Samples of locally sourced UK Diesel fuel spiked with the two organic compounds 2-(butan-2-yl)-1-(decyloxy)-4-(triphenylmethyl)benzene (TPMB) and 1,3-dibromotetrafluorobenzene (BFB) were subjected to laboratory-scale distillations to assess the suitability of TPMB and BFB as effective markers of Diesel fuel. Industrial-scale distillations of these spiked Diesel samples were performed to establish whether TPMB and BFB could be successfully and cost-effectively separated from Diesel on a significantly larger scale. Diesel distillate does not contain any TPMB; newly formulated performance criteria of an ideal, distillation resistant fuel marker clearly reject TPMB as a marker suitable for the tagging of Diesel. In contrast, BFB is retained in all fractions of distilled Diesel and largely satisfies the performance criteria of a distillation resistant fuel marker. BFB consequently functions as a significantly better fuel marker than TPMB for the tagging of Diesel. It is demonstrated that distillation is also a highly effective means of removing current overt dye markers. Conservative estimates suggest that an appropriately equipped laundering facility for the distillative removal of fuel markers or vice versa fuel from marked Diesel offers the potential of generating a vastly lucrative, multi-million pound annual profit.

Raman optical activity (ROA) has been exclusively observed in the visible (VIS) and near-infrared (NIR) spectral regions to date. During the last few years, we have designed, constructed and tested the first ROA instrument, operating in the deep-ultraviolet (DUV) spectral region employing 244-nm excitation. This novel DUV ROA instrument is based on a backscattering geometry and incident circular polarization modulation (ICP); it makes use of a fast DUV imaging lens-based spectrograph and specially designed DUV grade polarization optics. The performance of this instrument has been evaluated by analysing measured non-resonant DUV ROA spectra of non-absorbing enantiomeric liquid samples and by comparing these with corresponding ROA spectra recorded in the visible spectral region. Copyright (c) 2015 John Wiley & Sons, Ltd.

Mit inelastischer Neutronenstreuung (INS) wurde das Schwingungsspektrum eines Eisen-haltigen Fischer-Tropsch-Katalysators technischer Qualität erhalten, der einer großtechnischen Industrieanlage entnommen wurde. Über Eisen-Fischer-Tropsch-Katalysatoren wurde zuvor berichtet, dass sie kohlenstoffhaltige Spezies enthalten, und die INS-Spektren weisen zusätzlich auf partiell hydrierte aromatische Moleküle hin (siehe Bild). As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A recent in situ infrared study on the selective hydrogenation of C5 dienes and monoenes over a Pd/Al(2)O(3) catalyst only reported incomplete vibrational assignments for some of the reagents, intermediates and products encountered in that study This work uses a combination of infrared absorption spectroscopy, Raman, and inelastic neutron scattering to characterize the vibrational spectra of pentane, 1-pentene, cis- and trans-2-pentene, cis- and trans-1,3-pentadiene, 1,4-pentadiene, cyclopentane, and cyclopentene. Ab initio calculations of the potential energy surface, geometry, and vibrational transition energies were performed and simulations of the vibrational spectra compared to the experimental data Complete vibrational assignments for the majority of the molecules are presented. The potential for using gas-phase infrared measurements for studying heterogeneously catalyzed gas-phase reactions is also briefly considered.

Splitting it up: excellent agreement between the experimental and the quantum-chemically simulated Raman optical activity (ROA) spectrum of (+)-poly(trityl methacrylate) shows that the polymer backbone adopts a left-handed helical conformation while the trityl side groups display a left-handed propeller conformation. Thus ROA can be used to determine the complete structure of synthetic chiral polymers in solution.

On the ROA to somewhere: The first combined study of measured and computed Raman optical activity (ROA) of a transition metal complex under non-resonant scattering conditions is reported. ROA measurements of the two enantiomers of the dichloro[ethylenebis(4,5,6,7-tetrahydro-1-indenyl)] zirconium(IV) complex yield virtually mirror-image ROA spectra. The experimental spectra are directly comparable with predicted ROA spectra.

