: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

The physicochemical properties and structure of alkylammonium protic ionic liquids of RnH4-nNX (n = 1–3) family. A mini–review

Beware of proper validation of models for ionic Liquids

We focus on a series of protic ionic liquids (PILs) with imidazolium and alkylimidazolium (1R3HIm, R=methyl, ethyl, propyl, and butyl) cations. Using the literature data and our experimental results on the thermal and transport properties, we analyze the effects of the anion nature and the alkyl radical length in the cation structure on the above properties. DFT calculations in gas and solvent phase provide further microscopic insights into the structure and cation-anion binding in these PILs. We show that the higher thermodynamic stability of an ion pair raises the PIL decomposition temperature. The melting points of the salts with the same cation decrease as the hydrocarbon radical in the cation becomes longer, which correlates with the weaker ion-ion interaction inthe ion pairs. A comparative analysis of the protic ILs and corresponding ILs (1R3MeIm) with the same radical (R) in the cation structure and the same anion has been performed. The lower melting points of the ILs with 1R3MeIm cations are assumed to result from the weakening of both the ion-ion interaction and the hydrogen bond. 

Alkylimidazolium Protic Ionic Liquids: Structural Features and Physicochemical Properties

Phase behavior of twenty-one synthesized salts of triethanolammonium(tris (2-hydroethyl)ammonium) has been studied by the methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). It has been established that 18 of them are protic ionic liquids (PILs) with Tm   100 °C. The PILs have been divided into three groups according to their phase behavior in the DSC experiment. The phase behavior of each of the studied ionic liquids has been analyzed. Multiple regression has been obtained between the ionic liquids characteristics (such as melting, glass transition and decomposition temperatures) determined experimentally and the properties of the anions of the acids forming the PILs calculated by the quantum chemistry methods. It has been shown that there is a linear compensation effect between the changes in the entropy and enthalpy caused by triethanolammonium salts melting.

M. A. Кrestyaninov

Papers

Thermal properties of protic ionic liquids derivatives triethanolamine-based salts of mineral and organic acids