Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 37

September 20, 2004

Volume 43, Issue 37

Pages 4817–4963

    1. Cover Picture: Generation of Dynamic Constitutional Diversity and Driven Evolution in Helical Molecular Strands under Lewis Acid Catalyzed Component Exchange (Angew. Chem. Int. Ed. 37/2004) (page 4817)

      Nicolas Giuseppone, Jean-Louis Schmitt and Jean-Marie Lehn

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200490128

      Helices and grids two most fascinating architectures, which have been the subject of intense recent studies in view of their significance in chemistry, biology, and material science, are represented in the cover picture. They are interconnected in a thermodynamic equilibrium generated by a Lewis acid catalyzed pathway involving a constitutional dynamic reorganization, self-assembly, and control of helical folding. For further details see the Communication by J.-M. Lehn et al. on page 4902 ff.

    2. Graphical Abstract: Angew. Chem. Int. Ed. 37/2004 (pages 4820–4828)

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200490129

    3. You have free access to this content
    4. You have free access to this content
      On the Way to “Solid Nitrogen” at Normal Temperature and Pressure? Binary Azides of Heavier Group 15 and 16 Elements (pages 4834–4836)

      Carsten Knapp and Jack Passmore

      Article first published online: 20 AUG 2004 | DOI: 10.1002/anie.200401748

      Thumbnail image of graphical abstract

      Caution explosive! Homoleptic azides are of great interest as polynitrogen compounds particularly because of their high energy content. A recent breakthrough is the first synthesis and characterization of the highly sensitive neutral tellurium azide [Te(N3)4] and of ionic (N5)+[P(N3)6] containing 23 nitrogen atoms.

    5. Elisabethin A: A Marine Diterpenoid Yet To Surrender to Total Synthesis (pages 4837–4841)

      Giuseppe Zanoni and Maurizio Franzini

      Article first published online: 3 SEP 2004 | DOI: 10.1002/anie.200460570

      Thumbnail image of graphical abstract

      Mysterious and elusive, elisabethin A (1, pictured with the West Indian sea whip Pseudopterogorgia elisabethae from which it was isolated), has not yet succumbed to total synthesis—or has it? Two recent attempts at the synthesis of this challenging target are examined, but questions still remain as to the absolute configuration of the natural product and the synthetic material.

    6. Color Theory in Science and Art: Ostwald and the Bauhaus (pages 4842–4847)

      Philip Ball and Mario Ruben

      Article first published online: 4 AUG 2004 | DOI: 10.1002/anie.200430086

      Thumbnail image of graphical abstract

      A historical confluence of the streams of science and art took place in Dessau, Germany, in 1927. The main participants were the artists of the Bauhaus School (represented by a painting by Kandinsky, left) and the Nobel Laureate and avid painter Wilhem Ostwald, who presented his theory of color (the basis for the etching on the right).

    7. DNA-Templated Organic Synthesis: Nature's Strategy for Controlling Chemical Reactivity Applied to Synthetic Molecules (pages 4848–4870)

      Xiaoyu Li and David R. Liu

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200400656

      Thumbnail image of graphical abstract

      A surprisingly general way to control reactivity uses DNA base pairing to modulate the effective molarity of synthetic reactants. This approach mimics biosynthesis and enables complex mixtures in a single solution to react with efficiencies and selectivities that cannot be achieved using conventional laboratory synthesis (see scheme).

    8. Synthesis and Thermal Ring Opening of trans-3,4-Disilylcyclobutene (pages 4874–4876)

      Masahiro Murakami and Munehiro Hasegawa

      Article first published online: 20 AUG 2004 | DOI: 10.1002/anie.200460144

      Thumbnail image of graphical abstract

      A true test of the power of electronic stabilization is provided by a ring-opening reaction of trans-3,4-bis(trimethylsilyl)cyclobutene. The two bulky silyl groups prefer inward rotation, despite the steric constraints. Electronic stabilization arising from the delocalization of the HOMO electron density into the two antibonding orbitals overcomes the steric congestion (see picture).

    9. Catenation of Two Singlet Diradicals: Synthesis of a Stable Tetraradical (Tetraradicaloid) (pages 4876–4880)

      Amor Rodriguez, Fook S. Tham, Wolfgang W. Schoeller and Guy Bertrand

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460473

      Thumbnail image of graphical abstract

      Counting the calories: The coupling of two PBPB diradicals through an antiferromagnetic linker affords a singlet tetraradical, whereas when they are coupled through a ferromagnetic linker, a bis(bicyclic) system is obtained (see picture). The energy difference between the planar form and the bicyclic isomer of substituted PBPB derivatives is only a matter of a few kcal mol−1, thus a few kcal mol−1 can make a tremendous difference.

