Dynamic of the fluorescence of the complex Zn⁺⁺/bis-N- carbazolyl-distyrylbenzene

The discrimination between similar concentrations of the different metal ions is one of the important roles of fluorescent sensors. Here we present the study of the fluorescence dynamic of the chromophore bis-N-carbazolyl- distyrylbenzene (BCDSB) in acetonitrile/water (mmol/L), doped with metal ions such as K⁺; Ca⁺⁺; Mg⁺⁺; Zn⁺⁺(10 μmol/L). BCDSB has the fluorescence with λ_max, at 448 nm by excitation at λ_exc = 378 nm, lifetime 1.089 ns; quantum yield of the fluorescence is 0.68. With continuation of irradiation fluorescence quenching has been registered for all investigated metal ions. However, in the presence of Zn⁺⁺ oscillation of the intensity was observed. The energy activation of the oscillation as much as 15 kcal/mol was estimated. We believe, that the specificity of the complex Zn⁺⁺/BCDSB, is in an asymmetrical structure, formed via binding sites of Zn⁺⁺ with the electron-enriched binding sites of the BCDSB, excited in nπ* state. This asymmetrical complex structure can cause the photoinduced structural fluctuation in the complex coordination. fluorescent sensors; bis-N-carbazolyl-distyrylbenzene; Zn⁺⁺; oscillating quenching.