Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 39

October 4, 2004

Volume 43, Issue 39

Pages 5103–5273

    1. Cover Picture: Inner Core Structure Responds to Communication between Nanocapsule Walls (Angew. Chem. Int. Ed. 39/2004) (page 5103)

      Gareth W. V. Cave, Jochen Antesberger, Leonard J. Barbour, Robert M. McKinlay and Jerry L. Atwood

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200490135

      Nanoscale molecular capsules are assembled by means of noncovalent interactions and enclose over 1300 Å3 of molecular space. The supramolecular interactions between two independent nanocapsules lead to changes in the dynamic structure of the capsule walls. This dramatically alters the packing and fluidity of the guest matrix within the host. In their Communication on page 5263 ff., J. L. Atwood and co-workers provide valuable insight into the interactions and fluidity of the so-called “new phase of matter”.

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      Artificial Cells: Temperature-Dependent, Reversible Li+-Ion Uptake/Release Equilibrium at Metal Oxide Nanocontainer Pores (page 5115)

      Achim Müller, Dieter Rehder, Erhard T. K. Haupt, Alice Merca, Hartmut Bögge, Marc Schmidtmann and Gabriele Heinze-Brückner

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200490137

    3. Establishing the Molecular Basis for Molecular Electronics (pages 5120–5123)

      Ronald A. Wassel and Christopher B. Gorman

      Version of Record online: 16 SEP 2004 | DOI: 10.1002/anie.200301735

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      Molecular structure–property relationships for molecular electronics are beginning to emerge. Recent experiments lend credibility to the single-molecule nature of transport measurements and illustrate the molecular features that give rise to various interesting conductance behaviors (see picture).

    4. Bimetallic Figure-Eight Octaphyrins Split into Four-Pyrrolic Macrocycles (pages 5124–5128)

      Lechosław Latos-Grażyński

      Version of Record online: 15 SEP 2004 | DOI: 10.1002/anie.200460645

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      Molecular mitosis: Figure-eight octaphyrins form binuclear metal complexes that can split into two covalently spiro-linked corrolates. In a unique case binuclear CuII [36]octaphyrin divides thermally into two CuII [18]porphyrins presumably with participation of a transient spirocyclobutane species (see schematic representation).

    5. N-Heterocyclic Carbenes: Reagents, Not Just Ligands! (pages 5130–5135)

      Vijay Nair, Santhamma Bindu and Vellalath Sreekumar

      Version of Record online: 19 AUG 2004 | DOI: 10.1002/anie.200301714

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      Species of curiosity for a long time and more recently ligands for metals, nucleophilic heterocyclic carbenes deserve renewed attention as reagents and catalysts in organic synthesis. Their known chemistry (see scheme) foretells an impressive future.

    6. In the Golden Age of Organocatalysis (pages 5138–5175)

      Peter I. Dalko and Lionel Moisan

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200400650

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      Metal-free synthesis: An increasing number of asymmetric organic reactions can be catalyzed by a chiral organic molecule. Although substrate dependency remains an important issue in many cases, a large number of organocatalytic transformations are as efficient as current standards in asymmetric synthesis demand (see example).

    7. Synthesis and Manipulation of Orthogonally Protected Dendrimers: Building Blocks for Library Synthesis (pages 5178–5180)

      Mackay B. Steffensen and Eric E. Simanek

      Version of Record online: 12 AUG 2004 | DOI: 10.1002/anie.200460031

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      Fruits of the laboratory: Dendrimers containing up to six different functional groups can be prepared in multistep one-pot reactions by using a selective manipulation and deprotection strategy (see example). The authors call these multifunctional dendrimers molecular fruit-salad trees; they could function as useful building blocks for drug-delivery systems and novel materials.

    8. An Amphotericin B–Fluorescein Conjugate as a Powerful Probe for Biochemical Studies of the Membrane (pages 5181–5185)

      Andreas Zumbuehl, Damien Jeannerat, Scott E. Martin, Marc Sohrmann, Pasquale Stano, Tamas Vigassy, Daniel D. Clark, Stephen L. Hussey, Mathias Peter, Blake R. Peterson, Ernö Pretsch, Peter Walde and Erick M. Carreira

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460489

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      Not only skin deep: A fluorescein–amphotericin B conjugate with a new piperazine linker (see structure) was prepared and used as a probe of the biomembrane and the mechanism of action of amphotericin B both in vivo and in liposomal experiments. The amphotericin B analogue localizes at the membrane of yeast cells but is internalized by mammalian cells.