Teilung führt zur Erkenntnis: Aus der ausgezeichneten Übereinstimmung der experimentellen und quantenchemisch berechneten Daten des optisch aktiven Raman-Effekts (ROA) von (+)-Poly(tritylmethacrylat) geht eindeutig hervor, dass das Polymerrückgrat eine linksgängige helikale Konformation und die Trityl-Seitengruppen eine linkshändige Propellerkonformation einnehmen. Durch den ROA-Effekt ist somit die vollständige Strukturbestimmung synthetischer Polymere in Lösung möglich, wobei zwischen Beiträgen des Rückgrats und der Seitenketten deutlich unterschieden werden kann.

Verräterische Signatur: Die Glycanstruktur von intakter Hefe-Invertase, einem als Biokatalysator eingesetzten mannosereichen Glycoprotein, wurde durch ROA-Spektroskopie (Raman-optische Aktivität) untersucht. Es zeigte sich, dass die konformativen Präferenzen in mannosehaltigen Di- und Trisacchariden in den Glycanketten beibehalten werden, wobei die Polypeptid-Sekundärstruktur unterdrückt wird.

Polyproline II (PPII) helix is an extended secondary structure present in a number of proteins. PPII‐containing sequences mediate specific protein–protein interactions with partners containing appropriate cognate domains called PPII‐recognizing domains (PRDs) and are involved in the activation of intracellular signaling pathways. Thus, the identification of PPII structures in proteins is of great interest, not only to explore molecular and physiological mechanisms, but also to elaborate new potential drugs. By revisiting X‐ray crystal structures of liganded α‐type human estrogen receptor (ERα), we have identified an 11‐residue PPII‐helical sequence (D321AEPPILYSEY331) in the ligand‐binding domain of the receptor. The data recorded by far‐ultraviolet circular dichroism (far‐UV CD), vibrational Raman optical activity (ROA) and differential scanning calorimetry (DSC) show that the corresponding peptide (Ac‐DAEPPILYSEY‐NH2) is particularly well structured in PPII, with the same proportion of PPII as observed from X‐ray structures (∼85%). In addition, studies carried out on ERα‐negative Evsa‐T breast cancer cells transiently co‐transfected with a pcDNA3‐ERα plasmid and a Vit‐tk‐Luc reporter gene revealed that the peptide antagonizes the estradiol‐induced transcription providing perspectives for researching new molecules with antagonistic properties. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.

The samples used for the first observations of vibrational Raman optical activity (ROA) in 1972, namely both enantiomers of 1-phenylethanol and 1-phenylethylamine, have been revisited using a modern commercial ROA instrument together with state-of-the-art ab initio calculations. The simulated ROA spectra reveal for the first time the vibrational origins of the first reported ROA signals, which comprised similar couplets in the alcohol and amine in the spectral range approximately 280-400 cm(-1). The results demonstrate how easy and routine ROA measurements have become, and how current ab initio quantum-chemical calculations are capable of simulating experimental ROA spectra quite closely provided sufficient averaging over accessible conformations is included. Assignment of absolute configuration is, inter alia, completely secure from results of this quality. Anharmonic corrections provided small improvements in the simulated Raman and ROA spectra. The importance of conformational averaging emphasized by this and previous related work provides the underlying theoretical background to ROA studies of dynamic aspects of chiral molecular and biomolecular structure and behavior.

