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Graphical abstract Highlights • Among the studied imide-based ILs, [P 4442 ][Cy-Suc] has the lowest density and the highest viscosity. • CO 2 capture can be efficiently tuned by substitute on the imide-based anions of the ILs. • The capture capacity of CO 2 by [P 4442 ][Cy-Suc] is as high as 2.21 mol of CO 2 per mole of the IL. • The absorption process by imide-based ILs was highly reversible and energy-saving. Abstract Minimizing the release of CO 2 into the atmosphere is highly important due to the CO 2 concentration dependence of climate change. In this work, highly efficient capture of CO 2 is investigated through tuning ionic liquids (ILs) with imide-based anions. It is found that a superior high CO 2 capacity (2.21 mol mol−1) be achieved by the imide-based IL with 1,2-cyclohexanedicarboximide anion at 20 °C and 1.0 bar through a combination of chemical and physical absorption. Quantum chemical calculations and spectroscopic analysis suggests that the significant increase in the CO 2 capacity is due to the enhanced cooperative interactions between CO 2 and three active sites in the anion with electron-donating group. Furthermore, the adsorbed CO 2 can be readily stripped from the CO 2 -saturated IL through slightly heating or bubbling N 2 , and the IL may be recycled without loss of efficiency. [ABSTRACT FROM AUTHOR]

To illuminate the influence mechanism of anionic structure of ionic liquids (ILs) on the adsorption performance of surface molecularly imprinted polymers (MIPs), in this work, six newly designed MIPs were prepared on the surface of amino-poly(styrene-divinylbenzene) particles by using imidazolium ILs with the same cation [C 4 mim] + but different anions (Cl, CH 3 SO 3 , PF 6 , BF 4 , C 4 F 7 O 2 , C 4 F 9 SO 3 ) as template molecules, methacrylic acid as functional monomer, and ethylene dimethacrylate as cross-linker. The resulting MIP materials were characterized by IR and SEM, and the influence of hydrogen bond accepting ability of anions on the adsorption performance of the MIPs for the ILs was investigated in acetonitrile. It was found that adsorption capacity of the MIPs towards the ILs decreased in the order MIP [C4mim][Cl]  > MIP [C4mim][C4F7O2]  ≥ MIP [C4mim][BF4] and MIP [C4mim][CH3SO3]  > MIP [C4mim][C4F9SO3]  > MIP [C4mim][PF6] , which is in good agreement with the ability of anions of the ILs to form hydrogen bonds. Ultraviolet, 1 H-NMR and 35 Cl-NMR spectroscopy was then used to study the interactions of anions of the ILs with the functional monomer. It was found that the hydrogen bond interaction between anions of the ILs and acidic proton of the functional monomer was the main driving force for the high adsorption selectivity of the imprinted polymers, and the stronger hydrogen bond interaction indicates higher binding capacity and higher selectivity of the polymers towards the ILs. It was also verified that the ILs with stronger hydrogen bond accepting ability of anions could be selectively extracted by the corresponding IL-MIPs. These results may provide new insight into the recognition mechanism of MIPs for ILs, and are also useful for the rational design of this new class of imprinting materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyridinolate-based functional ILs with different structures were designed for SO 2 capture. • Anion order of SO 2 capacity is [4-PyO] > [3-PyO] > [2-PyO]. • Cation order of SO 2 capacity is [P 66614 ] > [P 4442 ] > [TMG]. • Viscosity of system increased first and then decreased with the increase of absorption capacity. A series of pyridinolate anion-functional ionic liquids (ILs) containing different kinds of cations were designed and prepared, including tri- n -hexyltetradecylphosphonium [P 66614 ], tri- n -butylethylphosphonium [P 4442 ], and 1,1,3,3-tetramethylguandinium [TMG] cations and pyridinolate [PyO] anions with different N positions. Densities and viscosities at different temperatures were measured because of their importance for the absorption of SO 2. Effect of different structures on the absorption of SO 2 was studied, including the type and the alkyl chain length of cations, and the N positions of [PyO] anions (2-, 3-, and 4-). Additionally, effects of SO 2 concentration and temperature for absorption were investigated. Especially, up to 6.00 and 2.53 mol SO 2 per mole IL could be obtained by [P 66614 ][4-PyO] at 1 bar and 0.1 bar of SO 2 , respectively, when absorptions performed at 20 °C. The results indicate that (1) the aprotic cations weakened the cation⋯anion interaction and resulted in the released active sites on the anions, and (2) N position has an influence on charge distribution of [PyO] anions and resulted in the tunable absorption of SO 2. Reversible SO 2 absorption and [P 66614 ][4-PyO] regeneration could be performed several times without losing efficiency. Furthermore, the mechanism of absorption was studied through FT-IR and NMR methods and the results showed that the absorption of SO 2 by [P 66614 ][4-PyO] includes physisorption and chemisorption. [ABSTRACT FROM AUTHOR]