ChemPhysChem

Cover image for Vol. 9 Issue 13

September 15, 2008

Volume 9, Issue 13

Pages 1805–1958

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Highlight
    7. Communications
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    1. Cover Picture: Complex Interfaces and their Role in Protein-Stabilized Soft Materials (ChemPhysChem 13/2008) (page 1805)

      Philipp Erni, Peter Fischer, Vishweshwara Herle, Martina Haug and Erich J. Windhab

      Article first published online: 9 SEP 2008 | DOI: 10.1002/cphc.200890052

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      The cover picture shows asymmetric drops covered with a globular protein, lysozyme, used to study the role of protein-stabilized interfaces in oil-in-water emulsions by Erni et al. in their manuscript on page 1833. Using a combination of interfacial stress measurements (frequency-dependent surface shear moduli shown on the cover picture) and in-situ structural probing (rheo-small angle light scattering pattern in the background), they demonstrate how in-plane interfacial stresses due to the macromolecular adsorption layer stabilize emulsion drops against deformation.

  2. Graphical Abstract

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    1. Graphical Abstract: ChemPhysChem 13/2008 (pages 1807–1813)

      Article first published online: 9 SEP 2008 | DOI: 10.1002/cphc.200890053

  3. News

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    3. Graphical Abstract
    4. News
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  4. Minireview

    1. Top of page
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    1. Dynamics of Supramolecular Association Monitored by Fluorescence Correlation Spectroscopy (pages 1819–1827)

      Wajih Al-Soufi, Belén Reija, Suren Felekyan, Claus A. M. Seidel and Mercedes Novo

      Article first published online: 29 AUG 2008 | DOI: 10.1002/cphc.200800330

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      Going through the motions: Supramolecular binding is a key process in many biological systems and in supramolecular assemblies. High-resolution fluorescence correlation spectroscopy (FCS) monitors the fluctuations in the detected fluorescence intensity, introduced by the supramolecular dynamics, and gives information about structure–dynamics relationships (see graphic).

  5. Highlight

    1. Top of page
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    3. Graphical Abstract
    4. News
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    1. Tamed Tigers: Stabilization of Reactive Carbenes (pages 1829–1831)

      Martin Albrecht

      Article first published online: 12 AUG 2008 | DOI: 10.1002/cphc.200800426

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      Taming wild carbenes: Following previous achievements in characterizing free carbenes—long considerered as curiosities and intermediates too reactive to be isolated—Schreiner and coworkers succeeded in stabilizing hydroxymethylene (see picture), the simplest of all oxycarbenes, by matrix isolation. This carbene gradually rearranges into its formaldehyde tautomer by a barrierless tunnelling process.

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Highlight
    7. Communications
    8. Articles
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    1. Complex Interfaces and their Role in Protein-Stabilized Soft Materials (pages 1833–1837)

      Philipp Erni, Peter Fischer, Vishweshwara Herle, Martina Haug and Erich J. Windhab

      Article first published online: 15 JUL 2008 | DOI: 10.1002/cphc.200800346

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      Gently dripping: A combination of interfacial stress measurements and in situ structural probing under shear flow shows how globular protein adsorption layers (emulsion drops stabilized by lysozyme shown in picture) control the small deformation response of emulsion drops in shear flow. In-plane interfacial stresses due to the macromolecular adsorption layer stabilize the drops against deformation.

    2. Cluster-Controlled Photofragmentation: The Case of the Xe–Pyrrole Cluster (pages 1838–1841)

      M. Laura Lipciuc, Fengyan Wang, Xueming Yang, Theofanis N. Kitsopoulos, George S. Fanourgakis and Sotiris S. Xantheas

      Article first published online: 4 AUG 2008 | DOI: 10.1002/cphc.200800288

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      Fission of the N[BOND]H bond in pyrrole can be “controlled” by clustering the system to a single noble-gas atom. Photofragmentation from the cluster takes place when the vertical excitation energy exceeds 5.27 eV (see picture). The measured intensity ratio between the slow and fast components of the H-atom fragment from the photolysis of pyrrole at 230 nm changes from 0.35 to 1.33 when the carrier gas is He versus Xe.

    3. Effects of Hydrogen Bonding on Tuning Photochemistry: Concerted Hydrogen-Bond Strengthening and Weakening (pages 1842–1846)

      Guang-Jiu Zhao and Ke-Li Han

      Article first published online: 8 AUG 2008 | DOI: 10.1002/cphc.200800371

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      Shifting H bonds: Concerted hydrogen-bond strengthening and weakening in different excited states can tune energy gaps between low-lying electronic states and thus account for the photochemistry of thiocarbonyl chromophores in alcoholic solutions (see picture). Also, the relationship between electronic spectral shifts and the electronic excited-state hydrogen-bonding changes is clarified.

