ChemPhysChem

Cover image for Vol. 11 Issue 17

December 3, 2010

Volume 11, Issue 17

Pages 3553–3771

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
    7. Highlight
    8. Communications
    9. Articles
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    1. Cover Picture: High-Resolution Surface Chemical Analysis of a Trifunctional Pattern Made by Sequential Colloidal Shadowing (ChemPhysChem 17/2010) (page 3553)

      Dr. Ryosuke Ogaki, Folmer Lyckegaard and Prof. Peter Kingshott

      Version of Record online: 26 NOV 2010 | DOI: 10.1002/cphc.201090084

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      The cover picture represents how three chemistries can be readily patterned on a surface by using a combination of colloidal lithography, physical vapour deposition and self-assembled monolayers, as described on p. 3609 by Kingshott et al. Inspired by a layer-cake concept, a sequential masking can be performed by overlaying a hexagonally close-packed monolayer of colloids on top of each other, where the second layer of colloids periodically masks the alternating interstitial spaces of the first layer. The gold layer (shown in yellow) is first deposited through the interstitial spaces of a first monolayer of colloids and the first set of thiols (biotinylated thiols, red) is immobilized. Another monolayer of HCP colloids is deposited on top and the subsequent deposition of gold is performed in the interstitial spaces, periodically burying the first set of thiols and creating a fresh gold surface for the immobilization of the second set of thiols (fluorinated thiols, green). The double layer of colloids is finally removed, revealing a periodical pattern of the two different thiols and the bare substrate (SiO2, blue). The pattern is confirmed by using time-of-flight secondary ion mass spectrometry, yielding a secondary ion image with sub-micron lateral resolution (right-hand image). The top left-hand corner represents the X-ray photoelectron spectra of the C 1s high-resolution scan, revealing that no replacement is taking place between the two set of thiols.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
    7. Highlight
    8. Communications
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    1. Inside Cover: A Time-Dependent Picture of the Ultrafast Deactivation of keto-Cytosine Including Three-State Conical Intersections (ChemPhysChem 17/2010) (page 3554)

      Dr. Jesús González-Vázquez and Prof. Dr. Leticia González

      Version of Record online: 26 NOV 2010 | DOI: 10.1002/cphc.201090085

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      The relaxation mechanism of cytosine is investigated by L. González and J. González-Vázquez on p. 3617 using ab initio molecular dynamics. Possible deactivation pathways include three-state conical intersections.

  3. Graphical Abstract

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    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
    7. Highlight
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  4. News

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
    7. Highlight
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  5. Minireview

    1. Top of page
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    1. Temperature Response of PNIPAM Derivatives at Planar Surfaces: Comparison between Polyelectrolyte Multilayers and Adsorbed Microgels (pages 3571–3579)

      Anna Burmistrova, Dr. Roland Steitz and Prof. Dr. Regine von Klitzing

      Version of Record online: 17 NOV 2010 | DOI: 10.1002/cphc.201000378

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      Two strategies for the design of thermosensitive coatings based on poly-N-isopropyl acrylamide (PNIPAM) derivatives are presented: 1) polyelectrolyte multilayers containing a diblock copolymer with a large PNIPAM block and 2) adsorption of PNIPAM microgel particles (see picture).

  6. Highlight

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
    7. Highlight
    8. Communications
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    1. Determining the Time Zero for Electronic Dynamics (pages 3581–3583)

      Dr. Giuseppe Sansone

      Version of Record online: 4 NOV 2010 | DOI: 10.1002/cphc.201000668

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      The final countdown: In a recent experiment a time delay of 20 as between the electrons emitted from different orbitals of neon atoms was measured by means of laser spectroscopy (see picture). The existence of such a delay has important implications for our understanding of electron correlation and for our capability to characterize electronic dynamics on their natural timescale.

  7. Communications

    1. Top of page
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    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
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    8. Communications
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    1. Biocompatible Magnetite Nanoparticles Trapped at the Air/Water Interface (pages 3585–3588)

      Dr. Cristina Stefaniu, Dr. Munish Chanana, Dr. Dayang Wang, Dr. Dmitri V. Novikov, Prof. Dr. Gerald Brezesinski and Prof. Dr. Helmuth Möhwald

      Version of Record online: 5 NOV 2010 | DOI: 10.1002/cphc.201000783

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      Interfacial captured nanoparticles: Energetically and kinetically stable Fe3O4@MEO2MA90-co-OEGMA10 nanoparticle (NP) layers (see picture) are formed at the air/water interface. Due to the unique hydrophilic–hydrophobic properties of the copolymer, the surface-active NPs are readily adsorbed at that interface, where they do not interchange with the bulk material but remain trapped. Above the critical surface coverage the NPs are dispersed in the aqueous subphase without precipitation.

