Enantioselective Michael additions of aldehydes to nitroalkenes catalyzed with ionically tagged organocatalyst

Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable.      

Benchmark ab initio proton affinity and gas-phase basicity of α-alanine based on coupled-cluster theory and statistical mechanics

We determine the proton affinity (PA) and gas-phase basicity (GB) of amino acid α-alanine at a chemically accurate level by performing explicitly-correlated CCSD(T)-F12b/aug-cc-pVDZ geometry optimizations and normal mode vibrational frequency calculations as well as CCSD(T)-F12b/aug-cc-pVTZ energy computations at the possible neutral and protonated geometries. Temperature effects at 298.15 K considering translational, rotational, and vibrational enthalpy and entropy corrections are obtained via standard statistical mechanics utilizing the molecular geometries and the harmonic vibrational energy levels. Both the amino nitrogen (N) and the carbonyl oxygen (O) atoms are proven to be potential protonation sites and a systematic conformational search reveals 3 N- and 9 O-protonated conformers in the 0.00–7.88 and 25.43–30.43 kcal/mol energy ranges at 0 K, respectively. The final computed PA and GB values at (0)298.15 K in case of N-protonation are (214.47)216.80 and 207.07 kcal/mol, respectively, whereas the corresponding values for O-protonation are (189.04)190.63 and 182.31 kcal/mol. The results of the benchmark high-level coupled-cluster computations are utilized to assess the accuracy of several lower-level cost-effective methods such as MP2 and density functional theory with various functionals (SOGGA11-X, M06-2X, PBE0, B3LYP, M06, TPSS).     

Low volatile monofunctional reactive diluents for radiation curable formulations

In the last decades the importance of UV curable formulations has increased continuously. Their fast curing speed, solvent-free polymerization conditions, and the formation of hard and highly crosslinked photopolymer networks represent major benefits. Commercial UV resins generally consist of multi-functional vinyl oligomers, photoinitiators, additives, and reactive diluents. Mono- and multi-functional reactive diluents serve as thinners to lower the overall resin viscosity and to improve processability. However, many monofunctional reactive diluents like isobornyl (meth)acrylate or benzyl (meth)acrylate exhibit high volatility, often already at room temperature. This causes adverse effects such as unpleasant odor, potential health risks, and changing resin composition during processing. A new group of monomers that show high potential for replacing traditional highly volatile reactive diluents are salicylate (meth)acrylates. In this work, salicylate-based thinners are synthesized, polymerized, and characterized with respect to their viscosity, volatility, thermal stability, photoreactivity, and thermomechanical properties of their homopolymers. Additionally, a first example of their diluting effect in a highly viscous difunctional polyester urethane methacrylate is demonstrated with 30 wt% of a cycloaliphatically and an aromatically substituted salicylate methacrylate. The polymers of the diluted resin exhibit similarly high glass transition temperatures of 110 and 126 °C, which are in the range of the polymers of the undiluted resin.     

Demixing in polystyrene/methylcyclohexane solutions

Cloudpoint data for polystyrene/methylcyclohexane solutions extending over moderate ranges of pressure and molecular weight are available in the literature. Those data are supplemented with new results from this laboratory to fill in gaps and extend the MW range (to 761 ≤ MW/amu ≤ 2 × 10⁷). The resulting data net is discussed and reasons to extend studies to higher pressure are presented. © 1996 John Wiley & Sons, Inc.     

In Vivo Endoscopic Tissue Identification by Rapid Evaporative Ionization Mass Spectrometry (REIMS)

Gastrointestinal cancers are a leading cause of mortality, accounting for 23 % of cancer‐related deaths worldwide. In order to improve outcomes from these cancers, novel tissue characterization methods are needed to facilitate accurate diagnosis. Rapid evaporative ionization mass spectrometry (REIMS) is a technique developed for the in vivo classification of human tissue through mass spectrometric analysis of aerosols released during electrosurgical dissection. This ionization technique was further developed by utilizing surface induced dissociation and was integrated with an endoscopic polypectomy snare to allow in vivo analysis of the gastrointestinal tract. We tested the classification performance of this novel endoscopic REIMS method in vivo. It was shown to be capable of differentiating between healthy layers of the intestinal wall, cancer, and adenomatous polyps based on the REIMS fingerprint of each tissue type in vivo.     