Vibrational Raman optical activity (ROA), measured as a small difference in the intensity of Raman scattering from chiral molecules in right- and left-circularly polarized incident light, or as the intensity of a small circularly polarized component in the scattered light, is a powerful probe of the aqueous solution structure of proteins. The large number of structure-sensitive bands in protein ROA spectra makes multivariate analysis techniques such as nonlinear mapping (NLM) especially favorable for determining structural relationships between different proteins. We have previously used NLM to map a large dataset of peptide, protein, and virus ROA spectra into a readily visualizable two-dimensional space in which points close to or distant from each other, respectively, represent similar or dissimilar structures. As well as folded proteins, our dataset contains ROA spectra from many natively unfolded proteins, proteins containing both folded and unfolded domains, denatured partially structured molten globule and reduced protein states, together with folded proteins containing little or no alpha-helix or beta-sheet. In this article, the relative positions of these systems in the NLM plot are used to obtain information about any residual structure that they may contain. The striking differences between the structural propensities of proteins that are unfolded in their native states and those that are unfolded due to denaturation may be responsible for their often very different behavior, especially with regard to aggregation. An ab initio simulation of the Raman and ROA spectra of an alanine oligopeptide in the poly(L-proline) II-helical conformation confirms previous suggestions that this conformation is a significant structural element in disordered peptides and natively unfolded proteins. The use of ROA to identify and characterize proteins containing significant amounts of unfolded structure will, inter alia, be valuable in structural genomics/proteomics since unfolded sequences often inhibit crystallization.

The binding of divalent copper ions to the full-length recombinant murine prion protein PrP23-231 at neutral pH was studied using vibrational Raman optical activity (ROA) and ultraviolet circular dichroism (UV CD). The effect of the Cu2+ ions on PrP structure depends on whether they are added after refolding of the protein in water or are present during the refolding process. In the first case ROA reveals that the hydrated alpha-helix is lost, with UV CD revealing a drop from approximately 25% to approximately 18% in the total alpha-helix content. The lost alpha-helix could be that comprising residues 145-156, located within the region associated with scrapie PrP formation. In the second case, ROA reveals the protein's structure to be almost completely disordered/irregular, with UV CD revealing a drop in total alpha-helix content to approximately 5%. Hence, although Cu2+ binding takes place exclusively within the unfolded/disordered N-terminal region, it can profoundly affect the structure of the folded/alpha-helical C-terminal region. This is supported by the finding that refolding in the presence of Cu2+ of a mutant in which the first six histidines associated with copper binding to the N-terminal region are replaced by alanine has a similar alpha-helix content to the metal-free protein. In contrast, when the protein is refolded in the presence of divalent manganese ions, ROA indicates the alpha-helix is reinforced, with UV CD revealing an increase in total alpha-helix content to approximately 30%. The very different influence of Cu2+ and Mn2+ ions on prion protein structure may originate in the different stability constants and geometries of their complexes.

A pair of enantiomerically pure quaternary ammonium salts with a chiral side chain, methyl-(R)-(1-methylpropyl)di(n-propyl)ammonium iodide 1 and methyl-(S)-(1-methylpropyl)di(n-propyl)ammonium iodide 2, and the related racemate, methyl-(rac)-(1-methylpropyl)di(n-propyl)ammonium iodide 3, were synthesized through a reductive alkylation procedure, starting from enantiomerically pure and, also, racemic forms of (rac)-(1-methylpropyl)amine. A spectroscopic chiroptical signature in solution was provided by the Raman optical activity spectra of compounds 1 and 2. The crystallographic structures of 1, 2, and 3 were examined by single crystal X-ray diffraction. 1 crystallizes in the tetragonal space group P4(3)2(1)2 (no. 96), a = b = 12.826 (2) A, c = 17.730 (2) A, V = 2916.9 (5) A(3), Z = 8, Flack coefficient 0.04 (2). 2 crystallizes in the tetragonal space group P4(1)2(1)2 (no. 92), a = b = 12.842 (1) A, c = 17.749 (2) A, V = 2927.0 (5) A(3), Z = 8, Flack coefficient 0.05 (2). The crystal structures and space groups for 1 and 2 are enantiomorphs and the crystallographic investigation confirmed the absolute configuration of the stereocenter in both compounds. 3 crystallizes in the monoclinic space group P2(1)/n(no. 14), a = 8.178 (1) A, b = 14.309 (2) A, c = 12.328 (2) A, beta = 96.811 (6) degrees, V = 1432.4 (2) A(3), Z = 4.

