Angewandte Chemie International Edition

Cover image for Vol. 45 Issue 27

July 3, 2006

Volume 45, Issue 27

Pages 4383–4525

    1. Cover Picture: Formation of Self-Organized Dynamic Structure Patterns of Barium Carbonate Crystals in Polymer-Controlled Crystallization (Angew. Chem. Int. Ed. 27/2006) (page 4383)

      Tongxin Wang, An-Wu Xu and Helmut Cölfen

      Version of Record online: 28 JUN 2006 | DOI: 10.1002/anie.200690092

      The Belousov–Zhabotinsky reaction with its typical concentric ring pattern is described for a precipitation for the first time by T. Wang, A.-W. Xu, and H. Cölfen in their Communication on page 4451 ff. The formation and self-organization of BaCO3 nanoparticles can be directed with a new phosphonated block copolymer: short to ultralong nanofibers and, ultimately, ring patterns are obtained. This system could help to explain natural pattern formation. The cover picture shows observed and simulated Belousov–Zhabotinsky ring patterns, as well as the molecular structure of the block copolymer.

    2. Functional Molecular Assemblies (pages 4396–4398)

      Jim A. Thomas

      Version of Record online: 28 JUN 2006 | DOI: 10.1002/anie.200602068

    3. Hypervalent Iodine Goes Catalytic (pages 4402–4404)

      Robert D. Richardson and Thomas Wirth

      Version of Record online: 28 JUN 2006 | DOI: 10.1002/anie.200601817

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      A dash of iodine: Different reactions relying on the power of hypervalent iodine reagents can now be performed with catalytic amounts of these compounds and a stoichiometric oxidant. Oxidations of alcohols, α-functionalizations of ketones, and spirocyclizations of phenol derivatives are possible.

    4. Stereochemical Uniformity in Marine Polyether Ladders—Implications for the Biosynthesis and Structure of Maitotoxin (pages 4406–4413)

      Andrew R. Gallimore and Jonathan B. Spencer

      Version of Record online: 12 JUN 2006 | DOI: 10.1002/anie.200504284

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      Odd one out: Marine polyether ladders are probably the most well-known of all marine natural products, not only for their fascinating structures, but also for their characteristic toxicity. A very straightforward model for the biosynthesis of all known polyether ladders, including maitotoxin (the largest and most toxic of this structural family; see formula) is described, but is the structure of this giant molecule really known?

    5. Shape-Persistent Macrocycles: Structures and Synthetic Approaches from Arylene and Ethynylene Building Blocks (pages 4416–4439)

      Wei Zhang and Jeffrey S. Moore

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200503988

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      Balance control: Kinetically controlled cyclooligomerization is impeded by the formation of higher oligomers (“overshooting”). Under reversible conditions, the product distribution is determined by the thermodynamic stability, which is balanced by both entropic and enthalpic factors. Methods based on dynamic covalent chemistry and the use of the energy gap principle enable the formation of target macrocycles by cyclooligomerization to be controlled.

    6. Lipid-Anchored Oligonucleotides for Stable Double-Helix Formation in Distinct Membrane Domains (pages 4440–4444)

      Anke Kurz, Andreas Bunge, Anne-Katrin Windeck, Maximilian Rost, Wolfgang Flasche, Anna Arbuzova, Denise Strohbach, Sabine Müller, Jürgen Liebscher, Daniel Huster and Andreas Herrmann

      Version of Record online: 21 JUN 2006 | DOI: 10.1002/anie.200600822

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      Anchoring for DNA: A lipophilic oligonucleotide consisting of 21 thymidine units and two lipophilic nucleotides L was synthesized and bound to vesicular surfaces (see fluorescence image). The membrane-bound oligonucleotide binds complementary DNA strands by formation of Watson–Crick base pairs. The lipid-anchored oligonucleotide is preferentially enriched in liquid-disordered membrane domains.

    7. Chiral, Bichromophoric Silicones: Ordering Principles of Structural Units in Complex Molecules (pages 4444–4447)

      Heinz Langhals and Oswald Krotz

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200504477

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      Enantiomer or racemate? For compound 1 this question can be answered with one glance. Racemic starting material forms the meso form of 1 with the expected UV/Vis spectra of the chromophore, whereas the enantiomeric compounds display color shifts and large CD effects indicative of strong intramolecular exciton interactions.

