ChemPhysChem

Cover image for Vol. 13 Issue 15

October 22, 2012

Volume 13, Issue 15

Pages 3409–3555

  1. Cover Pictures

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
    1. You have free access to this content
      Cover Picture: Activation of Carbon Dioxide over Zinc Oxide by Localised Electrons (ChemPhysChem 15/2012) (page 3409)

      Dr. Gargi Dutta, Dr. Alexey A. Sokol, Prof. C. Richard A. Catlow, Dr. Thomas W. Keal and Dr. Paul Sherwood

      Article first published online: 12 OCT 2012 | DOI: 10.1002/cphc.201290069

      Thumbnail image of graphical abstract

      Carbon dioxide can be transformed from an environmental hazard to a commodity, as shown on p. 3453 by A. A. Sokol et al. The unique mechanism of activation of carbon dioxide over zinc oxide is unravelled using advanced quantum mechanical methods. The key process is the CO2 chemisorption catalysed by a highly localized electron carrier trapped at a vacant oxygen interstitial surface site.

    2. You have free access to this content
      Inside Cover: Lowering Energy Barriers in Surface Reactions through Concerted Reaction Mechanisms (ChemPhysChem 15/2012) (page 3410)

      Dr. Sung Sakong, Christian Mosch, Ariel Lozano, Dr. H. Fabio Busnengo and Prof. Dr. Axel Groß

      Article first published online: 12 OCT 2012 | DOI: 10.1002/cphc.201290070

      Thumbnail image of graphical abstract

      Crucial steps in reactions on surfaces, such as methanol synthesis or hydrogen subsurface penetration, can be significantly facilitated when they occur in a concerted fashion, as shown on p. 3467 by A. Groß et al.

  2. Graphical Abstract

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
    1. Graphical Abstract: ChemPhysChem 15/2012 (pages 3411–3417)

      Article first published online: 12 OCT 2012 | DOI: 10.1002/cphc.201290071

  3. Editors' Selection

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
    1. Editors' Selection: ChemPhysChem 15/2012 (page 3418)

      Article first published online: 12 OCT 2012 | DOI: 10.1002/cphc.201290072

  4. News

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
  5. Review

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
    1. How Good Are Coarse-Grained Polymer Models? A Comparison for Atactic Polystyrene (pages 3428–3439)

      Dr. Hossein Ali Karimi-Varzaneh, Prof. Dr. Nico F. A. van der Vegt, Prof. Dr. Florian Müller-Plathe and Dr. Paola Carbone

      Article first published online: 19 JUN 2012 | DOI: 10.1002/cphc.201200111

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      A grain of truth: Different coarse-grained (CG) mapping schemes that have been developed to model atactic polystyrene are reviewed (see picture), with focus on their performances in predicting structural and dynamical properties of melts and solutions. The performances of CG models characterized by different degrees of coarse-graining and various techniques to develop the force field are reproducible.

  6. Communications

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
    1. New Chemical Insights Using Weakly Supported Voltammetry: The Reductive Cleavage of Aryl[BOND]Br Bonds is Reversible (pages 3441–3444)

      Yijun Wang, Edward O. Barnes and Prof. Richard G. Compton

      Article first published online: 6 AUG 2012 | DOI: 10.1002/cphc.201200480

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      Cyclic voltammetry carried out at a wide range of supporting electrolyte concentrations and compositions can elucidate additional kinetic and mechanistic details of the electrochemical reduction of aryl halides (see picture). The cleavage of the C[BOND]Br bond is reversible, driven by H abstraction and the second electron transfer. This is a new chemical insight, as the cleavage of such bonds has usually been regarded as irreversible.

