Preparation And Characterization Of Magnetic Ionic Liquids And Studies On Magnetic Properties

A novel series of magnetic ionic liquids (MILs) have been synthesized by introducing complex ions of metals into ionic liquids. The physicochemical properties, such as density, viscosity, melting point and onset temperatures etc, were investigated. Through researches on magnetic properties of these MILs, several magnetic theories were founded. And magnetic carbon nanotubes (MCNT) as the combination of single-walled carbon nanotube and special-designed MIL were prepared. The major work and innovative results for this dissertation are as follows:1) Two MILs systems [C4mim]Cl/FeCl3 and [C4mim]Br/FeCl3 were designed. And three magnetic ionic liquids, [C4mim]FeCl4, [C4mim]FeCl4+[C4mim]Fe2Cl7 and [C4mim]FeBrCl3 (main material in [C4mim]Br/FeCl3) were synthesized using standard method, which indicated that the molar ratio [C4mim]Cl/FeCl3 has crucial influence on the structure of complex ions, and there were ion exchange among complex ions.2) A novel route was designed for the synthesis of vinyl-functionalized imidazolium-based ionic liquids, and the reaction conditions such as reaction temperature, selection of nucleophile etc were optimized. Moreover, magnetic ionic liquids [Vmim]FeCl4 and [Vmim]Br/FeCl3 havingπ-πconjunction structure were synthesized from vinyl-functionalized imidazolium-based ionic liquids, and PMIL was prepared by polymerization of [Vmim]FeCl4.3) The single-walled carbon nanotubes functionalized by magnetic ionic liquid [Vmim]FeCl4 have been synthesized through the polymerization reaction of [Vmim]FeCl4 in methanol. And the structure of the functionalized single-walled carbon nanotubes was investigated by IR and Roman spectrum, which indicated that cation [Vmim]+ were supported on the surfaces of SCNTs, and anion [FeCl4]+ moved inside.4) A series of high stability geminal dicationic magnetic ionic liquids [Cn(mim)2]X2/FeCl3 (n=1, 2, X=Br, Cl) and [Cn(mim)2]2[Dy(SCN)7] (n=2, 4, 6, 8, 10) were prepared and their thermal properties were investigated. By slow evaporation method single crystals of [C4(mim)2]2[Dy(SCN)7] and [C6(mim)2]2[Dy(SCN)7] were obtained and characterized, which indicated that geminal dicationic structure resulted in an absolute different coordination environment of Dy3+ from that of [C6mim]2[Dy(SCN)7H2O].5) All the magnetic ionic liquids were characterized by SQUID, and influences of MILs structures on magnetic properties were investigated. Moreover, magnetic properties of MCNT were investigated, which indicated that the magnetic ionic liquid PMIL appeared an abvious transformation from paramagnetism to ferromagnetism, this might be due to the specialπ-πstructures of carbon nanotubes that could perfectly transfer electrons.