ChemPhysChem

Cover image for ChemPhysChem

May 16, 2003

Volume 4, Issue 5

Pages 409–530

    1. Cover Picture: Electrosurface Phenomena at Polymer Films for Biosensor Applications (ChemPhysChem 5/2003) (page 409)

      Ralf Zimmermann, Oliver Birkert, Günter Gauglitz and Carsten Werner

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200390075

    2. Quantum Control of Gas-Phase and Liquid-Phase Femtochemistry (pages 418–438)

      Tobias Brixner and Gustav Gerber

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200581

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      Femtochemical dreams: Active control over quantum-mechanical systems is a fascinating perspective of modern physics. In recent years, novel femtosecond laser technologies in combination with learning algorithms have made it possible to fulfill an old dream and manipulate gas-phase as well as liquid-phase femtochemical processes on a microscopic molecular level.

    3. Stripes and Superconductivity in Cuprates–Is there a Connection? (pages 439–444)

      N. Kumar and C. N. R. Rao

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200601

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      No stars but stripes are known to occur in cuprate superconductors (see picture) and there has been an implicit belief that stripes play a seminal role in superconductivity. Based on recent experiments, it now appears that the relation between the stripes and superconductivity is by no means established. There is need for crucial experiments to understand this important aspect.

    4. Femtochemistry of trans-Azomethane: A Combined Experimental and Theoretical Study (pages 445–456)

      Eric W.-G. Diau and Ahmed H. Zewail

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200579

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      Is breaking up hard to do? The photodissociation dynamics of trans-azomethane have long been the subject of much interest. The energetic molecule may break its two C[BOND]N bonds either via a concerted mechanism or in a stepwise manner. The authors present experimental evidence and a comprehensive theoretical analysis (see picture) that confirm the stepwise nature of the dissociation. The elementary steps have been identified and are discussed in detail.

    5. A Test for the Number of Coupled Spins I=1/2 in Magic-Angle-Spinning Solids: Zero-Quantum Recoupling of Multiple-Quantum Coherences (pages 457–465)

      Colan E. Hughes, Jörn Schmedt auf der Günne and Malcolm H. Levitt

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200470

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      Magic spin counting: A new test is proposed for counting the number of coupled spins I=1/2 in solids by magic-angle spinning NMR spectroscopy. By comparing the signal-decay curves from two experiments (see picture), it is possible to ascertain if a group of spins consists of exactly N spins or whether more are present. Applications to biological solid-state NMR spectroscopy are anticipated.

    6. Adsorption of CO2 and Coadsorption of H and CO2 on Potassium-Promoted Cu(115) (pages 466–473)

      Jens Onsgaard, Søren V. Hoffmann, Palle Møller, P. Jan Godowski, Jacob B. Wagner, Giorgio Paolucci, Alessandro Baraldi, Giovanni Comelli and Amela Groso

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200505

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      Steps, a closer look: Surface-sensitive techniques have been used to monitor the adsorption of carbon dioxide, and the coadsorption of carbon dioxide and atomic hydrogen, on a potassium-modified, stepped copper surface, Cu(115) (see graphic). The influence of the potassium in the sub-monolayer regime is examined.

    7. Studies on Intra-Supramolecular and Intermolecular Electron-Transfer Processes between Zinc Naphthalocyanine and Imidazole-Appended Fullerene (pages 474–481)

      Mohamed E. El-Khouly, Lisa M. Rogers, Melvin E. Zandler, Gadde Suresh, Mamoru Fujitsuka, Osamu Ito and Francis D'Souza

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200540

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      An unpaired pair: Efficient, photoinduced electron transfer in a complex bearing an imidazole coordinating entity (see picture), which is self-assembled by axial coordination of zinc naphthalocyanine and fulleropyrrolidine, is reported. The optical absorption, singlet emission, and electrochemical studies, as well as ab initio B3 LYP/3–21G(*) calculations revealed stable complex formation. Direct evidence for radical ion-pair formation in the dyad was obtained from picosecond transient-absorption studies.

