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.     

Enantioselective intramolecular hydroamination catalyzed by lanthanide ate complexes coordinated by N-substituted (R)-1,1'-binaphthyl-2,2'-diamido ligands

Ytterbium and lutetium ionic complexes derived from enantiopure substituted (R)-binaphthylamine ligands, of the general formula [Li(THF)n][Ln[(R)-C20H12(NR)2]2], have been investigated for the hydroamination/cyclization of several aminopentenes and an aminohexene. Complexes with isopropyl or cyclohexyl substituents on nitrogen atoms were found to be efficient catalysts under mild conditions for the formation of N-containing heterocycles with enantiomeric excesses up to 78%.     

A complexomic study of Escherichia coli using two-dimensional blue native/SDS polyacrylamide gel electrophoresis

Study of the complexome - all the protein complexes of the cell - is essential for a better understanding and more global vision of cell function. Using two-dimensional blue native/SDS-PAGE (2-D BN/SDS-PAGE) technology, the cytosolic and membrane protein complexes of Escherichia coli were separated. Then, the different partners of each protein complex were identified by LC-MS/MS. In this report, 306 protein complexes were separated and identified. Among these protein complexes, 50 heteromultimeric and 256 homomultimeric protein complexes were found. Among the 50 heteromultimeric protein complexes, 18 previously described protein complexes validate the technology. In this study, 109 new protein complexes were found, providing insight into the function of previously uncharacterized bacterial proteins.     

PEO‐Covered Nanoparticles by Emulsion Inversion Point (EIP) Method

This study reports the first PEO‐coated polymer nanoparticles synthesis by miniemulsion polymerization of nano‐emulsions prepared by the low‐energy emulsification method called EIP. The surfactant used was Brij 98, a PEO based non ionic commercial surfactant. The partial phase diagram of the system water/Brij 98/styrene was first determined. The Emulsion Inversion Point technique was then used on the water/Brij 98/styrene system to the formation of styrene‐in‐water nano‐emulsions. After miniemulsion polymerization, particle sizes as low as 36 nm were obtained. To the best of our knowledge, this method had not been used for polymerizable system up to now.

     

Commissioning of a multi‐beamline femtoslicing facility at SOLEIL

The investigation of ultrafast dynamics, taking place on the few to sub‐picosecond time scale, is today a very active research area pursued in a variety of scientific domains. With the recent advent of X‐ray free‐electron lasers (XFELs), providing very intense X‐ray pulses of duration as short as a few femtoseconds, this research field has gained further momentum. As a consequence, the demand for access strongly exceeds the capacity of the very few XFEL facilities existing worldwide. This situation motivates the development of alternative sub‐picosecond pulsed X‐ray sources among which femtoslicing facilities at synchrotron radiation storage rings are standing out due to their tunability over an extended photon energy range and their high stability. Following the success of the femtoslicing installations at ALS, BESSY‐II, SLS and UVSOR, SOLEIL decided to implement a femtoslicing facility. Several challenges were faced, including operation at the highest electron beam energy ever, and achievement of slice separation exclusively with the natural dispersion function of the storage ring. SOLEIL's setup also enables, for the first time, delivering sub‐picosecond pulses simultaneously to several beamlines. This last feature enlarges the experimental capabilities of the facility, which covers the soft and hard X‐ray photon energy range. In this paper, the commissioning of this original femtoslicing facility is reported. Furthermore, it is shown that the slicing‐induced THz signal can be used to derive a quantitative estimate for the degree of energy exchange between the femtosecond infrared laser pulse and the circulating electron bunch.     

Pierre Turq,an inspirational scientist in charge and at interfaces

Pierre Turq has made decisive contributions to the theory and to the multiscale simulation of charged systems, such as molten salts, electrolyte solutions and colloidal suspensions, in the bulk, at interfaces and under confinement. His research line focussed on dynamical properties and was characterised by constant efforts to connect his theoretical work to both experiments and practical applications. In this article, his colleagues and former students pay a tribute to his past and current research interests by illustrating some recent developments accomplished in his laboratory.     

