Synthesis And Property Studies Of Novel Pyrazole Fluorescence Probes Based On Schiff Base For The Detection Of Metal Ions

The compounds with pyrazole ring are Nitrogen heterocyclic compound which have attracted more and more attention because of their good coordination properties,fluorescence properties and easy modification.Pyrazole can be used as an important intermediate for certain pharmaceuticals and pesticides,and plays an important role in the research and development of medicine and pesticide.In this paper,a series of compounds based on Schiff base were designed and synthesized by using pyrazole compounds as raw materials,and their fluorescence properties and detection of metal ions were studied.（1）4-pyrazolylbenzaldehyde were synthesized by using Pyrazole and p-fluorobenzaldehyde,and then reacted with p-phenylenediamine to prepare one novel conjugate Schiff base.The structures of target compounds were identified by IR,¹HNMR,¹³CNMR,MS and elemental analysis.In this paper,the compounds were calculated by using the method of density functional theory,and the orbits of HOMO and LUMO were calculated and their molecular orbital distribution energy were also calculated,which facilitated to achieve the unity of theory and practice.Their fluorescence properties and the detection for metal ions were studied,in which the UV and fluorescence spectra were used.（2）Preparation of compound 3 by reaction of 3-methylpyrazole with p-fluorobenzaldehyde,then a novel conjugate Schiff base was synthesized by compound 3 and phenylenediamine.The structures and properties of the target products were characterized by FTIR,¹HNMR,¹³CNMR and elemental analysis.In this paper,the compounds were calculated by using the method of density functional theory,and the orbits of HOMO and LUMO were calculated and their molecular orbital distribution energy were also calculated,which facilitated to predict the fluorescence performance.The UV and fluorescence spectra were used to discuss related properties by using ultraviolet-visible spectrophotometer and fluorescence spectrometer.（3）The response time and the environmental adaptability of the fluorescent probe were further verified by testing the different reaction time and different pH,which provided the theoretical basis for the rapid detection of metal ions in the analogous biological environment.In this paper,two novel fluorescence enhanced probes were designed and synthesized by combining the excellent coordination properties of pyrazole compounds with the fluorescence properties of Schiff base.And these probes displayed significant fluorescence selectivity and sensitivity for particular metal ions,and which can be used for the rapid detection of metal ions in the analogous biological pH environment.Furthermore,these compounds were calculated by theoretical calculation methods,and the experimental results and theoretical calculations were combined successfully,which indicated that two novel compounds had good fluorescence properties and could be used as fluorescent probes for related metal ion detection.