Chemistry - A European Journal

Cover image for Vol. 17 Issue 52

December 23, 2011

Volume 17, Issue 52

Pages 14693–15071

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Communications
    7. Full Papers
    8. Correspondence
    9. Preview
    1. Cover Picture: Guest-Responsive Covalent Frameworks by the Cross-Linking of Liquid-Crystalline Salts: Tuning of Lattice Flexibility by the Design of Polymerizable Units (Chem. Eur. J. 52/2011) (page 14693)

      Dr. Yasuhiro Ishida, Hiroaki Sakata, Dr. Ammathnadu S. Achalkumar, Kuniyo Yamada, Dr. Yuki Matsuoka, Nobutaka Iwahashi, Dr. Sayaka Amano and Prof. Kazuhiko Saigo

      Article first published online: 16 DEC 2011 | DOI: 10.1002/chem.201190265

      Thumbnail image of graphical abstract

      Template polymerization of liquid crystalline salts affords a new type of chiral covalent framework, which can dynamically switch their nanoscaled structural order in response to the desorption and adsorption of chiral guest molecules. For more information see the Full Paper by Y. Ishida et al. on page 14752 ff.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Graphical Abstract
    5. News
    6. Communications
    7. Full Papers
    8. Correspondence
    9. Preview
    1. Inside Cover: Selective Two-Step Labeling of Proteins with an Off/On Fluorescent Probe (Chem. Eur. J. 52/2011) (page 14694)

      Kazuhisa Hirabayashi, Dr. Kenjiro Hanaoka, Dr. Manabu Shimonishi, Takuya Terai, Dr. Toru Komatsu, Dr. Tasuku Ueno and Prof. Dr. Tetsuo Nagano

      Article first published online: 16 DEC 2011 | DOI: 10.1002/chem.201190266

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      Fluorescent Probes In their Full Paper on page 14763 ff., T. Nagano et al. describe the selective two-step labeling of proteins with an off/on fluorescent probe. The probe consists of dichlorofluorescein conjugated with nitrilotriacetic acid (NTA)-Ni2+ as the His-tag recognition site and a 2,4-dinitrophenyl ether moiety, which quenches the probe's fluorescence by photoinduced electron-transfer (PeT) from the excited fluorophore to the 2,4-dinitrophenyl ether and also has reactivity with cysteine. Removal of the 2,4 dinitrophenyl ether quencher by a proximity-enhanced reaction with the cysteine residue of the modified tag results in a marked fluorescence increase.

  3. Graphical Abstract

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

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

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

      Structure and Dynamics of Triazole-Linked DNA: Biocompatibility Explained (pages 14714–14717)

      Dr. André Dallmann, Dr. Afaf H. El-Sagheer, Dipl.-Chem. Lars Dehmel, Dr. Clemens Mügge, Prof. Dr. Christian Griesinger, Prof. Dr. Nikolaus P. Ernsting and Prof. Dr. Tom Brown

      Article first published online: 30 NOV 2011 | DOI: 10.1002/chem.201102979

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      Blending in: A triazole-modified DNA duplex is perturbed in structure and dynamics, but this is delocalized over five base pairs. The conformation remains B-DNA and hydrogen bonds between the DNA phosphate oxygen and polymerases can be mimicked by the triazole nitrogen (see figure). The results explain the surprising biocompatibility of triazole-linked DNA.

    2. Macrocyclic Ligands

      TRAP, a Powerful and Versatile Framework for Gallium-68 Radiopharmaceuticals (pages 14718–14722)

      Dr. Johannes Notni, Jakub Šimeček, Prof. Dr. Petr Hermann and Prof. Dr. Hans-Jürgen Wester

      Article first published online: 6 DEC 2011 | DOI: 10.1002/chem.201103503

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      A veritable gallium TRAP: Triazacyclononane-phosphinic acid chelators (TRAP) form highly stable complexes with Ga3+ (see figure) extremely efficiently over a wide pH range. Homo- and heteromultimeric bioconjugates can be synthesized in a straightforward manner, all of which renders TRAP a chelator with ideal properties for 68Ga positron emission tomography (PET) imaging agent elaboration.

    3. C[BOND]H Functionalization

      Pd-Catalyzed Multiple C[BOND]H Functionalization to Construct Biologically Active Compounds from Aryl Aldoxime Ethers with Arenes (pages 14723–14726)

      Dr. Vedhagiri S. Thirunavukkarasu and Prof. Dr. Chien-Hong Cheng

      Article first published online: 6 DEC 2011 | DOI: 10.1002/chem.201102996

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      Functional fluorenones: Aromatic aldoxime ethers react with unactivated arenes catalyzed by palladium complexes to give biologically active fluoren-9-ones (see scheme). Multiple C[BOND]H bond activation and an oxidative cyclization are involved in the reaction.

