Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 8

February 11, 2005

Volume 44, Issue 8

Pages 1143–1277

    1. Cover Picture: “Double-Concave” Graphene: Permethoxylated Hexa-peri-hexabenzocoronene and Its Cocrystals with Hexafluorobenzene and Fullerene (Angew. Chem. Int. Ed. 8/2005) (page 1143)

      Zhaohui Wang, Florian Dötz, Volker Enkelmann and Klaus Müllen

      Version of Record online: 4 FEB 2005 | DOI: 10.1002/anie.200590023

      Highly twisted permethoxylated hexa-peri-hexabenzocoronene forms inclusion complexes with hexafluorobenzene and fullerene guest molecules. In addition to the “double-concave” surface which allows its coordination to suitable guest molecules on both sides, the flexible methoxy groups at the periphery of this host molecule adjust their orientation to the size and shape of the guest molecules. Further details are reported in the Communication by K. Müllen et al. on page 1247 ff.

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      Pd-Catalyzed Amination of Nucleoside Arylsulfonates to yield N6-Aryl-2,6-Diaminopurine Nucleosides (page 1154)

      Padmaja Gunda, Larry M. Russon and Mahesh K. Lakshman

      Version of Record online: 4 FEB 2005 | DOI: 10.1002/anie.200590025

    3. Photomagnetic Effects in Polycyanometallate Compounds: An Intriguing Future Chemically Based Technology? (pages 1160–1163)

      Andrea Dei

      Version of Record online: 14 JAN 2005 | DOI: 10.1002/anie.200461413

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      Out of the blue: Photoinduced magnetism in polymeric “Prussian Blue” analogues is a well understood phenomenon that can even occur near room temperature. The lessons learned are now being transferred to the synthesis of molecular cyanide-bridged single-molecule magnets (see picture; Mo yellow, C black, N blue, Cu purple) whose magnetic properties change drastically on light irradiation.

    4. DNA Codes for Nanoscience (pages 1166–1181)

      Bruno Samorì and Giampaolo Zuccheri

      Version of Record online: 5 NOV 2004 | DOI: 10.1002/anie.200400652

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      A question of scale: The interaction and recognition processes of DNA have been traditionally described on the Ångström scale. Embedded in DNA are also informational codes that control these processes on the nanoscale (see picture). Nanoscience can take advantage of these codes to control the self-assembly of biological and nonbiological molecules or their orientation on surfaces.

    5. Are β-Acylaminoacrylates Hydrogenated in the Same Way as α-Acylaminoacrylates? (pages 1184–1188)

      Hans-Joachim Drexler, Wolfgang Baumann, Thomas Schmidt, Songlin Zhang, Ailing Sun, Anke Spannenberg, Christine Fischer, Helmut Buschmann and Detlef Heller

      Version of Record online: 26 NOV 2004 | DOI: 10.1002/anie.200461716

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      Five catalyst–substrate complexes of the type [Rh(chiral ligand)(β-dehydroamino acid derivative)]BF4 were characterized for the first time by X-ray analysis (see example). Low-temperature NMR spectroscopy proved that three of these complexes are “major” substrate complexes, which lead to the main product in asymmetric hydrogenation, contrary to the known classical examples with analogous α-dehydroamino acid derivatives.

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      Biodegradable, Amorphous Copolyester-Urethane Networks Having Shape-Memory Properties (pages 1188–1192)

      Armin Alteheld, Yakai Feng, Steffen Kelch and Andreas Lendlein

      Version of Record online: 17 JAN 2005 | DOI: 10.1002/anie.200461360

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      In great shape: Star-shaped telechelic oligomers can be coupled with a junction unit to yield amorphous copolyester-urethane networks, which are not only biodegradable but can also be fixed in a new, temporary shape after they have been processed into a permanent shape. The permanent shape can be recovered by heating (see picture). Such polymer networks may find application in ophthalmology.

