Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 38

September 27, 2004

Volume 43, Issue 38

Pages 4965–5101

    1. Cover Picture: Methods for the Chemical Synthesis of Fullerenes (Angew. Chem. Int. Ed. 38/2004) (page 4965)

      Lawrence T. Scott

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200490132

      A high price in energy must be paid to impose curvature on the π system of a planar polycyclic aromatic hydrocarbon. This step was essential for the first chemical synthesis of C60 in isolable quantities, which stands as dramatic testimony to the power of the new synthetic methods devised for fullerene synthesis. In his Review on page 4994 ff., L. T. Scott describes the numerous syntheses of geodesic polyarenes reported, which serve to test the scope and limitations of the new methods.

    2. Basic Principles in Applied Catalysis. Edited by Manfred Baerns. (page 4979)

      Xander Nijhuis and Bert Weckhuysen

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200485195

    3. YbGaGe: Zero Thermal Expansion as a Result of an Electronic Valence Transition? (pages 4982–4984)

      Klaus Stöwe

      Version of Record online: 20 AUG 2004 | DOI: 10.1002/anie.200401757

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      In contrast to classic ZTE materials (ZTE=zero thermal expansion), the ZTE effect in YbGaGe (see crystal structure) is caused by the change in the valency of the ytterbium ion from +2.6 to +2 with decreasing temperature. This change in the valence state compensates for the contraction of the net as the temperature decreases.

    4. Unusually Slow Charge Recombination in Molecular Dyads (pages 4985–4987)

      Anthony Harriman

      Version of Record online: 26 JUL 2004 | DOI: 10.1002/anie.200301762

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      Shedding new light on the matter: Rather than the conventional approach of utilizing the cascade effect, charge separation can be stabilized in artificial photosynthetic systems simply by the geometry. In these latter systems, light-induced charge separation (CS) in a closely spaced molecular dyad is followed by exceptionally slow charge recombination (CR, see picture) to give a charge-separated state with a lifetime of up to 120 s.

    5. Ionic Liquids for the Convenient Synthesis of Functional Nanoparticles and Other Inorganic Nanostructures (pages 4988–4992)

      Markus Antonietti, Daibin Kuang, Bernd Smarsly and Yong Zhou

      Version of Record online: 27 AUG 2004 | DOI: 10.1002/anie.200460091

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      Crystalline nanoparticles can be prepared at ambient temperatures in ionic liquids—highly polar organic solvents with a preorganized solvent structure. The pronounced self-organization of the solvent is used in the synthesis of highly organized hybrid nanostructures like the lamellar silica shown in the picture.

    6. Methods for the Chemical Synthesis of Fullerenes (pages 4994–5007)

      Lawrence T. Scott

      Version of Record online: 9 SEP 2004 | DOI: 10.1002/anie.200400661

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      From corannulene to C60: Geodesic polyarenes can be synthesized in the laboratory by bending flat molecules and stitching them up into molecular bowls, baskets, and balls, using rational chemical methods.

    7. A Highly Luminescent Europium Complex Showing Visible-Light-Sensitized Red Emission: Direct Observation of the Singlet Pathway (pages 5010–5013)

      Chi Yang, Li-Min Fu, Yuan Wang, Jian-Ping Zhang, Wing-Tak Wong, Xi-Cheng Ai, Yi-Fang Qiao, Bing-Suo Zou and Lin-Lin Gui

      Version of Record online: 14 JUL 2004 | DOI: 10.1002/anie.200454141

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      Red glow in daylight … chemist's delight! An efficient transfer of excitation energy from the ligand to the luminescent states of the coordinated EuIII ion in 1 occurs from the singlet excited state of the ligand. The complex shows characteristic bright red Eu-centered emission with a quantum yield of 0.52 when sensitized with visible light.

    8. Direct Visual Detection of the Stereoselectivity of a Catalytic Reaction (pages 5013–5016)

      Rienk Eelkema, Richard A. van Delden and Ben L. Feringa

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460822

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      Color vision: The enantiomeric excess of the products of an enantioselective catalytic reaction can be determined by a liquid-crystal-based color test. After a simple workup, doping of the reaction product into a liquid crystal affords brightly colored LC phases, with colors depending on the enantiomeric excess of the product (see picture).

    9. Kinetic Self-Assembly: Selective Cross-Catenation of Two Sterically Differentiated PdII-Coordination Rings (pages 5016–5019)

      Akiko Hori, Ken-ichi Yamashita and Makoto Fujita

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460671

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      Magic rings: The trick of kinetically controlled cross-catenation of two different PdII-linked coordination rings (see picture) lies in the large difference in the catenation rate of the two rings as a result of steric hindrance of the ligands.

