Access to a new family of medium ring aromatic lactones

We report a new method for preparation of hydroxyacids as precursors of benzolactones using a simple and an efficient electrochemical step. This gives in only four steps six- to eleven-membered lactones with high isolated yields from conveniently substituted aryl bromides. The lactonisation was performed according to the Yamamoto's process.     

Thio-functionalised glucosinolates: unexpected transformation of desulfoglucoraphenin

Enzymatic desulfation of stable glucoraphenin affords desulfoglucoraphenin, which unexpectedly undergoes further transformations into cyclic nitrone-type derivatives.     

Surface-modified carbon felts: possible supports for combinatorial chemistry

It is possible to prepare carbon-based analogues of the Merrifield resin by electrochemical reduction of diazonium salts or oxidation of aryl acetates on high specific surface area carbon felts. These modified felts can undergo further reactions: nucleophilic substitution, Suzuki reaction, and finally reductive electrochemical cleavage, taking advantage of the conductivity of the carbon felt. This provides a simple example of the possible use of electrochemistry in combinatorial synthesis.     

Palladium-catalyzed coupling of N-tosylhydrazones with ortho substituted aryl halides: synthesis of 4-arylchromenes and related heterocycles

A convenient and efficient procedure for the synthesis of 4-arylchromenes, thiochromenes, and related heterocycles via a four step-sequence has been developed. The first three steps, which involve hydration of alkynes, hydrazones formation, and their Pd-coupling with ortho substituted aryl halides, furnished stereoselectively Z-trisubstituted olefins without any purification of the intermediates generated in each stage. These latter proved to be suitable precursors, in the last step, for the synthesis of the desired heterocycles of biological interest.     

Surface modification of poly(butylene terephthalate) nonwoven by photochemistry and biofunctionalization with peptides for blood filtration

The surface of meltblown poly(butylene terephthalate) (PBT) nonwoven was modified by photochemistry using the photolinker O‐succinimidyl 4‐azido‐2,3,5,6‐tetrafluorobenzoate for the introduction of activated ester functions and then coupling of molecular probes or biomolecules. Approximately 4000 pmol of (L )‐4,5‐[³H]‐lysine was fixed per PBT sample (1.13 cm²) and measured by liquid scintillation counting. The method consisted in a two‐step process: (a) coating of the clip (0.05 mg/sample) on the fibrous surface of the PBT followed by UV irradiation (30 min, 254 nm) and (b) coupling of amine‐terminated molecules (10^?3 M in phosphate buffer–CH₃CN [1/1, v/v], 20 h). Moreover, about 2000 pmol of ³H‐lysine can be immobilized on the PBT surface after UV irradiation (without clip) by aminolysis reactions with the created oxygenated functions. The derivatizations (via the clip and UV irradiation only) were stable after long‐term heating at 100 °C in water or under steam‐sterilization conditions. They induce neither modifications of the nonwoven morphology nor cytotoxicity. This method was applied for the grafting of peptides Gly‐Arg‐Gly‐Asp‐Ser and Gly‐Gly‐Gly‐Gly‐Gly to perform blood filtration experiments and to retain the leukocytes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Chiral Anthranyl Trifluoromethyl Alcohols: Structures,Oxidative Dearomatization and Chiroptical Properties

Chiral trifluoromethyl alcohol groups were introduced at the hindered ortho positions of 9,10-diphenylanthracenes to investigate their effects on the physical properties and reactivity towards oxidative dearomatization. In such compact structures, the position in different quadrants and the preferred orientation of the −CH(OH)CF₃ groups were determined by the relative and absolute configurations of each stereoisomer, respectively. As a consequence, the stereochemistry governs the organization of the H-bonded molecules in single crystals (homochiral dimers vs ribbon), whereas in chlorinated solvents, they all behave as discrete compounds. Concerning their reactivity, the stereospecific dearomative oxidation of these molecules leads to 9,10-bis-spiro-isobenzofuran-anthracenes, when using organic single-electron transfer oxidants. The chiroptical properties of the alcohols and the corresponding dearomatized products were compared and showed an important modulation of the intensity.     

Modeling of bubble detachment in reduced gravity under the influence of electric fields and experimental verification

A simple model for predicting bubble volume and shape at detachment in reduced gravity under the influence of electric fields is described in the paper. The model is based on relatively simple thermodynamic arguments and relies on and combines several models described in the literature. It accounts for the level of gravity and the magnitude of the electric field. For certain conditions of bubble development the properties of the bubble source are also considered. Computations were carried out for a uniform unperturbed electric field for a range of model parameters, and the significance of model assumptions and simplifications is discussed for the particular method of bubble formation. Experiments were conducted in terrestrial conditions and reduced gravity (during parabolic flights in NASAs KC-135 aircraft) by injecting air bubbles through an orifice into the electrically insulating working fluid, PF5052. Bubble shapes visualized experimentally were compared with model predictions. Measured data and model predictions show good agreement. The results suggest that the model can provide quick engineering estimates concerning bubble formation for a range of conditions (both for formation at an orifice and boiling) and such a model reduces the need for complex and expensive numerical simulations for certain applications. a Major axis of spheroid (m) - a _m Measured bubble height (m) - b Minor axis of spheroid (m) - b _m Measured bubble width (m) - A, B, C, F Parameters of the Kumar-Kuloor model - a/b Computed aspect ratio - a _m /b _m Measured aspect ratio - D Orifice diameter (m) - E Magnitude of the electric field (V/m) - g Gravitational acceleration (m/s²) - g _t Terrestrial gravity (g _t = 9.81 m/s²) - N _w Electrical Weber number - p Pressure (Pa) - Q Volume flow rate (m³/s) - r Radius of the spherical bubble (m) - R Radius of curvature at the tip of the bubble (m) - t Time (s) - t Time interval (s) - T Temperature (°C) - U Electrical potential (V) - u Velocity (m/s) - V Volume (m³) - x, y Dimensionless coordinates of the Cartesian coordinate system - x, y Scaled coordinates, Cheng-Chaddock model - X, Y Dimensional coordinates of the Cartesian coordinate system - Characteristic wave number (m^–1) - Eötvös number - Absolute dielectric permittivity (F/m) - Contact angle (deg.) - Gibbs free energy (J) - Surface tension (N/m) - Dynamic viscosity (Pa s) - Density (kg/m³) - cr Critical value - d Detachment - eq Equilibrium - g Gas - K Refers to the Kumar-Kuloor model - l Liquid - m Measured value - t Terrestrial     

Atomic force microscopy of model lipid membranes

Supported lipid bilayers (SLBs) are biomimetic model systems that are now widely used to address the biophysical and biochemical properties of biological membranes. Two main methods are usually employed to form SLBs: the transfer of two successive monolayers by Langmuir–Blodgett or Langmuir–Schaefer techniques, and the fusion of preformed lipid vesicles. The transfer of lipid films on flat solid substrates offers the possibility to apply a wide range of surface analytical techniques that are very sensitive. Among them, atomic force microscopy (AFM) has opened new opportunities for determining the nanoscale organization of SLBs under physiological conditions. In this review, we first focus on the different protocols generally employed to prepare SLBs. Then, we describe AFM studies on the nanoscale lateral organization and mechanical properties of SLBs. Lastly, we survey recent developments in the AFM monitoring of bilayer alteration, remodeling, or digestion, by incubation with exogenous agents such as drugs, proteins, peptides, and nanoparticles.