Assessing Solid Catalysts with Ionic Liquid Layers (SCILL) from Molecular Dynamics Simulations: On the Role of Local Charge Polarization.

Recent developments in molecular mechanics modelling of metal catalyst surfaces with interfaces to complex ad-layers or bulk liquids enable the study of 10 nm scale systems by molecular dynamics simulations of up to microseconds. Therein, electronic polarization as otherwise benchmarked by quantum calculations is mimicked via atom-centered partial charges that are adjusted dynamically to account for changes in local environment. Apart from thermal fluctuations, this encompasses molecule association and dissociation processes as well as externally applied voltage.

Evolution of Surface Tension and Hansen Parameters of a Homologous Series of Imidazolium-Based Ionic Liquids.

In this study, we systematically analyze the surface tension and Hansen solubility parameters (HSPs) of imidazolium-based ionic liquids (ILs) with different anions ([NTf], [PF], [I], and [Br]). These anions are combined with the classical 1-alkyl-3-methyl-substituted imidazolium cations ([CCIm]) and a group of oligoether-functionalized imidazolium cations ([(mPEG)Im]) based on methylated polyethylene glycol (mPEG). In detail, the influences of the length of the alkyl- and the mPEG-chain, the anion size, and the water content are investigated experimentally.

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.

Structure Formation in an Ionic Liquid Wetting Layer: A Combined STM, IRAS, DFT and MD Study of [C C Im][OTf] on Au(111).

In a solid catalyst with ionic liquid layer (SCILL), ionic liquid (IL) coatings are used to improve the selectivity of noble metal catalysts. To understand the origins of this selectivity control, we performed model studies by surface science methods in ultrahigh vacuum (UHV). We investigated the growth and thermal stability of ultrathin IL films by infrared reflection absorption spectroscopy (IRAS).