: 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

Application of deep eutectic solvents in analytical chemistry. A review

Partitioning behavior of organic chemicals has tremendous influences on their environmental distribution, reaction rates, bioaccumulation, and toxic effects. Polyparameter linear free energy relationships (PP-LFERs) have been proven to be useful to characterize the equilibrium partitioning of organic chemicals in various environmental and technical partitioning systems and predict the respective partition coefficients. Over the past decade, PP-LFER solute descriptors for numerous environmentally relevant organic chemicals and system parameters for environmentally important partitioning systems have been determined, extending substantially the applicability of the PP-LFER approaches. However, the information needed for the use of PP-LFERs including descriptors and parameters is scattered over a large number of publications. In this work, we review the state of the art of the PP-LFER approaches in environmental chemical applications. The solute descriptors and system parameters reported in the literature an...

Applications of polyparameter linear free energy relationships in environmental chemistry.

Recent advances on ionic liquid uses in separation techniques.

Ionic liquids (ILs) are a highly unique class of non-molecular solvents that possess melting points below 100 ºC.1 ILs that have melting points below room temperature are often referred to as room temperature ionic liquids (RTILs). ILs possess a wide variety of unique physico-chemical properties, including low or negligible vapor pressure at room temperature, high thermal and electrochemical stability, and high conductivity.2.

Advances of Ionic Liquids in Analytical Chemistry.

Estimation of the environmental properties of compounds from chromatographic measurements and the solvation parameter model.

Gas chromatography on wall-coated open-tubular columns with ionic liquid stationary phases.

Room-temperature ionic liquids (RTILs) are novel solvents composed entirely of ions. They can dissolve a wide range of compounds, while some possess virtually no vapor pressure over a wide temperature range, and have high thermal stability, low toxicity, and low flammability, properties desirable of green solvents. Applications that take advantage for their characteristic properties are starting to appear regularly embodied in techniques, such as liquid-phase microextraction, solid-phase microextraction, and microwave-assisted extraction. In this review, we present a contemporary picture of how, where and when to use ILs in sample-preparation techniques, while recognizing limitations that inhibit their use for some applications. Since the number of potential RTILs is very large, and only a small number have been evaluated in laboratory studies, it is important not to overgeneralize on their potential as general solvents based on this small database of rather limited chemical diversity.

Green sample-preparation methods using room-temperature ionic liquids for the chromatographic analysis of organic compounds

Applications of the solvation parameter model in reversed-phase liquid chromatography.

The reaction of a dinucleating bis(iminopyridine) ligand L bearing a xanthene linker (L = N,N'-(2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene-4,5-diyl)bis(1-(pyridin-2-yl)methanimine)) with Ni2(COD)2(DPA) (COD = cyclooctadiene, DPA = diphenylacetylene) leads to the formation of a new dinuclear complex Ni2(L)(DPA). Ni2(L)(DPA) can also be obtained in a one-pot reaction involving Ni(COD)2, DPA and L. The X-ray structure of Ni2(L)(DPA) reveals two square-planar Ni centers bridged by a DPA ligand. DFT calculations suggest that this species features NiI centers antiferromagnetically coupled to each other and their iminopyridine ligand radicals. Treatment of Ni2(L)(DPA) with one equivalent of ethyl propiolate (HCCCO2Et) forms the Ni2(L)(HCCCO2Et) complex. Addition of the second equivalent of ethyl propiolate leads to the observation of cyclotrimerised products by 1H NMR spectroscopy. Carrying out the reaction under catalytic conditions (1 mol% of Ni2(L)(DPA), 24 h, room temperature) transforms 89% of the substrate, forming primarily benzene products (triethyl benzene-1,2,4-tricarboxylate and triethyl benzene-1,3,5-tricarboxylate) in 68% yield, in a ca. 5 : 1 relative ratio. Increasing catalyst loading to 5 mol% leads to the full conversion of ethyl propiolate to benzene products; no cyclotetramerisation products were observed. In contrast, the reaction is significantly more sluggish with methyl propargyl ether. Using 1 mol% of the catalyst, only 25% conversion of methyl propargyl ether was observed within 24 h at room temperature. Furthermore, methyl propargyl ether demonstrates the formation of cyclooctatetraenes in significant amounts at a low catalyst concentration, whereas a higher catalyst concentration (5 mol%) leads to benzene products exclusively. Density functional theory was used to provide insight into the reaction mechanism, including structures of putative dinuclear metallocyclopentadiene and metallocycloheptatriene intermediates.

Nicole Lenca

Papers

Estimation of the environmental properties of compounds from chromatographic measurements and the solvation parameter model.

Gas chromatography on wall-coated open-tubular columns with ionic liquid stationary phases.

Green sample-preparation methods using room-temperature ionic liquids for the chromatographic analysis of organic compounds

Applications of the solvation parameter model in reversed-phase liquid chromatography.

Divergent reactivity of a new dinuclear xanthene-bridged bis(iminopyridine) di-nickel complex with alkynes.