    4. Homogeneous Catalysis

      The First Well-Defined Silver(I)-Complex-Catalyzed Cycloaddition of Azides onto Terminal Alkynes at Room Temperature (pages 14727–14730)

      Dr. James McNulty, Kunal Keskar and Dr. Ramesh Vemula

      Article first published online: 28 NOV 2011 | DOI: 10.1002/chem.201103244

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      Silver(I)-catalyzed click chemistry: Substituted 1,2,3-triazoles are versatile intermediates with an expanding array of applications. The discovery and application of a general AgI-catalyzed azide–alkyne cycloaddition reaction (AAC) leading to 1,2,3-triazoles is reported. The synthesis of a stable, well-defined AgI complex of type [AgI(L2)(OAc)] is described, along with the unprecedented ability of this complex to promote the general Ag-AAC at room temperature (see scheme).

    5. Heterogeneous Catalysis

      Activation of BaTaO2N Photocatalyst for Enhanced Non-Sacrificial Hydrogen Evolution from Water under Visible Light by Forming a Solid Solution with BaZrO3 (pages 14731–14735)

      Tamaki Matoba, Dr. Kazuhiko Maeda and Prof. Dr. Kazunari Domen

      Article first published online: 28 NOV 2011 | DOI: 10.1002/chem.201102970

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      No sacrifice needed! Activation of perovskite-type BaTaO2N (band gap: 1.8–1.9 eV) to improve photocatalytic activity for non-sacrificial H2 evolution from water under visible light (λ>420 nm) was achieved by forming a solid solution with BaZrO3, improving the performance six- to ninefold (see figure). The improvement is attributable to the increased driving force for the redox reactions and the reduced density of defects, which minimizes the undesirable electron–hole recombination.

    6. Molecular Recognition

      Specific Recognition of β-Cyclodextrin by a Tetraphenylethene Luminogen through a Cooperative Boronic Acid/Diol Interaction (pages 14736–14740)

      Yi Liu, Prof. Anjun Qin, Xiujuan Chen, Xiao Yuan Shen, Li Tong, Rongrong Hu, Prof. Jing Zhi Sun and Prof. Ben Zhong Tang

      Article first published online: 1 DEC 2011 | DOI: 10.1002/chem.201102613

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      An unexpected recognition of β-cyclodextrin (CD) from α- and γ-CDs was achieved. The emission from a diboronic acid-containing tetraphenylethene (TPEDB) was amplified upon addition of β-CD, whereas there was almost no response for α-, and γ-CDs. TPEDB is proposed to be anchored onto the wide rim of β-CD through the alternative and conceptually new cooperative boronic acid/diol dynamic binding interaction, resulting in the restriction of intramolecular rotations of its phenyl rings (see scheme).

    7. Lipids

      Formation of Lipid Bilayer Microarrays on Photo-Oxidized Polystyrene Surfaces (pages 14741–14744)

      Prof. Xiaojun Han, Guodong Qi, Xingtao Xu and Lei Wang

      Article first published online: 28 NOV 2011 | DOI: 10.1002/chem.201102941

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      A simple and flexible method has been developed to form lipid bilayer microarrays on a polystyrene surface. The resulting materials are believed to have extensive applications in the studies of bilayer-based biosensing, interaction between bilayer and cells, and membrane-protein-based drug screening.

  6. Full Papers

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

      A Perylene Diimide Rotaxane: Synthesis, Structure and Electrochemically Driven De-Threading (pages 14746–14751)

      Dr. Benjamin J. Slater, Dr. E. Stephen Davies, Dr. Stephen P. Argent, Dr. Harriott Nowell, Dr. William Lewis, Prof. Dr. Alexander J. Blake and Prof. Dr. Neil R. Champness

      Article first published online: 1 DEC 2011 | DOI: 10.1002/chem.201103090

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      Perylene diimides make excellent building blocks for the formation of [2]-rotaxanes. The rich electrochemistry of the perylene-based recognition site facilitates a pathway to different oxidation states and properties and allows a mechanism for electrochemically driven de-treading of the interlocked species (see figure).

    2. Liquid Crystals

      Guest-Responsive Covalent Frameworks by the Cross-Linking of Liquid-Crystalline Salts: Tuning of Lattice Flexibility by the Design of Polymerizable Units (pages 14752–14762)

      Dr. Yasuhiro Ishida, Hiroaki Sakata, Dr. Ammathnadu S. Achalkumar, Kuniyo Yamada, Dr. Yuki Matsuoka, Nobutaka Iwahashi, Dr. Sayaka Amano and Prof. Kazuhiko Saigo

      Article first published online: 6 DEC 2011 | DOI: 10.1002/chem.201102422

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      Solid-state hosts with covalent frameworks were obtained by the in situ cross-linking of liquid-crystalline salts composed of a polymerizable carboxylic acid and an enantiopure amino alcohol (see scheme). In response to the desorption and adsorption of the amino alcohol unit, the cross-linked polymers reversibly changed their structures. The dynamic properties of the cross-linked polymers could be tuned by the choice of cross-linking units.