    9. A Covalent-Chemistry Approach to Giant Macromolecules and Their Wetting Behavior on Solid Substrates (pages 5185–5188)

      Afang Zhang, Jörg Barner, Illdiko Göessl, Jürgen P. Rabe and A. Dieter Schlüter

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460390

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      Hair raising! Poly(methyl methacrylate) chains grown on a dendronized polymer (denpol) having repeat units with terminal 2-bromoisobutyramide groups produce a hairy surface. When adsorbed on mica, MoS2, and highly oriented pyrolytic graphite, the hairy denpol molecules have a quasi two dimensional backbone conformation. The 50-nm-long hairs bend back on the MoS2 (see image) and graphite substrates.

    10. Activation of an Autoregulated Protein Kinase by Conditional Protein Splicing (pages 5189–5192)

      Henning D. Mootz, Elyse S. Blum and Tom W. Muir

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460941

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      A protein rheostat: A strategy for controlling enzyme activity by cleavage of a low-affinity “pseudosubstrate” inhibitor from an autoregulated version of the enzyme (see figure) is described. Peptide-bond cleavage was mediated by conditional protein splicing. The small molecule rapamycin was used to induce intein trans-splicing of the catalytic subunit of cAMP-dependent protein kinase A (PKA).

    11. Sensing the Critical Point of High-Pressure Mixtures (pages 5192–5195)

      Jie Ke, Robert M. Oag, P. J. King, Michael W. George and Martyn Poliakoff

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460624

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      A new, general and objective approach to locating critical points of fluid mixtures is described (see picture). It is new because it exploits the fact that the liquid phase forms preferentially on the surface of the sensor. It is general because it can be used with any type of surface-sensitive sensor, and it is objective because it is based on the numerical output of a sensor rather than the visual image normally used for phase equilibrium studies.

    12. The Magnetic Möbius Strip: Synthesis, Structure, and Magnetic Studies of Odd-Numbered Antiferromagnetically Coupled Wheels (pages 5196–5200)

      Olivier Cador, Dante Gatteschi, Roberta Sessoli, Finn K. Larsen, Jacob Overgaard, Anne-Laure Barra, Simon J. Teat, Grigore A. Timco and Richard E. P. Winpenny

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460211

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      Understanding frustration: The control of structure through the choice of the template has allowed the synthesis of nona-nuclear metal wheels that contain {Cr8Ni} or {Cr7(VO)2} cores. Magnetic studies (see picture) of one of these wheels shows that it behaves as a magnetic Möbius strip. These are the first detailed magnetic studies of an odd-numbered ring larger than trinuclear and should help in the understanding of spin-frustrated systems.

    13. Stereodynamic Effects in the Adsorption of Ethylene onto a Metal Surface (pages 5200–5203)

      Luca Vattuone, Andrea Gerbi, Mario Rocca, Ugo Valbusa, Fernando Pirani, Franco Vecchiocattivi and David Cappelletti

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200461302

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      Molecular gymnastics: Ethylene molecules (C atoms in green) rotating along the principal axes impinge perpendicularly on an Ag (001) metal surface precovered with O2 (O atoms in red) and may stick in some favorable cases. The sticking probability S depends on the approach of the C[DOUBLE BOND]C bond to the surface: “helicopters” (d) stick better than “cartwheels” (b and c) or “cigars” (a).

    14. Difluoromethyl Phenyl Sulfone, a Difluoromethylidene Equivalent: Use in the Synthesis of 1,1-Difluoro-1-alkenes (pages 5203–5206)

      G. K. Surya Prakash, Jinbo Hu, Ying Wang and George A. Olah

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460815

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      A nucleophilic substitution–elimination reaction strategy in which difluoromethyl phenyl sulfone is used as a selective difluoromethylidene equivalent allows the facile synthesis of 1,1-difluoro-1-alkenes from primary alkyl halides (see scheme).

    15. Creation of Intestine-like Interior Space for Metal-Oxide Nanostructures with a Quasi-Reverse Emulsion (pages 5206–5209)

      Hua Gui Yang and Hua Chun Zeng

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460767

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      Gutsy chemistry: A solvothermal process has been developed for the controlled creation of interior space in TiO2 intestines (either hollow (see TEM image) or partially filled) or spheres in the anatase polymorph. A morphological transformation from intestine to sphere is observed when the water content of the water/2-propanol mixture is decreased.

    16. Tunable, Superhydrophobically Stable Polymeric Surfaces by Electrospinning (pages 5210–5213)

      Kazim Acatay, Eren Simsek, Cleva Ow-Yang and Yusuf Z. Menceloglu

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200461092

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      Dry films: An electrospinning process was used to form films with high water contact angles (166.7°) and low sliding-angles (4.3°). The electrospun films exhibit excellent superhydrophobic Cassie-regime stability: The figure shows a nonwetting water droplet, even after 400 Pa of uniaxial loading.

