In this study, we systematically analyze the surface tension and Hansen solubility parameters (HSPs) of imidazolium-based ionic liquids (ILs) with different anions ([NTf2]-, [PF6]-, [I]-, and [Br]-). These anions are combined with the classical 1-alkyl-3-methyl-substituted imidazolium cations ([CnC1Im]+) and a group of oligoether-functionalized imidazolium cations ([(mPEGn)2Im]+) based on methylated polyethylene glycol (mPEGn). In detail, the influences of the length of the alkyl- and the mPEGn-chain, the anion size, and the water content are investigated experimentally. For [CnC1Im]+-based ILs, the surface tension decreases with increasing alkyl chain length in all cases, but the magnitude of this decrease depends on the size of the anion ([NTf2]- < [PF6]- < [Br]- ≤ [I]-). Molecular dynamics (MD) simulations on [CnC1Im]+-based ILs indicate that these differences are caused by the interplay of charged and uncharged domains, in particular in the different anions, which affects the ability of the alkyl chains of the cation to orient toward the liquid-gas interface. An increase in the mPEGn-chain length of the [(mPEGn)2Im][A] ILs does not significantly influence the surface tension. These changes upon variation of the cation/anion combination do not correlate with the evolution of the HSPs for the two sets of ILs. Finally, our data suggest that significant water contents up to water mole fractions of x(H2O) = 0.25 do not significantly affect the surface tension of the studied binary IL-water mixtures.

We present the preparation and investigation of a fluorine-free surface-active bis-N-heterocyclic carbene (NHC) platinum(II) complex - trans-[Pt(mPEG3C8Im)2Cl2] - for interface-enhanced supported ionic liquid phase (SILP) catalysis within a group of (mPEGn)-substituted ionic liquids (ILs) ([(mPEGn)2Im][A] ILs). The complex was characterized by means of single-crystal X-ray diffraction (scXRD) analysis and multinuclear (1H, 13C, 195Pt) NMR spectroscopy, indicating the presence of two almost equimolar syn-anti-rotamers of the square-planar complex in solution. Angle-resolved X-ray photoelectron spectroscopy (ARXPS) revealed pronounced interface-accumulation of trans-[Pt(mPEG3C8Im)2Cl2] in IL solutions of [(mPEG2)2Im][A] (A-=I- and PF6 -).

Despite the presence of molecular hydrogen (H2) in various technical applications involving ionic liquids (ILs), its effect on the bulk and interfacial properties of ILs is poorly understood. The present study investigates the influence of dissolved H2 on the viscosity, surface tension, and phase composition of three imidazolium-based ILs by experiments and Molecular Dynamics (MD) simulations between (303 and 393) K from (0.1 to 31) MPa. The surface light scattering and pendant-drop experiments showed for all three ILs that the saturated liquid viscosity does not significantly change with increasing H2 pressure, while the surface tension decreases about 5% at 8 MPa. The MD simulations could be used to clarify microscopic origins for the behavior of the macroscopic properties. They revealed not only a compensation of compression and solvation effects due to hydrostatic pressure and dissolved H2 on the viscosity, but also a weak enrichment of H2 at the IL-gas interfaces.

Raw and processed data from MAS NMR, NMR in solution, Elemental analysis, N2 adsorption–desorption isotherms and Small Angle X-ray scattering (SAXS) measurements, for the article "Self-Assembled Supported Ionic Liquids".

Separation and reuse of the catalytically active metal complexes are persistent issues in homogeneous catalysis. Supported Ionic Liquid Phase (SILP) catalysts, where the catalytic center is dissolved in a thin film of a stable ionic liquid, deposited on a solid support, present a promising alternative. However, the dissolution of the metal center in the film leaves little control over its position and its activity. We present here four novel, task-specific ionic liquids [FPhn ImH R]I (n=1, 2; R=PEG2 , C12 H25 ), designed to self-assemble on a silica surface without any covalent bonding and offering a metal binding site in a controlled distance to the support. Advanced multinuclear solid-state NMR spectroscopic techniques under Magic Angle Spinning, complemented by molecular dynamics (MD) simulations, allow us to determine their molecular conformation when deposited inside SBA-15 as a model silica support. We provide here conceptual proof for a rational design of ionic liquids self-assembling into thin films, opening an avenue for a second, improved generation of SILP catalysts.

The present study provides a strategy for the determination of the viscosity and surface tension of high-viscosity fluids in the form of ionic liquids (ILs) at equilibrium conditions by combining surface light scattering (SLS) and the pendant-drop (PD) method within one experimental setup. Through the study of the same sample under identical conditions by both methods inside a closed system, the surface tension determined via the PD method can be directly used to evaluate the dynamics of surface fluctuations of ILs with an overdamped behavior probed by SLS for accessing their viscosity. In connection with the SLS experiments, variations in the applied detection geometries in reflection and transmission direction and in the probed wave vectors down to relatively small values were also addressed. The reliability and self-consistency of SLS and the PD method applied within the same sample cell has been proven by investigating the reference fluids tris(2-ethylhexyl) trimellitate (TOTM) and n -dodecane featuring relatively high and low viscosities. For the two studied model ILs of opaque to non-transparent color, i.e. , the hydrophobic 1-methyl-3-octylimidazolium hexafluorophosphate ([OMIM][PF 6 ]) and the hydrophilic 1,3-bis(2-(2-methoxyethoxy)ethyl)imidazolium iodide ([(mPEG 2 ) 2 Im]I), the combination of PD measurements and SLS experiments in reflection direction performed at ambient pressure between (303 and 373) K allowed access to the viscosity and surface tension with typical relative expanded uncertainties of (4 and 2) %. These results agree well with own viscosity data from capillary viscometry and experimental data in the literature, demonstrating the performance of the novel approach for the contactless in-situ measurement of viscosity and surface tension of fluids with relatively high-viscosity such as ILs.