    3. Fluorescent Probes

      Selective Two-Step Labeling of Proteins with an Off/On Fluorescent Probe (pages 14763–14771)

      Kazuhisa Hirabayashi, Dr. Kenjiro Hanaoka, Dr. Manabu Shimonishi, Takuya Terai, Dr. Toru Komatsu, Dr. Tasuku Ueno and Prof. Dr. Tetsuo Nagano

      Article first published online: 22 NOV 2011 | DOI: 10.1002/chem.201102664

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      Beaming up: A fluorescent probe with a nitrilotriacetic acid (NTA)-Ni2+ hexahistidine (His)-binding moiety and a 2,4-dinitrophenyl ether quencher moiety was found to have off/on fluorescence change owing to proximity-enhanced quencher cleavage on binding to a cysteine-modified His-tag (see scheme).

    4. Peptidomimetics

      Design, Synthesis, and Biological Evaluation of Novel Fluorinated Ethanolamines (pages 14772–14784)

      Prof. Dr. Santos Fustero, Dr. Ana C. Cuñat, Dr. Sonia Flores, Claribel Báez, Judit Oliver, Prof. Dr. Michael Cynamon, Prof. Dr. Michael Gütschow, Matthias D. Mertens, Dr. Oscar Delgado, Dr. Gary Tresadern and Dr. Andrés A. Trabanco

      Article first published online: 24 NOV 2011 | DOI: 10.1002/chem.201102078

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      BACE-ically good: Stereoselective synthesis of biologically active, fluorinated, ethanolamine-type peptidomimetics is described. Our synthesis strategy involves chiral sulfinyl imines as intermediates, by treatment of hemiaminal precursors with vinylmagnesium bromide (see scheme). The biological evaluation of the derivatives revealed compounds with remarkable BACE1 inhibitory activity as well as antimicrobial activity.

    5. Amination

      Installation of Amine Moieties into a Polycyclic Anodic Product Derived from 2,4-Dimethylphenol (pages 14785–14791)

      Joaquin Barjau, Dr. Jan Fleischhauer, Dr. Gregor Schnakenburg and Prof. Dr. Siegfried R. Waldvogel

      Article first published online: 24 NOV 2011 | DOI: 10.1002/chem.201102722

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      Pure resolution: Starting from 2,4-dimethylphenol, its polycyclic dehydrotetramer is readily obtainable by anodic treatment. Modification with optically pure amines allows the separation of the generated diastereoisomers, which equilibrate between the hemiketal and keto form (see scheme).

    6. Antitumor Agents

      C6–C8 Bridged Epothilones: Consequences of Installing a Conformational Lock at the Edge of the Macrocycle (pages 14792–14804)

      Dr. Weiqiang Zhan, Dr. Yi Jiang, Shubhada Sharma, Peggy J. Brodie, Prof. Susan Bane, Prof. David G. I. Kingston, Prof. Dennis C. Liotta and Dr. James P. Snyder

      Article first published online: 30 NOV 2011 | DOI: 10.1002/chem.201102630

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      Not quite rigid enough: A series of conformationally restrained epothilone analogues with a short bridge between the methyl groups at C6 and C8 was designed to mimic the binding pose assigned to the recently reported epothilone A–microtubule binding model.

    7. Bismuth Oxido Clusters

      From {Bi22O26} to Chiral Ligand-Protected {Bi38O45}-Based Bismuth Oxido Clusters (pages 14805–14810)

      Dirk Mansfeld, Linda Miersch, Tobias Rüffer, Dieter Schaarschmidt, Prof. Dr. Heinrich Lang, Tony Böhle, Ralf W. Troff, Prof. Dr. Christoph A. Schalley, Prof. Dr. Jens Müller and Prof. Dr. Michael Mehring

      Article first published online: 25 NOV 2011 | DOI: 10.1002/chem.201102437

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      Nanoscaled ligand-protected bismuth oxido clusters were synthesized by simple hydrolysis routes and ligand–exchange reactions. ESI mass spectrometry and infrared multi-photon dissociation tandem MS experiments provide information on cluster stability and nucleation processes. The use of butoxycarbonyl(BOC)-protected amino acids gave highly soluble chiral ligand-protected {Bi38O45} clusters showing optical activity as demonstrated by CD spectroscopy (see figure).

    8. Solid/Electrolyte Interface

      Equilibrium Lithium-Ion Transport Between Nanocrystalline Lithium-Inserted Anatase TiO2 and the Electrolyte (pages 14811–14816)

      Dr. Swapna Ganapathy, Dr. Ernst R. H. van Eck, Prof. Dr. Arno P. M. Kentgens, Prof. Dr. Fokko M. Mulder and Dr. Marnix Wagemaker

      Article first published online: 25 NOV 2011 | DOI: 10.1002/chem.201101431

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      Lithium-ion transport: The exchange of lithium ions across the solid/electrolyte interface (SEI) between an electrolyte and a lithium-inserted TiO2 anatase electrode has been studied by using 7Li NMR spectroscopy (see figure). The barrier to lithium-ion transport across the SEI depends on the composition of the electrolyte; this indicates that the SEI can form a rate-limiting barrier.