Electronic properties of 2D and 3D hybrid organic/inorganic perovskites for optoelectronic and photovoltaic applications

We herein investigate theoretically both 2D and 3D Hybrid Organic/inorganic perovskite crystal structures based on density functional theory (DFT) calculations and symmetry analyses. Our findings reveal the universal features of the electronic band structure for the class of lead-halide hybrids (R-NH \(_{3})_{n}\hbox {PbX}_{m}\) , where \((\mathrm{{n}}, \mathrm{{m}})=(2,4)\) and (1,3) respectively for 2D and 3D structures. Among those, the large spin-orbit coupling acting on the conduction band is shown to play a major role on the band gap of these materials. Moreover, this approach can easily be generalized to related layered and 3D hybrids, thus providing a clear-sighted inside in their electronic and optical properties.     

Ultrafast laser processing of drug particles in water for pharmaceutical discovery

The laser fragmentation technique has been extensively used to produce inorganic nanoparticles, but its practice on organic materials, especially on drugs, is less common. Here, we briefly review the recent advances in laser micro-/nanonization of organic materials and the rationale of using laser fragmentation for drug discovery. We present our case studies of two drug models: fenofibrate and naproxen. Both drugs were fragmented in water with femtosecond (fs) laser and characterized in terms of particle size distribution and physicochemical properties. Effects of fs laser fragmentation were also compared with nanosecond (ns) laser fragmentation and with conventional media milling technique. Fs laser was more suitable to produce sub-micron size drug particles than ns laser, but degradation of drugs after nanonization was also more pronounced than micronization. Physicochemical transformations such as oxidation, hydration and amorphisation might occur during the laser–material interactions. Laser nanonization showed improved dissolution kinetics, similar to media milling. Unlike the conventional milling techniques, laser fragmentation enabled the treatment of minute amount (as small as several milligrams) of drugs with high efficiency, thus is a useful tool for particle size reduction during the early phases of drug discovery.     

DNA Photosensitization by an “Insider”: Photophysics and Triplet Energy Transfer of 5‐Methyl‐2‐pyrimidone Deoxyribonucleoside

The main chromophore of (6‐4) photoproducts, namely, 5‐methyl‐2‐pyrimidone (Pyo), is an artificial noncanonical nucleobase. This chromophore has recently been reported as a potential photosensitizer that induces triplet damage in thymine DNA. In this study, we investigate the spectroscopic properties of the Pyo unit embedded in DNA by means of explicit solvent molecular‐dynamics simulations coupled to time‐dependent DFT and quantum‐mechanics/molecular‐mechanics techniques. Triplet‐state transfer from the Pyo to the thymine unit was monitored in B‐DNA by probing the propensity of this photoactive pyrimidine analogue to induce a Dexter‐type triplet photosensitization and subsequent DNA damage.     

Plate coating: influence of concentrated surfactants on the film thickness

We present a large range of experimental data concerning the influence of surfactants on the well-known Landau-Levich-Derjaguin experiment where a liquid film is generated by pulling a plate out of a bath. The thickness h of the film was measured as a function of the pulling velocity V for different kinds of surfactants (C(12)E(6), which is a nonionic surfactant, and DeTAB and DTAB, which are ionic) and at various concentrations near and above the critical micellar concentration (cmc). We report the thickening factor α = h/h(LLD), where h(LLD) is the film thickness obtained without a surfactant effect, i.e., as for a pure fluid but with the same viscosity and surface tension as the surfactant solution, over a wide range of capillary numbers (Ca = ηV/γ, with η being the surfactant solution viscosity and γ its surface tension) and identify three regimes: (i) at small Ca α is large due to confinement and surface elasticity (or Marangoni) effects, (ii) for increasing Ca there is an intermediate regime where α decreases as Ca increases, and (iii) at larger (but still small) Ca α is slightly higher than unity due to surface viscosity effects. In the case of nonionic surfactants, the second regime begins at a fixed Ca, independent of the surfactant concentration, while for ionic surfactants the transition depends on the concentration, which we suggest is probably due to the existence of an electrostatic barrier to surface adsorption. Control of the physical chemistry at the interface allowed us to elucidate the nature of the three regimes in terms of surface rheological properties.