    10. Evidence for the Coexistence of Two Bond-Stretch Isomers in Solution (pages 4880–4883)

      Amor Rodriguez, Ryan A. Olsen, Nima Ghaderi, David Scheschkewitz, Fook S. Tham, Leonard J. Mueller and Guy Bertrand

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460475

      Thumbnail image of graphical abstract

      Lowering the temperature breaks the σ bond in the interconversion of 1,3-dibora-2,4-diphosphoniocyclobutane-1,3-diyl and its bicyclo[1.1.0]butane bond-stretch isomer (see picture). Variable-temperature NMR and UV/Vis experiments demonstrate for the first time the existence of two bond-stretch isomers that feature a transannular bonding π overlap, which allows for the thermal ring closure and opening processes.

    11. Solution Structure and Reagent Binding of the Zinc Alkoxide Catalyst in the Soai Asymmetric Autocatalytic Reaction (pages 4884–4887)

      Ilya D. Gridnev, Jörg M. Serafimov and John M. Brown

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200353572

      Thumbnail image of graphical abstract

      All square: A {ZnO}2 square resting state in autocatalysis is revealed by NMR spectroscopy and endorsed by DFT calculations (see picture). Its dynamic behavior and reversible binding of excess iPr2Zn are defined.

    12. Isolation, Crystal and Solution Structure Determination, and Biosynthesis of Tubulysins—Powerful Inhibitors of Tubulin Polymerization from Myxobacteria (pages 4888–4892)

      Heinrich Steinmetz, Nicole Glaser, Eberhardt Herdtweck, Florenz Sasse, Hans Reichenbach and Gerhard Höfle

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460147

      Thumbnail image of graphical abstract

      Myxobacteria have it both ways: Whereas the epothilones stabilize the tubulin cytoskeleton and build microtubuli, tubulysins, which have now been isolated from Archangium gephyra and Angiococcus disciformis, have exactly the opposite effect. They induce the disintegration of the microtubuli, and even picomolar concentrations can cause cell death by apoptosis. Their effect on cell cultures exceeds that of the most active epothilones by 50-fold.

    13. The Topotactic Conversion of a Novel Layered Silicate into a New Framework Zeolite (pages 4892–4896)

      Takuji Ikeda, Yoshikatsu Akiyama, Yasunori Oumi, Akiko Kawai and Fujio Mizukami

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460168

      Thumbnail image of graphical abstract

      High-density silicate sheets made up of five-membered rings with Me4NOH molecules and K+ ions in the porelike interlayer space: This is the structure of the silicate PLS-1. When PLS-1 (left picture) was heated above 673 K under vacuum, the novel zeolite CDS-1 (right picture) was obtained as the result of topotactic dehydration–condensation reactions. CDS-1 is a pure silicate and thermally stable, and should therefore find a range of industrial uses.

    14. Supramolecular Self-Assembly of Giant Polymer Vesicles with Controlled Sizes (pages 4896–4899)

      Yongfeng Zhou and Deyue Yan

      Article first published online: 30 AUG 2004 | DOI: 10.1002/anie.200460325

      Thumbnail image of graphical abstract

      An ill-defined hyperbranched multiarm copolymer (see picture) with a high hydrophilic fraction (>60 %) self-assembles in water to form giant polymer vesicles (branched polymersomes). The size of the branched polymersomes can be easily controlled by adjusting the hydrophilic fraction of the copolymer, with the average diameter of the larger branched polymersomes exceeding 100 μm.

    15. WO2Cl2 Nanotubes and Nanowires (pages 4899–4902)

      A. Robert Armstrong, Jesus Canales and Peter G. Bruce

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460334

      Thumbnail image of graphical abstract

      Mixed-anion nanotubes and nanowires have been synthesized, for the first time, by a simple process of exfoliation and restacking. The WO2Cl2 (oxyhalide) nanotubes and nanowires (see picture) may have some properties of both the halide and oxide anions.

    16. Generation of Dynamic Constitutional Diversity and Driven Evolution in Helical Molecular Strands under Lewis Acid Catalyzed Component Exchange (pages 4902–4906)

      Nicolas Giuseppone, Jean-Louis Schmitt and Jean-Marie Lehn

      Article first published online: 14 JUL 2004 | DOI: 10.1002/anie.200460343

      Thumbnail image of graphical abstract

      A stir in the library: The efficient Sc(OTf)3-catalyzed transimination of helical oligohydrazone strands has been utilized to yield a highly diverse constitutional dynamic library through assembly, dissociation, and exchange of components. This library can subsequently undergo driven evolution in the presence of ZnII ions to express preferentially [2×2] gridlike arrays by component recombination.

