ChemPhysChem

Cover image for Vol. 9 Issue 11

August 4, 2008

Volume 9, Issue 11

Pages 1489–1650

  1. Cover Picture

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    3. Graphical Abstract
    4. News
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    1. Cover Picture: Application of Static Charge Transfer within an Ionic-Liquid Force Field and Its Effect on Structure and Dynamics (ChemPhysChem 11/2008) (page 1489)

      Tristan G. A. Youngs and Christopher Hardacre

      Version of Record online: 25 JUL 2008 | DOI: 10.1002/cphc.200890044

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      The cover picture illustrates that the calculated physical properties of ionic liquids can be tuned through uniform scaling of atomic charges to give ions with total charges less than ±1. For ionic liquids which possess strong hydrogen bonding interactions between the cation and anion (as is the case for 1,3-dimethylimidazolium chloride, the subject of this study) using ionic charges of ±1 tends to overestimate the liquid density, structuring, and cohesive energy density, and underestimate the diffusion coefficient. T. G. A. Youngs and C. Hardacre (page 1548) show that scaling the charges serves to correct these quantities by mimicking, in some sense, polarisation and charge transfer between the ions that occurs in the liquid state.

  2. Graphical Abstract

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  3. News

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  4. Minireview

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    1. From Biological towards Artificial Molecular Motors (pages 1503–1509)

      Moritz Mickler, Enrico Schleiff and Thorsten Hugel

      Version of Record online: 10 JUL 2008 | DOI: 10.1002/cphc.200800216

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      Learning from a virus: Novel single-molecule techniques allow the observation of single-molecular motors in real time under physiological conditions. Thus, previously inaccessible information about molecular motors, such as the DNA import motor of the bacteriophage ϕ29 (see figure) is unveiled. In contrast to this, artificial molecular motors are still at an early stage of development.

  5. Communications

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    1. Tunable Soret-Band Splitting of an Amphiphilic Porphyrin by Surface Pressure (pages 1511–1513)

      Gustavo de Miguel, Kohei Hosomizu, Tomokazu Umeyama, Yoshihiro Matano, Hiroshi Imahori, María T. Martín-Romero and Luis Camacho

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800270

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      Tuning with pressure: Splitting of the Soret band in the novel amphiphilic porphyrin (OD)3TPPS3 is reversibly tuned by applying surface pressure (see figure). The degenerated transition of the Soret band is broken as a result of the formation of an ordered monolayer, which causes individual coupling of the components Bx and By of the Soret band.

    2. Multiple-Charge Separation in Nanoscale Artificial Photosynthetic Models (pages 1514–1518)

      Xian-Fu Zhang, Xiaofeng Cui, Qiang Liu and Fushi Zhang

      Version of Record online: 27 MAY 2008 | DOI: 10.1002/cphc.200800191

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      Strong attraction: Hundreds of electron donors can be covalently attached to a single-walled carbon nanotube (SWCNT) to form a Dn[BOND]A artificial photosynthetic model (see figure). Multiple electrons are simultaneously or sequentially transferred to the nanotube upon light absorption and multiple-charge separation states (D+.)k[BOND]Ak.− are formed.

    3. Independent Tuning of Electronic Levels in Pentacene by Site-Specific Substitution (pages 1519–1523)

      Begoña Milián Medina, John E. Anthony and Johannes Gierschner

      Version of Record online: 9 JUN 2008 | DOI: 10.1002/cphc.200800122

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      Sensitive to position: Quantum-chemical calculations reveal site-specific substituent effects in pentacene via fluorination and methoxylation. The absolute position of HOMO and LUMO levels as well as the bandgap can be tuned independently of each other (see picture), thus paving a route to control electronic levels in (opto)electronic devices with minimum structural modification.