    4. Magnetically Enhanced Dielectrophoretic Assembly of Horseradish Peroxidase Molecules: Chaining and Molecular Monolayers (pages 1847–1850)

      Jianfei Sun, Haoyan Zhou, Yonglong Jin, Meng Wang, Yifei Li and Ning Gu

      Article first published online: 14 AUG 2008 | DOI: 10.1002/cphc.200800237

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      Synergy in assembly: The combination of a magnetostatic field with dielectrophoresis can assemble biological molecules—something not possible when these techniques are used in isolation. The AFM image shows horseradish peroxidase (HRP) monolayers. Electromagnetic treatment does not affect the molecular structure, as indicated by the uninhibited catalytic activity of HRP after treatment.

  7. Articles

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    1. On the Validity of Stokes–Einstein and Stokes–Einstein–Debye Relations in Ionic Liquids and Ionic-Liquid Mixtures (pages 1851–1858)

      Thorsten Köddermann, Ralf Ludwig and Dietmar Paschek

      Article first published online: 27 AUG 2008 | DOI: 10.1002/cphc.200800102

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      Structure and transport: The validity of Stokes–Einstein and Stokes–Einstein–Debye relations for imidazolium-based ionic liquids (ILs) is checked by using molecular dynamics simulations and can be related to dynamical heterogeneites in the system. The picture shows a snapshot of the simulation cell for an IL/chloroform mixture containing 80 % IL.

    2. Visualization of Intrinsically Disordered Regions of Proteins by High-Speed Atomic Force Microscopy (pages 1859–1866)

      Atsushi Miyagi, Yasuo Tsunaka , Takayuki Uchihashi , Kouta Mayanagi , Susumu Hirose, Kosuke Morikawa  and Toshio Ando 

      Article first published online: 12 AUG 2008 | DOI: 10.1002/cphc.200800210

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      High-speed AFM imaging of the heterodimeric FACT (facilitates chromatin transcription) protein reveals two tail-like structures protruding from its main body (see schematic picture). These very thin and undulating tail segments are identified as the intrinsically disordered regions of FACT predicted from the amino acid sequences, the mechanical properties of which, estimated from the AFM images, suggest that they have more relaxed structures than random coils.

    3. Efficient Photoconversion Distorts the Fluorescence Lifetime of GFP in Confocal Microscopy: A Model Kinetic Study on Mutant Thr203Val (pages 1867–1874)

      Gregor Jung, Michael Werner and Marc Schneider

      Article first published online: 27 AUG 2008 | DOI: 10.1002/cphc.200800276

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      Unexpected changes of fluorescence properties complicate the analysis of fluorescence resonance energy transfer (FRET)-based quantification schemes. The authors show how ubiquitous photoconversion of green fluorescent protein (GFP) can be detected and quantified by fluorescence lifetime microscopy (see picture; RPC=photoconverted anionic chromophore, Req=anionic chromophore state, Pdark=photobleached protein).

    4. Solvent as a Probe of Active Site Motion and Chemistry during the Hydrogen Tunnelling Reaction in Morphinone Reductase (pages 1875–1881)

      Sam Hay, Christopher R. Pudney, Michael J. Sutcliffe and Nigel S. Scrutton

      Article first published online: 30 JUL 2008 | DOI: 10.1002/cphc.200800303

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      Hydride transfer in morphinone reductase is not kinetically coupled to the subsequent N1 protonation of the reduced FMN cofactor. Further, the reaction is insensitive to modest changes in the solvent dielectric. This suggests the associated putative promoting motion is probably shielded from bulk solvent and thus localized in the active site.

    5. Kinetics of Helix-Handedness Inversion: Folding and Unfolding in Aromatic Amide Oligomers (pages 1882–1890)

      Nicolas Delsuc, Takahiro Kawanami, Julien Lefeuvre, Atsuomi Shundo, Hirotaka Ihara, Makoto Takafuji and Ivan Huc

      Article first published online: 25 AUG 2008 | DOI: 10.1002/cphc.200800310

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      A measure of stability: Chiral resolution of helically folded aromatic amide oligomers allows the monitoring of their rates of racemization and, using the Eyring equation, to calculate the energy barriers between folded and transient unfolded states. Racemization most likely occurs through the gradual propagation of an inversion center between two helical segments of opposite handedness (see figure).

    6. Molecular Logic Operations Based on Surfactant Nanoaggregates (pages 1891–1898)

      Junhong Qian, Yufang Xu, Xuhong Qian and Shenyi Zhang

      Article first published online: 14 AUG 2008 | DOI: 10.1002/cphc.200800009

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      It′s only logical: The photophysical properties of intramolecular charge-transfer fluorescent molecular sensors (based on naphthalenedicarboximide) are significantly affected by the pH value and the surfactant concentration (see picture). Multiple molecular logic functions and half addition/subtraction are performed in aqueous sodium dodecyl sulfate solution.

    7. Self-Assembled Au Nanoparticles as Substrates for Surface-Enhanced Vibrational Spectroscopy: Optimization and Electrochemical Stability (pages 1899–1907)

      Meikun Fan and Alexandre G. Brolo

      Article first published online: 14 AUG 2008 | DOI: 10.1002/cphc.200800099

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      Step by step: Nanostructured substrates comprising Au nanoparticles self-assembled on gold films are prepared by stepwise deposition (see picture) and used for surface-enhanced Raman scattering (SERS). The substrate has advantages in terms of reproducibility of the SERS signal, but it contains inherent spectral interferences. These interferences can be minimized for SERS under electrochemical conditions (PDT: 1,3-propanedithiol).

