Spectra And Electrochemical Behavior With Analytical Application Of Three Herocyclic Bis-Schiff Bases

1 We introduced the research status about Schiff base, Schiff base with S, thiazole and thiophene Schiff base,besides, we discussed seriously that thiazole and thiophene heterocycles Schiff bases are regarzed as fluorescence analysis reagent reacting with metal ions; Fluorescence quenching method is introduced and the application status, for fluorescence sensing analysis of metal ions,are also introduced; Electrochemical behavior of Schiff bases is reviewed; And, the significance and the main content of this artical are shown.2 The two new thiazole bis-Schiff bases:thiazole-5-carbaldehyde -ethyle nediamine (A) and thiazole-5-carbaldehyde-1,2-diaminocyclohexane (B)synthesized in our laboratory are regarded as researching object. The fluorescence spectra of these two compounds are investigated in 371 and 429nm, the fluorescence intensity have been increased and decreased respectively,when adding Zn2+ and Cu2+ metal ions to the Schiff bases and according with Lineweaver-Burk in certain consistency for Cu2+. So, the fluorescence detection methods for Cu2+ are erected; According to study, reacting btween compounds and metal ions are all static quenching, and,these Shiff bases and Cu2+ are coordinated with 1:1.Electrochemical behavior of two compounds are all an irreversible reduction process.3 The Shiff base thiophene-2-carbaldehyde-phenylenediamine is synthesized and characterized by IR.The fluorescence spectra of this compound is investigated in 376nm, the fluorescence intensity have been decreased respectively, when adding Cu2+ and Fe3+ to the compound and according with Lineweaver-Burk in certain consistency, So, the fluorescent detection methods for Cu2+ and Fe3+ are erected; When optimizing, reacting btween the compound and Cu2+:Linear range is 1×10-5～5×10-3mol/L, Limit of detection is 1.67×10-6mol/L, Relative standard deviation is 0.23%, reacting btween the compound and Fe3+:Linear range is 1×10-5～8×10-4mol/L Limit of detection is 7.65×10-7mol/L, Relative standard deviation is 0.16 %,The methods has far linear range,lower limit of detection and lower relative standard deviation than in organic system and other literatures[3/8-12]; According to study, reacting btween compounds and metal ions are all static quenching, and,these Shiff bases and metal ions are coordinated with 1:1; Electrochemical behavior of the compound is an irreversible reduction process.4 The fluorescence quantum yield, for thiophene-2-carbaldehyde-phenylenediamine in methanol, is measured based on the standard substance, naphthalene(1μg/mL) in ethanol. The yield of compound is 0.19Probably after being calculated.Therefor, thiophene bis-schiff bases should have certain value in fluorescence analysis,also,we can expand its'fluorescence application field by further studies and Improved reagent structure.