Studies On The Aggregation Behavior Of Some Ionic Liquids In Solutions By NMR

In recent years, ionic liquids (ILs) have been the subject of intense study in academic and industry. The chance that green chemistry is growing and the challenge that industry adjusts the material and product processing have spurred the exponentially growing research for ILs. ILs have shown great promising ap-plications in catalytic reaction, biochemistry, extraction, liquid crystal. The study of the aggregation behav-ior for ILs can give a reasonable explanation for the unusual phenomenon in IL-containing system and also provide some academic basic on the molar design of IL and industrial applications. As a part of the project supported by the National Natural Science Foundation of China (NO. 20573034), the major content of the present work is as follows:1. The chemical shifts of 1H and 13C and 1H T1 for aqueous solutions of a series of ionic liquids [Cnmim]Br (n = 4, 6, 8, 10, 12 ) have been determined at 298.2K as a function of ionic liquid concentra-tions. The critical aggregation concentrations and the aggregation number of the ILs have been determined. It is shown that when n>4, the ILs can form aggregates above critical aggregation concentration. The alkyl chain length of cation can be tailored to switch the aggregation behavior of ILs. The aggregation of ILs is driven by alkyl chain-ion inductive and hydrocarbon-hydrocarbon interactions. The structures of the ag-gregates of [Cnmim]Br (n = 6, 8, 10 ) in D2O have been obtained by NOESY techniques.2. The chemical shifts of 1H and 1H T1 for aqueous solutions of ionic liquids [C8mim]Cl, [C8mim][NO3], [C8mim][NO2], [C8mim][CH3COO], [C8mim]2[SO4] and [C8mim]3[PO4] and the chemical shifts of 13C of [C8mim][CH3COO] have been determined at 298.2K as a function of ionic liquid concen-trations. The critical aggregation concentrations and the aggregation number of the ILs have been deter-mined. The effect of the anions on the aggregation and hydration has been determined. The structures of the aggregates of these ILs in D2O have been obtained by NOESY techniques.3. The chemical shifts of 1H and 1H T1 for aqueous solutions of ionic liquids [C8py]Br, 4m-[C8py]Br, [C8mpyr]Br and OTAB have been determined at 298.2K as a function of ionic liquid concentrations. As-suming the pseudophase model of micellization, the critical aggregation concentrations of the ILs and the aggregation number of the ILs have been determined. The structures of the aggregates of these ILs in D2O have been obtained by NOESY techniques, the effects of the cations on the structures of the aggregates have been determined.4. The chemical shifts of 1H and 13C and 1H T1 of a series of ionic liquids [Cnmim]Br (n = 4, 6, 8 ) in CD3OD solutions have been determined at 298.2K as a function of ionic liquid concentrations. The effects of the dielectric constants on the aggregation and the solvation of the ILs in D2O, CD3OD, CDCl3 and ace-tone-d6 have been analyzed.