Chemistry - A European Journal

Cover image for Vol. 17 Issue 39

September 19, 2011

Volume 17, Issue 39

Pages 10785–11071

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
    1. Cover Picture: Conjugated Asymmetric Donor-Substituted 1,3,5-Triazines: New Host Materials for Blue Phosphorescent Organic Light-Emitting Diodes (Chem. Eur. J. 39/2011) (page 10785)

      Zhong-Fu An, Dr. Run-Feng Chen, Jun Yin, Guo-Hua Xie, Hui-Fang Shi, Prof. Taiju Tsuboi and Prof. Wei Huang

      Article first published online: 14 SEP 2011 | DOI: 10.1002/chem.201190190

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      The beauty of the trefoil has been shown in the molecular design of triazine-based optoelectronic materials through asymmetric substitutions of conjugated donors. These green (new) molecular trefoils exhibit a maximum external quantum efficiency up to 9.8 % as host materials for blue phosphorescent organic light-emitting diodes, due to their high solubility, thermostability, and high triplet energy, depending on the different substitution patterns. For more details see the Full Paper by W. Huang et al. on page 10871 ff.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
    1. Inside Cover: Conjugated 4-Methoxybipyrrole Thiophene Azomethines: Synthesis, Opto-Electronic Properties, and Crystallographic Characterization (Chem. Eur. J. 39/2011) (page 10786)

      Tshitundu Tshibaka, Sophie Bishop, Ivan Ulliel Roche, Stéphane Dufresne, William D. Lubell and William G. Skene

      Article first published online: 14 SEP 2011 | DOI: 10.1002/chem.201190191

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      The stark, reversible, color transitions between the neutral and oxidized states of azomethines composed of thiophene and bipyrrole units can be induced both electrochemically and chemically. For more details on the extended conjugation and enhanced opto-electronic properties of these compounds see the Full Paper by W. G. Skene, W. D. Lubell et al. on page 10879 ff.

  3. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
  4. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
  5. Concept

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
    1. Graphene

      Two-Dimensional Nanocomposites Based on Chemically Modified Graphene (pages 10804–10812)

      Dr. Dongqing Wu, Dr. Fan Zhang, Dr. Ping Liu and Dr. Xinliang Feng

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201101333

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      Hello, flat world! Due to the presence of multifunctional groups and flat morphology with nm thin thickness, chemically modified graphene (CMG) is regarded as an ideal template for the construction of two-dimensional nanocomposites with various functions. This Concept article will introduce the recent achievements in the bottom-up fabrication of CMG-based 2D nanocomposites, which represent the new directions in material sciences.

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
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    1. Alkali Metals

      Sodium and Potassium Salts of Mono- and Dianionic α-Iminopyridines (pages 10814–10819)

      Dr. Hari Pada Nayek, Dipl.-Chem. Nicholas Arleth, Dipl.-Chem. Ina Trapp, Dipl.-Chem. Matthias Löble, Dr. Pascual Oña-Burgos, M. Sc. Magdalena Kuzdrowska, Dr. Yanhua Lan, Prof. Dr. Annie K. Powell, Prof. Dr. Frank Breher and Prof. Dr. Peter W. Roesky

      Article first published online: 25 AUG 2011 | DOI: 10.1002/chem.201101646

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      Iminopyridine: The redox chemistry of N-2,6-diisopropylphenylimino-2-pyridine was investigated in detail, including cyclic voltammetry. Bulk samples of alkali metal salts of monoanionic radical and dianionic iminopyridine were synthesized and characterized by various methods (see figure). The radical form was fully investigated by magnetic measurements, EPR spectroscopy, and DFT calculations.

    2. Gas-Phase Reactions

      Gas-Phase Nucleophilic Aromatic Substitution between Piperazine and Halobenzyl Cations: Reactivity of the Methylene Arenium Form of Benzyl Cations (pages 10820–10824)

      Dr. Yunfeng Chai, Kezhi Jiang, Prof. Cuirong Sun and Yuanjiang Pan

      Article first published online: 25 AUG 2011 | DOI: 10.1002/chem.201101790

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      Methylene arenium involved in SNAr: The gas-phase nucleophilic aromatic substitution reactions of halobenzyl cations with piperazine through a cationic σ complex were studied using ESI mass spectrometry. This study demonstrates that the methylene arenium form of halobenzyl cations exhibits nucleophilic substitution reactivity at the phenyl ring (see scheme).

