On the Dynamic Interaction of n-Butane with Imidazolium-Based Ionic Liquids

Ionic Liquids: Advances and Applications in Phase Transfer Catalysis

Ionic liquids are a family of liquids that are composed entirely of ions and usually have melting points lower than 100 °C. Extensive research, along with the ever-growing interest of the scientific community, allowed for the development of a multitude of ionic liquids with low melting points. Such compounds are considered neoteric materials as well as ideal, custom-made solvents for a variety of different chemical transformations. In this regard, the importance of phase transfer catalysis is evident in a diversity of substrates and reactions. The use of phase transfer catalysts allows the reaction to proceed, facilitating the transfer of otherwise insoluble reactants to the desired phase. Recent scientific advances led to the emergence of ionic liquids, which are excellent candidates as phase transfer catalysts. The inherent fine-tuning capability of these molecules, along with the potential of phase transfer catalytic reactions, epitomize the sustainable aspect of this field of research. Herein, a cohesive report of such applications will be presented, including the period from the last decade of the 20th century up to date.

n-Butane, iso-Butane and 1-Butene Adsorption on Imidazolium-Based Ionic Liquids Studied with Molecular Beam Techniques

The interaction of molecules, especially hydrocarbons, at the gas/ionic liquid (IL) surface plays a crucial role in supported IL catalysis. The dynamics of this process is investigated by measuring the trapping probabilities of n‐butane, iso‐butane and 1‐butene on a set of frozen 1‐alkyl‐3‐methylimidazolium‐based ILs [C_nC₁Im]X, where n=4, 8 and X⁻=Cl⁻, Br⁻, [PF₆]⁻ and [Tf₂N]⁻. The decrease of the initial trapping probability with increasing surface temperature is used to determine the desorption energy of the hydrocarbons at the IL surfaces. It increases with increasing alkyl chain length n and decreasing anion size for the ILs studied. We attribute these effects to different degrees of alkyl chain surface enrichment, while interactions between the adsorbate and the anion do not play a significant role. The adsorption energy also depends on the adsorbing molecule: It decreases in the order n‐butane>1‐butene>iso‐butane, which can be explained by different dispersion interactions.

Poly(ionic liquid)-Based Efficient and Robust Antiseptic Spray

Exploring efficient and robust antibacterial materials is crucially important for human health and ecological security. Compared with intrinsically antibacterial materials, materials modified with antibacterial agents either by chemical or physical modification can simultaneously maintain basic functions and antibacterial properties. In particular, physical modification with antiseptic sprays is quite suitable for large-size objects in our daily life but restricted by high volatility of the antibacterial agents or poor adhesion strength between the antibacterial agents and the targeted objects. In this paper, we report a poly(ionic liquid) (PIL-Cn)-based efficient and robust antiseptic spray that exhibits long-term antibacterial properties against both Gram-positive and Gram-negative bacteria on diverse substrates, including glass, PE, and cotton. It is believed that this work will provide an alternative for current antiseptic sprays for usage in our daily life and hospitals.

On the Dynamic Interaction of n-Butane with Imidazolium-Based Ionic Liquids

The impact of a reactant from the gas phase on the surface of a liquid and its transfer through this gas/liquid interface are crucial for various concepts applying ionic liquids (ILs) in catalysis. We investigated the first step of the adsorption dynamics of n-butane on a series of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs ([C_n C₁ Im][Tf₂ N]; n=1, 2, 3, 8). Using a supersonic molecular beam in ultra-high vacuum, the trapping of n-butane on the frozen ILs was determined as a function of surface temperature, between 90 and 125 K. On the C₈ - and C₃ -ILs, n-butane adsorbs at 90 K with an initial trapping probability of ≈0.89. The adsorption energy increases with increasing length of the IL alkyl chain, whereas the ionic headgroups seem to interact only weakly with n-butane. The absence of adsorption on the C₁ - and C₂ -ILs is attributed to a too short residence time on the IL surface to form nuclei for condensation even at 90 K.