    17. A Unidirectional DNA Walker That Moves Autonomously along a Track (pages 4906–4911)

      Peng Yin, Hao Yan, Xiaoju G. Daniell, Andrew J. Turberfield and John H. Reif

      Article first published online: 30 AUG 2004 | DOI: 10.1002/anie.200460522

      Thumbnail image of graphical abstract

      There's no turning back for an autonomous DNA walker that moves along a self-assembled track, driven by the hydrolysis of ATP. The track contains three anchorages (A, B, C) at which the walker (★), a six-nucleotide DNA fragment, can be bound (see figure). The motion of the walker is unidirectional. At each step it is ligated to the next anchorage, then cut from the previous one by a restriction endonuclease.

    18. Unusual Magnetic Metal–Cyanide Cubes of ReII with Alternating Octahedral and Tetrahedral Corners (pages 4912–4915)

      Eric J. Schelter, Andrey V. Prosvirin, William M. Reiff and Kim R. Dunbar

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460614

      Thumbnail image of graphical abstract

      Two cyanide-bridged molecular cubes of general formula [{MCl}4{ReII(triphos)(CN)3}4], M=Fe, Co (depicted), triphos=1,1,1-tris(diphenylphosphanylmethyl)ethane, and their magnetic properties are reported. The cubes are prepared in good yields from the reaction of the ReII complex [Et4N][ReII(triphos)(CN)3] with the appropriate divalent metal halide and consist of octahedral ReII and tetrahedral M corners bridged by cyanide ligands.

    19. One-Pot Optical Resolution of Oligopeptide Helices through Artificial Peptide Bundling (pages 4915–4918)

      Yan-Ming Guo, Hideaki Oike, Naoko Saeki and Takuzo Aida

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460703

      Thumbnail image of graphical abstract

      The helical sense of the peptidic parts of a cyclodimeric zinc porphyrin host with helical oligopeptide units (1) determines whether a right- or left-handed oligopeptide guest (2) is selectively bound (see picture). In contrast, enantiomers of nonhelical peptidic guests containing a point chirality are hardly discriminated.

    20. You have free access to this content
      High-Energy-Density Materials: Synthesis and Characterization of N5+[P(N3)6], N5+ [B(N3)4], N5+ [HF2]n HF, N5+ [BF4], N5+ [PF6], and N5+ [SO3F] (pages 4919–4924)

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

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200454242

      Thumbnail image of graphical abstract

      23 nitrogens and only one phosphorus: The N5+ ion is combined with energetic anions in the form of N5+ [P(N3)6] and N5+ [B(N3)4] (see scheme), containing 91 and 96 wt %, respectively, of nitrogen. Also, the thermally unstable compound N5HF2n HF is prepared by metathesis from N5SbF6 and CsHF2. Its usefulness as a reagent for the synthesis of new N5+ salts is demonstrated with the preparation of N5PF6, N5BF4, and N5SO3F.

    21. You have free access to this content
      Polyazido High-Nitrogen Compounds: Hydrazo- and Azo-1,3,5-triazine (pages 4924–4928)

      My-Hang V. Huynh, Michael A. Hiskey, Ernest L. Hartline, Dennis P. Montoya and Richard Gilardi

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460366

      Thumbnail image of graphical abstract

      20 nitrogens and six carbons: The compounds 1 and 2, demonstrate that hydrazo and azo linkages can be used to desensitize polyazido high-nitrogen compounds and also decrease their volatility. The compound 2 has the highest experimentally measured heat of formation reported for energetic organic compounds (+2171 kJ mol−1).

    22. Synthesis and Self-Assembly of Organoclay-Wrapped Biomolecules (pages 4928–4933)

      Avinash J. Patil, Eswaramoorthy Muthusamy and Stephen Mann

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200453868

      Thumbnail image of graphical abstract

      Gift wrapped: Biomolecules can be enveloped within an ultrathin shell of an aminopropyl-functionalized magnesium (organo)phyllosilicate to produce aqueous dispersions of discrete protein–inorganic nanoparticles. Similar procedures but with organoclay oligomers that have pendent long-chain hydrophobic moieties result in self-assembly of the protein–inorganic nanoparticles into higher-order superstructures (see picture).

    23. Crystal Structure Determination of Zeolite Nu-6(2) and Its Layered Precursor Nu-6(1) (pages 4933–4937)

      Stefano Zanardi, Alberto Alberti, Giuseppe Cruciani, Avelino Corma, Vicente Fornés and Michela Brunelli

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460085

      Thumbnail image of graphical abstract

      A small-pore pentasil zeolite (Nu-6(2)), which has a new topology, is obtained by thermal treatment of the 4,4′-bipyridyl silicate Nu-6(1). Crystal structure solution of the new zeolite and its layered precursor was achieved by combining high resolution X-ray powder pattern, direct methods, and model building. Nu-6(2) is characterized by a 1D channel system of two independent sets of eight-membered rings (see picture).