    7. A Boryl Bridged Complex: An Unusual Coordination Mode of the BR2 Ligand (pages 1192–1194)

      Holger Braunschweig, Krzysztof Radacki, Daniela Rais and George R. Whittell

      Version of Record online: 20 JAN 2005 | DOI: 10.1002/anie.200462444

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      Building bridges: The combination of the Lewis acidic dichloroboryl complex [(η5-C5Me5)Fe(CO)2BCl2] and a Lewis basic [Pd(PR3)] fragment gives the first dinuclear monoboryl complex with a symmetric μ, η2 bridging BR2 ligand (see structure). The dative nature of the palladium–boron bonding interaction makes the dinuclear compound a rare example of a transition-metal borane complex.

    8. (Coumarin-4-yl)methyl Esters as Highly Efficient, Ultrafast Phototriggers for Protons and Their Application to Acidifying Membrane Surfaces (pages 1195–1198)

      Daniel Geißler, Yuri N. Antonenko, Reinhard Schmidt, Sandro Keller, Oxana O. Krylova, Burkhard Wiesner, Jürgen Bendig, Peter Pohl and Volker Hagen

      Version of Record online: 4 FEB 2005 | DOI: 10.1002/anie.200461567

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      Large jumps in pH on the nanosecond timescale can be achieved upon one- and two-photon flash photolysis of novel coumarinylmethyl esters, which are phototriggers for H+ (see scheme, F=pH-sensitive fluorescence indicator). The compounds are excellent tools for the study of rapid H+-triggered processes, for example, proton migration along membrane surfaces.

    9. Synthesis of the Heterocyclic Core of the GE 2270 Antibiotics and Structure Elucidation of a Major Degradation Product (pages 1199–1201)

      Golo Heckmann and Thorsten Bach

      Version of Record online: 14 JAN 2005 | DOI: 10.1002/anie.200461715

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      Two birds were killed with one stone by the synthesis of the trisubstituted pyridine (R,R)-1 and its diastereoisomer. In a short synthetic sequence for the construction of the GE 2270 thiazolyl peptides, 2,3,6-tribromopyridine was converted into pyridine 1 in only four steps (Bn=benzyl). In addition, the absolute and relative configuration of a major degradation product of GE 2270A was proven.

    10. Mutasynthesis of Aureonitrile: An Aureothin Derivative with Significantly Improved Cytostatic Effect (pages 1202–1205)

      Martina Ziehl, Jing He, Hans-Martin Dahse and Christian Hertweck

      Version of Record online: 11 JAN 2005 | DOI: 10.1002/anie.200461990

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      Tapping nature's biosynthetic potential: Formation of the rare p-nitro benzoate precursor of aureothin, a mixed polyketide metabolite of Streptomyces thioluteus, requires two key enzymes: a p-amino benzoate synthase and an N-oxygenase. Feeding of surrogates to engineered block mutants (e.g. S. lividans ZX1::pHJ97) reveals that the iterative modular aureothin polyketide also accepts p-cyano benzoate as the starter, which is subsequently processed to the nitrile analogue of aureothin, aureonitrile, which has improved cytostatic properties.

    11. Predicting New Ferromagnetic Nitrides from Electronic Structure Theory: IrFe3N and RhFe3N (pages 1205–1210)

      Jörg von Appen and Richard Dronskowski

      Version of Record online: 5 JAN 2005 | DOI: 10.1002/anie.200462247

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      Cutting corners: The perovskite-like ternary nitrides MFe3N of the iron- and platinum-group metals are theoretically investigated. All eight compounds are predicted as being ferromagnetic, with saturation moments between 7.1 and 9.2 μB per formula unit, and with larger M atoms preferentially occupying the corner position 1a (see picture). Two ternary nitrides, yet to be made, are predicted as lucrative synthetic goals.

    12. Direct Organocatalytic De Novo Synthesis of Carbohydrates (pages 1210–1212)

      Dieter Enders and Christoph Grondal

      Version of Record online: 14 JAN 2005 | DOI: 10.1002/anie.200462428

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      One small step for a catalyst: A biomimetic asymmetric synthesis of carbohydrates was accomplished by a proline-catalyzed aldol reaction of 2,2-dimethyl-1,3-dioxan-5-one as the methylene component with various aldehydes. This new organocatalytic C3+Cn strategy leads directly to selectively protected simple sugars and amino sugars.

