Cu+ and Cu+/2+ Fluorescent "Turn‐ON" Probing. (23rd December 2015) - Ha, Yonghwang
Abstract : Abstract : A novel Schiff base probe, carbamoyl salicylimine benzothiazole hydrazine, was prepared and measured for its probing ability. High sensitivity was shown for Cu + and Cu 2+ . When solvent polarity was regulated through a combination of H2 O and acetonitrile, selective sensing of Cu + or the total amount of Cu + and Cu 2+ was possible. In addition, a linear hypsochromic fluorescent shift of about 30 nm was shown. A binding stoichiometry of 1:1 exists at low concentration. Time‐dependent emission measurement showed an exponential decay curve (τ1 = 2.99 × 10 3 s, 10 equiv of Cu + ) and a linear decay line (slope = –0.0216, 5 equiv of Cu + ). Interference experiments in 50% acetonitrile in H2 O showed that the emission produced by Cu + and Cu 2+ was not disturbed by other metal ions or by acidity or basicity. Peroxynitrite changed the emission trends; Cu + emission decreased (78%) and Cu 2+ fluorescence increased (28‐ fold ). Biothiols, l ‐cysteine, dl ‐homocysteine, reduced glutathione, and N ‐acetyl‐l ‐cysteine affected the complete reversibility of Cu + ‐induced emission in 50% (v/v) acetonitrile in H2 O, relative to partial reversibility of Cu 2+ emission. Thus, by regulating the ratio between acetonitrile and H2 O, Cu + and Cu +/2+ can be probed selectively.