Spectroscopic methods, ionic liquids, solvent

Poole, C.R, Chromatographic and spectroscopic methods for the determination of solvent properties of room temperature ionic liquids, /. Chromatogr. A, 1037, 49-82, 2004. 

For many oxidation reactions, the presence of ionic liquids appears to have a beneficial effect in that increased reaction rates are observed and stabilisation of catalytically active intermediates in these solvents has been demonstrated by means of in situ spectroscopic methods in several cases. And while the oxygen solubility is very poor in common ionic liquids solid oxidants are often dissolved more efficiently, resulting in increased reaction rates, ever under biphasic conditions. 

The modem world of chemical synthesis is unthinkable without NMR spectroscopy. Especially in organic synthesis, the information content of a combination of various NMR techniques is tremendeous and unmatched by any other spectroscopic method. Thus, since ionic liquids ( ILs for short) are predominantly used as solvents these days, the application of magnetic resonance spectroscopy to ionic solvents has become very important. None the less, the unique properties of this modem solvent class has put quite some challenge to researchers trying to apply NMR for ILs. In this review, I will describe the development of NMR in modem (i.e. air- and moisture-stable, predominantly imidazolium-based) ILs of the last 8 years historically from an experimental perspective. If you are looking for a more substrate-specific point of view or are interested in the early developments with chloroaluminate ILs, you are kindly asked to refer to the recent literature [1],... 

Abstract In this paper we address two aspects of ionic liquids (ILs) that to date have either no or limited studies. They are (1) exploitation of unique features of ILs to develop novel spectroscopic methods which otherwise is not possible and (2) development of novel spectroscopic methods for the sensitive and accurate determination of thermal physical properties of ILs. In the first category, we have successfully developed a novel, highly sensitive and accurate method for the determination of enantiomeric compositions of chiral compounds with different sizes, shape and functional groups including pharmaceutical products. This method is based on the use of a chiral IL which serves both as a solvent and also as a chiral selector. We have also demonstrated that ILs can be used to substantially enhance the sensitivity of thermal lens measurements. In the second category, we have demonstrated that transient grating technique and thermal lens technique can be used for the sensitive, accurate, nondestructive determination of thermal physical properties of ILs. 

With the intensive development of ultrafast spectroscopic methods, reaction dynamics can be investigated at the subpicosecond time scale. Femtosecond spectroscopy of liquids and solutions allows the study of sol-vent-cage effects on elementary charge-transfer processes. Recent work on ultrafast electron-transfer channels in aqueous ionic solutions is presented (electron-atom or electron-ion radical pairs, early geminate recombination, and concerted electron-proton transfer) and discussed in the framework of quantum theories on nonequilibrium electronic states. These advances permit us to understand how the statistical density fluctuations of a molecular solvent can assist or impede elementary electron-transfer processes in liquids and solutions. 

Pees B., Paul J.M., Corpart J.M., Sindt M., Mieloszynski J.L. (2004). Surface properties of m-perfluorooctyl-aUcyl polyacrylates odd-even effect, Eur. Polym. Jour., vol.40, n°12, pp. 2727-2730 (December 2004) ISSN 0014-3057 Poole C.F. (2004). Chromatographic and spectroscopic methods for the determination of solvent properties of room temperature ionic liquids, /. Chromatogr., A, vol.1037, n°l-2, pp.49-82 (May 2004), ISSN 0021-9673... 

Poole, C. F. Chromatographic and Spectroscopic Methods for the Determination of Solvent Properties of Room Temperature Ionic Liquids. 

Solvation behavior can be effectively predicted using electronic structure methods coupled with solvation methods, for example, the combination of continuum solvation methods such as COSMO with DFT as implemented in DMoF of Accelrys Materials Studio. An attractive alternative is statistical-mechanical 3D-RISM-KH molecular theory of solvation that predicts, from the first principles, the solvation structure and thermodynamics of solvated macromolecules with full molecular detail at the level of molecular simulation. In particular, this is illustrated here on the adsorption of bitumen fragments on zeolite nanoparticles. Furthermore, we have shown that the self-consistent field combinations of the KS-DFT and the OFE method with 3D-RISM-KH can predict electronic and solvation structure, and properties of various macromolecules in solution in a wide range of solvent composition and thermodynamic conditions. This includes the electronic structure, geometry optimization, reaction modeling with transition states, spectroscopic properties, adsorption strength and arrangement, supramolecular self-assembly,"and other effects for macromolecular systems in pure solvents, solvent mixtures, electrolyte solutions, " ionic liquids, and simple and complex solvents confined in nanoporous materials. Currently, the self-consistent field KS-DFT/3D-RISM-KH multiscale method is available only in the ADF software. 

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