    8. Al[BOND]Eu and Al[BOND]Yb Donor–Acceptor Bonds (pages 4447–4451)

      Michael T. Gamer, Peter W. Roesky, Sergey N. Konchenko, Paola Nava and Reinhart Ahlrichs

      Version of Record online: 7 JUN 2006 | DOI: 10.1002/anie.200600423

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      Opposites attract: The compounds [(η5-C5Me5)2Ln[BOND]Al(η5-C5Me5)] (Ln=Eu, Yb; see scheme) represent the first compounds with a bond between aluminum and a 4f metal. The bonds are predominantly electrostatic with insignificant charge-transfer and covalent contributions.

    9. Formation of Self-Organized Dynamic Structure Patterns of Barium Carbonate Crystals in Polymer-Controlled Crystallization (pages 4451–4455)

      Tongxin Wang, An-Wu Xu and Helmut Cölfen

      Version of Record online: 21 JUN 2006 | DOI: 10.1002/anie.200601038

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      Intelligent design? Depending on the starting pH, ultralong nanofibers (see picture; left) or patterns of concentric circles (right) are produced in the polymer-controlled crystallization of BaCO3. The ring patterns are the first examples of nanoparticle self-organization that can be described by a Belousov–Zhabotinsky formalism.

    10. Determination of the Relative Configuration of a Five-Membered Lactone from Residual Dipolar Couplings (pages 4455–4460)

      Christina M. Thiele, Andreas Marx, Robert Berger, Jana Fischer, Markus Biel and Athanassios Giannis

      Version of Record online: 8 JUN 2006 | DOI: 10.1002/anie.200503247

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      syn- oranti-pathy? Determination of the relative configuration of the α-methylene-γ-butyrolactone 1 failed by conventional NMR methods, because structures in the conformational space of both diastereoisomers exist that fulfill the restraints from NOE and 3J coupling data equally well. Homo- and heteronuclear residual dipolar couplings were measured which indicate that 1 is trans configured.

    11. Seemingly Simple Stereoelectronic Effects in Alkane Isomers and the Implications for Kohn–Sham Density Functional Theory (pages 4460–4464)

      Stefan Grimme

      Version of Record online: 31 MAY 2006 | DOI: 10.1002/anie.200600448

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      A theoretical disaster: In contrast to general opinion, modern density functional methods are not able to even qualitatively describe the overall energetics of simple alkylation reactions (see scheme). The main reason is that the currently used hybrid functionals almost completely neglect the generally relevant electron correlation effects for medium-range electron–electron distances.

    12. HgI2⋅As4S4: An Adduct from HgI2 Molecules and Undistorted As4S4 Cages (pages 4464–4467)

      Michael F. Bräu and Arno Pfitzner

      Version of Record online: 7 JUN 2006 | DOI: 10.1002/anie.200600690

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      Unrattled cage: From the reaction of HgI2, As, and S, an adduct of linear HgI2 units and undistorted As4S4 cages is formed with only weak intermolecular interactions (see picture; Hg gray, I violet, S yellow, As blue). For the first time in this class of compounds, no polycationic network of Hg and S atoms is obtained. The optimization of the total energy prevents the formation of Hg[BOND]S bonds and the cleavage of the As4S4 cage.

    13. Chemical Synthesis of Mesoporous Carbon Nitrides Using Hard Templates and Their Use as a Metal-Free Catalyst for Friedel–Crafts Reaction of Benzene (pages 4467–4471)

      Frederic Goettmann, Anna Fischer, Markus Antonietti and Arne Thomas

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200600412

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      In the footsteps of Liebig and Berzelius: A material first synthesized in 1834, carbon nitride (C3N4), was synthesized in a graphitic mesoporous form by using silica nanoparticles as templates. The resulting electron-rich solid is an active catalyst for the Friedel–Crafts acylation of benzene with hexanoyl chloride. Presumably the catalysis arises from a shift of electron density from the MOs of the catalyst to the unoccupied orbitals of benzene (see picture).

    14. Gold-Catalyzed Intramolecular Carbothiolation of Alkynes: Synthesis of 2,3-Disubstituted Benzothiophenes from (α-Alkoxy Alkyl) (ortho-Alkynyl Phenyl) Sulfides (pages 4473–4475)

      Itaru Nakamura, Takuma Sato and Yoshinori Yamamoto

      Version of Record online: 12 JUN 2006 | DOI: 10.1002/anie.200601178

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      Gold forms rings: AuCl-catalyzed cyclization of (α-alkoxy alkyl) (ortho-alkynyl phenyl) sulfides 1 proceeds under mild conditions to give 3-(α-alkoxy alkyl) benzothiophenes 2 in high yields for a wide range of substrates (see scheme). The starting materials are readily available through acetalization of ortho-bromobenzenethiol and subsequent Sonogashira coupling. This methodology provides an atom-economic route to sulfur-containing heteroarenes.