    8. Ship-in-a-Bottle Synthesis of a Large Guest Occupying Two Y Zeolite Neighbour Supercages: Characterisation and Photocatalytic Activity of the Encapsulated Bipyrylium Ion (pages 483–487)

      Mercedes Alvaro, Esther Carbonell, Antonio Doménech, Vicente Fornés, Hermenegildo García and Manoj Narayana

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200548

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      Catalyst catching: The ship-in-a-bottle synthesis of bipyrylium dication (BTP) occupying two zeolite Y supercages (BTP@Y) was achieved by reaction of dichalcone and acetophenone in the presence of an acid Y zeolite (Si/Al 13). The photocatalytic activity of BTP@Y for the degradation of phenol in water (see graphic) has a lower initial reaction rate, but the same final degradation percentage as the parent 2,4,6-triphenylpyrylium ion.

    9. Photocatalytic and Photoelectrochemical Properties of Nitrogen-Doped Titanium Dioxide (pages 487–490)

      Shanmugasundaram Sakthivel and Horst Kisch

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200554

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      Sunlight cleans up! Easily obtainable nitrogen-doped titania (TiO2-N) photocatalyzes the oxidative removal of pollutants (see picture) from water and air in diffuse indoor daylight.

    10. Molecular-Template-Mediated Chemical Decoration (pages 490–494)

      Stephanie Hoeppener, Jörg Wonnemann, Lifeng Chi, Gerhard Erker and Harald Fuchs

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200583

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      Planely positioned! Surface-mediated adsorption or chemical reactions is strongly influenced by the geometric availability of adsorption sites. Here, the authors investigate this influence on linearly arranged, chemically active template layers consisting of lipid modified amino acid derivatives (see picture) to study and control the effect of the steric hindrance due to the molecular arrangement on HOPG surfaces.

    11. Molecular Arrangement of Fatty Acids at the Solid–Liquid Interface Visualized by Chemical Decoration (pages 494–498)

      Stephanie Hoeppener, Lifeng Chi and Harald Fuchs

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200584

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      Finding finely formed fat: A method to visualize the carboxylic groups of a highly ordered fatty acid template layer (see picture) by utilizing small probe molecules is demonstrated. STM investigations of the decorated surface strongly indicate a head-to-head arrangement of the fatty acid molecules at the solid–liquid interface.

    12. Polaron Pair versus Bipolaron on Oligothiophene Chains: A Theoretical Study of the Singlet and Triplet States (pages 498–505)

      Victor M. Geskin and Jean-Luc Brédas

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200446

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      Double positive charges on an isolated conjugated chain: do they remain together forming a single bipolaron (2+) entity (shown in picture) stabilized by strong geometry distortion even in the absence of a counterion or do they repel, yielding two separate polarons (+)? The balance is subtle. Our correlated ab initio and semiempirical calculations show that in oligothiophenes a polaron pair is preferred, for chains containing seven or eight rings and longer.

    13. Cholesteric Networks Based on Lyotropic Mixtures (pages 505–508)

      Gerold Schmitt, Reiner Giesa and Hans-Werner Schmidt

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200478

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      Color link: Ternary lyotropic cholesteric mixtures are formed by mixing small amounts of a chiral cholesteric dopant with nematic compounds both bearing photocrosslinkable groups and up to 35 wt % of a reactive solvent. The successful incorporation of rather inexpensive reactive solvent facilitates the technical application of these systems as organic effect pigments (see TEM) for automobiles and other purposes.

    14. Electrosurface Phenomena at Polymer Films for Biosensor Applications (pages 509–514)

      Ralf Zimmermann, Oliver Birkert, Günter Gauglitz and Carsten Werner

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200475

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      Sensitive surfaces: Thin polymer films as applied for sensitive elements of biosensors have been characterized by the combined determination of zeta potential and surface conductivity. Zeta potential versus pH plots indicate the acid–base characteristics of the polymer layers (see graphic). Surface conductivities reveal the accessibility of the interfacial volumes for mobile electrolyte ions.

