Self-assembly of an imidazolium surfactant in aprotic ionic liquids. 2. More than solvents

Unlocking the Fluorine-Free Buoy Effect: Surface-Enriched Ruthenium Polypyridine Complexes in Ionic Liquids

Controlling the local concentration of metal complexes at the surface of ionic liquids (ILs) is a highly sought-after objective due to its pivotal implications in supported ionic liquid phase (SILP) catalysis. Equally important is to avoid per- and polyfluorinated substances due to environmental concerns. Herein, we investigate the surface enrichment of Ru polypyridyl complexes with fluorine-free alkylic side groups of varying lengths and shapes, using the hydrophilic IL [C2C1Im][OAc] as solvent. Additional charged carboxylate groups are included into the polypyridyl ligands to increase the solubility of the complex in the IL. When the ligand system is functionalized with long and hydrophobic alkyl side chains, the complex predominantly localizes at the IL/vacuum interface, as deduced from angle-resolved X-ray photoelectron spectroscopy. Conversely, in the presence of short or more bulky substituents, no surface enrichment is observed. This buoy-like behaviour with fluorine-free side groups is explored for 0.05 %mol to 1 %mol solutions. Intriguingly, surface saturation occurs at approximately 0.5 %mol, which is beneficial to the efficient operation of catalytic systems featuring high surface areas, such as SILP catalysts.

Study of the molecular interaction of a phosphonium-based ionic liquid within myo-inositol and non-steroidal anti-inflammatory drugs

Ionic liquids (ILs) can be used as carriers and solubilizers as well as for increasing the effectiveness of drugs. In the present investigation, the micellar properties of phosphonium-based ionic liquids (PILs) such as trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate ([P666(14)][THPP]) and the effect of carbocyclic sugar-based myo-inositol (MI) and non-steroidal anti-inflammatory drugs (NSAIDs), i.e. ibuprofen (IBU) or aspirin (ASP), on the PIL micellar system were studied using surface tension, conductivity, colorimetry, viscometry, FTIR, and dynamic light scattering (DLS) at a temperature of 299 ± 0.5 K. The critical micelle concentrations (CMCs), particle size, zeta potential, and various interfacial parameters were also included i.e., efficiency of adsorption (pC20), surface tension at CMC (γCMC), minimum surface area per molecule (Amin), surface pressure at CMC (πCMC), maximum surface excess concentration (Γmax), and various thermodynamic parameters, such as standard Gibbs free energy of adsorption , standard Gibbs free energy of micellization per alkyl tail , standard Gibbs free energy of the air-water interface (ΔG(s)min), standard Gibbs free energy of transfer , and standard Gibbs free energy of micellization . The adsorption and micellization characteristics became more spontaneous, as shown by the more negative values of and . Viscosity-based rheological properties were calculated for various PIL + MI and PIL + MI + NSAID systems. According to the DLS data, the PIL (Z = 316.4 nm) micellar system generates substantially bigger micelles in an aqueous solution of MI + ASP (Z = 801.7 nm) than in MI + IBU (Z = 674.7 nm). FTIR spectroscopy revealed the interactions of PIL with MI + ASP and MI + IBU, where it was observed that MI + IBU shows good agreement with the PIL system compared to MI + ASP. The current research will have effects on pharmaceutical sciences, molecular biology, and drug delivery.

Aggregation Behavior of Ethoxylated Phytosterol Surfactants in Different Protic Solvents: An Insight from Dielectric Relaxation Studies

The micellar aggregation behavior of biocompatible surfactants, phytosterol ethoxylates (BPS-n, n is the oxyethylene (EO) chain length), containing polyoxyethylene chains in four organic solvents (glycerol (G), ethylene glycol (EG), formamide (FA), and N,N-dimethylformamide (DMF)) was studied by dielectric spectroscopy in the frequency range of 40 Hz to 110 MHz. Only the BPS-n/EG and BPS-n/G systems show distinct dielectric loss peaks near 104 Hz, indicating that BPS-n forms micellar aggregates in EG and G solvents, and the interfacial polarization (IP) between the aggregates and solvents leads to this relaxation. The dielectric spectra were analyzed based on the IP theory and a columnar dispersion model. The dielectric parameters of micelles, the permittivity and conductivity of micelles and solvents, and the volume fraction of the aggregates in solvents were calculated. On this basis, the binding numbers of each EO group on the hydrophobic chain to the solvent molecules EG and G were calculated to be 0.42 and 0.22, respectively. It was suggested that the aggregation appears to be related to the magnitude of the hydrogen bonding interactions. The lower number of EO group-binding solvents is because of the strong steric effect of alcohol solvents and the magnitude of the hydrogen bonding force.