Chemistry - A European Journal

Cover image for Vol. 14 Issue 33

November 17, 2008

Volume 14, Issue 33

Pages 10167–10499

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
    1. Cover Picture: Natural Gum Reduced/Stabilized Gold Nanoparticles for Drug Delivery Formulations (Chem. Eur. J. 33/2008) (page 10167)

      Sheetal Dhar, E. Maheswara Reddy, Anjali Shiras, Varsha Pokharkar and B. L. V. Prasad

      Version of Record online: 10 NOV 2008 | DOI: 10.1002/chem.200890134

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      Gellan gum, widely used… in the confectionary and food industries, has reducing and stabilizing properties that can be used to synthesize gum-capped gold nanoparticles. In their Full Paper on page 10244 ff., A. Shiras, V. Pokharkar, B. L. V. Prasad et al. demonstrate the synthesis of gellan gum capped gold nanoparticles that were loaded with an anticancer drug, doxorubicin hydrochloride. The drug-loaded gold nanoparticles show enhanced cytotoxicity effects on glioma cell lines, and could also be expanded to the delivery of other biologically active molecules.

  2. Graphical Abstract

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

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
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      Fragmentation of Carbohydrate Anomeric Alkoxyl Radicals: New Synthesis of Chiral 1-Fluoro-1-halo-1-iodoalditols (page 10179)

      Cosme G. Francisco, Concepción C. González, Alan R. Kennedy, Nieves R. Paz and Ernesto Suárez

      Version of Record online: 10 NOV 2008 | DOI: 10.1002/chem.200890136

      This article corrects:
  4. News

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

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Concept
    7. Communications
    8. Full Papers
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    1. Organomanganese Compounds

      Recent Synthetic Applications of Manganese in Organic Synthesis (pages 10184–10191)

      José M. Concellón, Humberto Rodríguez-Solla and Vicente del Amo

      Version of Record online: 27 AUG 2008 | DOI: 10.1002/chem.200800796

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      New reagents in organometallic chemistry: The development of the synthetic applications of organomanganese compounds has been relatively scarce to date. This fact is surprising, taking into account that manganese is a nontoxic, cheap metal. Advances in organomanganese chemistry are described (see scheme).

  6. Communications

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

      Bacterial Surface Engineering Utilizing Glucosamine Phosphate Derivatives as Cell Wall Precursor Surrogates (pages 10192–10195)

      Reiko Sadamoto, Takeshi Matsubayashi, Masataka Shimizu, Taichi Ueda, Shuhei Koshida, Toshiaki Koda and Shin-Ichiro Nishimura

      Version of Record online: 15 OCT 2008 | DOI: 10.1002/chem.200801734

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      New neighbors: N-Levulinoyl glucosamine phosphate derivatives were added to a culture media of lactic acid bacteria as bacterial cell wall precursors, which should be integrated into the bacterial cell wall. The incorporation was estimated by flow cytometry after specific fluorescence labeling of the surface-displayed ketone moiety. The derivatives with acetylated hydroxyl groups showed good incorporation due to increased hydrophobicity.

    2. Catalysis in Glycerol

      Rational Design of Sugar-Based-Surfactant Combined Catalysts for Promoting Glycerol as a Solvent (pages 10196–10200)

      Ayman Karam, Nicolas Villandier, Mathieu Delample, Carmen Klein Koerkamp, Jean-Paul Douliez, Robert Granet, Pierre Krausz, Joël Barrault and François Jérôme

      Version of Record online: 15 OCT 2008 | DOI: 10.1002/chem.200801495

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      A sugary treat: Here we report the great efficiency of sugar-based-surfactant combined catalysts for conducting selective base-catalyzed organic reactions in glycerol. Close control of the reaction selectivity was successfully obtained owing to the formation of catalytic hydrophobic pockets in glycerol (see figure). The advantages of our catalytic processes and its similarities with catalysis in water are also highlighted.

