ChemPhysChem

Cover image for Vol. 8 Issue 12

August 24, 2007

Volume 8, Issue 12

Pages 1733–1886

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
    10. Preview
    1. Cover Picture: Single DNA Molecule Isolation and Trapping in a Microfluidic Device (ChemPhysChem 12/2007) (page 1733)

      Momoko Kumemura, Dominique Collard, Christophe Yamahata, Naoyoshi Sakaki, Gen Hashiguchi and Hiroyuki Fujita

      Article first published online: 15 AUG 2007 | DOI: 10.1002/cphc.200790037

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      The cover picture shows a single DNA molecule trapped between floating aluminium electrodes by means of alternating current dielectrophoresis. The image was obtained by fluorescence microscopy using double-stranded lambda-phage DNA labelled with the YOYO-1 fluorescent dye. In their Article on page 1875 Kumemura et al. describe a method enabling the isolation and trapping of single DNA molecules in a microfluidic chip by using consecutively direct current electrophoresis and alternating current dielectrophoresis.

  2. Graphical Abstract

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    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
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    1. Graphical Abstract: ChemPhysChem 12/2007 (pages 1735–1742)

      Article first published online: 15 AUG 2007 | DOI: 10.1002/cphc.200790038

  3. News

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
    10. Preview
  4. Minireview

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
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    1. Ultrafast 2D–IR Spectroscopy of Transient Species (pages 1747–1756)

      Jens Bredenbeck, Jan Helbing, Christoph Kolano and Peter Hamm

      Article first published online: 6 JUL 2007 | DOI: 10.1002/cphc.200700148

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      Ultra-fast and multidimensional: Studies on transient structures and reaction mechanisms with the narrow-band pump/broad-band probe 2D–IR technique are presented. The potentials of this method are highlighted with examples from chemical {see figure, transient metal-to-ligand charge-transfer state in [Re(CO)3(dmbpy)Cl]}, physical and biophysical systems.

  5. Concept

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
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    1. Polymeric Actuators for Biological Applications (pages 1757–1760)

      Avishay Pelah and Thomas M. Jovin

      Article first published online: 6 JUL 2007 | DOI: 10.1002/cphc.200700294

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      Polymers in action: Actuators constructed from temperature-responsive polymers exploit reversible volume changes of the polymer to generate forces that deform cells. The picture shows reversible deformation of red blood cells in response to cycling poly(N-isopropylacrylamide) above and below its lower critical solution temperature of 32 °C.

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
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    1. Time-Resolved Optical Spectroscopy with Multiple Population Dimensions: A General Method for Resolving Dynamic Heterogeneity (pages 1761–1765)

      Emile van Veldhoven, Champak Khurmi, Xinzheng Zhang and Mark A. Berg

      Article first published online: 3 JUL 2007 | DOI: 10.1002/cphc.200700088

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      Dynamic heterogeneity: A new type of multidimensional experiment is demonstrated that distinguishes between heterogeneous and homogeneous causes of nonexponential relaxation. By varying the duration of an initial time period τ1, fast-relaxing molecules are removed from the decay during a second period τ2 (see figure).

    2. Electrodeposition of Chiral Polymer–Carbon Nanotube Composite Films (pages 1766–1769)

      Xuetong Zhang, Wenhui Song, Peter J. F. Harris and Geoffrey R. Mitchell

      Article first published online: 2 JUL 2007 | DOI: 10.1002/cphc.200700213

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      Achieving stereoselectivity: Chiral surface functionalisation of achiral conducting substrates by electrodeposition of chiral polyaniline–carbon nanotube composites with high optical activity is demonstrated. The SEM image of the composite film (see figure) consists of fibrous nanostructures twisting and tangling into a porous mat.

    3. 13C–13C Chemical Shift Correlation in Rotating Solids without 1H Decoupling During Mixing (pages 1770–1773)

      Christian Herbst, Kerstin Riedel, Jörg Leppert, Oliver Ohlenschläger, Matthias Görlach and Ramadurai Ramachandran

      Article first published online: 30 JUL 2007 | DOI: 10.1002/cphc.200700234

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      Adiabatic RF pulse schemes using inversion pulses with low power factor are difficult to implement but are shown to be feasible and advantageous for generating 13C–13C MAS solid-state NMR chemical shift correlation spectra via longitudinal magnetisation exchange without 1H decoupling during mixing (see figure).

    4. Promotion of Platinum-Ruthenium Catalyst for Electrooxidation of Methanol by Crystalline Ruthenium Dioxide (pages 1774–1777)

      Sheng-yang Huang, Chia-ming Chang, Kuan-wen Wang and Chuin-tih Yeh

      Article first published online: 17 JUL 2007 | DOI: 10.1002/cphc.200700238

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      Reversible redox reactions: The ruthenium on Pt–Ru/C electrocatalysts shows a reversible transformation (see figure), between RuO2 and Ru, during repetitive reductions (by hydrogen at Tr=620 K) and oxidations (by air at To=520 K). Electroactivity significantly increases after the oxidation treatment due to the formation of closely contacted domains between c-RuO2 and Pt.

