Study On Acenaphthopyrazine Fluorescent Probe For Polarity And Naphthalimide Fluorescent Probe For Cu~Ⅱ

The mechanism of fluorescent probe and nature of common fluorophore are introduced in this paper. Three series of fluorescent molecular probes have been designed and synthesized based on the former studies of our research group.Probe A (3-(N-butyl amino)-acenaphtho[1,2-b] pyrazine-8,9-dicarbonitrile) and probe B (3-(diethylene glycol amino)-acenaphtho[1,2-b] pyrazine-8,9-dicarbonitrile), a new kind of polar fluorescent probe based on ICT mechanism, were synthesized from acenaphthylene-1,2-dione via bromization, cyclization, and SnArH reaction. The fluorescence intensity of the probes significantly reduces with the increase of the polarity of solvents. The fluorescence quantum yield of probe A decreases more than600-fold from tetrachloromethane(φf=0.3642) to acetonitrile(φf=0.0006) and the maximum emission intensity red-shifts118nm from533nm in tetrachloromethane to651nm in N,N-dimethylformamide. Probe B, a kind of ratiometric fluorescent probe, has two emission peaks. With the increase of solvent polarity, the fluorescence intensity of one peak(500nm) is basically constant, while the fluorescence intensity of another peak reduces significantly and red-shifts69nm from539nm in tetrachloromethane to608nm in tetrahydrofuran. Based on that, a method of ratiometric fluorescence analysis to determinate water content in tetrahydrofuran and1,4-dioxane was proposed.Amide-DPA metamorphous acceptor fluorescent probe C based on PET mechanism was designed and synthesized, and the acenaphtho[1,2-b] pyrazine probe in solid state emits yellow fluorescence. Probe C is bound to lead ion (Ⅱ) in ratio of1:1with the fluorescence intensity increasing by22-fold and color of the solution became lighter. Probe C is recognized as an off-on probe for lead ion based on PET mechanism.A kind of naphthoylimine fluorescent probe E was synthesized from o-bromonitro-benzene via three steps including SnArH, reduction and Buchwald-Hartwig reaction. During spectrum measurement for metal ions, the Cu(Ⅱ) ion is speciallly recognized by probe E, which can realize two-channel detection and is regarded as a ratiometric fluorescent probe with high performance for Cu(Ⅱ) ion. Two recognization models are inferred here. On the one hand, under low concentration of Cu(Ⅱ) ion or short reaction time, fluorescence recovers and emission wavelength blue-shifts to433nm, which may stem from Cu(Ⅱ) ion decreasing the electron donating capacity of4-amino group conjugated with naphthoylimine and hindering PET effect of non-conjugated amino group. On the other hand, under high concentration of Cu(Ⅱ) ion or long reaction time, the emission wavelength red-shifts to520nm, which may come from Cu(Ⅱ) ion causing deprotonation of conjugated amino to increase the electron donating capacity.