    9. Enzyme Catalysis

      Probing the Intestinal α-Glucosidase Enzyme Specificities of Starch-Digesting Maltase-Glucoamylase and Sucrase-Isomaltase: Synthesis and Inhibitory Properties of 3′- and 5′-Maltose-Extended De-O-sulfonated Ponkoranol (pages 14817–14825)

      Razieh Eskandari, Kyra Jones, Dr. Kongara Ravinder Reddy, Dr. Kumarasamy Jayakanthan, Marcia Chaudet, Prof. David R. Rose and Prof. B. Mario Pinto

      Article first published online: 30 NOV 2011 | DOI: 10.1002/chem.201102109

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      Pro-choice: The synthesis of two C-3′- and C-5′-β-maltose-extended analogues of the naturally occurring sulfonium ion-inhibitor, de-O-sulfonated ponkoranol, is reported (see scheme). Evaluation of inhibitory activities against different subunits of recombinant intestinal enzymes maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI) showed some selectivity.

    10. Spin-Crossover Compounds

      Tuning the Transition Temperature and Cooperativity of bapbpy-Based Mononuclear Spin-Crossover Compounds: Interplay between Molecular and Crystal Engineering (pages 14826–14836)

      Zulema Arcis-Castíllo, Sipeng Zheng, Dr. Maxime A. Siegler, Dr. Olivier Roubeau, Salma Bedoui and Dr. Sylvestre Bonnet

      Article first published online: 1 DEC 2011 | DOI: 10.1002/chem.201101301

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      A model of cooperativity: The spin-crossover properties of different isomers of substituted spin-crossover compounds [Fe{R2(bapbpy)}(NCS)2] are presented. Both the cooperativity and transition temperature critically depend on the position of the substituents R on the terminal pyridine rings of the ligand (see figure); a simple model based on hydrogen-bonding networks is provided.

    11. Solar Cells

      Dye-Sensitized Solar Cells Based on Donor-π-Acceptor Fluorescent Dyes with a Pyridine Ring as an Electron-Withdrawing-Injecting Anchoring Group (pages 14837–14843)

      Dr. Yousuke Ooyama, Tomoya Nagano, Shogo Inoue, Dr. Ichiro Imae, Dr. Kenji Komaguchi, Prof. Dr. Joji Ohshita and Prof. Dr. Yutaka Harima

      Article first published online: 22 NOV 2011 | DOI: 10.1002/chem.201101923

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      Shine a light: The short-circuit photocurrent densities and solar energy-to-electricity conversion yields of dye-sensitized solar cells based on donor–acceptor π-conjugated (D-π-A) fluorescent dyes with a pyridine ring (see figure) are greater than those for D-π-A dye sensitizers with a carboxyl group as electron-withdrawing anchoring group. Strong coordinate bonds are formed between the pyridine ring and the Lewis acid sites of the TiO2 surface.

    12. Iodide sensors

      A Fluorescence Turn-on Sensor for Iodide Based on a Thymine–HgII–Thymine Complex (pages 14844–14850)

      Boling Ma, Prof. Fang Zeng, Fangyuan Zheng and Prof. Shuizhu Wu

      Article first published online: 24 NOV 2011 | DOI: 10.1002/chem.201102024

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      Lighting up for iodide: A fluorescence turn-on sensor for iodide has been developed based on a luminescence quenching and recovery strategy. An anthracene–thymine dyad was synthesized that formed a complex with a mercury(II) ion, which led to fluorescence quenching of the anthracene; the iodide anion extracts the mercury(II) ion from the complex and restores the fluorescence of the anthracene (see scheme).

    13. DNA Nucleosides

      2′-Aminoethoxy-2-amino-3-methylpyridine in Triplex-Forming Oligonucleotides: High Affinity, Selectivity and Resistance to Enzymatic Degradation (pages 14851–14856)

      Chenguang Lou, Montserrat Shelbourne, Prof. Keith R. Fox and Prof. Tom Brown

      Article first published online: 30 NOV 2011 | DOI: 10.1002/chem.201102287

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      Triplex glue that targets DNA: 2′-Aminoethoxy-2-amino-3-methylpyridine (AE-MAP, see scheme) has been made for the first time and incorporated into triplex-forming oligonucleotides (TFOs). It is a potent triplex stabilizer at high pH and is selective for GC base pairs. TFOs containing AE-MAP do not interact strongly with single stranded DNA. They are highly resistant to nucleases and have potential in gene knock-out studies.