    3. NMR Spectroscopy

      BDPA: An Efficient Polarizing Agent for Fast Dissolution Dynamic Nuclear Polarization NMR Spectroscopy (pages 10825–10827)

      Dr. Lloyd Lumata, Dr. S. James Ratnakar, Dr. Ashish Jindal, Prof. Dr. Matthew Merritt, Prof. Dr. Arnaud Comment, Prof. Dr. Craig Malloy, Prof. Dr. A. Dean Sherry and Prof. Dr. Zoltan Kovacs

      Article first published online: 25 AUG 2011 | DOI: 10.1002/chem.201102037

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      Teaching an old free radical new tricks: The stable free radical 1,3-bisdiphenylene-2-phenylallyl (BDPA) is an efficient polarizing agent in the dissolution dynamic nuclear polarization (DNP) of a variety of hydrophilic and hydrophobic compounds, such as tetramethylallene or [15N]choline (see figure). In addition, BDPA can be easily removed from the hyperpolarized solution by a simple mechanical filtration, when water is used for dissolution.

    4. Ligand Synthesis

      Improved Syntheses of Phosphine Ligands by Direct Coupling of Diarylbromophosphine with Organometallic Reagents (pages 10828–10831)

      Dr. Lei Liu, Prof. Dr. Hai-Chen Wu and Prof. Dr. Jin-Quan Yu

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201101467

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      Br versus Cl: It is found that the use of diarylbromophosphines instead of diarylchlorophosphines is crucial for their direct coupling with binaphthylmagnesium bromide or BINOL triflate. This finding has led to an improved preparation of both electron-deficient BINAP-type phosphine ligands and several important Buchwald's ligands.

    5. Solar Cells

      Enhancement of Photogenerated Electron Transport in Dye-Sensitized Solar Cells with Introduction of a Reduced Graphene Oxide–TiO2 Junction (pages 10832–10837)

      Junling Song, Dr. Zongyou Yin, Zijiang Yang, Dr. Pitchamuthu Amaladass, Shixin Wu, Jun Ye, Prof. Yang Zhao, Prof. Wei-Qiao Deng, Prof. Hua Zhang and Prof. Xue-Wei Liu

      Article first published online: 23 AUG 2011 | DOI: 10.1002/chem.201101263

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      Reduced graphene oxide (rGO) serves as an efficient electron-transport channel between dye molecules and the electrode in a dye-sensitized solar cell due to the formation of an rGO–TiO2 Schottky barrier junction, which can improve the interface contact between dye and TiO2 effectively and therefore enhance the photogenerated-electron transport/injection efficiency in the photoanode (see figure).

    6. DNA Quadruplexes

      G Quadruplexes Stabilised by 8-Oxo-2′-deoxyguanosine (pages 10838–10843)

      Dr. Vijay Singh, Armin Benz and Prof. Dr. Jörg S. Hartig

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201100284

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      Four is company: Four-stranded structures can be formed from sequences that contain non-natural analogues of 2′-deoxyguanosine. 8-Oxo-2′-deoxyguanosine, 2′-deoxyxanthosine as well as 8-oxo-2′-deoxyguanosine were found to support the formation of stable quadruplex structures (see figure).

    7. Organocatalysis

      Direct Arylation of Alkenes with Aryl Iodides/Bromides through an Organocatalytic Radical Process (pages 10844–10847)

      Chang-Liang Sun, Yi-Fan Gu, Prof. Dr. Bin Wang and Prof. Dr. Zhang-Jie Shi

      Article first published online: 16 AUG 2011 | DOI: 10.1002/chem.201101562

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      A radical addition: A KOtBu-complex-promoted radical arylation of polysubstituted alkenes with aryl iodides/bromides proceeds in high efficiency (see scheme). Benzofuran derivatives are also produced starting from readily available allyl 2-iodophenyl ethers.