    2. The Role of Electrode Curvature in Controlling Electron Transfer between the Photosynthetic Reaction Center Protein and Gold Nanoelectrodes (pages 3589–3591)

      Prof. Igor Griva, Dr. Joel M. Schnur and Dr. Nikolai Lebedev

      Version of Record online: 22 OCT 2010 | DOI: 10.1002/cphc.201000643

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      The electron transfer coupling element between gold nanoclusters and the photosynthetic reaction center protein from the bacterium Rhodobacter sphaeroides was calculated using the shortest-path algorithm. Changing the size of the metal cluster alters the rate of electron transfer between the protein and the metal by several orders of magnitude. The calculation also predicts the switching of electron transfer pathway within the protein depending on the size of the metal cluster.

    3. PbS Quantum Dot-Sensitized Photoelectrochemical Cell for Hydrogen Production from Water under Illumination of Simulated Sunlight (pages 3592–3595)

      Yasuaki Jin-nouchi, Takanori Hattori, Yasutaka Sumida, Dr. Musashi Fujishima and Prof. Hiroaki Tada

      Version of Record online: 4 NOV 2010 | DOI: 10.1002/cphc.201000593

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      Hydrogen production from water in the presence of S2− and SO32− ions in PEC cells using a PbS/mp-TiO2 photoanode under illumination of simulated sunlight is reported (see figure). A total conversion efficiency of 1.15 % is achieved with a hydrogen production rate of 5.2 mL h−1, demonstrating that the PbS QD–SPEC cell can efficiently convert solar energy to hydrogen energy.

    4. Electric-Field-Induced Reversible Viscosity Change in a Columnar Liquid Crystal (pages 3596–3598)

      Dr. Kosuke Kaneko, Atsuhiko Mandai, Dr. Benoît Heinrich, Dr. Bertrand Donnio and Prof. Dr. Tomonori Hanasaki

      Version of Record online: 5 NOV 2010 | DOI: 10.1002/cphc.201000587

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      Call the doctor! The electro-rheological (ER) effect of a silsesquioxane liquid crystal (LC) is investigated. The spherical shape of the LC plays a key role in avoiding the entanglement between neighboring molecules, which leads to a quick response to an applied electric field. The silsesquioxane LC shows a large ER response to an applied electric field in which the generated shear stress is more than 50 kPa (see picture).

    5. Thermosensitive Silver/Polydiacetylene Nanocrystals with Tunable Nonlinear Optical Properties (pages 3599–3603)

      Xin Chen, Jun Tao, Gang Zou, Wei Su, Qijin Zhang and Pei Wang

      Version of Record online: 24 NOV 2010 | DOI: 10.1002/cphc.201000416

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      Tune in and watch! A strategy is presented for the fabrication of a core–shell colloidal material comprising silver/poly(10, 12-pentecosadiynoic acid) (Ag/PPCDA) hybrid nanocrystals stabilized with thermally responsive poly(N-isopropylacrylamide) (PNIPAM) (see picture). The new composite material exhibits tunable nonlinear optical properties and is a good candidate for applications in environmentally sensitive photonic devices.

    6. Hydrogen Loading of Oxide Powder Particles: A Transmission IR Study for the Case of Zinc Oxide (pages 3604–3607)

      Dr. Heshmat Noei, Dr. Hengshan Qiu, Dr. Yuemin Wang, Prof. Dr. Martin Muhler and Prof. Dr. Christof Wöll

      Version of Record online: 22 JUN 2010 | DOI: 10.1002/cphc.201000312

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      Exposing ZnO nanoparticles to atomic and molecular hydrogen at room temperature decreases the transmission coefficient, which demonstrates that diffusion of hydrogen atoms to subsurface and bulk ZnO sites already occurs at these fairly low temperatures (see figure). The interstitial hydrogen atoms act as n-type shallow donors, which increase the density of electrons in the conduction band.