    14. Peptidomimetics

      Sheet-Like Assemblies of Charged Amphiphilic α/β-Peptides at the Air–Water Interface (pages 14857–14866)

      Shlomit Segman-Magidovich, Myung-ryul Lee, Vladimir Vaiser, Bernd Struth, Prof. Dr. Samuel H. Gellman and Dr. Hanna Rapaport

      Article first published online: 22 NOV 2011 | DOI: 10.1002/chem.201101775

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      Welcome to the fold: Four α/β-peptides, each containing 11 subunits with a 1:1 alternation of α- and β-residues, which generated a pleated structure, were designed (see stick-and-ball diagram). Self-assemblies of these unique amphiphilic oligomers showed that the identity of ionizable side chains and their positions within the α/β-peptide sequence exert strong effects on the propensity for and mode of self-association.

    15. NMR Spectroscopy

      Elucidation of the Chemical and Morphological Structure of Double-Network (DN) Hydrogels by High-Resolution Magic Angle Spinning (HRMAS) NMR Spectroscopy (pages 14867–14877)

      Prof. Dr. Pavletta Shestakova, Prof. Dr. Rudolph Willem and Prof. Dr. Elena Vassileva

      Article first published online: 27 OCT 2011 | DOI: 10.1002/chem.201101334

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      Double-network hydrogels: HRMAS NMR spectroscopy was used to address the structure and morphology of DNs, prepared from poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and poly(acrylamide). The results evidence that the toughening mechanism and the exceptionally strong mechanical properties of DNs originate from cooperative effects based on the formation of both covalent bonds and strong hydrogen bonds between the two polymer networks (see figure).

    16. Lithium Storage

      Electrochemically Fabricated Polypyrrole–Cobalt–Oxygen Coordination Complex as High-Performance Lithium-Storage Materials (pages 14878–14884)

      Dr. Bingkun Guo, Dr. Qingyu Kong, Dr. Ying Zhu, Ya Mao, Prof. Zhaoxiang Wang, Prof. Meixiang Wan and Liquan Chen

      Article first published online: 30 NOV 2011 | DOI: 10.1002/chem.201002379

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      Recharging the batteries: A polypyrrole–cobalt–oxygen complex was fabricated by electrochemically cycling PPy-coated Co3O4 between 0.0 and 3.0 V versus Li+/Li and proved to be a high-performance lithium-storage material. Raman and extended X-ray absorption fine structural spectroscopy and DFT calculations demonstrate that each cobalt atom is coordinated with two nitrogen atoms to form a PPy-Co layer, which are connected with oxygen atoms between them (see figure).

    17. Homogeneous Catalysis

      Stable N-Heterocyclic Carbene (NHC)–Palladium(0) Complexes as Active Catalysts for Olefin Cyclopropanation Reactions with Ethyl Diazoacetate (pages 14885–14895)

      Carmen Martín, Francisco Molina, Dr. Eleuterio Alvarez and Prof. Tomás R. Belderrain

      Article first published online: 2 DEC 2011 | DOI: 10.1002/chem.201102900

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      The Pd0/PdIIdilemma: Several [(NHC)Pd0] complexes are shown to act as very active catalysts in the olefin cyclopropanation reaction with ethyl diazoacetate as the carbene source. A mechanism (see scheme) for this transformation is proposed, in which the same catalytic species is responsible of the decomposition of EDA and subsequent cyclopropanation independent of the catalyst precursor.

    18. Continuous Symmetry Measures

      Electronic Structure and Symmetry in Conjugated π-Electron Systems (pages 14896–14906)

      Prof. Pere Alemany, Dr. David Casanova and Dr. Chaim Dryzun

      Article first published online: 8 DEC 2011 | DOI: 10.1002/chem.201101329

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      Continuous symmetry measures for the Hamiltonian, the molecular orbitals, or the electron density obtained from a simple Hückel model for molecules with conjugated π-electron systems reveals the basic relations between their symmetry and electronic structures. Ab initio calculations confirm these relations, and allow a much more accurate description of the influence of symmetry-breaking perturbations on the electronic structure (see figure).

    19. Polycyclic Aromatic Hydrocarbons

      Intramolecular Domino Electrophilic and Thermal Cyclization of peri-Ethynylene Naphthalene Oligomers (pages 14907–14915)

      Dr. Xiaobo Huang, Dr. Lintao Zeng, Zebing Zeng and Prof. Jishan Wu

      Article first published online: 1 DEC 2011 | DOI: 10.1002/chem.201102506

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      Aromatic polycycles: The synthesis and intramolecular cyclization of a series of peri-ethynylene naphthalene oligomers were investigated. Sequential thermal or electrophilic cyclizations (see scheme) gave five-membered-ring-containing polycyclic aromatic hydrocarbons.