Angewandte ChemieVolume 120, Issue 34 p. 6492-6494 Zuschrift Solution Structures of β Peptides from Raman Optical Activity† Josef Kapitán Dr., Josef Kapitán Dr. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this authorFujiang Zhu Dr., Fujiang Zhu Dr. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this authorLutz Hecht Dr., Lutz Hecht Dr. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this authorJames Gardiner Dr., James Gardiner Dr. Eidgenössische Technische Hochschule Zürich, Department für Chemie und Angewandte Biowissenschaften, Laboratorium für Organische Chemie, Wolfgang-Pauli-Strasse 10, Hönggerberg HCI, 8093 Zürich (Switzerland), Fax: (+41) 44-632-1144Search for more papers by this authorDieter Seebach Prof. Dr., Dieter Seebach Prof. Dr. seebach@org.chem.ethz.ch Eidgenössische Technische Hochschule Zürich, Department für Chemie und Angewandte Biowissenschaften, Laboratorium für Organische Chemie, Wolfgang-Pauli-Strasse 10, Hönggerberg HCI, 8093 Zürich (Switzerland), Fax: (+41) 44-632-1144Search for more papers by this authorLaurence D. Barron Prof. Dr., Laurence D. Barron Prof. Dr. laurence@chem.gla.ac.uk WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this author Josef Kapitán Dr., Josef Kapitán Dr. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this authorFujiang Zhu Dr., Fujiang Zhu Dr. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this authorLutz Hecht Dr., Lutz Hecht Dr. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this authorJames Gardiner Dr., James Gardiner Dr. Eidgenössische Technische Hochschule Zürich, Department für Chemie und Angewandte Biowissenschaften, Laboratorium für Organische Chemie, Wolfgang-Pauli-Strasse 10, Hönggerberg HCI, 8093 Zürich (Switzerland), Fax: (+41) 44-632-1144Search for more papers by this authorDieter Seebach Prof. Dr., Dieter Seebach Prof. Dr. seebach@org.chem.ethz.ch Eidgenössische Technische Hochschule Zürich, Department für Chemie und Angewandte Biowissenschaften, Laboratorium für Organische Chemie, Wolfgang-Pauli-Strasse 10, Hönggerberg HCI, 8093 Zürich (Switzerland), Fax: (+41) 44-632-1144Search for more papers by this authorLaurence D. Barron Prof. Dr., Laurence D. Barron Prof. Dr. laurence@chem.gla.ac.uk WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888Search for more papers by this author First published: 04 August 2008 https://doi.org/10.1002/ange.200801111Citations: 19 † L.H. and L.D.B. thank the EPSRC for a research grant (EP/F029713/1). J.G. was a Postdoctoral Fellow at ETH, 2004–2007, funded by the New Zealand Foundation for Research, Science and Technology (SWSS0401). Read the full textAboutPDF ToolsRequest permissionAdd to favorites ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Chiroptische Technik: Die gute Übereinstimmung zwischen dem experimentellen und dem quantenchemisch simulierten ROA-Spektrum eines β-Peptids mit (M)-314-helicaler Konformation (siehe Modellpeptid; blau N, rot O, grau C) belegt, dass die ROA-Spektroskopie das Potenzial hat, vollständige Peptidstrukturen in Lösung, einschließlich ihrer absoluten Helizität, aufzudecken. ROA=Raman-optische Aktivität. Citing Literature Volume120, Issue34August 11, 2008Pages 6492-6494 This is the German version of Angewandte Chemie. Note for articles published since 1962: Do not cite this version alone. Take me to the International Edition version with citable page numbers, DOI, and citation export. We apologize for the inconvenience. RelatedInformation