    8. Host–Guest Chemistry

      Encapsulation of Acenaphthene within C-Propan-3-ol-pyrogallol[4]arene Dimeric Nanocapsules (pages 10848–10851)

      Dr. Katrina K. Kline, Drew A. Fowler, Prof. Dr. Sheryl A. Tucker and Prof. Dr. Jerry L. Atwood

      Article first published online: 16 AUG 2011 | DOI: 10.1002/chem.201101297

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      Solvent-mediated guest encapsulation: The single-crystal X-ray diffraction structure and fluorescence emission data of a dimeric C-propan-3-ol-pyrogallol[4]arene nanocapsule acting as host to a fluorescent reporter molecule, acenapthene (see figure), are reported.

    9. Reductive Cyclization

      Rh-Catalyzed Reductive Cyclization of Enynes Using Ethanol as a Source of Hydrogen (pages 10852–10856)

      Dr. Ji Hoon Park, Dr. Soo Min Kim and Prof. Dr. Young Keun Chung

      Article first published online: 25 AUG 2011 | DOI: 10.1002/chem.201101745

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      H-eartfelt donation: A Rh-catalyzed reductive cyclization of unactivated 1,6-enynes was developed that uses an alcohol as hydrogen donor under mild reaction conditions (see scheme). The reaction is an environmentally friendly synthetic method and proceeds efficiently to give various exo-methylene-substituted pyrrolidines, tetrahydrofuran, and cyclopentane compounds in a highly selective manner in moderate to high yields.

    10. Biomimetics

      Harnessing Nature’s Insights: Synthetic Small Molecules with Peroxidase-Mimicking DNAzyme Properties (pages 10857–10862)

      Loic Stefan, Dr. Hai-Jun Xu, Prof. Claude P. Gros, Prof. Franck Denat and Dr. David Monchaud

      Article first published online: 29 AUG 2011 | DOI: 10.1002/chem.201101337

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      Substitute features: The demonstration that small DNAs can acquire enzymatic properties (DNAzyme activity) is appealing since it makes protein-based biotechnologies simpler. Herein, two further simplifications of this process are proposed: the substitution of DNAs for small molecules, called DOTA-templated synthetic G-quartets (DOTASQ), and of hemin for the more practically convenient iron(III) porphyrin (FeTPPS; see scheme).

  7. Full Papers

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
    1. Redox Chemistry

      How Does CuII Convert into CuI? An Unexpected Ring-Mediated Single-Electron Reduction (pages 10864–10870)

      Dr. Davide Barreca, Prof. Ettore Fois, Dr. Alberto Gasparotto, Dr. Roberta Seraglia, Prof. Eugenio Tondello and Dr. Gloria Tabacchi

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201101551

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      New light on Cu chemistry: A CuII-promoted hydrogen-abstraction/proton-delivery/electron-gain mechanism (see figure) leads to Cu reduction and formation of a CuI-CNCCN six-membered ring, showing a novel bonding scheme. Such a single-molecule copper “reduction without reductants” is studied through the fragmentation of a CuII precursor by combined ESI-MS with multiple collisional experiments and theoretical calculations.

    2. Donor–Acceptor Systems

      Conjugated Asymmetric Donor-Substituted 1,3,5-Triazines: New Host Materials for Blue Phosphorescent Organic Light-Emitting Diodes (pages 10871–10878)

      Zhong-Fu An, Dr. Run-Feng Chen, Jun Yin, Guo-Hua Xie, Hui-Fang Shi, Prof. Taiju Tsuboi and Prof. Wei Huang

      Article first published online: 2 SEP 2011 | DOI: 10.1002/chem.201101118

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      Bright candidates! Conjugated asymmetric donor-substituted 1,3,5-triazines (ADTs) have been synthesized by nucleophilic substitution of organolithium catalyzed by [Pd(PPh3)4] (see figure). Theoretical and experimental investigations show that ADTs possess high solubility and thermostability, high fluorescent quantum yield (35 %), low HOMO (−6.0 eV) and LUMO (−2.8 eV), and a high triplet energy (ET, 3.0 eV), making them good candidates for optoelectronic devices.

