Synthesis Of Hydrazide Schiff Base And Its Ion Recognition Performance

Chemosensors have been developed rapidly in recent years for its selectivity,fast detection,highly sensitivity and no expensive equipment is required.Schiff bases are good ligands for metal ions,with which they can form coordinate bonds.This characteristic has resulted in their extensive use in the production of sensors.In this work,we designed and synthesized a series of Schiff base ligands,and test their ability in the detection of metal ions.The main content is illustrated as follows:1.A series of Schiff base or bis-Schiff bases have been designed and synthesized by using isoniazid or nicotinc hydrazide and some other amines with several aldehyde or di-aldehyde,and target products were characterized by the mothods of 1H NMR,FT-IR.2.Four hydrazide Schiff bases were found as good Chemosensors in the experiment:Two 5,5'-methylenebis?salicylaldehyde?-based Schiff base 1 and 2,and two1,6-di?3'-hydroxyl-4'-fromyl phenoxy?hexane based Schiff base 3 and 4 were synthesized.All the four ligands showed selective fluorescent sensing for Al³⁺respectively,in DMSO/H2O?9:1,v/v?.The fluorescence intensity showed an enhancement for sensors,respectively,in the presence of Al³⁺,relative to that of the free sensors.The fluorescence intensity showed a good linear-ship with the concentration of Al³⁺ ion in a certain range.The sensor displays a 1:1 binding stoichiometry and exhibits a turn-on type fluorescence response toward Al³⁺.3.Two colorimetric sensors,derived from pentaerythrityltetramine and salicylaldehyde?5?or o-vanillin?6?,had been synthesized.The sensors coordinated to Fe?III?with 1:1 stoichiometry,as has been confirmed from the results of LC-MS spectrometry and UV-vis spectrum titration.Both sensors showed selective colorimetric sensing ability for Fe?II?and Fe?III?by changing color from light yellow to either orange or purple when immersed in water samples.The practical applicability studies showed satisfactory recovery and R.S.D.values for the detection of Fe³⁺ ions in environmental water samples.