    8. Pyrenyl Excimers Induced by the Crystallization of POSS Moieties: Spectroscopic Studies and Sensing Applications (pages 1908–1913)

      Hua Bai, Chun Li and Gaoquan Shi

      Article first published online: 29 AUG 2008 | DOI: 10.1002/cphc.200800149

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      Detection POSSible: A highly fluorescent pyrene derivative functionalized by a polyhedral oligomeric silsesquioxane (POSS) group has been synthesized and spin-coated into thin films. The crystallization of POSS moieties (see picture) leads to the formation of pyrene excimers and a porous film structure. The film exhibits rapid fluorescence quenching towards trinitrotoluene vapour.

    9. Defective Continuous Hydrogen-Bond Networks: An Alternative Interpretation of IR Spectroscopy (pages 1914–1919)

      Diedrich A. Schmidt and Kazushi Miki

      Article first published online: 26 AUG 2008 | DOI: 10.1002/cphc.200800236

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      Ions as network defects: A deconvolution method is used to analyze changes in the OH stretching band of low-concentration (≤0.2 m) aqueous solutions of NaCl and KCl. (See figure for the deconvolution of pure water.) These monovalent ions are treated as defects in the hydrogen-bond network of pure water, and the changes in the spectra at low defect concentration are quantified by an “order parameter”.

    10. Functional Tethered Bilayer Lipid Membranes on Aluminum Oxide (pages 1920–1924)

      Robert F. Roskamp, Inga K. Vockenroth, Nancy Eisenmenger, Julia Braunagel and Ingo Köper

      Article first published online: 14 AUG 2008 | DOI: 10.1002/cphc.200800248

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      Anchoring lipids: Ultrasmooth alumina surfaces, sputtered onto template-stripped gold, are suitable substrates for functional tethered bilayer membranes (tBLMs) that are anchored by lipids with phosphonic acid groups. The picture shows a schematic of the tBLM with two incorporated valinomycin molecules.

    11. New Molecular Cage Clusters of Pb by Encapsulation of Mg (pages 1925–1929)

      Sascha Schäfer and Rolf Schäfer

      Article first published online: 12 AUG 2008 | DOI: 10.1002/cphc.200800264

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      Endohedral clusters: A series of magnesium-doped lead clusters is observed in the gas phase. The dielectric properties of these assemblies are studied in a molecular-beam experiment. The observed vanishing dipole moments indicate highly symmetric cage structures (see picture), probably derived from the closo polyhedra found as structural motifs of alloys and borane dianions.

    12. Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy (pages 1930–1941)

      Sofie Cambré, Wim Wenseleers, Jelena Čulin, Sabine Van Doorslaer, Antonio Fonseca, Janos B. Nagy and Etienne Goovaerts

      Article first published online: 19 AUG 2008 | DOI: 10.1002/cphc.200800317

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      Resolving the interations of cobalt(II) porphyrins adsorbed on metallic and semiconducting CNTs is achieved by electron paramagnetic resonance spectroscopy revealing that metallic carbon nanotubes are the strongest acceptors. Absorption spectra (see figure) of the purified nanohybrids show large red-shifts.

    13. Cooperativity between the Dihydrogen Bond and the N⋅⋅⋅HC Hydrogen Bond in LiH–(HCN)n Complexes (pages 1942–1946)

      Qing-Zhong Li, Ting Hu, Xiu-Lin An, Bao-An Gong and Jian-Bo Cheng

      Article first published online: 19 AUG 2008 | DOI: 10.1002/cphc.200800320

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      Working together: The cooperativity between the dihydrogen bond and the N⋅⋅⋅HC hydrogen bond in LiH–(HCN)n is investigated at the MP2 level of theory. The bond lengths, dipole moments, and energies (see schematic) are analyzed. NBO analyses indicate that orbital interaction, charge transfer, and bond polarization are mainly responsible for the cooperativity between the two types of hydrogen bonds.

    14. Dual-Polarization Imaging of a Dual-Fluorophore Ion Sensor: A Single-Molecule Study (pages 1947–1953)

      Yin Lu, Richard K. Bowles and Matthew F. Paige

      Article first published online: 4 AUG 2008 | DOI: 10.1002/cphc.200800337

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      Multichromophoric systems: In dual-polarization, single-molecule imaging (see schematic), a fluorescence emission image is split into two orthogonal polarization images and the intensity ratio between the images provides information on the orientation of the constituent fluorophore(s). The relative orientation of the two constituent fluorophores of CG-2, a calcium ion sensor, is explored using this approach.

  8. Preview

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Highlight
    7. Communications
    8. Articles
    9. Preview
    1. Preview: ChemPhysChem 14/2008 (page 1958)

      Article first published online: 9 SEP 2008 | DOI: 10.1002/cphc.200890055

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