Abstract The toxicity of ethyl-, butyl-, octyl-, benzyl-, and allyl-substituted 1-alkyl-3-methylimidazolium, alkylpyridinium, N-alkyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium (choline derivatives) and alkyl-triethylammonium salts towards HeLa cells has been studied. The relative toxicities have been determined in the presence and absence of foetal bovine serum using an MTT assay after 24 and 48 h, and attempts to determine possible sources of the observed toxicity investigated using microscopy and by measuring the intracellular calcium concentration, presence of reactive oxygen species and mitochondrial membrane potential in cells exposed to 1-ethyl-3-methylimidazolium tetrafluoroborate.

Wang, Xuefeng; Ohlin,[1,2] C. André;[1] Lu, Qinghua;[1] Fei, Zhaofu;[3] Hu, Jun;[2] Dyson, Paul J. [3] "Cytotoxicity of ionic liquids and precursor compounds towards human cell line HeLa", Green Chem., 2007, 9, 1191-1197. Link.

1. School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai
2. School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai
3. Institut des Sciences et Ingeniérie Chimiques, Ecole Polytéchnique Fédérale de Lausanne, Lausanne, Switzerland

Abstract Dehydrohalogenation of haloaromatics in ionic liquids derived from ethylmethylimidazolium or similar salts has been performed using PdC, Pd(OAc)₂ and other catalysts using formate salts as a hydrogen source. In the ionic liquid [emim][BF₄], chlorobenzene was dehalogenated by up to 40%, bromobenzene up to 25% and iodobenzene up to 41% in 2 h. Reactions in the absence of the ionic liquid were also performed.

Ohlin, C. André;[1] Beni, Zoltan;[1] Laurenczy, Gabor;[1] Ruiz, Nuria;[2] Masdeu-Bulto, Anna Maria [2] "Heterogeneous dehalogenation of arylhalides in the presence of ionic liquids", Appl. Organomet. Chem., 2007, 21(3), 156-160. Link.

1. Institut des Sciences et Ingeniérie Chimiques, Ecole Polytéchnique Fédérale de Lausanne, Lausanne, Switzerland
2. Universitat Rovira i Virgili, Departament de Quimica Física i Inorganica, Tarragona, Spain

Abstract Biomaterial surface modification is an efficient way of improving cell-material interactions. In this study, sub-micrometer laser-induced periodic surface structures (LIPSS) were produced on polystyrene by laser irradiation. FT-IR analysis confirmed that this treatment also led to surface oxidation and anisotropic orientation of the produced carbonyl groups. As a consequence, the surface energy of the laser-treated polystyrene was 1.45 times that of the untreated polystyrene, as measured by contact-angle goniometry. Protein adsorption and rat C6 glioma cell behavior on the two substrates were investigated, showing that the changed physicochemical properties of laser-modified polystyrene surface led to an increase in the quantity of adsorbed bovine serum albumin and significantly affected the behavior of rat C6 glioma cells. In the early stages of cell spreading, cells explored their microenvironment using filopodium as the main sensor. Moreover, cells actively aligned themselves along the direction of LIPSS gradually and cell attachment and proliferation were significantly enhanced.

Wang, Xuefeng;[1,2] Ohlin, C. André;[1] Lu, Qinghua;[1] Hu, Jun [2] "Influence of physicochemical properties of laser-modified polystyrene on bovine serum albumin adsorption and rat C6 glioma cell behaviour", J. Biomed. Mater. Res. A, 2006, 78A, 746-754. Link.

1. School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai
2. School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai

Abstract We report a method for the preparation of multi-domain liquid crystal (LC) alignment layers on polyimide surfaces with laser-induced periodic surface structures. Atomic force microscopy confirmed that the laser-induced microstructures could be easily erased and re-constructed by repeated laser exposure. The microstructures demonstrated excellent abilities to align LCs in a multi-domain way. The intricate micropatterning of LCs with high resolution was obtained. The opto-electric properties of the LC cells were also determined. In addition, the method is available to a wide range of polymeric substrates, including flexible ones such as poly(ethylene terephthalate).