    3. C[BOND]H Activation

      Cross-Coupling Reaction between Alcohols through sp3 C[BOND]H Activation Catalyzed by a Ruthenium/Lewis Acid System (pages 10201–10205)

      Shu-Yu Zhang, Yong-Qiang Tu, Chun-An Fan, Yi-Jun Jiang, Lei Shi, Ke Cao and En Zhang

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801317

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      Only wasting water: A new transition-metal-catalyzed/Lewis acid mediated C[BOND]C cross-coupling reaction of various different alcohols (as green starting materials) has been realized (see scheme). A variety of functionalized alcohols could be straightforwardly synthesized in good to excellent yields through the selective activation of the sp3 C[BOND]H bond adjacent to the hydroxyl group of primary alcohols; furthermore, the only waste generated through the overall process is water.

    4. Donor–Acceptor Systems

      (Pentamethylcyclopentadienyl)ruthenium π-Complexes of Metalloporphyrins: Platforms with Novel Photo- and Electrochemical Properties (pages 10206–10210)

      Luciano Cuesta, Elizabeth Karnas, Vincent M. Lynch, Jonathan L. Sessler, Wiroaj Kajonkijya, Weihua Zhu, Min Zhang, Zhongping Ou, Karl. M. Kadish, Kei Ohkubo and Shunichi Fukuzumi

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/chem.200801748

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      Unusually accepting: A series of metalloporphyrin–ruthenocene complexes, synthesized by direct coordination of a [Ru(Cp*)]+ fragment to the π-electron “face” of several metallooctaethylporphyrins (see graphic), undergo efficient photoinduced electron transfer from the ruthenocene unit (acting as the electron donor) to the singlet excited state of the metalloporphyrin unit (acting as the electron acceptor) to give a charge-separated state.

    5. Self-Assembly

      π-Stacking Enhanced Dynamic and Redox-Switchable Self-Assembly of Donor–Acceptor Metallo-[2]Catenanes from Diimide Derivatives and Crown Ethers (pages 10211–10218)

      Gayane Koshkakaryan, Kumar Parimal, Jiuming He, Xiyun Zhang, Zeper Abliz, Amar H. Flood and Yi Liu

      Version of Record online: 15 OCT 2008 | DOI: 10.1002/chem.200801590

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      In search of a better recipe: Bigger is better. On changing from strong donor–acceptor pairs to very weak ones, divalent 4,4′-bipyridine was no longer a suitable filler ligand to give cyclized metal–ligand coordination [2]catenanes. The choice of 2,7-diazapyrene, which has a larger π surface, proved to be essential in providing extra stabilization interactions to ensure efficient assembly (see figure).

    6. Gold Catalysis

      Gold(I)-Catalyzed Cycloisomerization of Arylvinylcyclopropenes: An Efficient Synthetic Protocol for the Construction of Indene Skeletons (pages 10219–10222)

      Zhi-Bin Zhu and Min Shi

      Version of Record online: 16 OCT 2008 | DOI: 10.1002/chem.200801370

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      Excellent yields! Gold(I)-catalyzed cycloisomerization of vinylcyclopropenes to produce vinylindene derivatives in good to excellent yields under mild conditions has been achieved (see scheme).

    7. Chemical Bonds

      Chemical Bonding in the Inclusion Complex of He in Adamantane (He@adam): The Origin of the Barrier to Dissociation (pages 10223–10226)

      Tatyana Strenalyuk and Arne Haaland

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/chem.200800715

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      No He[BOND]C bonds: A study of the dissociation reaction of the inclusion complex He§adam (depicted here) shows that according to the Pauling/IUPAC definition of a chemical bond, the complex is held together by C[BOND]C but not He[BOND]C bonds.