    10. Remarkably Facile Ring-Size Control in Macrocyclization: Synthesis of Hemicucurbit[6]uril and Hemicucurbit[12]uril (pages 5019–5022)

      Yuji Miyahara, Kenta Goto, Masakazu Oka and Takahiko Inazu

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460764

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      A question of concentration: The condensation of ethyleneurea and formaldehyde can be controlled perfectly by the HCl concentration to provide either a hemicucurbit[6]uril 1, which functions as a host, or hemicucurbit[12]uril 2, which acts as a gelating agent, in yields of 94 and 93 %, respectively.

    11. Superclusters: A Host–Guest Complex with a Cyclic Array of Three Bridged MoFe3S4 Clusters (pages 5023–5025)

      Markos Koutmos and Dimitri Coucouvanis

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460154

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      Three reversible reductions are observed for a new cyclic tricubane cluster. In the solid state, the cluster displays a large, electron-rich pocket containing an encapsulated Et4N+ ion (see structure). These characteristics might allow the use of this cluster as a multielectron reducing agent.

    12. Vitamin B12 as a Ligand for Technetium and Rhenium Complexes (pages 5025–5029)

      Susanne Kunze, Fabio Zobi, Philipp Kurz, Bernhard Spingler and Roger Alberto

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460923

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      Robust complexes with a central {Co-CN-Re(Tc)} feature are formed when the cyanide ligand in vitamin B12 acts as bridging ligand between rhenium and technetium carbonyl complexes (see picture). This concept paves the way for radiolabeling of vitamin B12 or metal-mediated coupling of bioactive molecules.

    13. Linear, Redox-Active Pt6 and Pt2Pd2Pt2 Clusters (pages 5029–5032)

      Eri Goto, Rowshan A. Begum, Shuzhong Zhan, Tomoaki Tanase, Katsumi Tanigaki and Ken Sakai

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460707

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      A piece of jewelry is the complex [Pt4M2(μ-H)(μ-dpmp)4(XylNC)2](PF6)3 (M=Pt, see structure), which contains the longest platinum chain characterized so far. This complex and the related compound with M=Pd are redox-active and can be readily oxidized to the electron-deficient clusters [Pt4M2(μ-dpmp)4(XylNC)2](PF6)4 (M=Pt, Pd) with dynamic structural changes in the metal strings. Xyl=2,6-dimethylphenyl, dpmp=bis(diphenylphosphanylmethyl)phenylphosphane.

    14. Rigid and Flexible: A Highly Porous Metal–Organic Framework with Unusual Guest-Dependent Dynamic Behavior (pages 5033–5036)

      Danil N. Dybtsev, Hyungphil Chun and Kimoon Kim

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460712

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      A large H2sorption capacity and high surface area are properties of the depicted metal–organic porous material, which is easily synthesized on a large scale from readily available chemicals. The rigid framework of [Zn2(1,4-bdc)2(dabco)] (1,4-H2bdc=1,4-benzenedicarboxylic acid; dabco=diazabicyclo[2.2.2]octane) is also flexible enough to exhibit unusual guest-dependent dynamic behavior, as shown (DMF=N,N-dimethylformamide).

    15. Interlocked and Interdigitated Architectures from Self-Assembly of Long Flexible Ligands and Cadmium Salts (pages 5036–5040)

      Xin-Long Wang, Chao Qin, En-Bo Wang, Lin Xu, Zhong-Min Su and Chang-Wen Hu

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460758

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      Noninterpenetrating structures are formed by self-assembly of cadmium salts and long flexible ligands. In one case exceptional ninefold interlocked homochiral helices are built from achiral components (see picture). The helices are chemically independent but physically interwoven. This represents the highest degree of entanglement presently known for a noninterpenetrating system.

    16. Recognition of Polyimide Sequence Information by a Molecular Tweezer (pages 5040–5045)

      Howard M. Colquhoun and Zhixue Zhu

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460382

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      Specific monomer sequences in aromatic copolyimides are recognized through their π-stacking and hydrogen-bonding interactions with a sterically and electronically complementary molecular tweezer. These interactions enable the tweezer molecule to “read” monomer sequences comprising up to 27 aromatic rings by multiple adjacent binding to neighboring sites on the polymer chain (see picture).

