Design And Synthesis Of Manganese(Ⅱ) Complex Scintillators For X-ray Detection

In recent years,the luminescent manganese（Ⅱ）complex has shown great application prospects in the fields of flat panel display,information encryption,X-ray detection and imaging due to its advantages of high luminescent quantum efficiency,easy preparation,low cost and low toxicity.Among them,X-ray detection and imaging have become a research hotspot in recent years.The scintillator as a crucial component of X-ray imaging has the ability to convert ionizing radiation into visible photons.Luminescent manganese（Ⅱ）complex is considered as a potential scintillator material because of its excellent photophysical properties.However,there are few studies on the application of manganese（Ⅱ）complexes as scintillators in X-ray detection and imaging,and it is urgent to explore more new systems with excellent performance.In this work,a series of manganese（Ⅱ）complexes with novel structure and excellent properties were designed and synthesized by using different types of organic ligands and preparation methods.The crystal structure,photophysical properties and X-ray scintillation characteristics were systematically studied.In addition,the application of manganese（Ⅱ）complex scintillator in X-ray imaging was explored.The major research works are as follows:1.Design,synthesis and X-ray detection application of manganese（Ⅱ）complex scintillator based on bidentate phosphine oxide ligandTwo novel manganese（Ⅱ）complexes DDXPO-Mn Br₂ and[（DDXPO）₂Mn Br]Br were designed and prepared by regulating the coordination number and coordination mode based on the bidentate phosphine oxide organic ligand DDXPO.Firstly,the structure and photophysical properties of the complexes were studied.Among them,the complex[（DDXPO）₂Mn Br]Br exhibited a unique five-coordinated structure with bright yellow emission,and its photoluminescence quantum efficiency reached 93%,which was comparable to the common four-coordinated and six-coordinated manganese（Ⅱ）complexes.Subsequently,the scintillation characteristics and stability of the complex[（DDXPO）₂Mn Br]Br were investigated,and X-ray imaging of different objects was performed on the scintillator film prepared based on the complex.This was the first study on the application of efficient pentacoordinated manganese（Ⅱ）complexes in X-ray imaging.This study not only provides a guidance for the design and preparation of efficient luminescent manganese（Ⅱ）complexes,but also demonstrates the potential of manganese（Ⅱ）complexes as scintillators for X-ray imaging.2.Design,synthesis and X-ray detection application of manganese（Ⅱ）halide scintillator based on phosphonium saltsIn this work,a series of organic-inorganic hybrid metal manganese（Ⅱ）halides with tetrahedral coordination structure were prepared by a simple method.By analyzing and comparing the photophysical properties of these complexes,the effects of ligand and halogen atoms types on the luminescence quantum efficiency and lifetime of complexes were preliminarily explored.Under urltraviolet and X-ray irradiation,all of these complexes showed strong green luminescence,and the luminescence quantum efficiencies were above 85%.Among them,the complex(C₂₂H₂₂O₂P)₂Mn Br₄possessed the best X-ray scintillation performance.Its light yield was comparable to that of commercial Lu AG:Ce scintillation and the lowest detection limit was as low as 17.96 n Gy_air s^-1.And high-resolution X-ray imaging based on this scintillator film was realized.This work provides new ideas for the design and synthesis of manganese（Ⅱ）halide scintillators that can be used in X-ray imaging,and inspires us to think deeply about the structure-property relationship of scintillators.