    8. Chemical Bonding in the Inclusion Complex of He in Adamantane, He@adam: Antithesis and Complement (pages 10227–10231)

      Moritz von Hopffgarten and Gernot Frenking

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/chem.200801351

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      The analysis of the electronic structure of the inclusion complex He§adam using the AIM method justifies the notation of a He[BOND]C bond. The Pauli repulsion between helium and the adamantane cage induces an adjustment of the electronic structure of adamantane, which weakens the C[BOND]C bonds and concomitantly yields Coulombic attraction between He and the CH carbon atoms and is the origin of the genuine He[BOND]C bonds.

    9. Bond Theory

      The Implications of Symmetry of the External Potential on Bond Paths (pages 10232–10234)

      Erick Cerpa, Andreas Krapp, Alberto Vela and Gabriel Merino

      Version of Record online: 21 OCT 2008 | DOI: 10.1002/chem.200800934

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      Sixty-coordinate atom? Using a set of molecules in which the number of “bond” paths terminating at an atom is chemically meaningless (an example is shown here); the implications of symmetry of the external potential on the presence of bond paths are discussed.

  7. Full Papers

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

      1,3-Diindolylureas and 1,3-Diindolylthioureas: Anion Complexation Studies in Solution and the Solid State (pages 10236–10243)

      Claudia Caltagirone, Jennifer R. Hiscock, Michael B. Hursthouse, Mark E. Light and Philip A. Gale

      Version of Record online: 15 OCT 2008 | DOI: 10.1002/chem.200801639

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      Room at the anion? Three diindolylureas assemble around PO43− in the solid-state, saturating its coordination sphere with twelve hydrogen bonds (see figure).

    2. Drug Delivery

      Natural Gum Reduced/Stabilized Gold Nanoparticles for Drug Delivery Formulations (pages 10244–10250)

      Sheetal Dhar, E. Maheswara Reddy, Anjali Shiras, Varsha Pokharkar and B. L. V. Prasad

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/chem.200801093

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      Gold and gum: Natural gum reduced/capped gold nanoparticles upon subsequent loading of doxorubicin hydrochloride, an anti-cancer drug (see graphic), displayed superior cytotoxic effects on human glioma cell lines and also showed enhanced stability to electrolyte additions and pH changes.

    3. Carbohydrates

      Structural and Immunochemical Analysis of the Lipopolysaccharide from Acinetobacter lwoffii F78 Located Outside Chlamydiaceae with a Chlamydia-Specific Lipopolysaccharide Epitope (pages 10251–10258)

      Anna Hanuszkiewicz, Göran Hübner, Evgeny Vinogradov, Buko Lindner, Lore Brade, Helmut Brade, Jennifer Debarry, Holger Heine and Otto Holst

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/chem.200800958

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      On the scent of cross-reactivity: False-positive results in clinical diagnosis cause serious problems, not only to clinicians. A structural investigation of Acinetobacter lwoffii F78 lipopolysaccharide (see picture) is used to show the cause of the cross-reactivity of ChlamydiaAcinetobacter.

    4. Anion Sensing

      Size-Specific, Colorimetric Detection of Counteranions by Using Helical Poly(phenylacetylene) Conjugated to L-Leucine Groups through Urea Acceptors (pages 10259–10266)

      Ryohei Kakuchi, Sachiko Nagata, Ryosuke Sakai, Issei Otsuka, Hiroshi Nakade, Toshifumi Satoh and Toyoji Kakuchi

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801235

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      Grip and twist: Poly(phenylacetylene) with urea and L-leucine functionalities showed anion signaling properties based on the π-conjugated backbone. Anion size information can be successfully transferred to the chromophoric polyacetylene backbone through anion recognition (see figure) and detected by a visible color change.