    2. Fluorescence Enhancement and End-to-End Assembly of Bisacridinedione–Gold Nanorods by Calcium Ions (pages 3445–3448)

      Dr. Ranganathan Velu, Sungwook Jung, Nayoun Won, Kyuhyun Im, Prof. Sungjee Kim and Nokyoung Park

      Article first published online: 6 AUG 2012 | DOI: 10.1002/cphc.201200433

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      Gold nanorod end-to-end assembly is demonstrated by the selective complexation of a bisacridinedione foldamer with Ca2+ (see picture). This setup can be applied as a chemosensor for Ca2+ ions, as the complex shows selective red-shifting of the nanorod plasmon peak and enhancement in fluorescence from the acridinedione moieties upon exposure to Ca2+.

    3. Quantifying Large Effects of Framework Flexibility on Diffusion in MOFs: CH4 and CO2 in ZIF-8 (pages 3449–3452)

      Emmanuel Haldoupis, Dr. Taku Watanabe, Prof. Sankar Nair and Prof. David S. Sholl

      Article first published online: 18 JUL 2012 | DOI: 10.1002/cphc.201200529

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      Breathe in, breathe out: Efficient methods are introduced for assessing the role of framework flexibility on molecular diffusion in metal-organic frameworks (MOFs) that does not require defining a classical forcefield for the MOF. These methods combine ab initio MD of the MOF with classical MD simulation of the diffusing molecules. The effects of flexibility are shown to be large for CH4, but not for CO2, in ZIF-8 (see picture).

    4. Activation of Carbon Dioxide over Zinc Oxide by Localised Electrons (pages 3453–3456)

      Dr. Gargi Dutta, Dr. Alexey A. Sokol, Prof. C. Richard A. Catlow, Dr. Thomas W. Keal and Dr. Paul Sherwood

      Article first published online: 31 JUL 2012 | DOI: 10.1002/cphc.201200517

      Thumbnail image of graphical abstract

      The unique mechanism of activation of carbon dioxide over zinc oxide is unravelled using advanced quantum mechanical methods. The key process is the CO2 chemisorption catalysed by a highly localized electron carrier trapped at a vacant oxygen interstitial surface site. At the top of the reaction barrier CO2 pulls the electron from the vacancy and thus becomes active (see picture).

    5. Prediction of the Main Route in the TiO2-Photocatalyzed Degradation of Organic Compounds in Water by Density Functional Calculations (pages 3457–3461)

      Prof. Dr. Hiroaki Tada, Qiliang Jin and Prof. Dr. Hisayoshi Kobayashi

      Article first published online: 31 JUL 2012 | DOI: 10.1002/cphc.201200382

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      TiO2 photocatalysis: It is shown theoretically that during photocatalysis by TiO2 most organic molecules can be directly oxidized by trapped holes, while the oxidation of some organic molecules with low HOMO energies progresses mainly through indirect oxidation by .OH radicals (see picture).

    6. Revealing the Bonding Pattern from the Molecular Electron Density Using Single Exponential Decay Detector: An Orbital-Free Alternative to the Electron Localization Function (pages 3462–3465)

      Piotr de Silva, Prof. Jacek Korchowiec and Prof. Tomasz A. Wesolowski

      Article first published online: 24 JUL 2012 | DOI: 10.1002/cphc.201200500

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      A new tool, the single exponential decay detector (SEDD) is introduced to extract information about bonding and localization in atoms, molecules, or molecular assemblies. The practical evaluation of SEDD does not require any explicit information about the orbitals. The only quantity needed is the electron density (calculated or experimental) and its derivatives up to the second order (see graphic).

  7. Articles

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. Editors' Selection
    5. News
    6. Review
    7. Communications
    8. Articles
    1. Lowering Energy Barriers in Surface Reactions through Concerted Reaction Mechanisms (pages 3467–3471)

      Dr. Sung Sakong, Christian Mosch, Ariel Lozano, Dr. H. Fabio Busnengo and Prof. Dr. Axel Groß

      Article first published online: 7 AUG 2012 | DOI: 10.1002/cphc.201200526

      Thumbnail image of graphical abstract

      Concerted reaction mechanisms on surfaces can have significantly lower barriers than the single steps of which the concerted reaction mechanism consists. This is shown by periodic density functional theory calculations for two technologically important reactions, methanol synthesis on copper (see picture) and hydrogen subsurface penetration on palladium.