    15. Regio- and Enantioselective Epoxidation of Dienes by a Chiral Dioxirane: Synthesis of Optically Active Vinyl cis-Epoxides (pages 4475–4478)

      Christopher P. Burke and Yian Shi

      Version of Record online: 9 JUN 2006 | DOI: 10.1002/anie.200600840

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      Putting the O into olefins: A highly regio- and enantioselective epoxidation of conjugated dienes was developed using glucose-derived ketone 1 as catalyst and oxone (KHSO5) as oxidant to form vinyl cis-epoxides (see scheme).

    16. Control over Electron Transfer in Tetrathiafulvalene-Modified Single-Walled Carbon Nanotubes (pages 4478–4482)

      M. Ángeles Herranz, Nazario Martín, Stéphane Campidelli, Maurizio Prato, Georg Brehm and Dirk M. Guldi

      Version of Record online: 12 JUN 2006 | DOI: 10.1002/anie.200504354

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      Spaced out: Single-walled carbon nanotubes (SWNTs) with covalently linked tetrathiafulvalene (TTF) derivatives have been synthetized and fully characterized as potential donor–acceptor nanoconjugates. Near-infrared flourescence and transient absorption measurements showed that the charge recombination dynamics is a function of the spacer linking the two moieties and the donor ability of the different TTF derivatives.

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      Activators Regenerated by Electron Transfer for Atom-Transfer Radical Polymerization of (Meth)acrylates and Related Block Copolymers (pages 4482–4486)

      Wojciech Jakubowski and Krzysztof Matyjaszewski

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200600272

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      Staying active: The title method allows continuous and controlled polymerization with significantly less Cu catalyst than is required for conventional atom-transfer radical polymerization (as low as 10−3 mol % vs. monomer). The CuI activator is constantly regenerated by a reducing agent, which compensates for any loss of CuI as a result of radical termination reactions (see scheme).

    18. A Rhenium–Cyclohexane Complex with Preferential Binding of Axial C[BOND]H Bonds: A Probe into the Relative Ability of C[BOND]H, C[BOND]D, and C[BOND]C Bonds as Hyperconjugative Electron Donors? (pages 4486–4490)

      Douglas J. Lawes, Tamim A. Darwish, Timothy Clark, Jason B. Harper and Graham E. Ball

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200600313

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      Which bonds bind better? According to NMR experiments with the alkane complex [CpRe(CO)2(cyclohexane)] at low temperatures, complexation with an axial proton is preferred over that through an equatorial one by about 1.5 kJ mol−1. Calculations support this order of binding energies. The preference is proposed to be due to stronger electron donation through hyperconjugation from a C[BOND]H bond than from a C[BOND]C bond.

    19. A Redox-Active C3-Symmetric Triindole-Based Triazacyclophane (pages 4491–4494)

      Berta Gómez-Lor, Gunther Hennrich, Beatriz Alonso, Angeles Monge, Enrique Gutierrez-Puebla and Antonio M. Echavarren

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200600526

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      Spreading the charge: The highly stable dimeric radical cation of a C3-symmetric triazacyclophane (see picture), with the positive charge delocalized over the two molecules, offers an excellent model for the study of intermolecular communication depending on hole hopping.

    20. Overcrowded Organometallic Platinum(II) Complexes That Behave as Molecular Gears (pages 4494–4498)

      Raffaello Romeo, Salvatore Carnabuci, Lucia Fenech, Maria Rosaria Plutino and Alberto Albinati

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200600827

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      In gear: Dynamic 1H NMR studies on some organometallic platinum(II) compounds reveal a synchronism between rotation around the Pt[BOND]P bond and the oscillation of a phenanthroline ligand between two nonequivalent exchanging sites. The system behaves as a molecular-sized analogue of a mechanical gear (see picture; C gray, N blue, O red, P purple) whose dynamic properties can be tuned through small structural changes.

    21. Cyclopentadienylchromium Complexes of 1,2,3,5-Dithiadiazolyls: η2 π Complexes of Cyclic Sulfur–Nitrogen Compounds (pages 4498–4501)

      Hiu Fung Lau, Victor Wee Lin Ng, Lip Lin Koh, Geok Kheng Tan, Lai Yoong Goh, Tracey L. Roemmele, Sonja D. Seagrave and René T. Boeré

      Version of Record online: 8 JUN 2006 | DOI: 10.1002/anie.200600724

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      Diamagnetic π complexes are formed in the reaction between [{CpCr(CO)3}2] and dithiadiazolyl dimers [S2N2CR]2 (R=substituted phenyl rings) in which the heterocycles are η2-coordinated to the metal in endo (depicted) or exo fashion. The isomers interconvert in solution at room temperature. These complexes are remarkable for retaining intact the S[BOND]S bonds of the dithiadiazolyl radicals (C gray, H white, O red, Cr purple, S yellow, N blue, Cl green).

