Synthesis,Characterization Of Schiff Base Fluorescence Probes And Using For Selective Recognition Of Metal Ions

With the increase of industrialization,there are sorts of social problems arising the national attention,especially the environmental problems.The excessive metal ions in water cause harm to the environment and the health of human beings,and it will cause a series of lesions to biology.Therefore,it is significant to develop a mature and environment-friendly technology with safe and convenient operation for detecting the metal ions in the field of water environment monitoring.In numbers of metal ions detection,fluorescence probes have been widely favored by scientists because of its excellent optical properties,high sensitivity,specific coordination with the target ion and so on.Schiff bases can release fluorescence when they are coordinated with metal ions because the C=N isomerization is inhibited,so Schiff bases are deemed to the ideal substrates for synthesis of fluorescent probes.Compounds of chromone and coumarin derivatives can form stable complexes with metal ions because of their high fluorescence quantum yields.Therefore,they are always supposed to become the group of fluorescent probes.The fluorescent probes for Mg²⁺or Zn²⁺were designed and synthesized by selecting chromone and coumarin derivatives as fluorophores.The structures of the fluorescent probes were characterized by 1H-NMR,MS,and FT-IR,and their fluorescence detection performances were also studied.?1?Chromone derivative L1 was synthesized by 6-hydroxy-3-formyl-chromone and nicotinic acid hydrazide.Comparing L1 and the complex of L1 with Mg²⁺,the fluorescence intensity at 431 nm decreased,but a new strong fluorescence emission peak at 529 nm appeared,which indicated that L1 was a ratiometric fluorescence probe.We have learned that the largest fluorescence intensity of L1-Mg²⁺ was at ? = 529 nm and the detection limit of L1 for detecting Mg²⁺was 9.16 × 10-7mol/L and the coordination ratio is 1:1.?2?7-diethylamino-3-acetylcoumarin-?2'-furoyl?hydrazone L2 was synthesized by 7-diethylaminocoumarin-3-ethanone.The compound has a good selectivity for Zn²⁺,and could detect 1.40 × 10-7mol/L of Zn²⁺ in water environment.What's more,the other ions in the water did not interfere with the complex of L2 with Zn²⁺.?3?The coumarin derivative L3 has been designed by using 7-diethylamino-coumarin-3-ethanone.The ligand could form a stable complex with Mg²⁺ in a 1:1ratio,and its fluorescence intensity increased gradually upon of increasing concentrations of Mg²⁺.Therefore,the ligand L3 produced a strong fluorescence emission peak at ? = 506 nm.?4?The feasibility of providing analytical and rapid monitoring of Zn²⁺using L2-Zn²⁺ complex was discussed with reference to the actual situation of a county in southern Gansu province.