    5. Lithium Ion Motion in a Hybrid Polymer: Confirmation of a Decoupled Polyelectrolyte (pages 1778–1781)

      Flavio L. Souza, Elson Longo and Edson R. Leite

      Article first published online: 6 JUL 2007 | DOI: 10.1002/cphc.200700260

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      Lithium ion migration pathways in a hybrid matrix, counterions, and active sites were identified and understanding gained using Fourier-Transform infrared (FTIR) spectroscopy (see image).

    6. Conformational Adaptation in Supramolecular Assembly on Surfaces (pages 1782–1786)

      Florian Klappenberger, Marta Esther Cañas-Ventura, Sylvain Clair, Stéphane Pons, Uta Schlickum, Zhi-Rong Qu, Harald Brune, Klaus Kern, Thomas Strunskus, Christof Wöll, Alessio Comisso, Alessandro De Vita, Mario Ruben and Johannes V. Barth

      Article first published online: 18 JUL 2007 | DOI: 10.1002/cphc.200700370

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      Intermolecular hydrogen bonding of N,N′-diphenyl oxalic amides deposited on Au(111) drives a rotation of the aromatic substituents (see picture). This low-dimensional supramolecular surface nanosystem, based on conformationally adaptive tectons, is identified by molecular-level scanning tunnelling imaging, X-ray absorption measurements and first-principles modeling.

    7. Time-Resolved FT-IR Spectroscopy Traces Signal Relay within the Blue-Light Receptor AppA (pages 1787–1789)

      Teresa Majerus, Tilman Kottke, Wouter Laan, Klaas Hellingwerf and Joachim Heberle

      Article first published online: 10 JUL 2007 | DOI: 10.1002/cphc.200700248

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      Revealing intermediates: Time-resolved step-scan FT-IR difference experiments (see figure) on flavin-containing photoreceptors reveal photocycle intermediates which have been spectrally silent in previous UV/Vis experiments on Appa–BLUF. The data indicate blue-light induced proton transfer or a change in H-bonding in the vicinity of a carboxylic side chain which represent an important step in signal transfer from the chromophore to the protein surface.

  7. Articles

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
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    9. Book Review
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    1. Quenching and Recoupling of Echo Modulations in NMR Spectroscopy (pages 1791–1802)

      Karthik Gopalakrishnan, Nicolas Aeby and Geoffrey Bodenhausen

      Article first published online: 23 JUL 2007 | DOI: 10.1002/cphc.200700114

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      Echo modulations in multiple-refocusing sequences that arise from homonuclear scalar couplings can be quenched under certain circumstances. A comparison of average Hamiltonian theory with simulations and experiments offers new insight into this phenomenon (see figure).

    2. Calculation of EPR g Tensors for Transition-Metal Complexes Based on Multiconfigurational Perturbation Theory (CASPT2) (pages 1803–1815)

      Steven Vancoillie, Per-Åke Malmqvist and Kristine Pierloot

      Article first published online: 23 JUL 2007 | DOI: 10.1002/cphc.200700128

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      Two approaches for the calculation of the g tensor based on the CASSCF/CASPT2 method were implemented in the MOLCAS quantum chemistry software package. Both were applied to a series of transition-metal compounds (see picture) using extended basis sets and CASPT2 optimized geometries. While the g values for the d1 systems are superior to previous theoretical results, the g values for the d9 systems are too large compared to experiment.

    3. Analysis of Classical and Quantum Paths for Deprotonation of Methylamine by Methylamine Dehydrogenase (pages 1816–1835)

      Kara E. Ranaghan , Laura Masgrau , Nigel S. Scrutton, Michael J. Sutcliffe and Adrian J. Mulholland

      Article first published online: 3 AUG 2007 | DOI: 10.1002/cphc.200700143

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      Tunnelling in enzymes: Quantum mechanics/molecular mechanics simulations give an atomic level description of the classical and quantum paths for methylamine deprotonation in methylamine dehydrogenase (see picture). Comparison with a related enzyme (aromatic amine dehydrogenase) reveals that environmental effects leading to different transfer pathways are possible causes of the differences observed in the kinetic isotope effects between these two similar enzymes.

    4. Surfactant Fouling of Nanofiltration Membranes: Measurements and Mechanisms (pages 1836–1845)

      Katleen Boussu, Céline Kindts, Carlo Vandecasteele and Bart Van der Bruggen

      Article first published online: 5 JUL 2007 | DOI: 10.1002/cphc.200700236

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      Surfactant orientation on the membrane surface and the amount of adsorbed surfactant are two major factors that determine the degree of fouling in nanofiltration of aqueous surfactant solutions. For example, on a negatively charged membrane surface, adsorption of an anionic surfactant through its tail makes the surface more hydrophilic, but cationic surfactants can exhibit the same effect by forming hemimicelles (see sketch).