    5. Polymerization

      Living Radical Polymerization of Acrylates Mediated by 1,3-Bis(2-pyridylimino)isoindolatocobalt(II) Complexes: Monitoring the Chain Growth at the Metal (pages 10267–10279)

      Björn K. Langlotz, Julio Lloret Fillol, Jürgen H. Gross, Hubert Wadepohl and Lutz H. Gade

      Version of Record online: 22 OCT 2008 | DOI: 10.1002/chem.200801373

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      Caught in the act: The growing metal-bound polymer chain in the living radical polymerization of acrylates mediated by 1,3-bis(2-pyridylimino)isoindolatocobalt(II) acetylacetonates has been directly observed by liquid injection field desorption/ionization mass spectrometry (see picture).

    6. Metal–Organic Frameworks

      Structure and Charge Control in Metal–Organic Frameworks Based on the Tetrahedral Ligand Tetrakis(4-tetrazolylphenyl)methane (pages 10280–10285)

      Mircea Dincǎ, Anne Dailly and Jeffrey R. Long

      Version of Record online: 9 OCT 2008 | DOI: 10.1002/chem.200801336

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      Designed complexity: A strategy is used wherein a three-dimensional ligand enforces the extension of the ensuing metal–organic frameworks (see figure) in all three crystallographic directions, giving rise to rare garnet- and fluorite-type materials. An unprecedented post-synthetic charge reduction is demonstrated in one of the microporous frameworks, which also exhibits significant gas-uptake capacity.

    7. Supramolecular Chemistry

      The Dimeric “Hand-Shake” Motif in Complexes and Metallo–Supramolecular Assemblies of Cyclotriveratrylene-Based Ligands (pages 10286–10296)

      Christopher Carruthers, Tanya K. Ronson, Christopher J. Sumby, Aleema Westcott, Lindsay P. Harding, Timothy J. Prior, Pierre Rizkallah and Michaele J. Hardie

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801264

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      Shake on it: The hand-shake inclusion motif, in which the arm of an extended host molecule occupies the cavity of another host and vice versa, can be observed for the new cyclotriveratrylene-related ligands, within a discrete trinuclear complex and even in a cube-like [Ag4L4] tetrameric metallo-supramolecular assembly (see figure).

    8. Peptide Chemistry

      Disulfide Bond Creates a Small Connecting Loop in Aminoxy Peptide Backbone (pages 10297–10302)

      Dan Yang, Guo-Jun Liu, Zhi-Gang Jiao, Dan-Wei Zhang, Zheng Luo, Ke-Sheng Song and Min-Qin Chen

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200800095

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      Disulfide feedback-loop: Disulfide-bond formation between the side chains of cysteine–cysteine pairs is often critical to the folding behavior, stability, and functionality of proteins. We report that sulfur atoms can be introduced into the amide groups of aminoxy peptides to form a novel type of disulfide bridge (see figure), which creates a connecting loop in the peptide backbone.

    9. Protein Nanotubes

      Protein Nanotubes Comprised of an Alternate Layer-by-Layer Assembly Using a Polycation as an Electrostatic Glue (pages 10303–10308)

      Xue Qu, Gang Lu, Eishun Tsuchida and Teruyuki Komatsu

      Version of Record online: 24 SEP 2008 | DOI: 10.1002/chem.200800771

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      Rolled sandwich: Protein nanotubes (see figure) comprising an LbL assembly of human serum albumin, ferritin or myoglobin with a polycation as an electrostatic glue were prepared by templating synthesis using a porous polycarbonate membrane. The tubule wall thickness is dependent on the globular size of the protein at the same number of deposition cycles.

    10. Nanostructures

      Facile High-Yield Synthesis of Polyaniline Nanosticks with Intrinsic Stability and Electrical Conductivity (pages 10309–10317)

      Xin-Gui Li, Ang Li and Mei-Rong Huang

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801025

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      Chemical oxidative polymerization at room temperature was used to straightforwardly synthesize polyaniline (PAN) nanosticks (see depicted TEM image) with high yield, controllable size, intrinsic self-stability, high redispersibility, high purity, and optimizable conductivity. Synthesis of PAN nanosticks is thus achieved without using an external stabilizer.

