Synthesis Of Hexanuclear Manganese Oxygen Cluster Mn^Ⅲ{Mn₆^Ⅱ}₂ And Study On Proton Conductivity

In recent years,polyoxometalates（POMs）compounds have great potential in the development and application of proton conducting materials due to their determined chemical structure,large charge capacity and proton channels.However,the high water solubility and temperature response of polyoxometalates have also limited their development in proton conduction.Therefore,researchers tend to further synthesize certain composite materials to obtain materials with enhanced proton conductivity and stabilityandlowersolubilityinwater,suchas polyoxometalates-metal-organic-fra mework（P OM-MOF）and polyoxometalates-covalen-organic-fra mework（POM-COF）.Until recently,researchers have shown that synthesis of the inorganic-organic hybrid POM clusters provides a new convenient and cost-effective strategy for the construction of solid proton conductors.In the synthesis of inorganic-organic hybrid clusters,it has been well-established that reasonable design and choice of organic species（ie,cationic,anionic or nonionic）are vital.It is a general routine to synthesize POM hybrids by the use of ligands with both hydrophobic and oxygen-containing hydrophilic functional groups.In this thesis,fuel cells,proton exchange me mbrane materials,crystalline material proton conductors,proton conduction mechanisms,and manganese-based crystalline proton conductor materials are briefly introduced.Given the unique structures and properties of polynuclear Mn oxo-clusters,the synthetic strategy of inorganic-organic hybrid clusters has been applied,given rise to a new Lindqvist-type manganese homopolyacid oxygen cluster Mn^III{Mn₆^II}₂ with high proton conductivity.Main work in this thesis include:（1）A new inorganic-organic hybrid Mn^III{Mn₆^II}₂ cluster was synthesized by using manganese acetate and trimethylolpropane as raw materials from the HOAc-Na OAc buffer solution,with the addition of K₂CO₃ and propionic acid.The structure of Mn^III{Mn₆^II}₂ compound was determined by single crystal X-ray diffraction.The basic unit of Mn^III{Mn₆^II}₂ is the Lindqvist-type{Mn₆}.（2）The synthetic strategy of using functionalized tripod alcohols in the asse mbly of inorganic-organic hybrid clusters with novel structures and properties has been studied in details.It is shown that t he three alkoxide arms are able to coordinate with metal ions and direct the formation of multinuclear clusters.while the function group,which is connected with the quaternary carbon,such as alky groups,can be applied as a tool to enhance the processability of the synthesized soft functional materials.Mn^III{Mn₆^II}₂ has high thermal stab ility and poor solubility,as opposed to several polyoxometalates and other polynuclear clusters.（3）A series of measurements have been cattied out to characterize the Mn^III{Mn₆^II}₂ compounds,such as thermogravi metric analysis（TGA）,powder X-ray diffraction,ele mental analysis,Fourier Transform Infrared Spectrometer（KBr as background）,X-ray electron spectroscopy,magnetic properties.In particular,the proton conduction properties of the Mn^III{Mn₆^II}₂ compound were investigated,and the data of impedance test revealed that the maximum value 1.19×10^-3 S cm^-1,at 338K and 97%RH.