    17. The [NH3Cl]+ Ion (pages 5213–5217)

      Stefan Schneider, Ralf Haiges, Thorsten Schroer, Jerry Boatz and Karl O. Christe

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460544

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      Stable! The first stable salts containing a simple, inorganic cation with an N[BOND]Cl bond are prepared (see picture). They are [NH3Cl]+[BF4], [NH3Cl]+[AsF6], and [NH3Cl]+[SbF6] and can be safely prepared from (Me3Si)2NCl in mixtures of HF and the corresponding Lewis acids and could be used as storable generators for monochloramine gas.

    18. Linear Finite “Mers”—Homoleptic Polynuclear Heavy Alkaline Earth Metal Pyrazolates (pages 5218–5220)

      Julia Hitzbleck, Glen B. Deacon and Karin Ruhlandt-Senge

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460628

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      The bigger the better: Increasing metal size seems to be the determining factor in the formation of an unprecedented series of homoleptic linear pyrazolates of the heavy alkaline-earth metals (Ca, Sr, Ba, see picture, Ba=green, N=blue, C=black), with the formation of trinuclear calcium, tetranuclear strontium, and hexanuclear barium derivatives. The linear oligomers display a noteworthy array of metal–ligand bonds.

    19. Iterative One-Pot Synthesis of Oligosaccharides (pages 5221–5224)

      Xuefei Huang, Lijun Huang, Haisheng Wang and Xin-Shan Ye

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460176

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      Straight to the point! Preactivation of a p-tolyl thioglycoside donor, followed by sequential addition of p-tolyl thioglycosyl acceptors in one reaction flask allowed rapid syntheses of oligosaccharides independent of anomeric reactivities of donors and acceptors (see scheme). This strategy greatly streamlines the assembly of oligosaccharides.

    20. A Five-Coordinate Homoleptic Organotitanium(III) Compound (pages 5225–5228)

      Pablo J. Alonso, Larry R. Falvello, Juan Forniés, M. Angeles García-Monforte and Babil Menjón

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460111

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      Reversed Berry pseudorotation (see picture) results in a severely distorted trigonal-bipyramidal geometry with C2v symmetry in the paramagnetic (d1) anion [Ti(C6F5)5]2−, which was obtained by the low-temperature reaction of TiCl4x Et2O and LiC6F5 and is the first homoleptic organometallic compound containing a [TiR5]2− unit.

    21. Evidence for the Formation of an Iodosylbenzene(salen)iron Active Intermediate in a (Salen)iron(III)-Catalyzed Asymmetric Sulfide Oxidation (pages 5228–5230)

      Konstantin P. Bryliakov and Evgenii P. Talsi

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460108

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      Catalytic converter: A (salen)iron(III) complex (salen*=asymmetric bis(salicylidene)ethylenediamine ligand) can be used as a catalyst system for the asymmetric oxidation of aryl sulfides by iodosylbenzene (see scheme). An iodosylbenzene(salen)iron(III) species has been identified as the active intermediate by EPR and NMR spectroscopy. R=aryl, R′=alkyl.

    22. Three-Dimensional Structure of Large-Pore Mesoporous Cubic Iaequation imaged Silica with Complementary Pores and Its Carbon Replica by Electron Crystallography (pages 5231–5234)

      Yasuhiro Sakamoto, Tae-Wan Kim, Ryong Ryoo and Osamu Terasaki

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460449

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      A bicontinuous cubic structure was revealed by electron crystallography on a large-pore mesoporous silica with a cubic Iaequation imaged symmetry synthesized by using a triblock copolymer as a structure-directing agent. Its reconstructed structure (picture, left) is composed of an enantiomeric pair of interwoven three-dimensional mesoporous networks. Ordered complementary pores form interconnections between the two main channel systems at a special flat point of the G-surface (right).

    23. Hydrogen-Bonded Banana Liquid Crystals (pages 5235–5238)

      Nélida Gimeno, Maria Blanca Ros, José Luis Serrano and Maria Rosario de la Fuente

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460549

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      Top banana! Hydrogen-bonded bent complexes of benzoic acids (H donor) and nonmesomorphic V-shaped 4′-stilbazoles (H acceptor) give rise to polar smectic C (SmCP, see graphic) mesophases. The multifunctional character of these noncovalent materials is confirmed through their electrooptical, dielectric, and luminescent responses.

    24. Single-Crystal Hexagonal Disks and Rings of ZnO: Low-Temperature, Large-Scale Synthesis and Growth Mechanism (pages 5238–5242)

      Feng Li, Yong Ding, Puxian Gao, Xinquan Xin and Zhong L. Wang

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460783

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      Solution-phase synthesis of single-crystal ZnO disks and rings was achieved in high yield at low temperature (70–90 °C) by using an anionic surfactant as a template. The reaction can be controlled by means of the growth temperature and the molar ratio of reagents to favor formation of disks or rings. A growth mechanism is proposed on the basis of structural information provided by SEM and TEM.