    11. Immunochemistry

      Synthesis of Diaminopimelic Acid Containing Peptidoglycan Fragments and Tracheal Cytotoxin (TCT) and Investigation of Their Biological Functions (pages 10318–10330)

      Akiko Kawasaki, Yukie Karasudani, Yuji Otsuka, Mizuho Hasegawa, Naohiro Inohara, Yukari Fujimoto and Koichi Fukase

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801121

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      Immunochemistry: meso-Diaminopimelic acid (meso-DAP)-containing peptidoglycan (PGN) fragments were synthesized based on a newly developed method of DAP preparation. The study includes the first chemical synthesis of TCT (see scheme; Boc=tert- butoxycarbonyl, Z=benzyloxycarbonyl) and a repeating unit of DAP-type PGN, GlcNAc-(β1–4)-MurNAc-L-Ala-γ-D-Glu-meso-DAP-D-Ala. The immunostimulating activities produced by intracellular receptor Nod1 stimulation are also described.

    12. Supramolecular Chemistry

      Poly(p-phenylene ethynylene)s with Facially Amphiphilic Pendant Groups: Solvatochromism and Supramolecular Assemblies (pages 10331–10339)

      Yan Li, Guangtao Li, Xinyan Wang, Changxu Lin, Yihe Zhang and Yong Ju

      Version of Record online: 24 SEP 2008 | DOI: 10.1002/chem.200800986

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      Polymers with bile acid: The incorporation of facially amphiphilic bile acid groups into a conjugated polymer is demonstrated as an effective approach to guide the self-assembly of poly(p-phenylene ethynylene)s (PPEs). The bile acid decorated PPEs exhibit solvatochromism in a range of solvent systems, and judicious choice of the solvents affords nanoscale assemblies with adjustable size and morphology (see picture).

    13. Low-Dimensional Magnets

      Cobalt–Lanthanide Coordination Polymers Constructed with Metalloligands: A Ferromagnetic Coupled Quasi-1D Dy3+ Chain Showing Slow Relaxation (pages 10340–10347)

      You-Gui Huang, Xiu-Teng Wang, Fei-Long Jiang, Song Gao, Ming-Yan Wu, Qiang Gao, Wei Wei and Mao-Chun Hong

      Version of Record online: 26 SEP 2008 | DOI: 10.1002/chem.200800344

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      A new family? The metalloligand Co(2,5-pydc)33− (2,5-H2pydc=pyridine-2,5-dicarboxylate acid) is expected to be a good candidate for constructing a new family of single-chain magnets. Four lanthanide–cobalt coordination polymers based on this metalloligand were synthesized, as illustrated.

    14. Chemoselective Metalation

      Development of Highly Chemoselective Bulky Zincate Complex, tBu4ZnLi2: Design, Structure, and Practical Applications in Small-/Macromolecular Synthesis (pages 10348–10356)

      Taniyuki Furuyama, Mitsuhiro Yonehara, Sho Arimoto, Minoru Kobayashi, Yotaro Matsumoto and Masanobu Uchiyama

      Version of Record online: 24 SEP 2008 | DOI: 10.1002/chem.200800536

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      Crowding opens new reactivity: A new dianion-type bulky zincate, dilithium tetra-tert-butylzincate (tBu4ZnLi2) was developed (see picture). By using tBu4ZnLi2, the halogen–zinc exchange reaction of various functionalized organic halides, regioselective SN2′ reaction, and the chemoselective anionic polymerization of functionalized vinylmonomers were realized.

    15. Electrochromism and Luminescence

      Polysulfurated Pyrene-Cored Dendrimers: Luminescent and Electrochromic Properties (pages 10357–10363)

      Marc Gingras, Virginie Placide, Jean-Manuel Raimundo, Giacomo Bergamini, Paola Ceroni and Vincenzo Balzani

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801198

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      Optoelectronic devices: Dendrimers containing a pyrene core and polysulfurated branches show intense blue luminescence and a reversible color change from light yellow to deep blue upon mono-oxidation by chemical (AuCl4) or electrochemical methods (see picture). These properties could be exploited for optoelectronic devices.