    24. Polynuclear Olefin Polymerization Catalysis: Proximity and Cocatalyst Effects Lead to Significantly Increased Polyethylene Molecular Weight and Comonomer Enchainment Levels (pages 4937–4940)

      Hongbo Li, Liting Li and Tobin J. Marks

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460288

      Thumbnail image of graphical abstract

      Weight watching: In ethylene polymerization, approximately 70 fold increases in molecular weight are achieved with C1-Zr2 compared to ethylene-bridged C2-Zr2 (see scheme). With MAO as the cocatalyst, approximately 600 fold increases in polyethylene (PE) molecular weight are achieved with C2-Zr2Cl4 and C1-Zr2Cl4 compared to a mononuclear analogue. These results support the argument that Zr–Zr proximity significantly influences chain-transfer rates, and such effects are highly cocatalyst-sensitive.

    25. Tetranuclear Homo- and Heteroalumoxanes Containing Reactive Functional Groups: Syntheses and X-ray Crystal Structures of [{[LAl(Me)](μ-O)(MH2)}2] (pages 4940–4943)

      Sanjay Singh, S. Shravan Kumar, Vadapalli Chandrasekhar, Hans-Jürgen Ahn, Marianna Biadene, Herbert W. Roesky, Narayan S. Hosmane, Mathias Noltemeyer and Hans-Georg Schmidt

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460395

      Thumbnail image of graphical abstract

      A core with corners: The first alumoxane containing an {Al4O2} core as well as a gallium congener with an {Al2Ga2O2} core are prepared by the reaction of an organoaluminum monohydroxide with MH3⋅NMe3 (see formula; M=Al, Ga; Ar=2,6-iPr2C6H3). These compounds contain reactive hydride groups on the central M2O2 rings and methyl groups on the terminal aluminum atoms.

    26. Diazene Complexes of Copper: Synthesis, Spectroscopic Analysis, and Electronic Structure (pages 4944–4947)

      Kiyoshi Fujisawa, Nicolai Lehnert, Yoko Ishikawa and Ken-ichi Okamoto

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460415

      Thumbnail image of graphical abstract

      A strong antibonding π interaction has been shown by density functional calculations (see LUMO MO graph) to be a key characteristic of two new CuI–diazene complexes with hydrotris(pyrazolyl)borate ligands. The complexes have been further characterized by X-ray crystallography as well as 1H NMR, UV/Vis absorption, IR, far-IR, and resonance Raman spectroscopy.

    27. Arylbis(9-anthryl)methyl Cations: Highly Crowded, Near Infrared Light Absorbing Hydrocarbon Cations (pages 4947–4950)

      Yuichi Nishimae, Hiroyuki Kurata and Masaji Oda

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460480

      Thumbnail image of graphical abstract

      The highly crowded arylbis(9-anthryl)methyl cations (structure shown) have now been prepared. Their stability is due to the doubly benzo-annelated structure of anthracene, which prevents Nazarov-type cyclization from taking place. The most remarkable feature of these cations is that they exhibit strong absorptions in the near-infrared region (λmax=855–946 nm) in trifluoroacetic acid. Ar=p-anisyl, 1-naphthyl, 2-naphthyl, phenyl, p-tolyl.

    28. A Practical and Mild Method for the Highly Selective Conversion of Terminal Alkenes into Aldehydes through Epoxidation–Isomerization with Ruthenium(IV)–Porphyrin Catalysts (pages 4950–4954)

      Jian Chen and Chi-Ming Che

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460545

      Thumbnail image of graphical abstract

      Aldehydes in excellent yields were obtained from the ruthenium–porphyrin-catalyzed oxidation of various terminal alkenes with 2,6-dichloropyridine N-oxide under mild conditions. The aldehydes generated from these ruthenium-catalyzed alkene oxidations can be used in situ for olefination reactions with ethyl diazoacetate in the presence of PPh3 in a one-pot diazoacetate olefination starting from alkenes (see example).

    29. Supramolecular Assembly of Luminescent Gold(I) Alkynylcalix[4]crown-6 Complexes with Planar η22-Coordinated Gold(I) Centers (pages 4954–4957)

      Sung-Kong Yip, Eddie Chung-Chin Cheng, Li-Hua Yuan, Nianyong Zhu and Vivian Wing-Wah Yam

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200460744

      Thumbnail image of graphical abstract

      Au⋅⋅⋅Au interactions between the gold(I) centers arranged in a planar rhomboidal array in a novel class of luminescent tetranuclear gold(I) alkynylcalix[4]crown-6 complexes (see picture) give rise to rich luminescence behavior, with long-lived excited states and relatively high luminescence quantum yields.

    30. You have free access to this content
      Preview: Angew. Chem. Int. Ed. 37/2004 (page 4963)

      Article first published online: 16 SEP 2004 | DOI: 10.1002/anie.200490131

SEARCH

SEARCH BY CITATION