Design,Synthesis And Spectral Response Of Several Zinc Ion Fluorescence Probes

Light is one of the most convenient tools for people to understand and observe the macro and micro world,so fluorescence probe suppression using the change of light signal for sensing analysis is favored by people.In addition to being widely used in spectral analysis,ion detection and other analytical fields,Small molecule fluorescent probes have also become an important sensing and analysis tool for targeting to understand the dynamic level changes of certain substances in environmental and life sciences.In this paper,five compounds with different structures were designed and synthesized,and the specific binding of each compound to a metal cation and its spectral change and response mechanism were investigated respectively.Finally,three Zn2+probes and one Hg2+probe were found.The main results are as follows:1.Compound A1 was synthesized from 2-chloromethylpyridine and 8aminoquinoline,and its structure was characterized by NMR and HRMS.The recognition ability of compound A1 to metal ions in ethanol/water(9/1,v/v)solution was investigated.The results showed that under 310 nm excitation,compound A1 would show an obvious fluorescence emission peak at 485 nm after adding Zn2+,and the emission intensity increased with the increase of Zn2+ concentration,the addition of other metal ions does not cause significant changes in fluorescence spectra.Indicating that compound A1 was in ethanol/water(9/1,v/v)has the ability to recognize Zn2+specifically.The detection limit of compound A1 to Zn2+reached 0.427 μM by concentration titration curve.According to Job’s lot curve,the optimal binding ratio of compound A1 to Zn2+ was 1:1.In addition,compound A1 also had good antiinterference ability and reversibility.2.Compound A2 was obtained from 2-hydrazine benzothiazole and 5-methyl salicylic aldehyde,and 2,3-diamino-butenedionitrile was introduced into the o-position of phenolic hydroxyl group.Its structure was characterized by NMR and ESI-MS.UV and fluorescence spectra were used to determine the fluorescence emission at 510 nm after adding Zn2+into the DMSO/H2O(4/1,v/v)solution of compound A2.However,Adding Cd2+or other metal ions to the solution doesn’t produce similar fluorescence changes,which proved that compound A2 could specifically recognize Zn2+ and was not affected by Cd2+.At the same time,the solution of compound AZ changed from yellow to red obviously when Zn2+ was added to compound A2 under natural light,indicating that compound A2 can detect Zn2+with naked eyes.Compound A2 can also recognize Zn2+ under weak alkaline conditions,and has the advantages of mild detection environment and low detection limit.3.A new compound A3 was prepared by adding 2-hydrazyl pyridine with 2hydrazyl benzothiazole and 5-methyl salicylic aldehyde as raw materials.After the characterization of UV absorption spectrum and fluorescence emission spectrum,it was found that in the solution of DMSO/H2O(4/1,v/v),the fluorescence emission peak shifted from 503 nm to 580 nm after adding Hg2+to compound A3,indicating that compound A3 could recognize Hg2+ in the solution of DMSO-water system.According to Job’s plot curve and NMR titration,the chemical binding ratio of compound A3 to Hg2+ is 1:3,but compound A3 has poor anti-interference ability and is not suitable for identifying Hg2+ in complex environment.4,Compound A4 was obtained by introducing diethyl iminodiacetate with quinazolinone as fluorophore.After a series of spectral characterization,it was found in the solvent system of DMSO/H2O(4/1,v/v).Taking 320 nm as excitation light,compound A4 would produce an obvious fluorescence signal peak at 440 nm after adding Zn2+,and the solution would emit obvious blue fluorescence.Compound A4 has good anti-interference and reversibility,which has the potential of repeated utilization.In the range of pH=7-10,the fluorescence emission intensity of compounds 14 and Zn2+was little affected by pH changes,indicating that compound A4 has the potential to be used in cell fluorescence imaging.In addition,a naphthalimide derivative,compound A5,was successfully synthesized and gave a strong yellow-green light under 365 nm UV lamp.However,after a series of UV and fluorescence spectrum tests,it was found that compound A5 basically did not emit light in acetonitrile aqueous solution and had no specific recognition ability to metal cations.