Cover image for Vol. 6 Issue 1

January 14, 2005

Volume 6, Issue 1

Pages 1–194

    1. Cover Picture: Direct Visualization of Lipid Phase Segregation in Single Lipid Bilayers with Coherent Anti-Stokes Raman Scattering Microscopy (ChemPhysChem 1/2005) (page 1)

      Eric O. Potma and X. Sunney Xie

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200490060

      The cover picture shows lipid phase segregation in a single giant unilamellar vesicle (GUV) visualized with coherent anti-Stokes Raman scattering (CARS) microscopy. Phase segregation can be clearly observed, as is evidenced by the CARS image of the deuterated lipid (red) overlaid for clarity with the image of the undeuterated lipid (green). The high sensitivity of CARS microscopy allows visualization of the GUV single lipid bilayer when the Raman shift is tuned into the frequency of the symmetric stretching vibrational mode of CH2, which is abundant in lipid molecules. X. S. Xie et al. show in their Communication on page 77 that CARS microscopy opens up possibilities for intracellular studies of lipid domains.

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      Editorial: ChemPhysChem from Strength to Strength (pages 3–4)

      Peter Gölitz, Kira Márquez Pérez and Evelyn Wessel

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400562

    3. Graphical Abstract: ChemPhysChem 1/2005 (pages 5–12)

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200490062

    4. Determining the Gibbs Energy of Ion Transfer Across Water–Organic Liquid Interfaces with Three-Phase Electrodes (pages 16–28)

      Fritz Scholz and Rubin Gulaboski

      Article first published online: 1 DEC 2004 | DOI: 10.1002/cphc.200400248

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      Ions can be transferred between immiscible liquid phases across a common interface, with the help of three electrodes, when one phase is an organic droplet attached to a solid electrode and contains a redox probe (see picture; dmfc=decamethylferrocene). This novel approach has been successfully applied to determine the Gibbs energy of transfer of various anions and cations.

    5. Protein Unfolding and Refolding Under Force: Methodologies for Nanomechanics (pages 29–34)

      Bruno Samorì, G. Zuccheri and P. Baschieri

      Article first published online: 6 DEC 2004 | DOI: 10.1002/cphc.200400343

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      Protein nanomechanics: Protein unfolding on atomic force microscopy (AFM) based instrumentations is beginning to unveil the features of the complex potential-energy landscapes that regulate protein folding and unfolding and the paths on them that enable and explain function (a hypothetical force-tilted energy landscape is depicted in the Figure).

    6. What Do a Foam Film and a Real Gas Have In Common? (pages 35–42)

      Cosima Stubenrauch

      Article first published online: 13 DEC 2004 | DOI: 10.1002/cphc.200400340

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      Phase diagram of a foam film: The analogy between the pVm isotherms of a real gas and the Πh curves of a foam film allows the construction of a phase diagram of a nonionic foam film (see picture; q0=surface charge density). At large thicknesses and low disjoining pressures a common black film (CBF) is formed, whereas at low thicknesses the Newton black film (NBF) is the stable phase.

    7. Wiring Enzymes in Nanostructures Built with Electrostatically Self-Assembled Thin Films (pages 43–47)

      Ernesto J. Calvo and Alejandro Wolosiuk

      Article first published online: 13 DEC 2004 | DOI: 10.1002/cphc.200400312

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      All aboard! Electron transport in redox enzyme self-organized assemblies plays a key role in the transduction of biomolecular recognition events. Very often, traditional kinetic studies in isotropic environments cannot be applied to analyze modified surfaces at the molecular level (see picture). The authors present old and new concepts in electron transport in redox polymer-modified electrodes, which are relevant to biosensor design.

    8. Phase Behavior of Gel-Type Polymer Electrolytes and Its Influence on Electrochemical Properties (pages 49–53)

      Sang-Young Lee, Wolfgang H. Meyer and Gerhard Wegner

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400300

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      Composition-dependent glass transition temperature: The authors perform a quantitative analysis on the thermodynamic phase behavior of gel-type polymer electrolytes (GPE). The picture shows a differential scanning calorimeter (DSC) thermogram of poly(methyl methacrylate) (PMMA) based GPE as a function of composition (PC=propylene carbonate).