    13. Simulating the Dissolution and Growth of Zeolite Beta C (pages 1213–1217)

      May E. Chiu, Ben Slater and Julian D. Gale

      Version of Record online: 5 JAN 2005 | DOI: 10.1002/anie.200461545

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      A simple model of zeolite growth and dissolution has been constructed. Lattice-energy calculations suggest that both growth and dissolution, progressing through attachment or leaching of monomeric units, involves a number of exothermic and endothermic steps. Oligomeric units may play a key role in overcoming the most endothermic (rate-determining) steps of crystal growth associated with the pictured high-energy structure.

    14. N2S2Ni Metallothiolates as a Class of Ligands that Support Organometallic and Bioorganometallic Reactivity (pages 1217–1220)

      Marilyn V. Rampersad, Stephen P. Jeffery, Joseph H. Reibenspies, Cesar G. Ortiz, Donald J. Darensbourg and Marcetta Y. Darensbourg

      Version of Record online: 4 FEB 2005 | DOI: 10.1002/anie.200461747

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      It hinges on the ligand: The electron-donor ability of NiN2S2 ligands is compared to that of traditional diphosphine and diimine ligands. Structural comparison of NiN2S2 and o-phenanthroline (phen) complexes of {W(CO)4} and {PdX2} units shows asymmetry imposed by the hinge bonding of the NiN2S2 S donors (see superimposed structures) which favors stereo- and regioselective substrate addition.

    15. Total Synthesis of (−)-Colombiasin A and (−)-Elisapterosin B (pages 1221–1222)

      David C. Harrowven, David D. Pascoe, Daniela Demurtas and Heather O. Bourne

      Version of Record online: 4 FEB 2005 | DOI: 10.1002/anie.200462268

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      Intramolecular cycloaddition reactions are central in the total syntheses of colombiasin A (1) and elisapterosin B (2) described, which use (−)-dihydrocarvone as the starting material. A Moore rearrangement of a vinylcyclobutene is used to initiate the cycloaddition.

    16. Total Synthesis of (+)-Leucascandrolide A (pages 1223–1225)

      Qibin Su and James S. Panek

      Version of Record online: 17 JAN 2005 | DOI: 10.1002/anie.200462408

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      A convergent and enantioselective total synthesis of (+)-leucascandrolide (1) was accomplished in 17 steps. Central to this synthesis is the rapid and efficient integration of the bispyran moiety into 1 using two consecutive [4+2] annulation reactions between an aldehyde and the chiral silanes 2 and 3 (TMS=trimethylsilyl, Mes=mesityl=2,4,6-trimethylphenyl).

    17. Direct Access to Bicontinuous Skeletal Inorganic Plumber's Nightmare Networks from Block Copolymers (pages 1226–1229)

      Anurag Jain, Gilman E. S. Toombes, Lisa M. Hall, Surbhi Mahajan, Carlos B. W. Garcia, Wolfgang Probst, Sol M. Gruner and Ulrich Wiesner

      Version of Record online: 17 JAN 2005 | DOI: 10.1002/anie.200461156

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      Pipe-dream realized: The as-made nanocomposite derived from a block-copolymer-directed sol–gel synthesis consists of silica networks embedded in an organic matrix. Calcination of the structure at high temperatures gives a final skeletal silica network consistent with the morphology called plumber's nightmare (point group Imequation imagem; see small-angle X-ray scattering (SAXS) pattern of an inverse form of this morphology).

    18. 1J(C,H) Couplings to the Individual Protons in a Methyl Group: Evidence of the Methyl Protons' Engagement in Hydrogen Bonds (pages 1230–1232)

      Tomasz Ratajczyk, Igor Czerski, Krystyna Kamienska-Trela, Slawomir Szymanski and Jacek Wojcik

      Version of Record online: 17 JAN 2005 | DOI: 10.1002/anie.200461383

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      Bonding out of the blue: Strong evidence of the occurrence of specific hydrogen bonds, the so called blue-shifting hydrogen bonds, between hydrogen atoms of CH3 in 9-methyltriptycenes and halogen substituents in the peri position (see scheme) comes from low-temperature 1H NMR measurements that yield the 1J(C,H) values for the individual CH3 protons, as well as from natural bond orbital analysis and DFT calculations of the geometries and J couplings.