    3. Heterocyclic Compounds

      Conjugated 4-Methoxybipyrrole Thiophene Azomethines: Synthesis, Opto-Electronic Properties, and Crystallographic Characterization (pages 10879–10888)

      Tshitundu Tshibaka, Sophie Bishop, Ivan Ulliel Roche, Stéphane Dufresne, William D. Lubell and William G. Skene

      Article first published online: 31 AUG 2011 | DOI: 10.1002/chem.201101397

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      Azomethines for color: Asymmetric bipyrroles bisaldehydes have been condensed with diaminothiophenes. The resulting conjugated azomethines exhibited extended conjugation and enhanced opto-electronic properties. Stark reversible color transitions between their neutral and oxidized states could be induced both electrochemically and chemically (see figure).

    4. Supramolecular Chemistry

      Anion-Templated Supramolecular C3 Assembly for Efficient Inclusion of Charge-Dispersed Anions into Hydrogen-Bonded Networks (pages 10889–10897)

      Dr. Krunoslav Užarević, Ivica Đilović, Nikola Bregović, Prof. Vladislav Tomišić, Prof. Dubravka Matković-Čalogović and Prof. Marina Cindrić

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201101127

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      Who's in charge? Podand L, a selective NO3/SO42− receptor, recognizes differences in charge density of the investigated oxo- and fluoroanions. Charge-dispersed anions govern folding of HL+ to a hollow supramolecular macrocycle, with the anions anchored in the hydrophobic pockets of the hydrogen-bonded structure (see figure). This behavior is discussed in terms of the size and geometry of anions as well as the receptor's coordination capabilities to provide the most favorable surroundings for guest inclusion.

    5. Nanostructures

      Graphene Sheet/Porous NiO Hybrid Film for Supercapacitor Applications (pages 10898–10905)

      Dr. Xinhui Xia, Prof. Jiangping Tu, Yongjin Mai, Rong Chen, Prof. Xiuli Wang, Changdong Gu and Xinbing Zhao

      Article first published online: 11 AUG 2011 | DOI: 10.1002/chem.201100727

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      Fusion of chemicals: A graphene sheet/porous NiO hybrid film supported on nickel foam (see figure; left: film, right: nickel foam support) has been prepared by combining electrophoretic deposition and chemical-bath deposition. The obtained graphene sheet/porous NiO hybrid film exhibits superior pseudocapacitive performances with high capacitances (i.e., 400 and 324 F g−1 at 2 and 40 A g−1, respectively) and enhanced cycle life.

    6. Natural Products

      Unified Syntheses of Cavicularin and Riccardin C: Addressing the Synthesis of an Arene Adopting a Boat Configuration (pages 10906–10915)

      Dr. Sarah L. Kostiuk, Dr. Timothy Woodcock, Dr. Leo F. Dudin, Dr. Peter D. Howes and Prof. David C. Harrowven

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201101550

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      Rocking the boat: A concise total syntheses of cavicularin (ten steps) and riccardin C (seven steps) are reported. Key features are a convergent strategy used to assemble acyclic precursors and regioselective reduction and halogenation steps to facilitate a Wittig macrocyclisation and transannular ring contraction reactions in the endgame. Notably, several intermediates en route to cavicularin and riccardin C display boat-configured arenes in the solid state (see figure).

    7. Multifunctional Microspheres

      Multifunctional Manganese Carbonate Microspheres with Superparamagnetic and Fluorescent Properties: Synthesis and Biological Application (pages 10916–10923)

      Juan Peng, Li-Na Feng, Prof. Kui Zhang, Jing-Jing Li, Dr. Li-Ping Jiang and Prof. Jun-Jie Zhu

      Article first published online: 11 AUG 2011 | DOI: 10.1002/chem.201100899

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      Versatile labels: Multifunctional MnCO3 microspheres exhibiting excellent superparamagnetic and fluorescence properties, as well as outstanding solubility in water, were prepared. Antibodies immobilized on the microspheres can be used as versatile labels for fluorescence imaging and electrochemical immunosensors for ultrasensitive detection of α-fetoprotein (see figure).