    2. On-Bead Screens Sample Narrower Affinity Ranges of Protein–Ligand Interactions Compared to Equivalent Solution Assays (pages 3472–3480)

      Dr. Martin Hintersteiner, Christof Buehler and Prof. Manfred Auer

      Article first published online: 24 JUL 2012 | DOI: 10.1002/cphc.201200117

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      Quick screening: Generally, protein–ligand interaction data for bead-immobilised and solid-supported small molecules are handled in the same way as solution interactions. Herein a framework is presented for biophysical characterization of protein–ligand interactions on TentaGel beads, including the determination of affinity constants for immobilized ligands (see picture).

    3. Two-Photon Absorption and Time-Resolved Stimulated Emission Depletion Spectroscopy of a New Fluorenyl Derivative (pages 3481–3491)

      Prof. Kevin D. Belfield, Dr. Mykhailo V. Bondar, Alma R. Morales, Xiling Yue, Dr. Gheorghe Luchita, Dr. Olga V. Przhonska and Dr. Olexy D. Kachkovsky

      Article first published online: 7 AUG 2012 | DOI: 10.1002/cphc.201200405

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      The one- and two-photon stimulated emission spectra of a new fluorene derivative, (E)-1-(2-(di-p-tolylamino)-9,9-diethyl-9H-fluoren-7-yl)-3-(thiophen-2-yl)prop-2-en-1-one are obtained over a broad spectral range (see picture) and a new methodology for time-resolved fluorescence emission spectroscopy is proposed.

    4. Understanding the Role of Water in Aqueous Ruthenium-Catalyzed Transfer Hydrogenation of Ketones. (pages 3492–3496)

      Anna Pavlova and Prof. Evert Jan Meijer

      Article first published online: 27 AUG 2012 | DOI: 10.1002/cphc.201200454

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      Water Power: An accurate computational study on the role of water in transfer hydrogenation of formaldehyde with a ruthenium-based catalyst is reported, using a water-specific model (see picture). In contrast to previous studies of gas-phase models, the reaction mechanism in aqueous solution is found to be sequential, with the hydride transfer preceding the transfer of the proton donated by a solvent molecule.

    5. How Can a Hydrophobic MOF be Water-Unstable? Insight into the Hydration Mechanism of IRMOFs (pages 3497–3503)

      Marta De Toni, Romain Jonchiere, Dr. Pluton Pullumbi, Dr. François-Xavier Coudert and Prof. Dr. Alain H. Fuchs

      Article first published online: 20 JUL 2012 | DOI: 10.1002/cphc.201200455

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      Having it both ways: Ab initio molecular dynamics gives insight into the hydration mechanism of metal-organic frameworks from the IRMOF family (see picture), showing how they can be both hydrophobic and water unstable.

    6. Effects of Fluorine Substitution on the Shape of Neurotransmitters: the Rotational Spectrum of 2-(2-Fluorophenyl)Ethanamine (pages 3504–3509)

      Prof. Sonia Melandri, Dr. Anna Merloni and Dr. Assimo Maris

      Article first published online: 13 AUG 2012 | DOI: 10.1002/cphc.201200528

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      Small but effective: Fluorine is commonly used in medicinal chemistry to modulate a molecule′s physical and chemical properties. Our high-resolution spectral data in the gas phase and theoretical calculations show that the substitution effect of just one single hydrogen atom with fluorine produces a fine tuning of the molecule′s conformational properties (see picture). This must be taken into account when modeling the properties of ligands and their interactions with the receptor.