    4. Facile and Controlled Synthesis of Ultra-Thin Low Dielectric Constant Meso/Microporous Silica Films (pages 1524–1527)

      Richard A. Farrell, Nikolay Petkov, Karim Cherkaoui, Heinz Amenitsch, Justin D. Holmes, Paul K. Hurley and Michael A. Morris

      Version of Record online: 15 MAY 2008 | DOI: 10.1002/cphc.200800158

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      Fancy films: Microporous zeolite silicalite-1 nanoparticles with regular particle dimensions are dispersed within self-assembled mesoporous silica thin films in order to fabricate thin films with low dielectric constants. The mesoporous component functions as a binder material which increases the adhesion of the zeolite films to the underlying silicon substrate without augmenting the dielectric constant.

    5. DNA Molecules on GaP (100) Surfaces: Spectroscopic Characterization and Biospecificity Assessment (pages 1528–1530)

      Rosangelly Flores-Perez, Dmitry Y. Zemlyanov and Albena Ivanisevic

      Version of Record online: 3 JUN 2008 | DOI: 10.1002/cphc.200800166

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      Mind the bioactive GaP: Carboxylic acid-terminated GaP(100) surfaces are used to capture DNA molecules. The well-packed mixed biotin-modified DNA and alkyl-chains self-assemble onto the substrate (see figure) and exhibit good reproducibility, specificity and bioactivity confirmed by the use of nanoparticles and Cy3 fluorophore conjugates with streptavidin.

    6. Ruthenium(II) Complexes for Two-Photon Absorption-Based Optical Power Limiting (pages 1531–1535)

      Camille Girardot, Bertrand Cao, Jean-Christophe Mulatier, Patrice L. Baldeck, Jérôme Chauvin, Didier Riehl, Jacques A. Delaire, Chantal Andraud and Gilles Lemercier

      Version of Record online: 10 JUL 2008 | DOI: 10.1002/cphc.200800186

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      Long-lived excitation: Novel bifluorene-substituted 1,10-phenanthroline-based RuII coordination complexes are presented (see picture). They fulfil several requirements for optimized optical power limiting in the visible-NIR, as they are stable, soluble and transparent at low laser fluences. The two-photon absorption of these complexes are strongly related to those of the ligand.

    7. Secondary Kinetic Isotope Effects as Probes of Environmentally-Coupled Enzymatic Hydrogen Tunneling Reactions (pages 1536–1539)

      Sam Hay, Jiayun Pang, Phillip J. Monaghan, Xi Wang, Rhiannon M. Evans, Michael J. Sutcliffe, Rudolf K. Allemann and Nigel S. Scrutton

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800291

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      The secondary kinetic isotope effect for hydride transfer from NADPH to dihydrofolate catalyzed by dihydrofolate reductase (see traces) is neither temperature dependent nor exalted. In environmentally coupled models of H-tunneling, the secondary isotope effects do not report on promoting motions, but reflect the active site geometry attained immediately prior to H transfer (i.e. the ‘tunnelling ready configuration′).

  6. Articles

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    1. Post-Deposition Opal Evolution (pages 1541–1547)

      Iulian Popa and Frank Marlow

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800159

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      Still alive: An artificial opal is a highly ordered assembly of nanoscopic spheres made by drying from a suspension. After drying, it is considered as stable, but herein, transformations in the dry state are revealed. The time evolution of the optical transmission spectra for polystyrene opals is followed for two days after deposition. The spectra show pronounced changes associated with a new sintering mechanism (see figure).

    2. Application of Static Charge Transfer within an Ionic-Liquid Force Field and Its Effect on Structure and Dynamics (pages 1548–1558)

      Tristan G. A. Youngs and Christopher Hardacre

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800200

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      Ionic-liquid models in which the ionic charges are assumed to be ±1 e overestimate the intermolecular attractions between ions. The use of scaled-charge sets may be of benefit in the simulation of such systems (see image), thus providing an alternative to computationally expensive polarizable force fields.

