Thermophysical Properties of Newly Synthesized Ammonium-Based Protic Ionic Liquids: Effect of Temperature, Anion and Alkyl Chain Length

Constructing protic porous ionic liquids via one-step coupling neutralization reaction for extraction-adsorption coupled desulfurization

Porous ionic liquids (PILs) offer a distinctive combination of liquid-like fluidity and solid porosity, making them well-suited for various applications including separation, catalysis, and energy storage. Nevertheless, the design limitations and complex synthesis processes have hindered the development of PILs. Here, the one-step coupling neutralization reaction (OCNR) method has been first proposed for the controllable synthesis of functionalized protic porous ionic liquids (PPILs). Specifically, three types of PPILs have been synthesized based on tuning the position of the corona amino functional groups. The results indicate the crucial role of protic ion pairs in the formation of pure liquid PPILs with low viscosity. The extraction efficiency has obviously increased after introducing the porous materials from 38.5% to 51.9%. The results showed PPILs play good extraction-adsorption coupled desulfurization (EADS) performance. The density functional theory (DFT) results show that both the protic ion pairs and the porous structure have significant roles in EADS, with the former offering CH···π interactions, while the latter provides hydrogen bonding (CH···O) interactions. Ultimately, the strategy simplifies the synthesis process, providing a new idea for the directional design of low-viscosity PILs with specific functions.

Synthesis and characterization of ammonium-based protic ionic liquids for carbon dioxide absorption

A series of ammonium-based protic ionic liquids (APILs) namely ethanolammonium pentanoate [ETOHA][C5], ethanolammonium heptanoate [ETOHA][C7], triethanolammonium pentanoate [TRIETOHA][C5], triethanolammonium heptanoate [TRIETOHA][C7], tributylammonium pentanoate [TBA][C5] and tributylammonium heptanoate [TBA][C7] was synthesized via proton transfer. Their structural confirmation and physiochemical properties namely thermal stability, phase transition, density, heat capacity (Cp) and refractive index (RI) have been determined. Specifically, [TRIETOHA] APILs have crystallization peaks ranging from -31.67 to -1.00 °C, owing to their large density values. A comparison study revealed the low Cp values of APILs in comparison to monoethanolamine (MEA) which could be advantageous for APILs to be used in CO2 separation during recyclability processes. Additionally, the performance of APILs toward CO2 absorption was investigated by using a pressure drop technique under a pressure range of 1-20 bar at 298.15 K. It was observed that [TBA][C7] recorded the highest CO2 absorption capacity with the value of 0.74 mole fraction at 20 bar. Additionally, the regeneration of [TBA][C7] for CO2 absorption was studied. Analysis of the measured CO2 absorption data showed marginal reduction in the mole fraction of CO2 absorbed between fresh and recycled [TBA][C7] thus proving the promising potential of APILs as good liquid absorbents for CO2 removal.

Adjustment of the Structure of the Simplest Amino Acid Present in Nature-Glycine, toward More Environmentally Friendly Ionic Forms of Phenoxypropionate-Based Herbicides

The use of chemicals for various purposes in agriculture has numerous consequences, such as the contamination of ecosystems. Thus, nowadays it is perceived that their development should adhere to the principles of green chemistry elaborated by Paul Anastas. Consequently, to create more environment-friendly herbicides, we elaborated a 'green' synthesis method of a series of ionic liquids (ILs) containing cations derived from glycine. The appropriately modified cations were combined with an anion from the group of phenoxy acids, commonly known as 2,4-DP. The products were obtained with high yields, and subsequently, their properties, such as density, viscosity and solubility, were thoroughly examined to elucidate existing structure-property relationships. All ILs were liquids at room temperature, which enabled the elimination of some serious issues associated with solid active forms, such as the polymorphism or precipitation of an active ingredient from spray solution. Additionally, the synthesized compounds were tested under greenhouse conditions, which allowed an assessment of their effectiveness in regulating the growth of oilseed rape, selected as a model dicotyledonous plant. The product comprising a dodecyl chain exhibited the greatest reduction in the fresh weight of plants, significantly surpassing not only a commercially used reference herbicide but also the potassium salt of 2,4-DP.

Special Issue on “Sustainable Modellings, Processes and Applications for Societal Development”

Global society has experienced a tremendous development since the institution of civilization [...]