    8. pH Indicators

      Rational Design, Synthesis, and Spectroscopic and Photophysical Properties of a Visible-Light-Excitable, Ratiometric, Fluorescent Near-Neutral pH Indicator Based on BODIPY (pages 10924–10934)

      Prof. Noël Boens, Prof. Wenwu Qin , Dr. Mukulesh Baruah, Prof. Wim M. De Borggraeve, Prof. Aleksander Filarowski , Nick Smisdom, Prof. Marcel Ameloot, Dr. Luis Crovetto, Prof. Eva M. Talavera and Prof. Jose M. Alvarez-Pez

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201002280

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      Deeply BODIPY: A visible-light-excitable, ratiometric, brightly fluorescent indicator for near-neutral pH measurements has been designed, synthesized by conjugatively linking a BODIPY fluorophore at the 3-position to the pH-sensitive ligand imidazole through an ethenyl bridge, and spectroscopically characterized. It emits intense green–yellow fluorescence at lower pH and intense orange fluorescence at higher pH (see figure).

    9. Decarboxylation Reactions

      Water- and Acid-Mediated Excited-State Intramolecular Proton Transfer and Decarboxylation Reactions of Ketoprofen in Water-Rich and Acidic Aqueous Solutions (pages 10935–10950)

      Dr. Ming-De Li, Dr. Chi Shun Yeung, Dr. Xiangguo Guan, Dr. Jiani Ma, Dr. Wen Li, Dr. Chensheng Ma and Prof. David Lee Phillips

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201003297

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      Rule of three: The decarboxylation reaction of ketoprofen in water-rich and acidic solutions induced by means of water- and/or acid-mediated triplet excited-state intramolecular proton transfer (ESIPT; see figure) was investigated by using nanosecond transient-absorption and nanosecond time-resolved resonance Raman spectroscopic measurements.

    10. Photoresponsive Materials

      Regulation of Folding and Photochromic Reactivity of Terarylenes through a Host–Guest Interaction (pages 10951–10957)

      Dr. Takuya Nakashima, Ryosuke Fujii and Prof. Tsuyoshi Kawai

      Article first published online: 16 AUG 2011 | DOI: 10.1002/chem.201101495

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      Guest-induced: Molecular folding is observed for photochromic terarylenes induced by the presence of a guest species. The molecules are brought into a conformation favorable for photocyclization by the binding of a guest molecule in collaboration with intramolecular interactions such as CH⋅⋅⋅N hydrogen bonding and S⋅⋅⋅N interactions (see scheme).

    11. High-Separation Performance of Chromatographic Capillaries Coated with MOF-5 by the Controlled SBU Approach (pages 10958–10964)

      Alexander S. Münch, Dr. Jürgen Seidel, Anja Obst, Prof. Dr. Edwin Weber and Prof. Dr. Florian O. R. L. Mertens

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201100642

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      Based on special surface preparation techniques using self-assembled monolayers and the controlled SBU approach (CSA) for the deposition of metal–organic frameworks, MOF-CSA-based coatings in capillary columns for gas chromatography have been produced (see graphic, orange trace: MOF-based, blue trace: commercially available PLOT column).

    12. Nanotubes

      High-Speed Carbon Nanotube Actuators Based on an Oxidation/Reduction Reaction (pages 10965–10971)

      Ken Mukai, Dr. Kinji Asaka, Dr. Kenji Hata, Prof. Toribio Fernández Otero and Prof. Hideaki Oike

      Article first published online: 8 AUG 2011 | DOI: 10.1002/chem.201003641

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      High-speed actuators! Actuators with a high-speed response under a high-frequency (more than 100 Hz) applied square-wave voltage of ±2 V have been developed with an electrode composed of millimeter-long single-walled carbon nanotubes and ionic liquids. Detailed studies reveal that the high-speed response (see figure) originates from the electric current generated by an oxidation/reduction (redox) reaction in addition to electric double-layer charging.

    13. Reaction Mechanisms

      Nature of the Intermediates in Gold(I)-Catalyzed Cyclizations of 1,5-Enynes (pages 10972–10978)

      Verónica López-Carrillo, Núria Huguet, Ángeles Mosquera and Prof. Antonio M. Echavarren

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201101749

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      Completing the circle: The gold-catalyzed cycloisomerization of 1,5-enynes affords different products of endo-dig cyclization, including the first examples in which the intermediate cyclopropyl gold(I) carbenes are trapped to form biscyclopropane derivatives in a concerted process (see scheme).