    5. In-situ Flow-Cell IRAS Observation of Intermediates during Methanol Oxidation on Low-Index Platinum Surfaces (pages 1846–1849)

      Masashi Nakamura, Koji Shibutani and Nagahiro Hoshi

      Article first published online: 18 JUL 2007 | DOI: 10.1002/cphc.200700244

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      Principal facets: The adsorption behaviors of reaction intermediates in methanol oxidation on Pt single crystals are investigated. Adsorbed formate, which is not a reactive intermediate but a catalyst-poisoning species, is spectroscopically observed on Pt(111) (see figure). In contrast, the high reactivity on Pt(110) is due to a lack of poisoning by formate adsorption.

    6. X-Ray Spectroscopic and Diffraction Study of the Structure of the Active Species in the NiII-Catalyzed Polymerization of Isocyanides (pages 1850–1856)

      Gerald A. Metselaar, Erik Schwartz, René de Gelder, Martin C. Feiters, Serge Nikitenko, Grigory Smolentsev, Galina E. Yalovega, Alexander V. Soldatov, Jeroen J. L. M. Cornelissen, Alan E. Rowan and Roeland J. M. Nolte

      Article first published online: 23 JUL 2007 | DOI: 10.1002/cphc.200700251

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      Metal-based polymerisation: EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) measurements and simulations complement single crystal diffraction data to elucidate the structure of the active complex (see figure) in the Ni-catalyzed polymerization of isocyanides.

    7. Self-Assembled Organic Nanostructures: Effect of Substituents on the Morphology (pages 1857–1862)

      Wei Su, Yuexing Zhang, Chuntao Zhao, Xiyou Li and Jianzhuang Jiang

      Article first published online: 6 JUL 2007 | DOI: 10.1002/cphc.200700246

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      The morphology of self-assembled nanostructures of substituted perylene-3,4:9,10-tetracarboxydiimides (see SEM images) was effectively controlled using alkoxy and thioalkyl substituents. Using density functional theory (DFT), this control could be ascribed to the different degree of twisting of the conjugated perylene system and the different bending of the different substituents with respect to the plane of naphthalene ring (see structures).

    8. Effect of Group II Metal Cations on Catecholate Oxidation (pages 1863–1869)

      Alexander V. Lebedev, Marina V. Ivanova, Alexander A. Timoshin and Enno K. Ruuge

      Article first published online: 16 JUL 2007 | DOI: 10.1002/cphc.200700296

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      Leading role for calcium: The effects of Ca2+ on the free-radical chain reactions of catecholate complexes are investigated. In Ca2+-free solutions, pyrocatechol autoxidation (see figure) generates a weak steady-state EPR signal (g=2.0045). On addition of calcium the Ca2+–semiquinonate spectrum (g=2.0043) is observed.

    9. In Situ and On-Line Monitoring of Hydrodynamic Flow Profiles in Microfluidic Channels Based on Microelectrochemistry: Optimization of Channel Geometrical Parameters for Best Performance of Flow Profile Reconstruction (pages 1870–1874)

      Christian Amatore, Oleksiy V. Klymenko, Alexander Oleinick and Irina Svir

      Article first published online: 31 JUL 2007 | DOI: 10.1002/cphc.200700297

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      Spline function representation of flow profile was used as the basis for a mathematical optimization of a microfluidic channel equipped with two microband electrodes that allows fast and precise flow reconstruction. In the picture, the optimal areas of the (W, Pe) plane for reconstructing the flow profile are superimposed on that predicted by considering limiting mass-transport regimes in a channel (W and G are dimensionless electrode and gap widths and Pe is the Péclet number).

    10. Single DNA Molecule Isolation and Trapping in a Microfluidic Device (pages 1875–1880)

      Momoko Kumemura, Dominique Collard, Christophe Yamahata, Naoyoshi Sakaki, Gen Hashiguchi and Hiroyuki Fujita

      Article first published online: 12 JUL 2007 | DOI: 10.1002/cphc.200700268

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      DNA bridges: A double stranded λ-DNA molecule is isolated by dc electrophoresis and trapped by ac dielectrophoresis between aluminium electrodes in a microfluidic chip [see device (left) in figure and DNA bridge between electrodes (right)]. This single-molecule trapping technique is highly effective, allowing long DNA fragments to be instantly captured in stretched formation.

  8. Book Review

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
    10. Preview
  9. Preview

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Concept
    7. Communications
    8. Articles
    9. Book Review
    10. Preview
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      Preview: ChemPhysChem 13/2007 (page 1886)

      Article first published online: 15 AUG 2007 | DOI: 10.1002/cphc.200790040

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