    16. Pincer Complexes

      Exploring the Reactivity of C(sp3)-Cyclometalated IrIII Compounds in Hydrogen Transfer Reactions (pages 10364–10368)

      Clarite Azerraf and Dmitri Gelman

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801728

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      PCP facilitates hydrogenation: A PC(sp3)P-based cyclometalated IrIII pincer complex (see crystal structure in picture) is formed by DMF decarbonylation and is shown to have exceptional stability, owing to the coordination chemistry of the rigid 1,8-bis(diisopropylphosphino)triptycene ligand. Furthermore, it exhibits exceptional catalytic activity in the transfer hydrogenation of ketones, even under non-inert reaction conditions.

    17. Radical Reactions

      Intramolecular 1,8-Hydrogen-Atom Transfer Reactions in (1[RIGHTWARDS ARROW]4)-O-Disaccharide Systems: Conformational and Stereochemical Requirements (pages 10369–10381)

      Cosme G. Francisco, Antonio J. Herrera, Alan R. Kennedy, Angeles Martín, Daniel Melián, Inés Pérez-Martín, Luis M. Quintanal and Ernesto Suárez

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801414

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      Long-range intramolecular functionalisation: Regioselective 1,8- versus 1,6-hydrogen-atom transfer promoted by alkoxyl radicals between the two pyranose units in (1[RIGHTWARDS ARROW]4)-disaccharide models afforded 1,3,5-trioxocane and spiro ortho-ester rings (see scheme).

    18. Microreactors

      A Novel Electrosynthetic System for Anodic Substitution Reactions by Using Parallel Laminar Flow in a Microflow Reactor (pages 10382–10387)

      Daisuke Horii, Fumihiro Amemiya, Toshio Fuchigami and Mahito Atobe

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801511

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      Anodic substitution reactions proceeded smoothly without affecting the oxidation of the nucleophile in a single flow-through operation by the combined use of ionic liquids as reaction media and parallel laminar flow in a microflow reactor (see figure).

    19. Homogeneous Catalysis

      Rapid Ketone Transfer Hydrogenation by Employing Simple, In Situ Prepared Iridium(I) Precatalysts Supported by “Non-N[BOND]H” P,N Ligands (pages 10388–10395)

      Rylan J. Lundgren and Mark Stradiotto

      Version of Record online: 16 OCT 2008 | DOI: 10.1002/chem.200801530

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      Rapid turnover: Mixtures of [{IrCl(cod)}2] (cod: η4-1,5-cyclooctadiene) and NaPF6 with (o-tBu2P-C6H4)NMe2 afforded a remarkably active catalyst system for the transfer hydrogenation of ketones, whereas the use of (αSS)-1,1′-bis[α-(dimethylamino)benzyl]-(R,R)-2,2′-bis(dicyclohexylphosphino)ferrocene (Cy-Mandyphos) under similar conditions enabled the Ir-mediated reduction of aryl alkyl ketones with unprecedented efficiency (see scheme).

    20. Polymers

      Synthesis, Microwave-Assisted Polymerization, and Polymer Properties of Fluorinated 2-Phenyl-2-oxazolines: A Systematic Study (pages 10396–10407)

      Matthias Lobert, Hanneke M. L. Thijs, Tina Erdmenger, Rebecca Eckardt, Christoph Ulbricht, Richard Hoogenboom and Ulrich S. Schubert

      Version of Record online: 26 SEP 2008 | DOI: 10.1002/chem.200800671

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      Given all the possibilities… living cationic ring-opening polymerization was performed on all possible fluorinated 2-phenyl-2-oxazolines. Selected thermal properties and surface properties of the resulting polymers reveal structure–property relationships for the polymerization rates (kp), thermal properties, and the surface energies (SEs; see the picture).

