Design And Synthesis Of Photoelectric Functional Coordination Polymers And Their Radiation Detection Properties

With the development of science and technology,the use of high-energy rays has become an indispensable part of people’s daily life.Among them,cathode-rays and X-rays are widely used in field emission display,medical diagnosis,high energy physics,geological exploration and other fields.However,high-energy rays are harmful to organisms to a certain extent.Therefore,developing high-energy ray detection materials with excellent performance and better exerting the application value of high-energy rays have become the research focus of researchers.Coordination polymers（CPs）are crystalline materials formed by self-assembly of inorganic metal or metal cluster units and organic linkers.The CPs have the advantages of structural designability and functional tunability.The synergistic effect of the inorganic and organic components contained in the material can provide advantages that cannot be achieved by a single inorganic or organic component.At present,CPs have shown excellent performance and potential application value in the fields of fluorescence,scintillation,catalysis,proton conduction,radiation detection,nonlinear optics and so on.In this thesis,based on the functional unit theory,carboxylic fused-ring aromatic hydrocarbons and sulfonic acid organic semiconductors were selected as organic ligands,and specific functional CPs were synthesized with specific metal building units by solvothermal and conventional solution methods.Subsequently,the crystal structure analysis and related performance characterization（such as photoluminescence,scintillation luminescence,electrical conductivity,etc.）of the synthesized CPs materials were carried out,and the performance mechanism was further studied.The main research work of this paper is as follows:1.Study on the synthesis and cathode-ray scintillation of d10 configuration metal-based coordination polymers based on fused-ring aromatic hydrocarbon ligands.We use polycyclic aromatics 5-[（naphthalene-1-ylmethyl）-amino]-isophthalic acid（H₂Nyaia）with Zn（NO₃）₂·5H₂O and Cd（NO₃）₂·4H₂O for the syntheses of two cases of cathode-ray scintillation CPs: Zn-SCP:[Zn（Nyaia）（DMA）]n and Cd-SCP:(Cd（Nyaia）（H₂O）]n·n H₂ O,where DMA = N,N-dimethylacetamide.Photoluminescence（PL）and cathodoluminescence（CL）spectra show that the aggregation-induced quenching effect of the organic ligand H₂ Nyaia in the complex is effectively suppressed.Both Zn-SCP and Cd-SCP exhibited better scintillation performance than the organic scintillator anthracene under cathode ray irradiation.The CL phenomenon at different accelerating voltages showed that the scintillation performance was positively correlated with the accelerating voltage within the accelerating voltages ranging from 10 to 30 k V.The increase of the accelerating voltage increases the penetration depth of the electron beam in the material and increases the number of luminescent centers,thus enhancing the scintillation performance of the complex.This phenomenon also confirms the indirect detection ability of the two complexes for cathode-rays.This study provides a research idea for the design and synthesis of efficient and stable cathode-ray scintillation CPs in the future,and also provides new ideas for the design and synthesis of new scintillation materials for field emission displays（FEDs）and correlated cathodoluminescence electron microscopy（CCLEM）in the future.2.Study on the design and synthesis with direct X-ray detection performanc of semiconductor coordination polymer based on heavy metal lead（Ⅱ） ions.Heavy metal Pb（Ⅱ）was assembled with organic semiconductor 7-iodo-8-hydroxyquinoline-5-sulphonic acid（IHQS）ligands,and a semiconductor CP was successfully synthesized under solvothermal conditions: [Pb（IQS）]n Pb-CP.Based on the regulation effect of coordination on the band gap,the forbidden band width of complex Pb-CP can reach 2.52 e V.Complex Pb-CP showed a good photocurrent response under X-ray irradiation.The π–π interaction between organic ligands provides an effective path for the transport of carriers,and the heavy metal Pb can effectively absorb X-rays.Based on the synergistic effect of the two,the complex Pb-CP is expected to be used for room temperature radiation detection.Based on the synergistic effect of the two,the room temperature radiation detector prepared from complex Pb-CP has a product（μτ）of carrier mobility and lifetime of 5.77 × 10–4 cm2V-1 and a sensitivity（S）of 55.80 μCGyair-1 cm-2,which is expected to be an excellent material for direct X-ray detection at room temperature.3.Study on the design and synthesis with direct X-ray detection performanc of semiconductor coordination polymer based on heavy metal silver（I）ions.We chose 7-iodo-8-hydroxyquinoline-5-sulphonic acid（IHQS）with lead-free heavy metal Ag（Ⅰ）for the syntheses of a semiconductor complex [Ag（IQS）]n n H₂ O Ag-CP.The complex Ag-CP showed a good photocurrent response under X-ray irradiation.In the structure of complex Ag-CP,there are π–π interactions between the adjacent organic ligands in the one-dimensional chain and between two adjacent one-chains,which provides the possibility for efficient carrier transport.Heavy atoms Ag and I have a good absorption effect on X-rays,and the synergistic effect of metal elements and organic elements makes the carrier mobility and lifetime product（μτ）of the radiation detector made of Ag-CP as high as 7.16 × 10–4 cm2V-1,the sensitivity（S）is as high as 71.42 μCG yair-1 cm-2,and it is expected to be an excellent material for direct X-ray detection.In this thesis,guided by function and functional unit theory,by selecting appropriate organic ligands and metal units,cathode-ray scintillation-type coordination polymers and X-ray responsive semiconductor coordination polymers were designed and synthesized.The relationship between the structure and properties of the complexes is discussed in depth,which provides a theoretical basis and experimental guidance for the design of functional materials with cathode ray scintillation and direct X-ray detection.