  8. Articles

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Minireview
    7. Highlight
    8. Communications
    9. Articles
    10. Preview
    1. High-Resolution Surface Chemical Analysis of a Trifunctional Pattern Made by Sequential Colloidal Shadowing (pages 3609–3616)

      Dr. Ryosuke Ogaki, Folmer Lyckegaard and Prof. Peter Kingshott

      Version of Record online: 12 NOV 2010 | DOI: 10.1002/cphc.201000737

      Thumbnail image of graphical abstract

      Layer cake: Up to three chemistries can be periodically patterned at alternative positions on a single substrate by using a combination of colloidal assembly, self assembled monolayers and PVD (see picture). High-resolution imaging of the patterned surface is carried out by time of flight secondary ion mass spectrometry with submicron-sized patterned features.

    2. A Time-Dependent Picture of the Ultrafast Deactivation of keto-Cytosine Including Three-State Conical Intersections (pages 3617–3624)

      Dr. Jesús González-Vázquez and Prof. Dr. Leticia González

      Version of Record online: 10 NOV 2010 | DOI: 10.1002/cphc.201000557

      Thumbnail image of graphical abstract

      Three is better than two: The first deactivation steps of keto-cytosine are investigated using mixed quantum–classical dynamics. The results indicate that conical intersections involving three states are involved in the relaxation of keto-cytosine to the ground state.

    3. The Origin and Dynamics of Soft X-Ray-Excited Optical Luminescence of ZnO (pages 3625–3631)

      Dr. Lidia Armelao, Dr. Franziskus Heigl, Dr. Sophie Brunet, Dr. Ramaswami Sammynaiken, Dr. Tom Regier, Dr. Robert I. R. Blyth, Dr. Lucia Zuin, Dr. Rami Sankari, Dr. Johannes Vogt and Prof. Tsun-Kong Sham

      Version of Record online: 15 NOV 2010 | DOI: 10.1002/cphc.201000730

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      The interplay of size, crystallinity, morphology and excitation energy is correlated with the optical emissions in ZnO materials, providing direct evidence of the different behaviour and crucial role of bulk and surface defects in the origin of luminescence (see picture). Soft X-ray excited optical luminescence (XEOL), allowing site-specific chemical information and luminescence information concurrently, and time-resolved XEOL from a synchrotron light source was used to obtain the results.

    4. Real-Time Probing of Ion Pairing Dynamics with 2DIR Spectroscopy (pages 3632–3637)

      Kwang-Hee Park, Seung Ryul Choi, Dr. Jun-Ho Choi, Prof. Dr. Sungnam Park and Prof. Dr. Minhaeng Cho

      Version of Record online: 10 NOV 2010 | DOI: 10.1002/cphc.201000595

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      Ion pairing dynamics are probed by using a chemical exchange 2DIR spectroscopic technique in real time (see picture). The dissociation time constant of the LiSeCN contact ion pair in N,N-dimethyl formamide solution is determined to be 420±40 ps.

    5. Self-Assembly of a Low-Symmetry Monodendron Containing Two Asymmetrically Linked Molecular Wedges (pages 3638–3644)

      Jānis Lejnieks, Dr. Xiaomin Zhu, Jingbo Wang, Dr. Ahmed Mourran, Dr. Helmut Keul, Prof. Martin Möller, Dr. Denis V. Anokhin and Dr. Dimitri A. Ivanov

      Version of Record online: 26 OCT 2010 | DOI: 10.1002/cphc.201000567

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      Peculiar structure: The shape of the low-symmetry monodendron resembles that of a fiddler crab (see picture). The compound exhibits a structure in which three alkyl chains crystallize whereas the other two remain in the amorphous state. Crystalline and amorphous domains are well-ordered in 3D. The self-assembled 2D and 3D structures were investigated by synchrotron X-ray scattering and scanning force microscopy.

    6. Tunable Electronic Properties of a Proton-Responsive N,N-Dimethylaminoazobenzene Fullerene (C60) Dyad (pages 3645–3655)

      K. Senthil Kumar and Prof. Archita Patnaik

      Version of Record online: 18 OCT 2010 | DOI: 10.1002/cphc.201000564

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      A curious quest for azobenzenes beyond photoisomerisation leads to the observation of frontier molecular orbital (FMO) switching (see figure) in a first prototype fullerene (C60) N,N-dimethylaminoazobenzene dyad. The spectroscopic signatures are assigned to specific protonated structures with the aid of time-dependent density functional theory (TD-DFT), shedding light on the fundamental, yet fascinating, phenomenon of protonation-induced FMO switching.