Experimental Investigation on Thermophysical Properties of Ammonium-Based Protic Ionic Liquids and Their Potential Ability towards CO2 Capture

Ionic liquids, which are extensively known as low-melting-point salts, have received significant attention as the promising solvent for CO₂ capture. This work presents the synthesis, thermophysical properties and the CO₂ absorption of a series of ammonium cations coupled with carboxylate anions producing ammonium-based protic ionic liquids (PILs), namely 2-ethylhexylammonium pentanoate ([EHA][C5]), 2-ethylhexylammonium hexanoate ([EHA][C6]), 2-ethylhexylammonium heptanoate ([EHA][C7]), bis-(2-ethylhexyl)ammonium pentanoate ([BEHA][C5]), bis-(2-ethylhexyl)ammonium hexanoate ([BEHA][C6]) and bis-(2-ethylhexyl)ammonium heptanoate ([BEHA][C7]). The chemical structures of the PILs were confirmed by using Nuclear Magnetic Resonance (NMR) spectroscopy while the density (ρ) and the dynamic viscosity (η) of the PILs were determined and analyzed in a range from 293.15K up to 363.15K. The refractive index (n_D) was also measured at T = (293.15 to 333.15) K. Thermal analyses conducted via a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC) indicated that all PILs have the thermal decomposition temperature, T_d of greater than 416K and the presence of glass transition, T_g was detected in each PIL. The CO₂ absorption of the PILs was studied up to 29 bar at 298.15 K and the experimental results showed that [BEHA][C7] had the highest CO₂ absorption with 0.78 mol at 29 bar. The CO₂ absorption values increase in the order of [C5] < [C6] < [C7] anion regardless of the nature of the cation.

Novel benzo[b]thieno[2,3-d]thiophene derivatives with an additional alkyl-thiophene core: synthesis, characterization, and p-type thin film transistor performance

Newly synthesized benzo[b]thieno[2,3-d]thiophene derivatives were employed as active layers of organic field effect transistors, and these transistors showed decent electrical performance.

Experimental investigation of density, viscosity, and surface tension of aqueous tetrabutylammonium-based ionic liquids

The physical properties such as density, dynamic viscosity, and surface tension of aqueous tetrabutylammonium-based ionic liquids were measured experimentally by varying temperature (283.4 to 333.4 K) and concentration of ILs (10-50 wt%) at an interval of 10 K and 10 wt% respectively. In this study, the aqueous tetrabutylammonium-based ionic liquids namely tetrabutylammonium acetate [TBA][OAC], tetrabutylammonium bromide [TBA][Br], and tetrabutylammonium hydroxide [TBA][OH] was used to investigate the influence of temperature and concentration of ILs on the physical properties data was examined. It is observed that both density and surface tension increase with increasing concentration of [TBA][Br], whereas the opposite trend is observed for [TBA][OAC] and [TBA][OH] respectively. This is due to stronger molecular interaction between [TBA][Br] and water compared to other ILs. The dynamic viscosity of all aqueous ILs increases with increasing IL concentration. The measured physical properties of ILs decrease as temperature increases. Furthermore, the experimental data is correlated and compared with that of the calculated model; the agreement was satisfactory. Graphical abstract.

Physical and chemical properties of binary mixtures of dibutylammonium-based ionic liquids and water

Ionic liquids are used in different processes owing to their low vapor pressure, large viscosity range, chemical and thermal stability, and superior conductance even without water. These features make them flexible and tunable, indicating their possible use as substitutes for commonly used compounds in many processes. The objective of this study was to evaluate the properties of aqueous binary solutions for three different ionic liquids (ILs): dibutylammonium acetate, dibutylammonium propanoate, and dibutylammonium butanoate. The measured properties were density, speed of sound, and conductivity, and their isentropic compressibility and thermal expansion coefficient were calculated based on these properties. The temperature range used for measurements was 293.15–323.15 K. Mathematical models were used for each ionic liquid + water mixture to fit the density and speed of sound data. The increase in the alkyl chain leads to a tendency to decrease the values of density, speed of sound, and conductivity of the solutions. However, decreasing the dilution in water, the density, the conductivity and the speed of sound initially increase and then decrease, exhibiting a maximum in the initial water concentration range which indicates the formation of aggregates. Critical micellar concentrations at 298 K were determined through conductivity data. Enhancing the temperature leads to a decrease on density and sound velocity.

Cryopreservation of mammalian cells using protic ionic liquid solutions

Cryopreservation has facilitated considerable advances in both medical technology and scientific research. However, further developments have been limited by the relatively low number of effective cryoprotective agents. Even after fifty years of research, most protocols rely on the same two toxic agents, i.e. dimethylsulfoxide or glycerol. Ionic liquids are a class of promising solvents which are known glass formers and may offer a less-toxic alternative. The research presented here investigates ten protic ionic liquids as potential cryoprotective agents. The liquids are screened for key properties including cellular toxicity, permeability and thermal behaviour. The most promising, ethylammonium acetate, was then tested as a cryoprotective agent on a model cell line and was found to be as effective as the common cryoprotectant, dimethylsulfoxide. This work reports the first use of a protic ionic liquid as an effective cryoprotective agent for a mammalian cell line. This will inform the development of a suite of potential new ionic liquid-based cryoprotectants that could potentially allow the cryopreservation of new cell types.