    14. Main Group Element Cations

      Stannylium Ions, a Tin(II) Arene Complex, and a Tin Dication Stabilized by Weakly Coordinating Anions (pages 10979–10984)

      Dr. Annemarie Schäfer, Dipl.-Chem. Florian Winter, Dipl.-Chem. Wolfgang Saak, Detlev Haase, Prof. Dr. Rainer Pöttgen and Prof. Dr. Thomas Müller

      Article first published online: 23 AUG 2011 | DOI: 10.1002/chem.201101938

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      On a knife edge: Whether the product of the reaction of stannylenes with silyl arenium ions is a stannylium ion (1), a homoleptic tin(II) arene complex (2), or an ion pair of a tin dication and the counterion (3) crucially depends on small variations of the substituents at the tin atom and on the nature of the weakly coordinating anion. In particular, arene complex 2 holds a high synthetic potential as a strong electrophilic source for SnII.

    15. Temperature Effects

      Hydrolysis of Plutonium(VI) at Variable Temperatures (283–343 K) (pages 10985–10993)

      Dr. Linfeng Rao, Dr. Guoxin Tian, Dr. Plinio Di Bernardo and Dr. PierLuigi Zanonato

      Article first published online: 23 AUG 2011 | DOI: 10.1002/chem.201100120

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      It's all aboutT: The hydrolysis of PuVI (see scheme), as well as NpV and UVI, is enhanced by a few orders of magnitude as the temperature increases from 283 K to 343 K. Such enhancement, resulting mainly from the increase in the degree of ionization of water at higher temperatures, could have a significant impact on the migration behavior of PuVI in the geological repository of nuclear waste.

    16. Multivalent Nanoparticles

      Highly Efficient Control of Thrombin Activity by Multivalent Nanoparticles (pages 10994–11000)

      Chia-Lun Hsu, Prof. Huan-Tsung Chang, Prof. Chao-Tsen Chen, Shih-Chun Wei, Yen-Chun Shiang and Prof. Chih-Ching Huang

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201101081

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      Antagonistic relationship: Incorporation of sulfated galactose acid into thrombin-binding-aptamer (TBA)-conjugated gold nanoparticles (TBA–AuNPs) shows a highly effective inhibition of thrombin activity towards fibrinogen (see figure). The anticoagulant activity was antagonized by TBA-complementary-sequence (cTBA)-modified AuNPs through TBA/cTBA multivalent hybridization on the NP surface.

    17. Molecular Devices

      Acid/Base Controllable Molecular Recognition (pages 11001–11007)

      Dr. Kent A. Nielsen, Steffen Bähring and Prof. Jan O. Jeppesen

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201101266

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      Hosting or eating? In this self-complexing tetraTTF-calix[4]pyrrole (ouroboros)—containing a calix[4]pyrrole “head” and a phenol “tail”—acid/base-controlled locking (eating) and unlocking (hosting) is utilized to control the molecular recognition of 1,3,5-trinitrobenzene (see scheme).

    18. Biaryl Diphosphines

      Catalytic Palladium Phosphination: Modular Synthesis of C1-Symmetric Biaryl-Based Diphosphines (pages 11008–11016)

      Dr. Laurence Bonnafoux, Rafael Gramage-Doria, Prof. Françoise Colobert and Dr. Frédéric R. Leroux

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201101529

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      No external ligand needed! A new class of nonsymmetrical diphosphines built on biaryl scaffolds is presented. For the first time, the undesired phosphafluorene side-product is avoided thanks to double palladium-catalyzed C–P cross-coupling of dihalide substrates obtained by “aryne” coupling (see figure). The reaction is extremely fast and proceeds without the addition of any external ligand.

    19. Metal-Templated Assembly

      Dynamic Multicomponent Hemiaminal Assembly (pages 11017–11023)

      Dr. Lei You, S. Reid Long, Dr. Vincent M. Lynch and Prof. Dr. Eric V. Anslyn

      Article first published online: 23 AUG 2011 | DOI: 10.1002/chem.201101085

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      Change the diversity! A simple metal-mediated multicomponent assembly based on reversible covalent bond formation is described (see scheme). The diversity of the system can be easily varied with the potential for dynamic combinatorial library creation and subsequent molecular recognition.