    7. Spin-Labeled Heparins as Polarizing Agents for Dynamic Nuclear Polarization (pages 3656–3663)

      Björn C. Dollmann, Dr. Andrei L. Kleschyov, Dr. Vasily Sen, Dr. Valery Golubev, Prof. Dr. Laura M. Schreiber, Prof. Dr. Hans W. Spiess, Dr. Kerstin Münnemann and Dr. Dariush Hinderberger

      Version of Record online: 19 OCT 2010 | DOI: 10.1002/cphc.201000559

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      Enhanced signals: Spin-labeled (SL) heparins are introduced as a class of polarizing agents for Overhauser-type dynamic nuclear polarization (DNP). All presented SL-heparins show high 1H DNP enhancement factors up to E=−110. These high enhancements—despite broad continuous-wave electron paramagnetic resonance (CW EPR) lines—are achieved by using heterogeneously distributed (along the heparin backbone) spin labels.

    8. Mechanism of Proton Relaxation for Enzyme-Manipulated, Multicomponent Gold–Magnetic Nanoparticle Chains (pages 3664–3672)

      Hamsa Jaganathan, Richard L. Gieseck, Katherine Hudson, Michael Kellogg, Aneesh K. Ramaswamy, Kimberly E. Raver, Tyler Smith, Ashley N. Vacchiano, Andrew Wager and Prof. Albena Ivanisevic

      Version of Record online: 12 NOV 2010 | DOI: 10.1002/cphc.201000397

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      Cut and paste: Restriction enzymes cut DNA-scaffolded chains of gold and superparamagnetic metal-oxide nanoparticles (NPs) into shorter fragments which are glued together by a ligase to give multicomponent NP chains (see schematic structure) having the potential to serve as magnetic resonance imaging (MRI) agents by shortening the proton relaxation times, which can be compared for various constructs in the form of a coloured heat map.

    9. Vaporisation of a Dicationic Ionic Liquid Revisited (pages 3673–3677)

      Joana Vitorino, Dr. João P. Leal, Dr. Peter Licence, Dr. Kevin R. J. Lovelock, Dr. Peter N. Gooden, Dr. Manuel E. Minas da Piedade, Dr. Karina Shimizu, Prof. Luís P. N. Rebelo and Dr. José N. Canongia Lopes

      Version of Record online: 5 NOV 2010 | DOI: 10.1002/cphc.201000723

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      Vaporizing by trios: The vaporization of a dicationic ionic liquid (see picture) analyzed using a ion-cyclotron resonance mass spectrometry technique is discussed herein.

    10. Hydrogen Sulfide Adsorption on MOFs and MOF/Graphite Oxide Composites (pages 3678–3684)

      Camille Petit, Barbara Mendoza and Prof. Teresa J. Bandosz

      Version of Record online: 13 OCT 2010 | DOI: 10.1002/cphc.201000689

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      A copper-based metal-organic framework (MOF) and its composites with graphite oxide (GO) are tested for hydrogen sulfide removal. H2S is both physically and chemically adsorbed on the materials. In the latter case, it reacts with the MOF component and form copper sulfide, inducing a color change of the adsorbent (see picture). Composites allow better adsorption than the MOF because they provide stronger dispersive forces.

    11. Biradicaloid Character of Thiophene-Based Heterophenoquinones: The Role of Electron–Phonon Coupling (pages 3685–3695)

      Dr. Daniele Fazzi, Dr. Eleonora V. Canesi, Prof. Fabrizia Negri, Dr. Chiara Bertarelli and Prof. Chiara Castiglioni

      Version of Record online: 15 NOV 2010 | DOI: 10.1002/cphc.201000675

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      Quinoid versus biradicaloid character of the ground state of heterophenoquinones (see picture) is investigated with quantum-chemical calculations and vibrational spectroscopy. The biradicaloid character of the ground state is shown to increase with the length of the π conjugation and with the number of thiophene rings. The frequency turning point of the most intense Raman-active mode is reproduced well by modulating the biradicaloid contribution to the ground-state structure.

    12. Modulating the Photochemistry of Bipyridylic Compounds by Symmetric Substitutions (pages 3696–3703)

      Dr. Juan M. Ortiz-Sánchez, Dr. Ricard Gelabert, Prof. Miquel Moreno and Prof. José M. Lluch

      Version of Record online: 18 OCT 2010 | DOI: 10.1002/cphc.201000596

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      Modulating photochemistry though substituent effects: Symmetric bisubstitutions on bipyridylic compounds modify the photochemistry by either enhancing or decreasing the probability to obtain a stable photochromic tautomer that can revert to the original form upon irradiation of different wavelength (see scheme).