    9. Theoretical Characterisation of the Electronic Excitation in Liquid Water (pages 53–58)

      Massimiliano Aschi, Marco D′Abramo, Carla Di Teodoro, Alfredo Di Nola and Andrea Amadei

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400265

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      Exciting water: Molecular dynamics (MD) simulations and perturbed matrix method (PMM) calculations were used to obtain detailed information about electronic excitation in liquid water. The graphic shows the excitation spectrum of liquid water at 300 K as obtained by the PMM calculations.

    10. Transfer of Noise into Signal through One-Way Coupled Chemical Oscillators (pages 58–61)

      Zhonghuai Hou, Kun Qu and Houwen Xin

      Article first published online: 7 DEC 2004 | DOI: 10.1002/cphc.200400222

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      Local noise in, remote signal out! 20 continuously stirred tank reactors (CSTR), all tuned near the Hopf bifurcation, are one-way coupled together. When the first one is subjected to external parameter noise, oscillation is induced which propagates along the chain with considerable amplification and noise suppression. As a consequence, a rather regular signal is observed at the end of the chain (see picture).

    11. Observation of an AB Phase in Bidisperse Nanocrystal Superlattices (pages 61–65)

      Aaron E. Saunders and Brian A. Korgel

      Article first published online: 13 DEC 2004 | DOI: 10.1002/cphc.200400382

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      Nanocrystal metamaterials: The self- assembly of ordered solids comprised of nanocrystals with different properties is of great interest. Ordered two- and three-dimensional nanocrystal superlattices with a rock salt structure (see graphic) were formed by drying a dispersion containing large magnetic (iron) and small noble metal (gold) nanocrystals with carefully controlled size ratios.

    12. The Effect of Polarity on Coadsorbed Molecular Nanostructures of Substituted Phthalocyanine and Thiol Molecules (pages 65–70)

      Zhi-Yong Yang, Sheng-Bin Lei, Li-Huan Gan, Li-Jun Wan, Chen Wang and Chun-Li Bai

      Article first published online: 13 DEC 2004 | DOI: 10.1002/cphc.200400293

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      Different adlayer structures were fabricated by coadsorption of differently substituted phthalocyanine/thiol molecules and investigated using scanning tunnelling microscopy (STM, see graphic). The molecular polarity was considered to be responsible for the formation of different adlayer structures.

    13. Directed Organic Grafting on Locally Doped Silicon Substrates (pages 70–74)

      Julienne Charlier, Laurent Baraton, Christophe Bureau and Serge Palacin

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400373

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      Tailoring the interface: Electrografting of methacrylonitrile (pMAN) films on unevenly doped silicon substrates was studied by using several techniques. The graphic shows electrografting of pMAN on a) a deoxidised, locally doped silicon substrate and b) an oxidised, locally doped silicon substrate.

    14. Three-Color Single-Molecule Fluorescence Resonance Energy Transfer (pages 74–77)

      Jean-Pierre Clamme and Ashok A. Deniz

      Article first published online: 13 DEC 2004 | DOI: 10.1002/cphc.200400261

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      A molecular ruler: A three-color single-molecule fluorescence resonance energy transfer (FRET) method is presented (see Figure inset), which can be used to simultaneously measure multiple molecular distance changes during molecular conformational changes and binding. The ability to directly study conformational subpopulations in a mixture of molecules with different interdye distances is highlighted by the well-separated peaks in the two- dimensional histogram in the Figure.

    15. Direct Visualization of Lipid Phase Segregation in Single Lipid Bilayers with Coherent Anti-Stokes Raman Scattering Microscopy (pages 77–79)

      Eric O. Potma and X. Sunney Xie

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400390

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      Imaging of giant vesicles: Coherent anti-Stokes Raman scattering (CARS) microscopy is used for imaging of giant vesicles of binary mixtures of lipids. The vibrational selectivity of the CARS microscope allows determination of molecules based on differences in the vibrational modes. The picture shows Raman and CARS spectra as well as CARS images of a deuterated giant unilamellar vesicle.

