Synthesis And Ion Recognition Property Of Hydrazone Based Fluorescent Probes

Fuorescent probes have the advantages of special selectivity and high sensitivity for the recognition of metal ions.They had been widly develped to determine content of trace metal ions in the field of chemistry,biology,environmental science being no use of expensive equipments and no pretreatment of the samples.In this paper,a series of Schiff base compounds were designed and synthesized to investgate their ion recognition properties.Several fluorescent probes with good recognition properties were screened from these compounds.The binding ratio of probe to metal ions,coordination mode and fluorescence sensing mechanisms were determined by the method of Job's,spectral titration,nuclear magnetic titration,mass spectrometry etc..Simultaneously,competitive selectivity experiments were performed and actual application of these probes to real water samples for determination the content of Al³⁺,Zn²⁺were also investgated.The main content is illustrated as follows:1.Anovelaldehydecompoundwassynthesizedusing1,2,4,5-tetrabromomethylbenzene as raw materials,and then reacted with a series of hydrazide and monoamine to obtain a series of Schiff bases.In addition,isophthalic dihydrazide derived from dimethyl isophthalate was synthesized,and reacting with a monoaldehyde compound to produce a series of hydrazone Schiff bases;Using Oxalyl dihydrazine,isoniazid,benzohydrazide and other hydrazide compound reacted with aldehyde generated corresponding hydrazone Schiff base compounds.All the products were characterized by the mothods of ¹H NMR and FT-IR specturms.2.Four hydrazone Schiff bases with good selective recognition abilities to Al³⁺were found in the experiments:isophthaloyl hydrazide based Schiff base?probe 1?,2-furoyl hydrazide based Schiff base?probe 2?,isoniazid based Schiff base?probe 3?,nicotine hydrazide based Schiff base?probe 4?.With the addition of Al³⁺,probes 1,2,3 and 4in DMF/H₂O?7/3,v/v?,DMSO/H₂O?19/1,v/v?,or DMSO/H₂O?7/3,v/v?solution have good fluorescence enhancement recognition effects to Al³⁺.The complex of 1:2ratio were determined by molar ratio method,Job's,UV titration,nuclear magnetic titration and mass spectrometry.The coordination modes of the probes to Al³⁺were speculated.Reversible experiments showed that probes 1,2,3 and 4 are reversible probes.Practical application studies showed probes 2,3 and 4 can be applied to detect content of Al³⁺in actual water samples.3.Two fuorescent probes owing good selective recognition abilities to Zn²⁺also were found in the experiments:Isopropanolamine based Schiff base?probe 5?and ethanolamine based Schiff base?probe 6?.After adding Zn²⁺to the solution of DMSO/H₂O?19/1,v/v?mixture,the fluorescence intensity of the system was also remarkablely enhanced.According to fluorescence titration,Job's,molar ratio method,nuclear magnetic titration and mass spectrometry analysis,probes 5 and 6 formed 1:1complexes with Zn²⁺.The coordination modes and sening mechanisms of probes 5and 6 to Zn²⁺were hypothesized.Reversible experiments showed that probes 5 and 6are reversible probes.