    15. Pt Nanoparticles Dispersed in a Mesostrucured Silica Matrix: Towards Self-Organized 3D Nanocomposite (pages 514–517)

      Pierre Thomas, Auguste Fernandes, Pierre Lecante, Roland Coratger, Marc Verelst, Fabrice Dassenoy and Walter Vogel

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200543

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      Entrapment on the nanoscale! Nanoparticles have been self-assembled inside a silica matrix using a “bottle-around-the-ship” approach. This new route is strongly inspired by the chemistry of mesoporous materials. Silica walls are built in solution around Pt nanoparticles self-assembled as micelles (see picture).

    16. Relativistic DFT Calculations of Polyoxotungstate 183W NMR Spectra: Insight into their Solution Structure (pages 517–519)

      Alessandro Bagno, Marcella Bonchio, Andrea Sartorel and Gianfranco Scorrano

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200300636

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      Mapping an uncharted territory: The good correlation between experimental and calculated 183W NMR chemical shifts of polyoxotungstates (see picture) may allow the prediction and assignment of the spectra of unstable or unknown species, and also allow the counterion effect to be addressed.

    17. Supercritical Carbon Dioxide-Induced Phase Changes in (Ionic Liquid, Water and Ethanol Mixture) Solutions: Application to Biphasic Catalysis. (pages 520–522)

      Vesna Najdanovic-Visak, Ana Serbanovic, José M. S. S. Esperança, Henrique J. R. Guedes, Luís P. N. Rebelo and Manuel Nunes da Ponte

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200300663

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      The best of both worlds: Phase changes in ionic liquid + water systems, induced by addition of ethanol and supercritical carbon dioxide, allow reaction cycles to proceed as depicted, combining the high rates of one-phase conditions with easy separation of products; characteristic of biphasic catalysis. The (usually slow) epoxidation of isophorone by hydrogen peroxide, catalysed by sodium hydroxide, was rapidly carried out in these conditions, with complete recovery of the reaction product by supercritical CO2 decompression.

    18. How Diradicaloid Is a Stable Diradical? (pages 522–525)

      Yousung Jung and Martin Head-Gordon

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200200668

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      Splitting orbitals: By using an occupation-number scale, the extent to which observable diradicals are diradicaloid is quantified by calculations, and the factors controlling this character are discussed. A deeper understanding of how the stability of the singlet diradical is affected by ligand substitution (see picture) will help synthesize more stable singlet diradicals with controllable amounts of diradical character that bridge the regime between unstable, and thus unattainable “pure” diradicals, and normal closed-shell molecules.

    19. Trapping Metal Nanoclusters in “Soap and Water” Soft Crystals (pages 526–528)

      Erika Eiser, Fatima Bouchama, Mehul B. Thathagar and Gadi Rothenberg

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200300721

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      Rods and dots: Quantum dots (2–5 nm in diameter) of copper, silver, gold, palladium, and ruthenium are easily trapped in self-assembled “soft crystal” gels made of water and surfactants. The gels are made of long micellar rods in direct hexagonal packing, aqueous outside and oily inside (see picture). The hydrophobic interaction between the clusters, stabilising shell, and the oily phase keeps the clusters inside. The use of toluene, instead of cyclohexane, is the key to enable the trapping of very small clusters of various metals in tight confinement. Structural development is monitored by small-angle Xray scattering (SAXS). The possible applications of this discovery to make thin nanowires by cold-welding and design of new nanocatalyst templates are discussed.

    20. Preview: ChemPhysChem 5/2003 (page 530)

      Version of Record online: 9 MAY 2003 | DOI: 10.1002/cphc.200390077

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