    21. Supramolecular Chemistry

      Interaction of Dinuclear Ruthenium(II) Supramolecular Cylinders with DNA: Sequence-Specific Binding, Unwinding, and Photocleavage (pages 10408–10414)

      Jaroslav Malina, Michael J. Hannon and Viktor Brabec

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801364

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      Supramolecular cylinders: A three-stranded RuII helicate [Ru2L3]4+ (L=C25H20N4), in which three bis-pyridylimine ligands are wrapped about the two metal centers in a helical fashion (see picture), unwinds negatively supercoiled plasmid DNA and binds preferentially to regular alternating purine–pyrimidine sequences. On irradiation by visible and UVA light, [Ru2L3]4+ induces single-strand breaks and cleaves DNA mainly at guanine residues contained in regularly alternating purine–pyrimidine nucleotides.

    22. Carbene Chemistry

      Functionalised Saturated-Backbone Carbene Ligands: Yttrium and Uranyl Alkoxy–Carbene Complexes and Bicyclic Carbene–Alcohol Adducts (pages 10415–10422)

      Polly L. Arnold, Ian J. Casely, Zoë R. Turner and Christopher D. Carmichael

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801321

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      Get a backbone: A new and modular route to proligands for bidentate, saturated backbone alkoxy–carbenes is reported, along with protonolysis reactions that afford the first early transition metal, and the first f-block saturated carbene complexes (see figure). The uranyl carbene complexes exhibit exceptionally high-frequency carbene chemical shifts for the carbenic carbon.

    23. Gas-Phase Acidity

      α,β-Unsaturated and Saturated Derivatives of Be, Mg, and Ca: Are They Carbon or Metal Acids in the Gas Phase? (pages 10423–10429)

      Ane Eizaguirre, Otilia Mó, Manuel Yáñez and Jean-Claude Guillemin

      Version of Record online: 10 OCT 2008 | DOI: 10.1002/chem.200801012

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      The acid test: Despite the fact that the X[BOND]H bonds in R[BOND]XH (X=Mg, Ca; R=methyl, ethyl, vinyl, ethynyl) derivatives exhibit the expected Xδ+[BOND]Hδ− polarity, they behave as metal acids in the gas phase (see figure). Most importantly, ethyl, vinyl, and ethynyl derivatives that contain Be, Mg, and Ca heteroatoms are among the strongest gas-phase acids that contain main-group heteroatoms.

    24. Reaction Mechanisms

      Mechanism of the Intramolecular Hydroamination of Alkenes Catalyzed by Neutral Indenyltitanium Complexes: A DFT Study (pages 10430–10436)

      Carsten Müller, Rainer Koch and Sven Doye

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801445

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      DFT calculations suggest that the [Ind2TiMe2]-catalyzed hydroamination of alkenes proceeds via Ti–imido–amido complexes as the catalytically active species (see figure). These complexes are either involved in a [2+2]-cycloaddition with the alkene or a newly proposed insertion of the alkene into the Ti[BOND]N single bond. Both catalytic cycles possess very similar energy profiles.

    25. Network Transformations

      Ancillary Ligands and Spectator Cations as Controlling Factors in the Construction of Coordination and Hydrogen-Bonded Networks with the tert-Bu-C[TRIPLE BOND]C⊃Agn (n=4, 5) Supramolecular Synthon (pages 10437–10444)

      Liang Zhao, Chong-Qing Wan, Jie Han, Xu-Dong Chen and Thomas C. W. Mak

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200800968

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      Under control: Control of the crystallization process and tuning of interlayer separation are made possible by using ancillary nitrile ligands to induce the construction and transformation of two-dimensional silver–ethynide–trifluoroacetate supramolecular networks by alternative modes of coordination and hydrogen-bonding linkages (see figure).