    22. Reaction of Two Different α-Allenols in a Heterocyclization/Cross-Coupling Sequence: Convenient Access to Functionalized Buta-1,3-dienyl Dihydrofurans (pages 4501–4504)

      Benito Alcaide, Pedro Almendros and Teresa Martínez del Campo

      Version of Record online: 7 JUN 2006 | DOI: 10.1002/anie.200601055

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      In a single step a highly functionalized buta-1,3-dienyl-substituted 2,5-dihydrofuran unit can be formed from two different α-allenol derivatives through a novel heterocyclization/cross-coupling sequence (see scheme). The reactions are fast and totally chemo- and regioselective: No homocoupling products or heterocycles other than the five-membered oxacycle are formed.

    23. A Nitridic Clathrate: P4N4(NH)4(NH3) (pages 4505–4508)

      Friedrich Karau and Wolfgang Schnick

      Version of Record online: 31 MAY 2006 | DOI: 10.1002/anie.200600551

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      A new structure type, predicted as a possible candidate clathrasil structure, is exhibited by P4N4(NH)4(NH3), which is the first microporous nitridic clathrate (see picture; blue N, pink P, dark gray H). P4N4(NH)4(NH3) was synthesized at 11 GPa and 600 °C, and its crystal structure was determined by powder X-ray diffraction. The presence of intercalated ammonia was verified by mass chromatography and IR spectroscopy.

    24. Bionanotube Tetrapod Assembly by In Situ Synthesis of a Gold Nanocluster with (Gp5–His6)3 from Bacteriophage T4 (pages 4508–4512)

      Takafumi Ueno, Tomomi Koshiyama, Toshimitsu Tsuruga, Toshiaki Goto, Shuji Kanamaru, Fumio Arisaka and Yoshihito Watanabe

      Version of Record online: 13 JUN 2006 | DOI: 10.1002/anie.200504588

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      Tubular balls: Self-assembly of an Au nanocluster with bionanotubes of bacteriophage T4 gene product 5 (gp5) trimers has been demonstrated (see picture). The triad of His6 fragments at the C terminus of (gp5–His6)3 contributed to the construction of an ordered tetrapod-like bionanotube assembly and the formation of Au nanoclusters with uniform size distribution.

    25. SNP Genotyping by Using Photochemical Ligation (pages 4512–4515)

      Shinzi Ogasawara and Kenzo Fujimoto

      Version of Record online: 31 MAY 2006 | DOI: 10.1002/anie.200600790

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      A chip for single mismatches: Results obtained with a photochemical-ligation-based DNA chip for enhanced discrimination of single-nucleotide polymorphisms (see scheme) show that the reaction takes place over a period of hours, with the 50 % stage reached within 10 minutes. A single mismatch in the target sequence yielded extremely little ligated product (a rate 103-fold lower than for the complementary case).

    26. Low-Field Negative-Resistance Effect in a Charge-Ordered State of Thiazyl-Radical Crystals (pages 4516–4518)

      Kentaro Okamoto, Toshiyuki Tanaka, Wataru Fujita, Kunio Awaga and Tamotsu Inabe

      Version of Record online: 7 JUN 2006 | DOI: 10.1002/anie.200600596

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      Resistance is useful: A thiazyl-radical salt, [NT]3[GaCl4] (see structural diagram), exhibits negative resistance (see graph) in a charge-ordered state of the square columnar network of NT molecules. As the negative-resistance effect is observed at low electrical fields and high temperatures (290 K), it is potentially attractive for applications such as electrical devices.

    27. Evolving Proteins of Novel Composition (pages 4518–4521)

      Jin Kim Montclare and David A. Tirrell

      Version of Record online: 8 JUN 2006 | DOI: 10.1002/anie.200600088

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      Changing its nature: Global incorporation of noncanonical amino acids can alter the behavior of proteins in useful ways. In some cases, however, replacement of natural amino acids by noncanonical analogues (blue bars in picture) can cause loss of protein stability. After several generations, functional proteins of non-natural composition were prepared through residue-specific incorporation combined with directed evolution.

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