Enantioseparation of chiral benzimidazole derivatives by electrokinetic chromatography using sulfated cyclodextrins

Baseline separation of 18 new substituted benzimidazole derivatives, potent AMP‐activated protein kinase (AMPK) activators, with one chiral center, was achieved by CD‐EKC using sulfated and highly sulfated CDs (SCDs and HS‐CDs) as chiral selectors. The influence of the type and concentration of the chiral selectors on the enantioseparations was investigated. The SCDs exhibit a very high enantioselectivity power since they allow excellent enantiomeric resolutions compared to those obtained with the neutral CDs. The enantiomers were resolved with analysis times around 6 min using 25 mM phosphate buffer at pH 2.5 containing either β‐S‐CD, HS‐β‐CD, HS‐γ‐CD (3 or 4% w/v) at 25°C, with a voltage of 20 kV. The apparent association constants of the inclusion complexes were calculated. The study of the solute structure‐enantioseparation relationships seems to show the high contribution of the interactions between the solutes phenyl ring and the CDs to the enantiorecognition process. The optimized method was briefly validated (LOD less than 1%) and the purity of enantiomers of compound 3 was determined. The enantiomer migration shows reversal order depending on the kind of CD.     

Bayesian Inference of a Parametric Random Spheroid from its Orthogonal Projections

Methodology and Computing in Applied Probability - The paper focuses on a new method for the inference of a parametric random spheroid from the observations of its 2D orthogonal projections. Such a...     

N. Charton,A. Feldermann,A. Theis,M. H. Stenzel,T. P. Davis,C. Barner‐Kowollik,Initiator efficiency of 2,2′‐azobis(isobutyronitrile) in bulk dodecyl acrylate free‐radical polymerizations over a wide conversion and molecular weight range (2004) 42(20) 5170–5179

The original article to which this Erratum refers was published in J Polym Sci Part A: Polym Chem (2004) 42(20) 5170–5179. No abstract.     

Two-photon absorption method for the study of collisional relaxation of atoms in a perturber bath

A two-photon absorption study was performed with sodium vapour at about 300°C perturbed by noble gases at densities between 0.5 x 10¹⁹ and 6 x 10¹⁹ atoms/cm³. The collisional relaxation of the 3P_{$\text{3}\text{2}$} and 3P_{$\text{1}\text{2}$} states has been measured for several noble gases. The origin of relaxation is interpreted as the result of a reactive collision leading to an excited molecular state. The recombination rate coefficients of the three-body reaction are calculated and their values are compared to those given by Scheps and Gallagher.     

Experimental studies of two-photon absorption of sodium perturbed by collisions with noble gas atoms

This study was performed with sodium vapor at about 300°C perturbed by noble gases at densities between 0.5 x 10¹⁹ and 6 x 10¹⁹ atoms/cm³. We have measured the rate of two-photon absorption for step-wise processes, which occur if the exciting frequency is resonant with one of the transition frequencies ω_ri or ω_fr with i, r, and f referring, respectively, to the initial, the relay and the final state. By varying the exciting frequency, we obtain collision profiles which may be difficult to obtain by other methods. The shifts and widths for the transitions 3S-3P_{$\text{3}\text{2}$}, 3S-3P_{$\text{1}\text{2}$}, and 3P_{$\text{3}\text{2}$}-5S have been measured for several noble gases. The observed variation of the profiles with perturber gas pressure suggests possible quenching of the relay state by noble gas molecules present in the mixture.     

Theoretical and experimental studies of the interatomic spectrum induced in the mixture Rb-Xe

We have studied the fluorescence of the “blue” satellite bands associated with the forbidden transition 5S-4D of rubidium perturbed by xenon. The experimental data have been compared with theoretical results arising from an estimate of the dipole intensity induced by collisions. These bands are shown to be well correlated with the 4D level. The observed intensities justify the interpretation we have suggested. The expected population inversion between the 4D and 5P levels, when the satellite bands are pumped, has been confirmed experimentally.     

Modeling of the adsorption behavior and the chromatographic band profiles of enantiomers : Behavior of methyl mandelate on immobilized cellulose

The adsorption isotherms of (−)- and (+)-methyl mandelate from a hexane-isopropanol (90:10) solution were measured on a chromatographic column packed with 4-methylcellulose tribenzoate coated on silica. These isotherms are accounted for by a bi-Langmuir isotherm model, the two Langmuir terms having widely different initial slopes and saturation capacities, but each term having the same saturation capacity for the two enantiomers. The competitive isotherms were also measured. They are in excellent agreement with the prediction of a competitive bi-Langmuir model based on the single-component isotherms. The individual band profiles are in agreement with the profiles calculated from these isotherms. Thus, a simplified competitive isotherm can be used to model a separation on a chiral stationary phase the recognition mechanism of which is not well identified and the adsorption behavior of which is certainly not ideal.     

Squaric acid is a suitable building-block in 4C-Ugi reaction: access to original bivalent compounds

The 4C-Ugi reaction requires an acidic component as one of the building-blocks. We report here the first use of squaric acid for this reaction to access original symmetrical compounds. The scope and conditions of the reaction were explored.     

Philip S. Magee: a life in QSAR

A brief account of the career of Philip S. Magee, a distinguished member of the QSAR community.     

Molecular Design in Practice: A Review of Selected Projects in a French Research Institute That Illustrates the Link between Chemical Biology and Medicinal Chemistry

Chemical biology and drug discovery are two scientific activities that pursue different goals but complement each other. The former is an interventional science that aims at understanding living systems through the modulation of its molecular components with compounds designed for this purpose. The latter is the art of designing drug candidates, i.e., molecules that act on selected molecular components of human beings and display, as a candidate treatment, the best reachable risk benefit ratio. In chemical biology, the compound is the means to understand biology, whereas in drug discovery, the compound is the goal. The toolbox they share includes biological and chemical analytic technologies, cell and whole-body imaging, and exploring the chemical space through state-of-the-art design and synthesis tools. In this article, we examine several tools shared by drug discovery and chemical biology through selected examples taken from research projects conducted in our institute in the last decade. These examples illustrate the design of chemical probes and tools to identify and validate new targets, to quantify target engagement in vitro and in vivo, to discover hits and to optimize pharmacokinetic properties with the control of compound concentration both spatially and temporally in the various biophases of a biological system.