In order to rationalize subtle details in the liquid phase toluene Raman backscattering spectra, an analysis was performed based on a quantum-mechanical Hamiltonian operator comprising rotation of the methyl group and the angular dependence of vibrational frequencies and polarizability derivatives. The separation of the methyl torsion from the other vibrational motions appears to be necessary in order to explain relative intensity ratios of several bands and an anomalous broadening of spectral intensity observed at 1440 cm(-1). These results suggest that the CH3 group in the liquid phase rotates almost freely, similarly as in the gaseous phase, and that the molecule consequently exhibits effectively C(2v) point group symmetry. A classical description and an adiabatic separation of the methyl rotation from other molecular motion previously used in peptide models is not applicable to toluene because of a strong coupling with other vibrational motions. Density functional computations, particularly the BPW91 functional, provide reasonable estimates of harmonic frequencies and spectral intensities, as well as qualitatively correct fourth-order anharmonic corrections to the vibrational potential.

Rich and complex Raman scattering and Raman optical activity (ROA) spectra have been measured monitoring the pH induced alpha-helix-to-disordered conformational transition in poly(L-glutamic acid). Two-dimensional (2D) correlation techniques have been applied to facilitate a comprehensive analysis of these two complementary spectral sets. Synchronous contour plots have identified band assignments of alpha-helical and disordered conformations, and have revealed bands characteristic of changes in the protonation state of the polypeptide. Asynchronous plots, on the other hand, have probed the relative sequential orders of intensity changes indicating a decrease in intensity of alpha-helical bands in the backbone skeletal stretch region, followed by a subsequent decrease in intensity in the extended amide III and amide I regions, underlying the appearance of disordered structure, including poly(L-proline) II (PPII) helix. The application of a 2D correlation 'moving' window has also disclosed two distinct phases during helix unfolding in the alpha-helix-to-disordered transition, occurring at approximately pH 4.9 and approximately pH 5.2, possibly a result of the difference in helical stability between the end and central regions of the alpha-helix. This paper demonstrates the potential value of combining 2D Raman, 2D ROA and moving window correlation techniques for the detailed investigation of complex and subtle changes of secondary structure during the unfolding mechanisms of polypeptides and proteins.

A state-of-the-art single grating spectrograph for Raman scattering studies within the deep ultraviolet (DUV) region of the electromagnetic spectrum is discussed. It is based on a high throughput DUV version of a single-stage monochromator originally designed for use in the visible spectral region. Its key components are two identical, newly designed calcium fluoride camera lenses each consisting of five different individual optical elements. The first of these lenses collimates the Raman scattered DUV radiation entering the spectrometer through its entrance slit. The second lens focuses the collimated beam of dispersed Raman scattered DUV radiation emerging from a high-resolution reflection grating onto a charge coupled device (CCD) detector with enhanced DUV sensitivity. A novel high transmission edge filter is used as a blocking device for a sufficient rejection of the Rayleigh line generating a relatively sharp transmittance cutoff at a Stokes Raman wavenumber shift of about similar to 450 cm(-1) employing 257 nm DUV excitation. Overall, this new spectrograph enables rapid collection of Stokes DUV Raman scattered photons at f/2 wide apertures with sufficiently large signal-to-noise ratios (SNRs) in relatively short acquisition times and with an effective spectral resolution of approximately similar to 6 cm(-1). Backscattered Raman spectra of the following chemicals are presented as typical results illustrating the excellent performance characteristics of this new DUV spectrograph for a variety of experimental conditions within different scattering scenarios and for a relatively wide range of commonly used sample preparation techniques: neat cyclohexane, laboratory air, polycrystalline D-glucose, single Crystal L-alanine and a dilute aqueous solution of 2'-deoxyadenosine. Copyright (C) 2005 John Wiley & Sons, Ltd.