    25. Functionalized Carbon Nanotubes for Plasmid DNA Gene Delivery (pages 5242–5246)

      Davide Pantarotto, Ravi Singh, David McCarthy, Mathieu Erhardt, Jean-Paul Briand, Maurizio Prato, Kostas Kostarelos and Alberto Bianco

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460437

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      Genetic vaccination and gene therapy research could benefit from the application of carbon nanotubes. Functionalized, positively charged, water-soluble carbon nanotubes are able to penetrate into cells (see figure) and can transport plasmid DNA by formation of noncovalent DNA–nanotube complexes. Such nanotubes can be used as novel nonviral delivery systems for gene transfer.

    26. Nanofibers from Functionalized Dendritic Molecules (pages 5246–5249)

      Maryna Ornatska, Kathy N. Bergman, Beth Rybak, Sergiy Peleshanko and Vladimir V. Tsukruk

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460315

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      One-dimensional supramolecular assembly of dendrimers (see picture) has been achieved by multiple weak interactions between highly branched molecules with irregular structures. This finding contradicts the widely accepted assumption that precise matching of directional interactions and steric constraints is required to facilitate long-range one-dimensional supramolecular assembly.

    27. Spin Trapping of 13C-Labeled p-Benzynes Generated by Masamune–Bergman Cyclization of Bicyclic Nine-Membered Enediynes (pages 5249–5253)

      Toyonobu Usuki, Takashi Mita, Martin J. Lear, Parthasarathi Das, Fumihiko Yoshimura, Masayuki Inoue, Masahiro Hirama, Kimio Akiyama and Shozo Tero-Kubota

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200454133

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      A new spin on things? Spin trapping of 13C-labeled bicyclic mimics of natural nine-membered enediynes provided persuasive evidence for the spontaneous thermal generation of biradicals 1 and the differential reactivity of the resulting C3 and C6 radical centers (see scheme; ST spin trap; TBS tert-butyldimethylsilyl).

    28. Development of a Ruthenium-Catalyzed Asymmetric Epoxidation Procedure with Hydrogen Peroxide as the Oxidant (pages 5255–5260)

      Man Kin Tse, Christian Döbler, Santosh Bhor, Markus Klawonn, Wolfgang Mägerlein, Herbert Hugl and Matthias Beller

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460528

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      Novel pyboxazines and the known pybox ligands are used in the ruthenium-catalyzed asymmetric epoxidation of olefins with H2O2 (see scheme). This new catalytic system is successful in the conversion of differently substituted aromatic olefins and gives ee values of up to 84 %.

    29. T-Shaped Nets of Antimony Atoms in the Binary Antimonide Hf5Sb9 (pages 5260–5262)

      Abdeljalil Assoud, Katja M. Kleinke, Navid Soheilnia and Holger Kleinke

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460488

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      T time: The new binary antimonide Hf5Sb9 forms a unique variant of a square-planar net, namely an unprecedented yet simple T-shaped net (see picture, green) formed by antimony atoms (red). The electronic structure and bonding in the solid state are analyzed by theoretical methods.

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      Inner Core Structure Responds to Communication between Nanocapsule Walls (pages 5263–5266)

      Gareth W. V. Cave, Jochen Antesberger, Leonard J. Barbour, Robert M. McKinlay and Jerry L. Atwood

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200460711

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      The facile self-assembly of six pyrogallol[4]arene molecules leads to a globular truncated octahedron, which encapsulates a guest cluster consisting of ethyl acetate and water molecules (see scheme). The interactions between host capsules can be controlled by derivatization of the exterior surface of the capsule.

    31. A Molecular Multiproperty Switching Array Based on the Redox Behavior of a Ferrocenyl Polychlorotriphenylmethyl Radical (pages 5266–5268)

      Christian Sporer, Imma Ratera, Daniel Ruiz-Molina, Yuxia Zhao, José Vidal-Gancedo, Klaus Wurst, Peter Jaitner, Koen Clays, André Persoons, Concepció Rovira and Jaume Veciana

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200454150

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      All change: Three different output signals, chromic, nonlinear optical, and magnetic, can be altered simultaneously with the molecular switch based on radical 1. The electrochemical reduction and oxidation of 1 is completely reversible. These redox cycles can be repeated several times, and the corresponding changes in the optical properties can be monitored by visible spectroscopy.

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      Preview: Angew. Chem. Int. Ed. 39/2004 (page 5273)

      Version of Record online: 29 SEP 2004 | DOI: 10.1002/anie.200490138