Non-bilayer formation in the DPPE-DPPG vesicle system induced by deep rough mutant of Salmonella minnesota R595 lipopolysaccharide

The vesicle system consisting of 80 mol% dipalmitoylphosphatidylethanolamine (DPPE) and 20 mol% dipalmitoylphosphatidylglycerol (DPPG) undergoes to structural changes caused by various concentrations of Salmonella minnesota R595 lipopolysaccharide (LPS). The phenomenon was investigated by methods applying small- and wide-angle X-ray scattering (SAXS and WAXS), calorimetry (DSC) and freeze-fracture. In the low LPS concentration regime (investigated at 0.02 LPS/DPPE–DPPG molar ratio) a phase separation was observed. Two kind of domains are formed which are rich and poor in DPPE and in these domains cubic and lamellar structures are present, respectively. Increasing the LPS concentration up to 0.1 LPS/DPPE–DPPG molar ratio the phase separation is more expressed and the temperature domains of the phase transitions are more different. Increasing the temperature chain melting of the lamellar phase occurs first and destruction of the cubic phase is observed later. At high LPS concentration (equimolar ratio of LPS/DPPE–DPPG), where this amphiphilic molecule cannot be considered any more a guest molecule, the cubic structure dominates the phase behaviour of the LPS molecules.     

Cobalt(II) complexes with disubstituted 3-aminopyrazole derivative: Mononuclear Co(II) complex with in situ prepared formamidine ligand

In the reaction of Co(NO₃)₂ · 6H₂O with 4-acetyl-3-amino-5-methylpyrazole (aamp) two octahedral Co(II) complexes, [Co(aamp)₂(H₂O)₄](NO₃)₂, 1, and [Co(ampf)(MeOH)₂NO₃]NO₃ (ampf = N,N′-bis(4-acetyl-5-methylpyrazole-3-yl)formamidine), 2, were obtained, depending on the reaction conditions. The presence of water in the reaction system leads to incorporation of water molecules into the crystal lattice and 1 was formed. In an anhydrous environment, due to addition of CH(OEt)₃, the fusion of two aamp was induced through their NH₂-groups, incorporating the methine group of CH(OEt)₃. As a result, complex 2, containing an adenino-mimetic NNO pharmacophore ligand, was obtained. The crystal and molecular structure of both compounds was determined. The coordination of aamp in 1 was achieved through N2 of the pyrazole ring. On the contrary, in 2, an unusual coordination mode of pyrazole is found: one of the pyrazole moieties, due to steric hindrance, coordinates through the oxygen atom of the acetyl group instead of N2. The complexes were characterized by elemental analysis and electronic spectra. For 2 a comprehensive IR spectral analysis is given. The metal-ligand interactions in 2 are analyzed by quantum chemical computations. The desolvation mechanism of both compounds is discussed in detail.     

First-principles prediction and partial characterization of the vibrational states of water up to dissociation

A new, accurate, global, mass-independent, first-principles potential energy surface (PES) is presented for the ground electronic state of the water molecule. The PES is based on 2200 energy points computed at the all-electron aug-cc-pCV6Z IC-MRCI(8,2) level of electronic structure theory and includes the relativistic one-electron mass-velocity and Darwin corrections. For H₂¹⁶O, the PES has a dissociation energy of D₀ = 41 109 cm⁻¹ and supports 1150 vibrational energy levels up to 41 083 cm⁻¹. The deviation between the computed and the experimentally measured energy levels is below 15 cm⁻¹ for all the states with energies less than 39 000 cm⁻¹. Characterization of approximate vibrational quantum numbers is performed using several techniques: energy decomposition, wave function plots, normal mode distribution, expectation values of the squares of internal coordinates, and perturbing the bending part of the PES. Vibrational normal mode labels, though often not physically meaningful, have been assigned to all the states below 26 500 cm⁻¹ and to many more above it, including some highly excited stretching states all the way to dissociation. Issues to do with calculating vibrational band intensities for the higher-lying states are discussed.     

Aeroacoustics research in Europe: The CEAS-ASC report on 2010 highlights

The Council of European Aerospace Societies (CEAS) Aeroacoustics Specialists Committee (ASC) supports and promotes the interests of the scientific and industrial aeroacoustics community on an European scale and European aeronautics activities internationally. In this context, “aeroacoustics” encompasses all aerospace acoustics and related areas. Each year the committee highlights some of the research and development projects in Europe.This paper is a report on highlights of aeroacoustics research in Europe in 2010, compiled from information provided to the ASC of the CEAS.At the end of 2010, project X-NOISE EV of the Seventh Framework Programme of the European Commission has been launched as a continuation of the X-Noise series, with objectives of reducing aircraft noise and reaching the goal set by the ACARE 2020 Vision.Some contributions submitted to the editor summarizes selected findings from European projects launched before or concluded in 2010, while other articles cover issues supported by national associations or by industries. Furthermore, a concise summary of the workshop on “Aeroacoustics of High-Speed Aircraft Propellers and Open Rotors” held in Warsaw in October is included in this report.Enquiries concerning all contributions should be addressed to the authors who are given at the end of each subsection.