    3. Fabrication of Stable Polyaniline Foams and Their Photoelectric Conversion Behaviors (pages 1559–1563)

      Liping Heng, Xinyi Wang, Jin Zhai, Zhongwei Sun and Lei Jiang

      Version of Record online: 18 JUN 2008 | DOI: 10.1002/cphc.200800063

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      Polymeric foams: Polyaniline foam films are prepared over a large scale with different pore sizes (see figure). The foam structure enhances the photovoltaic behaviour as the light-harvest efficiency and charge-transfer ability are increased due to the introduction of conductive polymer/electrolyte interfaces.

    4. CO Adsorption on a LaNi5 Hydrogen Storage Alloy Surface: A Theoretical Investigation (pages 1564–1569)

      Song Han, Xin-Bo Zhang, Si-Qi Shi, Masanori Kohyama, Hideaki Tanaka, Nobuhiro Kuriyama, Naoki Taoka, Teruo Kaneko and Qiang Xu

      Version of Record online: 20 JUN 2008 | DOI: 10.1002/cphc.200800080

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      Crossing the bridge: At low coverages, CO favors adsorption on Ni[BOND]Ni bridge sites of the LaNi5 (001) surface. With an increase in CO coverage, the decrease in adsorption energy is much larger for Ni[BOND]Ni[BOND]CO bridge adsorption than that for Ni[BOND]CO on-top adsorption (see graph). Thus on-top adsorption becomes more important at high CO coverages.

    5. Electronic and Vibrational Spectroscopy of 1-Methylthymine and its Water Clusters: The Dark State Survives Hydration (pages 1570–1577)

      Matthias Busker, Michael Nispel, Thomas Häber, Karl Kleinermanns, Mihajlo Etinski and Timo Fleig

      Version of Record online: 11 JUL 2008 | DOI: 10.1002/cphc.200800111

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      Survival of the dark state: Relaxation pathways of the DNA-base thymine with 1ππ*/1nπ* and 1ππ*/S0 conical intersections and barriers (see figure) have been identified which are not significantly altered by hydration. Support for this mechanism is provided from vibrational spectroscopic studies and ab initio theory.

    6. Reversible Self-Assembly of Carboxylated Peptide-Functionalized Gold Nanoparticles Driven by Metal-Ion Coordination (pages 1578–1584)

      Satyabrata Si, Manoj Raula, Tapas K. Paira and Tarun K. Mandal

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800121

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      Multidimensional nanostructures self-assemble upon addition of heavy-metal ions to carboxylated peptide-functionalized gold nanoparticles in aqueous solution (see schematic). The process is completely reversible by adding an alkaline solution of ethylenediaminetetraacetic acid (EDTA), and the accompanying changes in color (depicted) and spectral properties can be used to detect heavy-metal ions in solution.

    7. Interfacial Organization of Y-Shaped Rod–Coil Molecules Packed into Cylindrical Nanoarchitectures (pages 1585–1592)

      Libin Liu, Jung-Keun Kim and Myongsoo Lee

      Version of Record online: 10 JUL 2008 | DOI: 10.1002/cphc.200800124

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      The reason Y: Two kinds of cylindrical nanoarchitectures form at the air/water interface upon compression of Y-shaped molecules with a flexible poly(ethylene oxide) (PEO) chain of 21 or 34 ethylene oxide units (see picture). These structures result from the different tilting angle offered by the mismatch of the cross-sectional areas of the PEO chain and the benzene rings with attached alkyl chains as well as from the different PEO contents of the molecules.

    8. Influence of Solvent Polarity and Hydrogen Bonding on the Electronic Transition of Coumarin 120: A TDDFT Study (pages 1593–1602)

      Wenwei Zhao, Lu Pan, Wensheng Bian and Jianping Wang

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800131

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      A linear correlation of the absorption maximum λmax of Coumarin 120 (C120) with the solvent polarity function (see picture) is revealed by time-dependent (TD) DFT/polarizable continuum model (PCM) calculations. The experimental λmax of C120 in nine solvents is well described by the PCM-TDDFT scheme augmented with explicit inclusion of a few H-bonded solvent molecules.