    16. A Microscopic Model for the Fluctuations of Local Field and Spontaneous Emission of Single Molecules in Disordered Media (pages 81–91)

      Renaud A. L. Vallée, Mark Van Der Auweraer, Frans C. De Schryver, David Beljonne and Michel Orrit

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400439

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      A microscopic, local field model is developed to describe the observed temporal fluctuations of the spontaneous emission rate of single molecules embedded in a disordered medium at room temperature. The model takes into account the elongated shape and specific polarizability of the probe molecule, as well as the discrete and inhomogeneous nature of the structure of its near surrounding (see picture; A=probe molecule).

    17. Structure and Electronic Properties of Fullerenes C52q+: Is C522+ an Exception to the Pentagon Adjacency Penalty Rule? (pages 92–100)

      Sergio Díaz-Tendero, Fernando Martín and Manuel Alcamí

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400273

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      Exceptional fullerenes: Several isomers of neutral and charged C52 fullerenes were studied (see graphic). The most stable neutral isomer is different from the most stable dication isomer. The dication C522+ represents an exception to the pentagon adjacency penalty rule, which can be explained as being a consequence of the electronic structure and the near-perfect sphericity of the most stable isomer.

    18. Oligomer-to-Polymer Transition in Short Ethylene Glycol Chains Connected to Mobile Hydrophobic Anchors (pages 101–109)

      Motomu Tanaka, Florian Rehfeldt, Matthias F. Schneider, Christian Gege, Richard R. Schmidt and Sérgio S. Funari

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400336

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      From chains to brushes: Rich thermotropic phases of lipids with oligo(ethylene glycol) chains were found by a combination of calorimetry and X-ray scattering experiments (see picture). The shorter ethylene glycol chains (N=3, 6, and 9) seem to assume a helical oligomer conformation, whereas the lamellar periodicities of the lipids with longer chains (N=12 and 15) can be interpreted well with the scaling theorem.

    19. EPR Characterisation of CuII Complexes of Poly(propylene imine) Dendromesogens: Using the Orienting Effect of a Magnetic Field (pages 110–119)

      Natalia Domracheva, Anisoara Mirea, Markus Schwoerer, Laura Torre-Lorente and Günter Lattermann

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400328

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      Liquid-crystalline dendrimers derived from poly(propylene imine), complexed with CuII ions, were studied by EPR spectroscopy. The orienting effect of a high magnetic field was used to resolve the anisotropic superfine structure due to the N atoms of the dendrimer and thus obtain information on the coordination environment of the CuII ions. The proposed CuII coordination sites in the 1st generation dendrimer are shown in the picture.

    20. Folding Structures of Isolated Peptides as Revealed by Gas-Phase Mid-Infrared Spectroscopy (pages 120–128)

      Joost M. Bakker, Christian Plützer, Isabel Hünig, Thomas Häber, Isabelle Compagnon, Gert von Helden, Gerard Meijer and Karl Kleinermanns

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400345

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      Folding of peptides: Infrared spectra of unprotected peptides containing tryptophan were measured in the gas phase. The number of detected conformers decreased with peptide size, which indicated a trend toward relaxation to a global minimum. The combination of IR data with theoretical calculations allowed the distinction between stretched and folded conformations of the peptides (see Figure).

    21. A New Heptanuclear Dendritic Ruthenium(II) Complex Featuring Photoinduced Energy Transfer Across High-Energy Subunits (pages 129–138)

      Fausto Puntoriero, Scolastica Serroni, Maurilio Galletta, Alberto Juris, Antonino Licciardello, Claudio Chiorboli, Sebastiano Campagna and Franco Scandola

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400240

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      Light hearted: A sequence of two-step electron-transfer processes (see picture) allows ultrafast energy transfer across high-energy subunits in light-harvesting antenna dendrimers.