    13. Reversible Carrier-Type Transitions in Gas-Sensing Oxides and Nanostructures (pages 3704–3712)

      Dr. Andrew D. Arulsamy, Kristina Eleršič, Martina Modic, Dr. Uroš Cvelbar and Prof. Dr. Miran Mozetič

      Version of Record online: 12 NOV 2010 | DOI: 10.1002/cphc.201000572

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      Reversible carrier-type transition: Rigorous theoretical details are given to explain why and how a given gas molecule interacts via physisorption on an oxide surface to initiate the carrier-type transition (see picture). The renormalized polarizability functional is used to prove that there is only one origin for this carrier-type transition, even though there are three causes.

    14. Strength in Numbers: Effects of Acceptor Abundance on FRET Efficiency (pages 3713–3721)

      Dr. Ákos I. Fábián, Tünde Rente, Prof. János Szöllősi, Prof. László Mátyus and Dr. Attila Jenei

      Version of Record online: 8 OCT 2010 | DOI: 10.1002/cphc.201000568

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      Spectroscopic ruler for molecular distances: Fluorescence resonance energy transfer (FRET) is a strongly distance-dependent process between a donor and an acceptor molecule which can be exploited for studies in biological systems (see graph). Manipulation of fluorophore/protein ratios of conjugated antibodies has large impact on the transfer efficiency and expands the potential of FRET measurements.

    15. Refractive Index of Liquid Mixtures: Theory and Experiment (pages 3722–3733)

      Prof. João Carlos R. Reis, Prof. Isabel M. S. Lampreia, Prof. Ângela F. S. Santos, Prof. Maria Luísa C. J. Moita and Dr. Gérard Douhéret

      Version of Record online: 18 OCT 2010 | DOI: 10.1002/cphc.201000566

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      A thermodynamic formalism is developed to analyse refractive index data of liquid mixtures. A positive change of refractive index upon ideal mixing is predicted and interpreted in terms of London dispersion forces. The correlation between excess refractive indices and excess molar volumes is pear-shaped for an amphiphile/water system at different temperatures (see picture).

    16. On the Relative Merits of Equilibrium and Non-Equilibrium Simulations for the Estimation of Free-Energy Differences (pages 3734–3743)

      Prof. Xavier Daura, Dr. Roman Affentranger and Prof. Alan E. Mark

      Version of Record online: 15 NOV 2010 | DOI: 10.1002/cphc.201000562

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      Moving targets: A simple dissipative system is used to test the merits of performing equilibrium or non-equilibrium simulations to estimate free-energy differences. For moving a single methane molecule in water (see picture), where the work distribution is Gaussian, simulating under quasi-equilibrium conditions is most efficient. For non-equilibrium approaches, pulling rates as low as 1 nm ns−1 are problematic, casting doubt on the validity of many studies involving biomolecules.

    17. Surfactant-Free Self-Assembly of Nanocrystals into Ellipsoidal Architectures (pages 3744–3751)

      Dr. Bo Peng, Dong Chen, Dr. Zhengtao Deng, Ting Wen, Dr. Xianwei Meng, Xiangling Ren, Prof. Jun Ren and Prof. Fangqiong Tang

      Version of Record online: 12 NOV 2010 | DOI: 10.1002/cphc.201000458

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      Ellipsoidal ZnS architectures with zinc blende structure are formed by surfactant-free self-assembly. The growth process can be divided into two stages: formation of ellipsoidal architectures via oriented attachment, the kinetics of which is attributed to charge–charge, charge–dipole, and dipole–dipole interactions of ZnS nanocrystals; and Ostwald ripening, which results in multishelled, rattle-type, and hollow structures (see picture).

    18. Influence of N-Alkyl Substituents and Counterions on the Structural and Mesomorphic Properties of Guanidinium Salts: Experiment and Quantum Chemical Calculations (pages 3752–3765)

      Martin Butschies, Dr. Sven Sauer, Elena Kessler, Prof. Dr. Hans-Ullrich Siehl, Dr. Birgit Claasen, Dr. Peter Fischer, Dr. Wolfgang Frey and Prof. Dr. Sabine Laschat

      Version of Record online: 17 NOV 2010 | DOI: 10.1002/cphc.201000444

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      The anion makes the difference: The synthesis of various guanidinium salts with varying alkoxy chain lengths and additional N-alkyl substituents is reported (see picture). Mesomorphic properties are studied by differential-scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. All liquid-crystalline guanidinium salts exhibit smectic A mesophases.

  9. Preview

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