    26. NMR Spectroscopy

      Computational NMR Spectroscopy of Organoarsenicals and the Natural Polyarsenic Compound Arsenicin A (pages 10445–10452)

      Petri Tähtinen, Giacomo Saielli, Graziano Guella, Ines Mancini and Alessandro Bagno

      Version of Record online: 8 OCT 2008 | DOI: 10.1002/chem.200801272

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      From crime stories to DFT: Nature continues to surprise us with a tantalizing variety of unusual molecules, such as the polyarsenic sponge metabolite arsenicin A. Although it has the deceptively simple empirical formula C3H6As4O3, an accurate structure determination has proved difficult. Now DFT calculations of NMR spectra have unambiguously established it to have an adamantane-like structure (see picture; As purple, C dark gray, H light gray, O red).

    27. Photooxidation

      The pH Effect on the Naphthoquinone-Photosensitized Oxidation of 5-Methylcytosine (pages 10453–10461)

      Hisatsugu Yamada, Kazuhito Tanabe, Takeo Ito and Sei-ichi Nishimoto

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200800840

      Thumbnail image of graphical abstract

      A change in the conditions: Under slightly acidic conditions, the mC radical cation favors irreversible deprotonation at the C(5) methyl group to form a methyl-centered radical, leading to a higher yield of the alkali-labile oxidation products. In contrast, the mC radical cation competitively undergoes deprotonation at the N(4) amino group under neutral or basic conditions (see scheme).

    28. Liquid Crystals

      Supramolecular Helical Fluid Columns from Self-Assembly of Homomeric Dipeptides (pages 10462–10471)

      Channabasaveshwar V. Yelamaggad, Govindaswamy Shanker, R. V. Ramana Rao, Doddamane S. Shankar Rao, Subbarao Krishna Prasad and Vommina V. Suresh Babu

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200801607

      Thumbnail image of graphical abstract

      Helical fluid columns: Hexacatenar homomeric dipeptides, the first of their kind, self-assemble into novel supramolecular helical fluid columns (see figure). Of special significance, a pair of enantiomers derived from L/D-alanine exhibit ferroelectric behavior with high spontaneous polarization values. Additionally, all these supramolecules form stable organogels (in ethanol) comprising helical fibers.

    29. Organocatalysis

      The Role of Noninnocent Solvent Molecules in Organocatalyzed Asymmetric Michael Addition Reactions (pages 10472–10485)

      Mahendra P. Patil and Raghavan B. Sunoj

      Version of Record online: 1 OCT 2008 | DOI: 10.1002/chem.200800877

      Thumbnail image of graphical abstract

      A successful prediction: Density functional studies on a proline-catalyzed Michael addition reaction between ketones/aldehydes and β-nitrostyrene indicate that the standard transition-state models are inadequate in reproducing the experimentally reported enantio- and diastereoselectivities of this reaction. Systematic studies of solvent-assisted transition-state models indicate that two solvent molecules engage in cooperative hydrogen bonding (see picture).

    30. Synthetic Methods

      Gold- and Silver-Catalyzed Tandem Amination/Ring Expansion of Cyclopropyl Methanols with Sulfonamides as an Expedient Route to Pyrrolidines (pages 10486–10495)

      Weidong Rao and Philip Wai Hong Chan

      Version of Record online: 22 SEP 2008 | DOI: 10.1002/chem.200801242

      Thumbnail image of graphical abstract

      Precious help: Efficient gold-catalyzed conversion of C[BOND]O to C[BOND]N bonds with formation of pyrrolidines is described. The tandem bond-forming strategy makes use of substituted cyclopropyl methanols and sulfonamides as substrates (see scheme). The mechanism is thought to involve tandem amination, cyclopropane ring-opening, and intramolecular hydroamination processes.

  8. Preview

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Concept
    7. Communications
    8. Full Papers
    9. Preview
    1. Preview: Chem. Eur. J. 34/2008 (page 10499)

      Version of Record online: 11 NOV 2008 | DOI: 10.1002/chem.200890138

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