    7. Spectral Diffusion of Single Dibenzoterrylene Molecules in 2,3-Dimethylanthracene (pages 3510–3515)

      Yuxi Tian, Pedro Navarro, Boleslaw Kozankiewicz and Prof. Michel Orrit

      Article first published online: 23 JUL 2012 | DOI: 10.1002/cphc.201200463

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      Highly diffusing: Single dibenzoterrylene molecules embedded in the dipolar disordered crystal 2,3-dimethylanthracene are studied at 1.25 K. Broad linewidths, high saturation excitation intensities and strong spectral diffusions are observed (see picture), which are explained by a combination of the static disorder with the slight reorientations of the methyl groups of the host molecules.

    8. The Adsorption of Oxygen and Coadsorption of CO and Oxygen on Structurally Well-Defined PdAg Surface Alloys (pages 3516–3525)

      Dr. Arnold P. Farkas, Dr. Thomas Diemant, Dr. Joachim Bansmann and Prof. Dr. R. Jürgen Behm

      Article first published online: 7 AUG 2012 | DOI: 10.1002/cphc.201200477

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      Planar PdAg surface alloys: Oxygen adsorption on PdxAg1−x/Pd(111) surface alloys is dominated by ensemble effects and is limited to Pd3 threefold-hollow sites. Coadsorption of CO on oxygen pre-covered surfaces is possible on different Pdx adsorption sites. Additionally, CO converts to CO2 even at low temperatures (see picture). Complete reactive removal of the remaining Oad is achieved after heating.

    9. Unusual Regioselective Electrophilic Substitutions in Quinoline Foldamers: Conceptual DFT and Frontier Molecular Orbital Analysis Reveal the Crucial Role of Folding and Substituents (pages 3526–3534)

      Madishetti Shravani, Shanigaram Balaiah, Dr. Kolupula Srinivas, Dr. K. Bhanuprakash and Dr. Ivan Huc

      Article first published online: 7 AUG 2012 | DOI: 10.1002/cphc.201200397

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      Computer backup: The experimentally observed unusual regioselectivity in quinoline (Q) foldamers is investigated by molecular modeling techniques. Conceptual DFT and frontier molecular orbital studies clearly demonstrate the significant role of folding and substituents on the backbone of the aromatic oligoamides in dictating the regioselectivity (see picture).

    10. Contributions of Various Noncovalent Bonds to the Interaction between an Amide and S-Containing Molecules (pages 3535–3541)

      Upendra Adhikari and Prof. Steve Scheiner

      Article first published online: 31 JUL 2012 | DOI: 10.1002/cphc.201200412

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      Attractive forces: The interaction between a peptide group and S-containing molecules that mimic those observed in proteins is explored by ab initio calculations (see picture). A range of different sorts of noncovalent forces are observed, which include H-bonds, both conventional and nonconventional, as well as charge-transfer-type interactions.

    11. Hyperfine Coupling Constants of β-Phosphorylated Nitroxides: A Tool to Probe the Cybotactic Effect by Electron Paramagnetic Resonance (pages 3542–3548)

      Prof. Gérard Audran, Dr. Paul Brémond, Prof. Sylvain R. A. Marque and Germain Obame

      Article first published online: 7 AUG 2012 | DOI: 10.1002/cphc.201200420

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      Nitrogen hyperfine coupling constants of nitroxides measured by electron paramagnetic resonance are used to probe the cybotactic effect of solvents. The results show a strong dependence of the cybotactic effect on both the steric strain and the bulkiness around the nitroxyl moiety.

    12. Dramatic Fluorescence Enhancement of Bare Carbon Dots through Facile Reduction Chemistry (pages 3549–3555)

      Ran Shen, Kai Song, Prof. Huarong Liu, Prof. Yuesheng Li and Prof. Hewen Liu

      Article first published online: 24 JUL 2012 | DOI: 10.1002/cphc.201200018

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      Reduce to improve: Reduction by aqueous NaBH4 is an efficient way to enhance the fluorescence of aqueous carbon dots (CDs). We found that the structure of CDs can be regarded as semiconductive surface layers over conductive graphite cores (see picture). Chemical reduction increases the number of surface defects leading to conjugation of the defect areas. Thus, the surface is changed to improve fluorescence properties.

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