    19. Metal-Free Cross-Coupling Reactions of Aryl Sulfonates and Phosphates through Photoheterolysis of Aryl–Oxygen Bonds (pages 1232–1236)

      Marco De Carolis, Stefano Protti, Maurizio Fagnoni and Angelo Albini

      Version of Record online: 12 JAN 2005 | DOI: 10.1002/anie.200461444

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      Photochemical cleavage of Ar[BOND]O bonds in phenyl esters substituted with electron-donating groups offers a convenient method for the arylation of alkenes and arenes. The reaction proceeds by an SN1 mechanism via a triplet phenyl cation to form allylbenzene or biphenyl derivatives under mild conditions (see scheme).

    20. Methyl Group Rotation Driven by Proton Transfer through a Long-Range Chemical Interaction (pages 1237–1240)

      Hiroshi Ushiyama and Kazuo Takatsuka

      Version of Record online: 14 JAN 2005 | DOI: 10.1002/anie.200461459

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      Coupling drives the rotation: A theoretical study of proton-transfer dynamics of 5-methyltropolone (5MTR) has identified a long-range mechanical interaction. Methyl group rotation can be driven by proton transfer because of coupling between hyperconjugation and tautomerization within 5MTR (see HOMO–LUMO interaction). A quantum-mechanical mechanism is presented in which this molecule undergoes a conformational change.

    21. Using Dipoles to Control the Directionality of Functional Groups: Syn- and Anti-Oriented Benzene-1,3-dicarboxamides (pages 1241–1244)

      Mark S. Betson, Jonathan Clayden, Ho Kam Lam and Madeleine Helliwell

      Version of Record online: 14 JAN 2005 | DOI: 10.1002/anie.200461787

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      Poles apart: The relative orientation of a pair of functional groups—amides in this case—can be controlled by the choice of the substituent that lies between them. Groups which are effectively cylindrically symmetrical (Me, Cl) allow direct interaction between the dipoles of the amides and induce an anti orientation, whereas polar groups (OCOR, OSO2R, SO2R) interact with the dipole of both amides to yield a syn orientation (see picture).

    22. Theoretical and Synthetic Studies on [Zn25-C5Me5)2]: Analysis of the Zn[BOND]Zn Bonding Interaction (pages 1244–1247)

      Diego del Río, Agustín Galindo, Irene Resa and Ernesto Carmona

      Version of Record online: 20 JAN 2005 | DOI: 10.1002/anie.200462175

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      More than 1 g of the dizinc compound [Zn25-C5Me5)2] can be readily obtained in a single preparation. Density functional calculations reveal that the Zn[BOND]Zn bond is relatively strong and derives mainly from interaction between the Zn 4 s orbitals (see picture).

    23. “Double-Concave” Graphene: Permethoxylated Hexa-peri-hexabenzocoronene and Its Cocrystals with Hexafluorobenzene and Fullerene (pages 1247–1250)

      Zhaohui Wang, Florian Dötz, Volker Enkelmann and Klaus Müllen

      Version of Record online: 26 NOV 2004 | DOI: 10.1002/anie.200461445

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      Extremely nonplanar permethoxylated hexa-peri-hexabenzocoronene can be prepared by using a facile ferric chloride cyclodehydrogenation procedure. The combination of a rigid “double-concave” aromatic core with 18 flexible methoxy groups at the periphery makes it a remarkable host molecule, as revealed by single-crystal analysis of its crystalline inclusion complexes with hexafluorobenzene and fullerene guest molecules (see crystal structure).

    24. Solid-State Structure and Temperature/Evacuation-Induced Dehydration of Sodium Saccharinate 1.875 Hydrate (pages 1251–1254)

      Panče Naumov, Gligor Jovanovski, Orhideja Grupče, Branko Kaitner, A. David Rae and Seik Weng Ng

      Version of Record online: 5 JAN 2005 | DOI: 10.1002/anie.200461043

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      Sweet solution: The P21/n (Z=64) structure of the commercial sweetener sodium saccharinate, which has an unusually large unit cell of 15.6 nm3, is an occupational and displacive modulation of an idealized C2/m (Z=8) structure that results from a structural misfit. This determination (see picture) shows—after more than 150 years of use of the compound as a food additive—that it is better regarded as a 1.875 hydrate than a dihydrate.