Li, Xin; Lu, Xuemin; Lu, Qinghua; Ohlin, C. André "Re-writable multi-domain liquid crystal alignment layers through laser-induced micropatterning", Japanese J. Appl. Phys. Part 2, 2006, 45(20-23), L591-L594. Link.

School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240, P. R. China

Abstract The Diels-Alder reaction between cyclopentadiene and methyl acrylate in ionic liquids has been studied in detail. The effect of contamination of the ionic liquids by common impurities, viz. sodium and chloride ions, and water, on the selectivity has been investigated. The presence of high concentrations of chloride was found to decrease the selectivity. Anion and, in particular, cation effects have been investigated using an extensive series of air-stable room temperature ionic liquids, and kinetic parameters have been determined. It has been found that strongly interacting groups, particularly electrophilic moieties on the cation, accelerate the formation of the endo products. Substrate solubility intimately connected to the selectivity was found to be mainly anion dependent. An NMR-based solvent parameter scale and semi-empirical models are used to analyse the results and provide a tool for the prediction of selectivities in ionic liquids.

Vidis, Ana; Ohlin, C. André; Laurenczy, Gàbor; Küsters, Ernst; Sedelmeier, Gottfried; Dyson, Paul J. "Rationalisation of solvent effects in the Diels-Alder reaction between cyclopentadiene and methyl acrylate in room temperature ionic liquids", Adv. Synth. Catal., 2005, 347(2-3), 266-274. Link.

Abstract A series of ‘dual-functionalised’ ionic liquids, comprising imidazolium cations with various functionalities and the nitrile functionalised anion [CH₃CH(BF₃)CH₂CN]^- have been prepared; some exhibit very low viscosities - a highly valuable property in many applications.

Zhao, Dongbin; Fei, Zhaofu; Ohlin, C. André; Laurenczy, Gàbor; Dyson, Paul J. "Designing 'dual-functionalise' ionic liquids: synthesis and characterisation of imidazolium salts with a nitrile-functionalised anion", Chem. Commun., 2004, 19, 2500-2501. Link.

Abstract The solubility of carbon monoxide in 37 ionic liquids and in some organic solvents has been determined using high-pressure ¹³C NMR spectroscopy; a method for predicting the CO solubility is demonstrated, and it was shown that the rate of the hydroformylation of 5-hexen-2-one does not correlate with the CO solubility, as expected from the determined relative solubility of CO compared to H₂.

Ohlin, C. André; Dyson, Paul J.; Laurenczy, Gàbor "Carbon monoxide solubility in ionic liquids: determination, prediction and relevance to hydroformylation", Chem. Commun., 2004, 9, 1070-1071. Link.

Abstract The solubility of hydrogen and the corresponding Henry coefficients for 11 ionic liquids have been determined in situ at 100 atm H₂ pressure and are much lower than expected; attempts to correlate the solubility of hydrogen in the ionic liquids with the rate of reaction for the hydrogenation of benzene to cyclohexane in these solvents have been made.

Dyson, Paul J.; Laurenczy, Gàbor; Ohlin, C. André; Vallance, James; Welton, Tom "Determination of hydrogen concentration in ionic liquid and the effect (or lack of) on rates of hydrogenation", Chem. Commun., 2003, 19, 2418-2419. Link.

Abstract This work reports the hydrogenation of carbon dioxide/inorganic carbonate salts to formic acid/formate in two phase systems comprising an ionic phase, in which the catalyst is immobilized, and an aqueous phase in which the carbonates and formate are confined, is reported. The reactions were followed in situ by multinuclear NMR. Pressurized H₂ gas was used for the reduction.

Ohlin, C. André; Laurenczy, Gàbor "Carbon dioxide reduction in biphasic aqueous-ionic liquid systems by pressurised hydrogen", High Pressure Research, 2003, 23(3), 239-242. Link.