    9. Nanodroplet Cluster Formation in Ionic Liquid Microemulsions (pages 1603–1609)

      Yanan Gao, Andreas Voigt, Liane Hilfert and Kai Sundmacher

      Version of Record online: 24 JUN 2008 | DOI: 10.1002/cphc.200800157

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      Drop by drop: A unique self-assembled cluster nanostructure is observed in reverse bmimBF4-in-toluene ionic liquid microemulsions (see picture). The large nanodroplet clusters consist of small ionic liquid microemulsion droplets. These novel nanodroplet clusters may have some unusual and unique properties with a number of interesting possibilities for potential applications.

    10. Structure of Pyridazine in the S1 State: Experiment and Theory (pages 1610–1616)

      Doo-Sik Ahn, Kyo-Won Choi, Sun Jong Baek, Young S. Choi, Sungyul Lee, Heechol Choi, Kyoung Koo Baeck and Sang Kyu Kim

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800168

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      Matters of state: High-level ab initio calculations predict a distorted planar geometry for the most stable structure of the S1 state of pyridazine. Resonance-enhanced two-photon ionization and mass-analyzed threshold ionization experiments support the structural change of C2v(S0)–Cs(S1)–C2v(D0) upon electronic excitation or ionization (see picture).

    11. Determination of the Degree of Charge-Transfer Contributions to Surface-Enhanced Raman Spectroscopy (pages 1617–1623)

      Cat Chenal, Ronald L. Birke and John R. Lombardi

      Version of Record online: 9 JUL 2008 | DOI: 10.1002/cphc.200800221

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      Quantitative clear contributions: The degree of charge transfer (PCT), a dimensionless parameter, provides an experimental tool to express the amount of charge-transfer contribution to an observed spectral line in SERS. The usefulness of this parameter is tested on various systems (see figure showing degree of charge transfer in p-aminothiophenol).

    12. Selective Homogeneous and Heterogeneous Gold Catalysis with Alkynes and Alkenes: Similar Behavior, Different Origin (pages 1624–1629)

      Mónica García-Mota, Noemí Cabello, Feliu Maseras, Antonio M. Echavarren, Javier Pérez-Ramírez and Nuria Lopez

      Version of Record online: 9 JUN 2008 | DOI: 10.1002/cphc.200800246

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      Spoiled for choice: Homogeneous and heterogeneous gold catalysts (see picture) are active and selective for several processes, particularly, selective alkyne activation. A detailed experimental and theoretical analysis uncovers that the exceptional alkynophilicity of gold is thermodynamically driven for heterogeneous catalysts, but kinetically driven for homogeneous catalysis.

    13. Computational Study on the Antifreeze Glycoproteins as Inhibitors of Clathrate-Hydrate Formation (pages 1630–1635)

      Armando Cruz-Torres, Ascención Romero-Martínez and Annia Galano

      Version of Record online: 10 JUL 2008 | DOI: 10.1002/cphc.200800241

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      Bursting the bubble: The presence of AATA peptides in the vicinity of water cavities not only leads to the formation of stable complexes with different peptide/cavity ratios, but also to the deformation of the cavity (see picture). Both these factors play a role in the ability of glycoproteins to inhibit clathrate hydrate formation.

    14. Highly Accurate CCSD(T) and DFT–SAPT Stabilization Energies of H-Bonded and Stacked Structures of the Uracil Dimer (pages 1636–1644)

      Michal Pitoňák, Kevin E. Riley, Pavel Neogrády and Pavel Hobza

      Version of Record online: 23 JUN 2008 | DOI: 10.1002/cphc.200800286

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      Setting a standard: Benchmark CCSD(T) interaction energies for the H-bonded and stacked uracil dimer (see figure) are determined up to the aug-cc-pVTZ level. These accurate interaction energies are compared to those obtained from various computational procedures, namely the SCS-MP2, SCS(MI)-MP2, MP3, DFT-D, M06-2X and DFT-SAPT methods.

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      Preview: ChemPhysChem 12/2008 (page 1650)

      Version of Record online: 25 JUL 2008 | DOI: 10.1002/cphc.200890047

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