    20. Asymmetric Catalysis

      Asymmetric Iodoamination of Chalcones and 4-Aryl-4-oxobutenoates Catalyzed by a Complex Based on Scandium(III) and a N,N′-Dioxide Ligand (pages 14916–14921)

      Yunfei Cai, Prof. Dr. Xiaohua Liu, Jun Li, Weiliang Chen, Wentao Wang, Dr. Lili Lin and Prof. Dr. Xiaoming Feng

      Article first published online: 8 DEC 2011 | DOI: 10.1002/chem.201102453

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      Highly diastereo- and enantioselective iodoamination of chalcones and 4-aryl-4-oxobutenoates, as well as of a trifluoro-substituted enone, in the presence of a chiral complex based on ScIII and a N,N′-dioxide ligand (0.5–2 mol %) has been developed. This method delivers the desired vicinal anti-α-iodo-β-amino products regioselectively with excellent yields and enantioselectivity (see scheme).

    21. Ligand Design

      The Synthesis of a New Class of Chiral Pincer Ligands and Their Applications in Enantioselective Catalytic Fluorinations and the Nozaki–Hiyama–Kishi Reaction (pages 14922–14928)

      Dr. Qing-Hai Deng, Prof. Dr. Hubert Wadepohl and Prof. Dr. Lutz H. Gade

      Article first published online: 3 NOV 2011 | DOI: 10.1002/chem.201102375

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      A pincer with a twist: A Wittig coupling is the key step in the modular synthesis of chiral pincer ligands 1 (boxmi). Their NiII complexes catalyze the enantioselective fluorination of oxindoles and cyclic β-ketoesters with extremely high enantioselectivity, whereas their use in Cr-catalyzed enantioselective Nozaki–Hiyama–Kishi reactions of aldehydes gave the corresponding alcohols.

    22. Nucleophilic Aromatic Substitution

      Evidences for the Key Role of Hydrogen Bonds in Nucleophilic Aromatic Substitution Reactions (pages 14929–14934)

      Dr. Nicolas Chéron, Dr. Laurent El Kaïm, Dr. Laurence Grimaud and Dr. Paul Fleurat-Lessard

      Article first published online: 23 NOV 2011 | DOI: 10.1002/chem.201102463

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      Make it happen: With hydrogen bonds, the energies of some transition states are lowered and this allows a reaction to proceed. This feature has been studied more precisely with nucleophilic aromatic substitutions and demonstrated in the particular cases of intermolecular additions of amines onto halogenonitrobenzenes and on the Ugi–Smiles reactions (see scheme).

    23. Ligand Effects

      Air-Stable Platinum and Palladium Complexes Featuring Bis[2,4-bis(trifluoromethyl)phenyl]phosphinous Acid Ligands (pages 14935–14941)

      Dr. Boris Kurscheid, Beate Neumann, Dr. Hans-Georg Stammler and Prof. Dr. Berthold Hoge

      Article first published online: 6 DEC 2011 | DOI: 10.1002/chem.201102347

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      Walking in the air: Two phosphinous acid ligands bind to a square-planar platinum complex (see scheme). Removal of one proton affords anionic cis-configured complex 2. A second deprotonation is accompanied by rearrangement to the trans dianion 3.

    24. Hydrogen Bonding

      Giant Deuteron Migration During the Isosymmetric Phase Transition in Deuterated 3,5-Pyridinedicarboxylic Acid (pages 14942–14951)

      Samantha J. Ford, Oliver J. Delamore, Prof. John S. O. Evans, Prof. Garry J. McIntyre, Prof. Mark R. Johnson and Dr. Ivana Radosavljević Evans

      Article first published online: 23 NOV 2011 | DOI: 10.1002/chem.201101104

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      A giant step for deuterium: A remarkable isotope effect is observed for proton and deuteron migration in 3,5-pyridinedicarboxylic acid. The deuteron moves by 0.32(1) Å and the structure changes from a low-temperature N[BOND]D⋅⋅⋅O form to a high-temperature N⋅⋅⋅D[BOND]O form (see figure).

    25. Gels

      Organogel–Hydrogel Transformation by Simple Removal or Inclusion of N-Boc-Protection (pages 14952–14961)

      Tanmoy Kar, Subhra Kanti Mandal and Dr. Prasanta Kumar Das

      Article first published online: 22 NOV 2011 | DOI: 10.1002/chem.201101173

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      Boc switch: Amino acid/dipeptide-based common structural scaffolds have been used to develop both organo- and hydrogelators. Transformation between these gelators of extreme polarity solvents was achieved simply by pH-responsive inclusion or removal of a Boc moiety (see figure).

