Molecular Design, Synthesis And Properties Of N-vinylimidazolium Magnetic Ionic Liquids

Ionic liquids (ILs) are composed mostly of organic ions, which is liquid state (-50-200°C)with negligible vapour pressure. Compared with conventional organic solvents, ILs havearoused increasing interest due to their unique properties such as wide liquid range, high ionicconductivity, wide electrochemical potential window, nonflamm-ability, etc. as a special softfunctional materials, ILs can be applied in various fields, such as function materials, organicsynthesis, liquid-liquid separation, biological catalysis, etc. Additionally, their chemical andphysical properties can be tailored by judicious selection of cation, anion, and substituents tosatisfy specific requirement.As novel substance systems, the research of ILs is still in its infancy, and the basic data aredeficiency. The researches, such as the analysis of molecular structure, structure-propertyrelationship, the method of molecular design, and so on, relatively lag behind. In particular,the researches for the species and their elated basic theories of functional ILs further lack,which seriously impact the application and development of the new type of functionalmaterials, i.e., ILs.Based on molecular designing, three series new type of N-vinylimidazolium halide,N-vinyl-imidazolium tetrahalogenidoferrate and N-vinylimidazolium tetraisothiocyanatecobalt functional ILs with olefinic bonds or magnetic group were designed and synthesized.The relationship between molecular structure and properties, such as magnism, conductivity,viscosity, surface properties, etc., were investigated. In additional, N-vinylimidazoliummagnetic ILs (MILs) has been used as the preparation of polymer materials, which canprovide significant research basis and theoretical foundation for the design, synthesis of newfunctional ILs and the preparation and application of magnetic polymer materials. The maincontents in this work were carried out as follows.Using microwave-assisted synthesis method, a series of founction ILs with olefinic bond(polymerizable ILs),1-alkyl/ester-3-vinylimidazolium halide ([RVIM]X), were designed andsynthesized. Using change anion reaction, a series of1-alkyl-3-vinylimidazoliumtetrahalogenidoferrate ([RVIM][FeX4]) and1-alkyl-3-vinylimidazolium tetraisothiocyanatecobalt ([RVIM]2[Co(NCS)4]) difunctional (olefinic bond and magnism) ILs, i.e., polymer- izable MILs, were designed and synthesized.(VIM)4]Co(NCS) complex crystal was firstlyobtained in acetone. The crystal structure was determined by X-ray crystallography, infraredspectrum and elemental analysis, which indirectly proof relative space position of anion andcation in [RVIM][Co(NCS)4] MILs.With B3PW91/6-311G(2d,p), the mechanism of the alkylation reaction for N-vinylimizazo-lium with straight haloalkane was discussed using density functional theory (DFT), and thetransition state and product structure were confirmed. The result shows the alkylation reactionfor N-vinylimizazolium with straight haloalkane is mainly SN2reaction. According toactivation energy, enthalpy and other thermodynamic parameters, the reason for the influenceof straignt haloalkane on alkylation reaction can be interpreted, which presented definitetheory basis for design and synthesis of [RVIM]X ILs.Adopting DSC determination method, the phase diagram of [BVIM]Cl—FeCl3binarysystem were successfully measured and drawn, and the influence of the proportion of[BVIM]Cl ILs and FeCl3on the structure and composition of [BVIM][FexCly] ILs wereinvestigated, for example, when the molar percentage of FeCl3is0.5,[RVIM][FeCl4] MILs,with good stability and high purity, can be synthesized, which provides a significant basis forthe synthesis of [RVIM][FexCly] MILs.The molecular structure of FeCl3,[FeCl4]ˉ,[Fe2Cl7]ˉhas been optimized usingUHF/6-31G(d) quantum chemistry ab initio calculation method. The microstructures of[RVIM]X,[RVIM][FeX4] and was researched using density functional theory (DFT) atUHF/6-31G(d) level, infrared spectroscopy, nuclear magnetic resonance spectrum, Ramanspectrum, and ultraviolet spectrum. And the important parameters, such as bond length, bondangle, charge distribution, dipole moment and interaction energies of ion pairs, etc., for[RVIM]X and [RVIM][FeX4] functional ILs were also obtained.[RVIM]X,[RVIM][FeX4]and (RVIM)2[Co(NCS)4] properties, such as magnism, conductivity, solubility, surface tension,etc., were discussed. Additionally, combining the caculation results with the experimentalresults, the structure-properties relationship were established.MILs polymer and MILs polymer gels, with good thermal stability and magnetism, can beprepared with (RVIM)2[Co(NCS)4] and [RVIM][FeX4] difunctional ILs as monomersrespectively. The result indicates the participation of difunctional ILs can improve the thermalstability of polymer and gel. A new way is developed for the preparation of new magnetic functional materials in the study.