Highly Efficient Carbon Monoxide Capture by Carbanion‐Functionalized Ionic Liquids through C‐Site Interactions

A novel method for the highly efficient and reversible capture of CO in carbanion‐functionalized ionic liquids (ILs) by a C‐site interaction is reported. Because of its supernucleophilicity, the carbanion in ILs could absorb CO efficiently. As a result, a relatively high absorption capacity for CO (up to 0.046 mol mol⁻¹) was achieved under ambient conditions, compared with CO solubility in a commonly used IL [Bmim][Tf₂N] (2×10⁻³ mol mol⁻¹). The results of quantum mechanical calculations and spectroscopic investigation confirmed that the chemical interaction between the C‐site in the carbanion and CO resulted in the superior CO absorption capacities. Furthermore, the subsequent conversion of captured CO into valuable chemicals with good reactivity was also realized through the alkoxycarbonylation reaction under mild conditions. Highly efficient CO absorption by carbanion‐functionalized ILs provides a new way of separating and converting CO.     

Ambient Lithium–SO2 Batteries with Ionic Liquids as Electrolytes

Li‐SO₂ batteries have a high energy density but bear serious safety problems that are associated with pressurized SO₂ and flammable solvents in the system. Herein, a novel ambient Li‐SO₂ battery was developed through the introduction of ionic liquid (IL) electrolytes with tailored basicities to solvate SO₂ by reversible chemical absorption. By tuning the interactions of ILs with SO₂, a high energy density and good discharge performance with operating voltages above 2.8 V were obtained. This strategy based on reversible chemical absorption of SO₂ in IL electrolytes enables the development of the next generation of ambient Li‐SO₂ batteries.     

Gluing Ionic Liquids to Oxide Surfaces: Chemical Anchoring of Functionalized Ionic Liquids by Vapor Deposition onto Cobalt(II) Oxide

Ionic liquids (IL) hold a great potential as novel electrolytes for applications in electronic materials and energy technology. The functionality of ILs in these applications relies on their interface to semiconducting nanomaterials. Therefore, methods to control the chemistry and structure of this interface are the key to assemble new IL‐based electronic and electrochemical materials. Here, we present a new method to prepare a chemically well‐defined interface between an oxide and an IL film. An imidazolium‐based IL, which is carrying an ester group, is deposited onto cobalt oxide surface by evaporation. The IL binds covalently to the surface by thermally activated cleavage of the ester group and formation of a bridging carboxylate. The anchoring reaction shows high structure sensitivity, which implies that the IL film can be adhered selectively to specific oxide surfaces.     

Delineating the Mechanism of Ionic Liquids in the Synthesis of Quinazoline‐2,4(1H,3H)‐dione from 2‐Aminobenzonitrile and CO2

Ionic liquids (ILs) are versatile solvents and catalysts for the synthesis of quinazoline‐2,4‐dione from 2‐aminobenzonitrile and CO₂. However, the role of the IL in this reaction is poorly understood. Consequently, we investigated this reaction and showed that the IL cation does not play a significant role in the activation of the substrates, and instead plays a secondary role in controlling the physical properties of the IL. A linear relationship between the pK _a of the IL anion (conjugate acid) and the reaction rate was identified with maximum catalyst efficiency observed at a pK _a of >14.7 in DMSO. The base‐catalyzed reaction is limited by the acidity of the quinazoline‐2,4‐dione product, which is deprotonated by more basic catalysts, leading to the formation of the quinazolide anion (conjugate acid pK _a 14.7). Neutralization of the original catalyst and formation of the quinazolide anion catalyst leads to the observed reaction limit.     

Preorganization and Cooperation for Highly Efficient and Reversible Capture of Low‐Concentration CO2 by Ionic Liquids

A novel strategy based on the concept of preorganization and cooperation has been designed for a superior capacity to capture low‐concentration CO₂ by imide‐based ionic liquids. By using this strategy, for the first time, an extremely high gravimetric CO₂ capacity of up to 22 wt % (1.65 mol mol⁻¹) and excellent reversibility (16 cycles) have been achieved from 10 vol. % of CO₂ in N₂ when using an ionic liquid having a preorganized anion. Through a combination of quantum‐chemical calculations and spectroscopic investigations, it is suggested that cooperative interactions between CO₂ and multiple active sites in the preorganized anion are the driving force for the superior CO₂ capacity and excellent reversibility.