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Enantioselectivities were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using monodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with cyclohexanone.

The intrinsic conformer specific vibrational spectra of two subunits of the core pentasaccharide of N-linked glycans, the alpha(1,3) and alpha(1,6) dimannosides is recorded in the gas phase. These measurements and computational studies are used to enable their conformational assignment and identify characteristic vibrational signatures associated with particular conformational families, including those that do or do not display inter-ring hydrogen bonding across the glycosidic linkage.

The conformation of phenyl-substituted monosaccharides and their singly hydrated complexes are investigated in the gas phase by means of a combination of mass selected, conformer specific ultraviolet and infrared double resonance hole burning spectroscopy experiments, and ab initio quantum chemistry calculations. In each case, the water molecule inserts into the carbohydrate at a position where it can replace a weak intramolecular by two stronger intermolecular hydrogen bonds.

Poly(ehtyleneglycol 400)/(LiCl)x electrolytes present conductivities on the order of 10(super -4)Scm(super -1) at 25 degrees Celsius is the highlighted study. This permits classification of these materials as good liquid polymer electrolytes.

Research into the conformational landscapes of 2-amino-1-phenylethanol and its 1:1 water complexes is presented. Local information gained from infrared spectroscopy gives valuable insights into the general geometry of nonrigid molecular conformers and their hydrated complexes.

Infrared (IR)/ultraviolet (UV) hole-burning spectroscopy is used for examining the aggregation of the protected segment (Ac-VQIVYK-NHMe) in the NH stretch region in a cold molecular beam in order to characterize its structure and identify the noncovalent interactions responsible for aggregation and stabilization in amyloid peptides. The studies have shown that the tau-protein fragments form extended [beta]-strands that are combined in a [beta]-sheet through characteristic backbone hydrogen bonds, indicating that this secondary structure is very energetic and is readily formed in the gas phase.

The inherent conformational preferences of the capped hexapeptide Ac-VQIVYK-NHMe are characterized in the gas phase by using infrared/ultraviolet (IR/UV) double-resonance spectroscopy. The studies have shown that in the protonated tau-peptide fragment, the lysine N[H.sub.3.sup.+] is bound to the peptide backbone and has altered the neutral [beta]-strand/[beta]-turn conformation into a random-coil-like structure.

The conformational structures of protonated polyalanine peptides, [Ala.sub.n][H.sup.+] are investigated in the gas phase. Results show that the peptide [Ala.sub.3][H.sup.+] exhibits an unfolded shape with likely dynamic interconversion between different conformations.

The application of infrared photofragment spectroscopy to the amino acids tyrosine and phenylalanine, and two pentapeptides, bradykinin fragment 1-5 and [Leu]-enkephalin, all bound to a potassium cation is presented. The striking feature in the [Leu]-enkephalin spectrum is the high infrared activity of the tyrosine side-chain modes, which can be clearly identified from comparison to the experimental spectrum, but which is not reproduced by the DFT calculations.

While probing benzyl lactoside isolated in the gas phase using UV and IR ion-dip, it is found that the disaccharide unit adopts only a single, rigid structure. The biological implications of this discovery are discussed.

Partially resolved ultraviolet rotational band contours associated with the S1

We report a newly developed technique for the in situ real-time gas analysis of reactors commonly used for the production of nanomaterials, by showing case-study results obtained using a dedicated apparatus for measuring the gas composition in reactors operating at high temperature (<1000 °C). The in situ gas-cooled sampling probe mapped the chemistry inside the high-temperature reactor, while suppressing the thermal decomposition of the analytes. It thus allows a more accurate study of the mechanism of progressive thermocatalytic cracking of precursors compared to previously reported conventional residual gas analyses of the reactor exhaust gas and hence paves the way for the controlled production of novel nanomaterials with tailored properties. Our studies demonstrate that the composition of the precursors dynamically changes as they travel inside of the reactor, causing a nonuniform growth of nanomaterials. Moreover, mapping of the nanomaterials reactor using quantitative gas analysis revealed the actual contribution of thermocatalytic cracking and a quantification of individual precursor fragments. This information is particularly important for quality control of the produced nanomaterials and for the recycling of exhaust residues, ultimately leading toward a more cost-effective continuous production of nanomaterials in large quantities. Our case study of multiwall carbon nanotube synthesis was conducted using the probe in conjunction with chemical vapor deposition (CVD) techniques. Given the similarities of this particular CVD setup to other CVD reactors and high-temperature setups generally used for nanomaterials synthesis, the concept and methodology of in situ gas analysis presented here does also apply to other systems, making it a versatile and widely applicable method across a wide range of materials/manufacturing methods, catalysis, as well as reactor design and engineering. [ABSTRACT FROM AUTHOR]

The article discusses the structural motif and stability of cross-Β structure of insoluble amyloid fibril deposits from misfolded proteins associated with Alzheimer's disease (AD) and type-II diabetes. It explores the transition of the amyloid-like dimer for the hexapeptide and compares it with quantum-chemical predictions and structures found in the disease-related tau proteins. It shows that β-sheet aggregation can compensate for the energetic cost of protein unfolding.

The intrinsic conformer specific vibrational spectra of two important subunits of the core pentasaccharide of N-linked glycans, the α(1 3) and α(1 ,6) dimannosides, have been recorded in the gas phase. Coupling these measurements with a computational exploration of their conformational landscapes has enabled their conformational assignment and has identified characteristic vibrational signatures associated with particular conformational families-including those that do or do not display inter-ring hydrogen bonding across the glycosidic linkage. In addition, the IA spectra of the monosaccharide moieties provide benchmarks, through which the conformational assignments can be refined. This introduces a general concept of modularity and secondary structure in oligosaccharides-essential for the success of similar studies on larger oligosaccharides in the future. [ABSTRACT FROM AUTHOR]