Synthesis And Fluorescence Properties Of Coordination Polymers Based On Mercaptan Ligands

In the past 30 years,the research of coordination polymers has been extended to the level of multi-discipline and fields,and has received wide attention.It's a type of super molecular which are constructed compounds by using the coordination bonds to connect the metal center with organic ligands.They also can divide into one-dimensional,two-dimensional,and three-dimensional structures by the characteristics of the structure extending in space.Among them,fluorescent coordination polymers have received a lot of attention as new light-emitting materials.On the one hand,coordination polymers have the designability of structure and function,and fluorescent materials with adjustable luminescence can be designed according to requirements;on the other hand,fluorescent coordination polymers with abundant organic functional groups and metal centers can be used as fluorescence sensing materials,realize the sieving and recognition of target molecules.Transition metal sulfides with?B elements,such as Zn S and Cd S,have excellent luminescence properties and have been widely used in phosphors,fluorescent coatings,fluorescent glass and other fields.As pure inorganic luminescent materials,there are lacking of functional tunability and modifiability in fluorescence,which limits their further applications,such as sensing and detection applications.In this paper,we selected Zn and Cd with?B group as the metal center,designed and synthesized 3 coordination polymers with thiol ligands with different functional groups at the para-position as the functional unit.These compounds kept the light-emitting properties of the Zn S/Cd S,and organic functional groups on its surface were fully modified,in order to achieve the broadening of their application range and functional diversity.We explored the properties and synthesis rules of these compounds,and studied their fluorescent properties and applications as sensing materials.The main research results are as follows:(1)Using 4-aminothiophenol as the functional unit and Cd as the metal center,a novel one-dimensional coordination polymer Cd(SPh NH₂)Cl·H₂O(compound 1)was designed and synthesized by solvothermal method.The compound has good fluorescence properties,showing a green light emission of 554 nm under 360 nm excitation light.We disperse it in N,N-dimethylformamide.When trinitrophenol(PA)is added,the fluorescence of 1 is quenched.We use it for fluorescence sensing to detect trinitrophenol.The coordination polymer showed an ultra-high selective detection of trinitrophenol.When the amount of trinitrophenol was 100 n M,the fluorescence quenching rate was 84.5%.(2)A novel two-dimensional coordination polymer material Zn(OAc)SPh NH(compound 2)was designed and synthesized by hydrothermal method with 4-aminothiophenol as the functional element and Zn as the metal center.The compound shows good thermal stability and water stability,and has good fluorescence emission and typical semiconductor properties.We use it as a sensing material in a chemical resistance humidity sensor.Compound 2 shows good humidity sensing performance,with linear response and high response value in a large relative humidity range(10%-100%RH)(the current has 3 orders of magnitude change at 60%RH),Faster response speed and response recovery speed,but also has good cycle stability.(3)A new three-dimensional coordination polymer Cd(SPh F)₂(compound 3)was designed and synthesized using 4-fluorothiophenol as the bridging ligand by solvothermal method.Among them,the Cd atom is coordinated with the four S atoms on 4-fluorothiophenol to form a three-dimensional open skeleton structure.The compound has good fluorescence properties,showing 525 nm green light emission under 360 nm excitation light,and can be used as a potential luminescent material.In addition,we also studied the effect of defects on the fluorescence performance.The introduction of defects can cause fluorescence quenching,which indicates that the fluorescence emission is the intrinsic emission of the material.