    22. Theoretical Analysis of Pyridine Protonation in Water Clusters of Increasing Size (pages 139–147)

      M. Carmen Sicilia, Camelia Muñoz-Caro and Alfonso Niño

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400344

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      Rings of water molecules play a role in the protonation of pyridine in water clusters, which was theoretically studied as a prototypical case of the protonation of organic bases. The picture shows the solvated (S5) and protonated (P5) forms in a cluster of five water molecules. Analysis of the vibrational modes for the strongest bands in the IR spectra of the complexes suggests that protonation of pyridine occurs via concerted proton transfers among the water rings of the structure.

    23. Ab Initio Molecular Dynamics Simulation of a Water–Hydrogen Fluoride Equimolar Mixture (pages 148–153)

      Christian Simon and Michael L. Klein

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400284

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      The nature of the ions present in a 50 % aqueous solution of hydrogen fluoride was investigated using ab initio molecular dynamics. Contrary to the case of an equimolar crystal, where H3O+ and F are found, the solution contains H3O+, H5O2+, HF2 and FH[BOND]OH2. The latter fluctuates between FH⋅⋅⋅OH2 and F⋅⋅⋅H[BOND]OH2 (see picture), and the presence of undissociated HF suggests that an improvement in the traditional concept of acidity may be required.

    24. Surface- and Resonance-Enhanced Micro-Raman Spectroscopy of Xanthene Dyes: From the Ensemble to Single Molecules (pages 154–163)

      T. Vosgröne and A. J. Meixner

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200400395

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      Surface-enhanced resonance Raman scattering (SERRS) spectra of various rhodamine dyes, of pyronine G and thiopyronine adsorbed on isolated silver clusters were recorded at the ensemble level and at the single-molecule level. The picture shows the superposition of a scanning electron microscopy (SEM) image and a Raman scan from a sample with typical clusters of Ag nanoparticles.

    25. Optical Saturation in Fluorescence Correlation Spectroscopy under Continuous-Wave and Pulsed Excitation (pages 164–170)

      Ingo Gregor, Digambara Patra and Jörg Enderlein

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400319

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      Fluorescence correlation spectroscopy (FCS) has become an important technique for measuring diffusion and interactions of fluorescent molecules in solution. A widely overlooked fact is the enormous sensitivity of the measured FCS curves on the excitation intensity due to optical saturation, as shown in the Figure. The authors study this dependence both for continuous-wave and pulsed excitations.

    26. Magnetic Circular Dichroism Study of Directly Fused Porphyrins (pages 171–179)

      Atsuya Muranaka, Masaki Yokoyama, Yotaro Matsumoto, Masanobu Uchiyama, Akihiko Tsuda, Atsuhiro Osuka and Nagao Kobayashi

      Article first published online: 13 DEC 2004 | DOI: 10.1002/cphc.200400378

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      Q-band assignments: The magnetic circular dichroism (MCD) spectra of directly fused porphyrins have been measured (see picture), and their Q bands assigned based on the results of INDO/s calculations. On the basis of Michl's perimeter model, the calculated frontier molecular orbitals can be correlated with the observed positive MCD signs in the near-infrared region.

    27. Ab Initio Study of Free-Radical Polymerizations: Cost-Effective Methods to Determine the Reaction Rates (pages 180–189)

      V. Van Speybroeck, K. Van Cauter, B. Coussens and M. Waroquier

      Article first published online: 9 DEC 2004 | DOI: 10.1002/cphc.200400277

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      Absolute rate constants for carbon-centered radicals to ethene are calculated by a variety of electronic-structure methods, which range from post- Hartree–Fock to pure and hybrid density functional methods. The principal aim is to identify cost-effective theoretical methods to calculate the kinetics of free-radical polymerization reactions (see graphic), which are important for the formation of polyethylene.

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      Preview: ChemPhysChem 1/2005 (page 194)

      Article first published online: 7 JAN 2005 | DOI: 10.1002/cphc.200490061