    17. C[BOND]C Coupling and C[BOND]H Bond Activation—Unexpected Pathways in the Reactions of [Yb(η5-C13H9)2(thf)2] with Diazadienes (pages 5045–5048)

      Alexander A. Trifonov, Elena A. Fedorova, Georgy K. Fukin, Nikolai O. Druzhkov and Mikhail N. Bochkarev

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200461001

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      A couple of surprises: The reactions of [(C13H9)2Yb(thf)2] with diazadienes (2,6-iPr2C6H3)N[DOUBLE BOND]CR[BOND]CR[DOUBLE BOND]N(2,6-iPr2C6H3) (R=H, Me) result in unexpected YbII complexes, which arise either from the coupling of the fluorene and the diazadiene ligands (when R=H, see picture) or from C[BOND]H bond activation of the diazadiene ligand (when R=Me).

    18. Metastable Vanadium Dioxide Nanobelts: Hydrothermal Synthesis, Electrical Transport, and Magnetic Properties (pages 5048–5052)

      Junfeng Liu, Qiuhong Li, Taihong Wang, Dapeng Yu and Yadong Li

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460104

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      Made-to-measure nanobelts: Metastable vanadium dioxide single-crystal nanobelts (see picture) were prepared by a hydrothermal reduction method by treating an ammonium metavanadate solution with formic acid. The morphology of the belts could be adjusted by varying the reaction parameters, such as temperature, pH, and reaction time.

    19. Distannylation of Strained Carbon–Carbon Triple Bonds Catalyzed by a Palladium Complex (pages 5052–5055)

      Hiroto Yoshida, Kenji Tanino, Joji Ohshita and Atsutaka Kunai

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460189

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      Oxidative addition of a distannane to a palladium(0) complex occurs during the distannylation of in situ generated arynes with distannanes in the presence of a catalytic amount of a palladium/tert-octyl isocyanide (tOcNC) complex to give 1,2-distannylarenes in moderate to high yields (see scheme). Bisarynes and cyclohexynes can also be used as substrates for the reaction.

    20. A Weak Attractive Interaction between Organic Fluorine and an Amide Group (pages 5056–5059)

      Fraser Hof, Denise M. Scofield, W. Bernd Schweizer and François Diederich

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460781

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      A combination of a chemical double-mutant cycle and a linear free energy relationship has demonstrated that a weak attractive interaction (−0.8 to −1.5 kJ mol−1) exists between an organic fluorine substituent and the face of an amide functional group (see picture). This study supports recent results that have suggested that such an attraction may be operative in enzyme–inhibitor interactions.

    21. Supramolecular Dynamics of Cyclic [6]Paraphenyleneacetylene Complexes with [60]- and [70]Fullerene Derivatives: Electronic and Structural Effects on Complexation (pages 5060–5062)

      Takeshi Kawase, Naoki Fujiwara, Masaki Tsutumi, Masaji Oda, Yutaka Maeda, Takatsugu Wakahara and Takeshi Akasaka

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460630

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      Stable inclusion complexes are formed between a carbon nanoring and C70 as well as methano[70]fullerene derivatives. 1H NMR spectroscopic studies show that at low temperatures the guest molecules are situated either above or below the center of the cavity. The presence of the bulky ester groups results in the interconversion between the complexes (see scheme, ΔG ≈ 11.0 kcal mol−1) being faster than decomplexation.

    22. Synthesis of Highly Substituted 1,3-Butadienes by Palladium-Catalyzed Arylation of Internal Alkynes (pages 5063–5065)

      Tetsuya Satoh, Shinji Ogino, Masahiro Miura and Masakatsu Nomura

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460409

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      Four molecules are coupled together by the single treatment of aryl boronic acids with alkynes in the absence or presence of iodobenzene under palladium catalysis to afford 1,4-diaryl-1,3-butadienes as the major product. Addition of a silver salt as oxidant and/or base effectively enables the selective catalytic production of the π-conjugated compounds.

    23. Enantioselective Hydrogenation of β-Ketoesters with Monodentate Ligands (pages 5066–5069)

      Kathrin Junge, Bernhard Hagemann, Stephan Enthaler, Günther Oehme, Manfred Michalik, Axel Monsees, Thomas Riermeier, Uwe Dingerdissen and Matthias Beller

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460190

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      Efficient and stable chiral monodentate phosphine ligands can be used in the ruthenium-catalyzed enantioselective hydrogenation of β-ketoesters (see scheme). The catalysts are remarkably temperature-tolerant, and enantioselectivities of up to 95 % ee are possible, even at 100–120 °C. R=C6H5, p-CH3OC6H4, p-CF3OC6H4, iPr, Et, C6D5.