    26. Superoxides

      Photochemically Initiated Oxidative Carbon–Carbon Bond-Cleavage Reactivity in Chlorodiketonate NiII Complexes (pages 14962–14973)

      Caleb J. Allpress, Dr. Atta M. Arif, Dylan T. Houghton and Dr. Lisa M. Berreau

      Article first published online: 8 DEC 2011 | DOI: 10.1002/chem.201101962

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      Turn on the light: NiII complexes containing a 2-chloro-1,3-diketonate ligand undergo oxidative cleavage to produce carboxylic acids upon irradiation with UV light under aerobic conditions (see scheme). This reactivity, which involves the formation of reduced nickel species that activate dioxygen, has relevance to enzymatic systems that catalyze the oxidative cleavage of β-diketone substrates.

    27. Reaction Mechanisms

      Does a Concerted Non-Insertive Mechanism Prevail over a σ-Insertive Mechanism in Catalytic Cyclohydroamination by Magnesium Tris(oxazolinyl)phenylborate Compounds? A Computational Study (pages 14974–14986)

      Dr. Sven Tobisch

      Article first published online: 25 NOV 2011 | DOI: 10.1002/chem.201101490

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      Rival mechanistic pathways for C[DOUBLE BOND]C bond activation in alkaline-earth metal-catalysed hydroamination: Computational mechanistic analysis provides sound evidence for the operation of an (ToM)Mg[BOND]N amido σ-bond insertive mechanism with turnover-limiting aminolysis for aminoalkene cyclohydroamination (see scheme).

    28. Zeolites

      Well-Organized Zeolite Nanocrystal Aggregates with Interconnected Hierarchically Micro–Meso–Macropore Systems Showing Enhanced Catalytic Performance (pages 14987–14995)

      Dr. Xiao-Yu Yang , Dr. Ge Tian, Dr. Li-Hua Chen, Dr. Yu Li , Dr. Joanna C. Rooke, Dr. Ying-Xu Wei, Prof. Dr. Zhong-Min Liu, Dr. Zhao Deng, Prof. Dr. Gustaaf Van Tendeloo and Prof. Dr. Bao-Lian Su 

      Article first published online: 23 NOV 2011 | DOI: 10.1002/chem.201101594

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      Quasi-solid-state crystallization was used to prepare micro–meso–macroporous zeolitic architectures from amorphous bimodal meso–macroporous aluminosilicates (see figure). The resulting micro–meso–macroporous materials are composed of zeolite MFI nanocrystals, and have interconnected pores on three length scales. The synthetic strategy can be extended to prepare micro–meso–macroporous architectures of other zeolites (e.g., ZSM-5, beta, TS-1).

    29. Phosphate Transfer

      Activating Water: Important Effects of Non-leaving Groups on the Hydrolysis of Phosphate Triesters (pages 14996–15004)

      Prof. Anthony J. Kirby, Michelle Medeiros, Pedro S. M. Oliveira, Dr. Elisa S. Orth, Dr. Tiago A. S. Brandão, Eduardo H. Wanderlind, Almahdi Amer, Dr. Nicholas H. Williams and Prof. Faruk Nome

      Article first published online: 21 NOV 2011 | DOI: 10.1002/chem.201101926

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      How the spectators control the game: The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained not by intramolecular catalysis, but by the electronic activating effects of the non-leaving (“spectator”) groups (S) on P[BOND]O cleavage (see scheme).

    30. Oxygen Heterocycles

      Striking Alkenol Versus Allenol Reactivity: Metal-Catalyzed Chemodifferentiating Oxycyclization of Enallenols (pages 15005–15013)

      Prof. Dr. Benito Alcaide, Dr. Pedro Almendros, Dr. Teresa Martínez del Campo, Dr. María C. Redondo and Dr. Israel Fernández

      Article first published online: 1 DEC 2011 | DOI: 10.1002/chem.201102100

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      An efficient chemodivergent metal-catalyzed methodology for generating different highly functionalized oxygen heterocycles from common enallenes, involving the controlled Au-, Pt-, Pd-, or Fe-catalyzed oxycyclization reactions of enallenol substrates, has been developed (see scheme).

    31. Lanthanides

      Rare-Earth Metal Allyl and Hydrido Complexes Supported by an (NNNN)-Type Macrocyclic Ligand: Synthesis, Structure, and Reactivity toward Biomass-Derived Furanics (pages 15014–15026)

      Dipl.-Chem. Elise Abinet, Dipl.-Chem. Daniel Martin, Dipl.-Chem. Sabine Standfuss, Dipl.-Chem. Heiko Kulinna, Dr. Thomas P. Spaniol and Prof. Dr. Jun Okuda

      Article first published online: 1 DEC 2011 | DOI: 10.1002/chem.201102145

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      Rare catalysts: Hydrosilylation of furfural and deoxygenation of furan under ring-opening conditions was catalyzed by neutral complexes [Ln(Me3TACD)(η3-C3H5)2] (Ln=Y, La, Ce, Pr, Nd, Sm) supported by the 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane Me3TACD ion. Monocationic allyl [Ln(Me3TACD)(η3-C3H5)(thf)2][B(C6X5)4] (Ln=La, Ce, Nd, X=H, F) and hydrido complexes [Ln(Me3TACD)H2]n (Ln=Y, La, Sm, n=3,4) were synthesized from the bis(allyl) precursors and characterized (see picture).