    25. Covalent Immobilization of a TiW5 Polyoxometalate on Derivatized Silicon Surfaces (pages 1254–1257)

      R. John Errington, Sagar S. Petkar, Benjamin R. Horrocks, Andrew Houlton, Lars H. Lie and Samson N. Patole

      Version of Record online: 4 FEB 2005 | DOI: 10.1002/anie.200461065

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      Covalent ties: The polyoxometalate (nBu4N)3[(MeO)TiW5O18] is easily anchored to alkanol-functionalized surfaces of porous and single-crystal silicon (see picture, polyhedra: polyoxometalate, dark blue: Si surface). Scanning tunneling microscopy reveals the growth of 35–50 nm diameter islands on functionalized Si(111), which suggests that the immobilized polyoxometalates act as nucleation sites for electrostatic aggregation.

    26. Formation of [60]Fullerene Nanoclusters with Controlled Size and Morphology through the Aid of Supramolecular Rod–Coil Diblock Copolymers (pages 1257–1261)

      Norifumi Fujita, Taketomo Yamashita, Masayoshi Asai and Seiji Shinkai

      Version of Record online: 20 JAN 2005 | DOI: 10.1002/anie.200461174

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      On the starting block: Polystyrene-block-poly(4-vinylpyridine) and a [60]fullerene carboxylic acid combine to form spherical supramolecular aggregates (see picture), the size and morphology of which can be controlled by changing the block composition ratio in the copolymer. The method is generally applicable to the construction of organic nanoparticles.

    27. Redox-Active Porous Metal–Organic Framework Producing Silver Nanoparticles from AgI Ions at Room Temperature (pages 1261–1265)

      Hoi Ri Moon, Ji Hyun Kim and Myunghyun Paik Suh

      Version of Record online: 12 JAN 2005 | DOI: 10.1002/anie.200461408

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      Hi ho silver! Coordination polymer chains assembled from a NiII hexaazamacrocycle and sodium 4,4′-biphenyldicarboxylate can be packed to form a porous framework (see picture). Nanocomposites of silver particles and matrix can be prepared by immersing the framework in AgNO3 solution, and the matrix-free silver nanoparticles (≈3 nm) isolated by treatment of the solid with boiling dioctyl ether containing oleic acid.

    28. A Controllable Electrochemical Fabrication of Metallic Electrodes with a Nanometer/Angstrom-Sized Gap Using an Electric Double Layer as Feedback (pages 1265–1268)

      Juan Xiang, Bo Liu, Sun-Tao Wu, Bin Ren, Fang-Zu Yang, Bing-Wei Mao, Yuan L. Chow and Zhong-Qun Tian

      Version of Record online: 12 JAN 2005 | DOI: 10.1002/anie.200461797

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      Potential feedback: Metallic electrodes with controlled gap widths ranging from about 10 nm down to several angstroms (as determined by SEM measurements) can be fabricated electrochemically by using a simple potential feedback system with a unique electrode configuration (see picture). The working principle is based on the potential distribution in the electric double-layer. The process is simple, controllable, and reproducible.

    29. Mass Production and High Photocatalytic Activity of ZnS Nanoporous Nanoparticles (pages 1269–1273)

      Jin-Song Hu, Ling-Ling Ren, Yu-Guo Guo, Han-Pu Liang, An-Min Cao, Li-Jun Wan and Chun-Li Bai

      Version of Record online: 14 JAN 2005 | DOI: 10.1002/anie.200462057

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      Self-assembly of hexagonal 3–5-nm ZnS nanocrystals can be used for the large-scale production of zinc sulfide nanoporous nanoparticles (NPNPs). The uniform, spherical NPNPs are monodisperse and have surface areas on the order of 156 m2 g−1. The ZnS NPNPs are more effective photocatalysts than Degussa P25 titania or ZnS nanocrystals in the photodegradation of eosin B at ambient temperature (see picture).

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