    24. A Linear Free Energy Relationship for Gas-Solid Interactions: Correlation between Surface Rate Constant and Diffusion Coefficient of Oxygen Tracer Exchange for Electron-Rich Perovskites (pages 5069–5073)

      Rotraut Merkle, Joachim Maier and Henny J. M. Bouwmeester

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460081

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      The variation of the activation enthalpy for surface oxygen exchange equation imageO2+equation imageequation image+2 h. with sample composition in (Ln,Sr)(Mn,Fe,Co)O3−z perovskites is rigidly coupled to the variation of the overall reaction enthalpy (see picture). This is the first mechanistically well-established example of a Hammett-like relationship for inorganic gas-solid reactions.

    25. A Sleeping Host Awoken by Its Guest: Recognition and Sensing of Imidazole-Containing Molecules Based on Double Cu2+ Translocation inside a Polyaza Macrocycle (pages 5073–5077)

      Luigi Fabbrizzi, Francesco Foti, Stefano Patroni, Piersandro Pallavicini and Angelo Taglietti

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460568

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      pH-driven double Cu2+ion translocation occurs inside an heteroditopic macrocycle. The movement opens and closes the system allowing or preventing it to function as receptor for bidentate anions. When imidazole is added to a solution buffered at an appropriate pH value, opening of the system and substrate binding can be induced by the substrate itself, which results in a sharp color change (see picture).

    26. Inverted N-Confused Porphyrin Dimer (pages 5077–5081)

      Tomoya Ishizuka, Atsuhiro Osuka and Hiroyuki Furuta

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200460017

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      A covalently linked N-fused porphyrin dimer was synthesized by treatment of the monomer with Ag(OCOCF3). Subsequent reaction of this dimer with NaOMe led to a porphyrin dimer with two α,β-bound (“confused”) pyrrole rings (see scheme) which adopt the inverted conformation. The dimer exhibits aromaticity in spite of its highly distorted structure.

    27. Unusual Reactivity at a Platinum Center Determined by the Ligands and the Solvent Environment (pages 5081–5084)

      Gabriella Tamasi, Renzo Cini, Francesco P. Intini, Maria F. Sivo and Giovanni Natile

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200454111

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      The use of ancillary ligands resulted in the formation of (trans-[PtCl3(OH2){N[DOUBLE BOND]C(OCH3)CH2CH2CH2}2]+ (see structure), the first intermediate aqua species in the oxidation of platinum(II) to platinum(IV) to be isolated and characterized. In chloroform this complex, but not the corresponding chloro species, reacts with excess Cl with O-demethylation of the ligands, indicating the importance of the coordinated water molecule.

    28. Organic–Inorganic Hybrid Nanoparticles with a Complex Hollow Structure (pages 5084–5087)

      Jianzhong Du and Yongming Chen

      Version of Record online: 3 SEP 2004 | DOI: 10.1002/anie.200454244

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      Secret chambers: Organic–inorganic hybrid nanoparticles (see picture) with a complex hollow structure were prepared by the self-assembly of a reactive block copolymer, poly(ethylene oxide)-block-poly[3-(trimethoxysilyl)propyl methacrylate], in DMF/water. Within these hybrid large-compound vesicles, several cavities are separated by crosslinked hybrid bilayers of uniform thickness.

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      Total Synthesis of Thiostrepton, Part 1: Construction of the Dehydropiperidine/Thiazoline-Containing Macrocycle (pages 5087–5092)

      K. C. Nicolaou, Brian S. Safina, Mark Zak, Anthony A. Estrada and Sang Hyup Lee

      Version of Record online: 3 SEP 2004 | DOI: 10.1002/anie.200461340

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      A cornerstone of the RNA-binding antibiotic thiostrepton, namely the dehydropiperidine–thiazoline macrocyclic domain (see formula), was constructed through a hetero-Diels–Alder-type dimerization of an azadiene and selective elaboration of the resulting dehydropiperidine system.

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      Total Synthesis of Thiostrepton, Part 2: Construction of the Quinaldic Acid Macrocycle and Final Stages of the Synthesis (pages 5092–5097)

      K. C. Nicolaou, Mark Zak, Brian S. Safina, Sang Hyup Lee and Anthony A. Estrada

      Version of Record online: 3 SEP 2004 | DOI: 10.1002/anie.200461341

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      The flagship of the thiopeptide class of antibiotics, thiostrepton (see formula), was synthesized by fusion of the quinaldic acid moiety onto the dehydropiperidine–thiazoline macrocycle (see above) followed by demasking of its sensitive functionalities.

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      Preview: Angew. Chem. Int. Ed. 38/2004 (page 5101)

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/anie.200490134