    32. Photocatalysis

      Subtle Ligand Effects in Oxidative Photocatalysis with Iridium Complexes: Application to Photopolymerization (pages 15027–15031)

      Prof. Jacques Lalevée, Dr. Mathieu Peter, Dr. Frédéric Dumur, Dr. Didier Gigmes, Dr. Nicolas Blanchard, Dr. Mohamad-Ali Tehfe, Dr. Fabrice Morlet-Savary and Prof. Jean Pierre Fouassier

      Article first published online: 28 NOV 2011 | DOI: 10.1002/chem.201101445

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      A light touch: Three-component iridium-based photocatalytic systems are effective in polymerization reactions under very soft irradiation conditions, for example, blue LED bulb irradiation. Six IrIII complexes in combination with an iodonium salt and a silane catalyzed the radical polymerization of acrylates and ring-opening polymerization of epoxy monomers, giving polymers with photoluminescence properties (see figure).

    33. Nanostructures

      Hierarchical TiO2 Microspheres: Synergetic Effect of {001} and {101} Facets for Enhanced Photocatalytic Activity (pages 15032–15038)

      Zhaoke Zheng, Prof. Dr. Baibiao Huang, Jibao Lu, Xiaoyan Qin, Xiaoyang Zhang and Prof. Dr. Ying Dai

      Article first published online: 8 DEC 2011 | DOI: 10.1002/chem.201101466

      Thumbnail image of graphical abstract

      Makes good face: A facile strategy was developed to synthesize hierarchical TiO2 microspheres consisting of anatase nanosheets or decahedrons. Owing to the synergetic effect between well-formed {001} and {101} facets, the TiO2 microspheres consisting of nano-decahedrons with 45 % {001} facets show superior photoreactivity (more than 4.8-times) compared to the nanosheets with 82 % {001} facets (see picture).

    34. Isocyanide Insertion

      Synthesis of 4-Aminoquinazolines by Palladium-Catalyzed Intramolecular Imidoylation of N-(2-Bromoaryl)amidines (pages 15039–15044)

      Dr. Gitte Van Baelen, Sander Kuijer, Lukáš Rýček, Dr. Sergey Sergeyev, Elwin Janssen, Dr. Frans J. J. de Kanter, Prof. Dr. Bert U. W. Maes, Dr. Eelco Ruijter and Prof. Dr. Romano V. A. Orru

      Article first published online: 28 NOV 2011 | DOI: 10.1002/chem.201102468

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      What CO can do, R[BOND]NC does, too! In analogy to carbonylative cross-coupling reactions, a Pd-catalyzed intramolecular imidoylative cross-coupling reaction of N-(2-bromophenyl)amidines, smoothly yielding 4-aminoquinazolines, has been developed (see scheme). After optimization of the reaction with respect to the Pd source, ligand, base, solvent, and temperature, a series of diversely substituted 4-aminoquinazolines of significant pharmaceutical interest were prepared.

  7. Correspondence

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    1. Bioinorganic Chemistry

      Comment on “A Nickel(II)-Based Radical-Ligand Complex as a Functional Model of Hydrogenase” (pages 15046–15048)

      Dr. Matthias Stein

      Article first published online: 13 DEC 2011 | DOI: 10.1002/chem.201002985

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      Where is the spin? Nickel bisthiolenes form paramagnetic monoanionic species. The non-innocence of the sulfur ligands makes a definite assignment of the oxidation state of the central metal atom difficult. EPR spectroscopy and DFT calculations reveal that there is an even distribution of unpaired spin between the nickel and each of the ligands (ca. 1/3 each). There is no evidence for a NiII-based radical ligand complex as indicated in the original publication.

    2. Response to Comment on “A Nickel(II)-Based Radical-Ligand Complex as a Functional Model of Hydrogenase” (pages 15049–15050)

      Prof. Sabyasachi Sarkar

      Article first published online: 13 DEC 2011 | DOI: 10.1002/chem.201100996

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      Paramagnetic, monoanionic and square-planar nickel bisdithiolene complexes are best described as having delocalized class-III mixed-valent radical anionic ligands coordinated to a closed shell low-spin d8 central metal, based on combined structural and spectroscopic studies given in several publications. They can be described by the resonance structures [NiII(L2−)(L−.)] [LEFT RIGHT ARROW] [NiII(L−.)(L2−)]. In our formulation we have not differentiated the ligand “L”, which can carry the charges 2− or 1−. and vice versa.

  8. Preview

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    4. Graphical Abstract
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    1. You have free access to this content
      Preview: Chem. Eur. J. 1/12 (page 15071)

      Article first published online: 16 DEC 2011 | DOI: 10.1002/chem.201190269

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