    20. Asymmetric Catalysis

      L-Proline/CoCl2-Catalyzed Highly Diastereo- and Enantioselective Direct Aldol Reactions (pages 11024–11029)

      Dr. Ananta Karmakar, Dr. Tapan Maji, Dipl.-Chem. Sebastian Wittmann and Prof. Dr. Oliver Reiser

      Article first published online: 17 AUG 2011 | DOI: 10.1002/chem.201101299

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      Better with metal: The catalytic system CoCl2/L-proline (1:2) is an excellent catalyst for direct aldol reactions of cyclic and acyclic ketones with aromatic and aliphatic aldehydes (see scheme). High diastereoselectivity (anti/syn, 45:1), enantioselectivity (more than 99 % ee), and excellent yields (93 %) were observed. In situ chelation of CoCl2 and proline is proposed to promote the reaction through formation of a 6-membered transition state.

    21. Metal–Ligand Interactions

      Bis(acetylacetonato)ruthenium Complexes of Noninnocent 1,2-Dioxolene Ligands: Qualitatively Different Bonding in Relation to Monoimino and Diimino Analogues (pages 11030–11040)

      Dipanwita Das, Dr. Biprajit Sarkar, Dr. Doyel Kumbhakar, Dr. Tapan Kumar Mondal, Dr. Shaikh M. Mobin, Dr. Jan Fiedler, Dr. Francisco A. Urbanos, Prof. Dr. Reyes Jiménez-Aparicio, Prof. Dr. Wolfgang Kaim and Prof. Dr. Goutam Kumar Lahiri

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201101009

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      Noninnocence and experience: Weak intramolecular metal–ligand interaction and close intermolecular semiquinone–semiquinone contacts result in a complex paramagnetism of [RuIII(acetylacetonate)2(Q.−)] (see figure), which can further undergo reduction and oxidation. This behavior contrasts with the diamagnetism established for monoimino and diimino analogues.

    22. Multifunctional Catalysts

      Preparation of Mononuclear, Homodinuclear, and Heterotrinuclear Complexes by Salicylaldiminato-Functionalized Imidazolium Salt: Approach to Multifunctional Catalysts (pages 11041–11051)

      Rui Zhong, Ya-Nong Wang, Xu-Qing Guo, Dr. Zhen-Xia Chen and Dr. Xiu-Feng Hou

      Article first published online: 23 AUG 2011 | DOI: 10.1002/chem.201101557

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      Nuclear family: Salicylaldiminato-functionalized imidazolium salts were used to develop a series of mononuclear, homodinuclear, and heterotrinuclear complexes. The heterotrinuclear complex (Ni/Ir) was applied as a multifunctional catalyst (see scheme) in the dehalogenation/transfer hydrogenation of haloacetophenones, in which a catalytic cooperativity between different metals was also observed.

    23. Nanoparticles

      Tuning Molecular Recognition in Water-Soluble Nanogels with Enzyme-Like Activity for the Kemp Elimination (pages 11052–11059)

      Ania Servant, Prof. Karsten Haupt and Dr. Marina Resmini

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201002747

      Thumbnail image of graphical abstract

      A stable relationship! The TEM images demonstrate the stabilization of imprinted nanoparticles with the use of non-ionic surfactant Tween 20 (see figure). This stabilization leads to increased catalytic activity and higher imprinting efficiency.

    24. Asymmetric Synthesis

      Isothiourea-Catalysed Asymmetric C-Acylation of Silyl Ketene Acetals (pages 11060–11067)

      Philip A. Woods, Louis C. Morrill, Dr. Ryan A. Bragg and Dr. Andrew D. Smith

      Article first published online: 18 AUG 2011 | DOI: 10.1002/chem.201100995

      Thumbnail image of graphical abstract

      Iso-Si-o-ureas: Isothioureas promote the asymmetric C-acylation of silyl ketene acetals, giving 3-acyl-3-aryl or 3-acyl-3-alkylfuranones in good yields and moderate to excellent enantioselectivities (up to 98 % ee, see scheme).

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      Preview: Chem. Eur. J. 40/2011 (page 11071)

      Article first published online: 14 SEP 2011 | DOI: 10.1002/chem.201190194

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