Study On Synthesis And Metal Ion Recognition Performance Of Ferrocenyl Schiff Base

Ferrocene derivatives have attracted wide spread attention due to their redox properties and good thermal stability.Ferrocene is considered to be a good electron donor with excellent structure,good biological activity and electrochemical properties.It can be used to prepare sensors,redox active acceptors,conductive materials and drug development and other fields etc.At the same time,ferrocene derivatives are also considered as sensor molecules with excellent chemical sensing properties.Schiff base is popular because of its good photophysical properties.In particular,The fluorescent properties of Schiff base are used as chemical sensors due to their high selectivity and sensitivity to metal ions,and they also are widely used in detection fields.In this paper,a series of ferrocene-containing Schiff bases were synthesized by combining a ferrocene derivative with a hydrazine dithioformate through a nucleophilic addition-elimination reaction,and their ion recognition properties were studied,and developed a series of new fluorescent chemical sensor that can be used for the detection of multi-metal ion differences.(1)Synthesis of acetyl ferrocene with a yield of 86.7%.Nine hydrazine dithioformate derivatives were synthesized with hydrazine hydrate,carbon disulfide,and haloalkane as raw materials with a yield of 83.3-88.6%.(2)Using acyl ferrocene and nine hydrazino dithioformates as raw materials,eighteen ferrocene-containing Schiff bases(LI-L18)were obtained by the method of solvent-free grinding.The structure was analyzed by FT-IR,1H NMR and 13C NMR.Taking N'-(1-ferrocenyl-ethylene)-hydrazine dithioformate as an example,the effects of the amount of catalyst,grinding time and molar ratio of reactants on the synthesis reaction were explored.The best reaction conditions are fowlling as:grinding time 20min,the molar ratio:1:1.2:1.2(acyl ferrocene:p-toluenesulfonic acid:hydrazine dithioformate),and the yield gets 91.8%.In addition,the solvent-free grinding has some advantages such as green,short time,and economy.(3)The research results show that the Schiff base L1-18 has the highest fluorescence intensity in methanol solution,and shows different sizes of selectivity to 16 ionic metals.Among them,Ce3+,Cu2+ and Fe3+ have the best recognition performance.It is aimed at Fe3+ with high selectivity and good competitiveness,and the color of changes can be detected by the naked eye.Schiff base L1-18 can be selected as a fluorescent chemical sensor that recognizes multiple ions,and has good stability,selectivity and anti-interference ability.Schiff bases have different fluorescence intensities in different solvents.Screening out the fluorescence detection in methanol solution;study L1-18 for 16 kinds of metal ions(Co2+,Ni2+,Pb2+,zn2+,Cr3+,Al3+,Cu2+,Mn2+,Fe3+,Ce3+,Pr3+,Dy3+,Tb3+,La3+,Nd3+,Ho3+).The results show that L1-L18 has good selectivity to Fe3+.When Fe3+.is added alone,the fluorescence intensity of L1-L18 is significantly reduced and almost quenched,and the color of the solution changes from colorless to pale yellow.Cu2+,L1-L9,L10,L12,L14,L17,and L18 significantly decreased the fluorescence intensity;when Ce3+ was added alone,the fluoresceIce intensity of L9 increased significantly.Under the same conditions,other metal ions can cause changes in the fluorescence intensity of the system,but the changes are not obvious.Therefore,L1-L18 can be found to have good selectivity.Through the fluorescence titration of the recognition metal ions,it was found that as the concentration of the recognition ions(Cu2+,Fe3+)increased proportionally,the fluorescence intensity of the system continued to decrease.For Fe3+,only after adding 2-3 times,the fluorescence intensity of L1-L18 was almost completely quenched and changed from colorless to dark yellow.When Ce3+ was added,the fluorescence intensity of the L9 system significantly increased,and the fluorescence intensity gradually decreased after continued addition,which had certain specificity.In addition,since the response of many sensors is affected by the presence of interfering ions,the anti-interference ability of the sensors is studied in this paper.L1-L18 shows good selectivity and anti-interference ability in the presence of interference ions.