Angewandte Chemie International Edition

Cover image for Vol. 44 Issue 16

April 15, 2005

Volume 44, Issue 16

Pages 2305–2457

    1. Cover Picture: Self-Assembly and Cross-Linking of Bionanoparticles at Liquid–Liquid Interfaces (Angew. Chem. Int. Ed. 16/2005) (page 2305)

      Justin T. Russell, Yao Lin, Alexander Böker, Long Su, Philippe Carl, Heiko Zettl, Jinbo He, Kevin Sill, Ravisubhash Tangirala, Todd Emrick, Kenneth Littrell, Pappannan Thiyagarajan, David Cookson, Andreas Fery, Qian Wang and Thomas P. Russell

      Version of Record online: 13 APR 2005 | DOI: 10.1002/anie.200590052

      Interfacial activities of the cowpea mosaic virus (CPMV) between two immiscible liquids are examined by fluorescent labeling. The cover picture shows a ribbon diagram of CPMV, fluorescence laser scanning confocal microscopy images of perfluorodecalin droplets in water encapsulated by a layer of CPMV, and the structure of a CPMV particle labeled with a fluorescent dye and biotin. In their Communication on page 2420 ff., T. P. Russell, Q. Wang, and co-workers describe the formation of robust membranes by the self-assembly of CPMV bionanoparticles at liquid–liquid interfaces.

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    3. Fluorine in Organic Chemistry. By Richard D. Chambers. (pages 2322–2323)

      G. K. Surya Prakash

      Version of Record online: 13 APR 2005 | DOI: 10.1002/anie.200485265

    4. Strategies for Catalytic Asymmetric Electrophilic α Halogenation of Carbonyl Compounds (pages 2324–2327)

      Martin Oestreich

      Version of Record online: 13 APR 2005 | DOI: 10.1002/anie.200500478

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      Mission possible: Today, catalytic asymmetric variants of nearly all fundamental bond-forming reactions are known, yet catalyst-controlled enantioselective construction of carbon–halogen bonds (see scheme; X=F, Cl, Br) was still missing. This gap has now been filled by a cornucopia of conceptually diverse approaches that provide a novel tool for asymmetric organic synthesis.

    5. Electrophilic Activation and Cycloisomerization of Enynes: A New Route to Functional Cyclopropanes (pages 2328–2334)

      Christian Bruneau

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462568

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      The chemistry of triangles: Various types of functional cyclopropane structures (see picture) can be prepared through efficient and selective activation of the triple bond of enynes with electrophilic metal (Au, Pt, and Ru) derivatives. Nucleophilic addition of the double bond then generates metal–cyclopropylcarbenoid intermediates, which undergo skeleton rearrangements and formation of fused rings that contain at least one cyclopropane subunit.

    6. Gas-Phase Catalysis by Atomic and Cluster Metal Ions: The Ultimate Single-Site Catalysts (pages 2336–2354)

      Diethard K. Böhme and Helmut Schwarz

      Version of Record online: 18 MAR 2005 | DOI: 10.1002/anie.200461698

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      Not just hot air: Complete catalytic cycles under strictly thermal conditions can be studied by means of modern mass spectrometry, and the underlying elementary processes have been uncovered (see picture for the Fe+-mediated oxidation of methane by molecular oxygen, with methanol as a catalytic co-reductant). Examples cover aspects of catalysis pertinent to areas as diverse as atmospheric chemistry and surface chemistry.

    7. Glory-Scattering Measurement of Water–Noble-Gas Interactions: The Birth of the Hydrogen Bond (pages 2356–2360)

      Vincenzo Aquilanti, Elena Cornicchi, Marc Moix Teixidor, Nadja Saendig, Fernando Pirani and David Cappelletti

      Version of Record online: 1 APR 2005 | DOI: 10.1002/anie.200462704

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      Incipient hydrogen bonds in water–noble gas complexes, which increase in strength from He to Xe, are manifested by progressive alignment along the O[BOND]H bond (see picture) according to ab initio calculations. The strength of the interaction in excess of that expected for pure van der Waals forces was assessed experimentally by molecular beam scattering.

    8. The Origin of One-Bond C–H Coupling Constants in OCH Fragments: Not Primarily nO[RIGHTWARDS ARROW]equation image Delocalization (pages 2360–2364)

      Gabriel Cuevas, Karina Martínez-Mayorga, María del Carmen Fernández-Alonso, Jesús Jiménez-Barbero, Charles L. Perrin, Eusebio Juaristi and Néstor López-Mora

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200461583

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      Conforming couples: Coupling constants 1JCH and C[BOND]H bond lengths were calculated for various conformations of tetrahydropyran, ethyl methyl ether, and dimethyl ether. The dependence of 1JCH on the H-C-O-C dihedral angle does not parallel the nO[RIGHTWARDS ARROW]equation image delocalization (see picture). Dipolar interactions that affect electron densities are proposed to be responsible.

    9. Facile Synthetic Methods for the Diversification of Catena-Polyphosphorus Cations (pages 2364–2367)

      Neil Burford, C. Adam Dyker and Andreas Decken

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462997

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      A limited number and variety of polyphosphorus cations exist in comparison to their neutral (polyphosphines) and anionic (polyphosphides) counterparts. A general and facile method has now been developed for the preparation of phosphinophosphonium, diphosphinophosphonium, and cyclotetraphosphinophosphonium cations from polyphosphines. Furthermore, the stability of the cyclopentaphosphorus ring is emphasized (see crystal structure of [Ph6P5]+).

    10. Cobalt-Catalyzed syn Hydrophosphination of Alkynes (pages 2368–2370)

      Hirohisa Ohmiya, Hideki Yorimitsu and Koichiro Oshima

      Version of Record online: 14 MAR 2005 | DOI: 10.1002/anie.200500255

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      Treatment of terminal and internal alkynes with diphenylphosphane in the presence of catalytic amounts of a base and cobalt(II) acetylacetonate affords, with perfect and universal syn selectivity, the (E)-alkenyldiphenylphosphane derivatives in good yield (see scheme, acac=acetylacetonate).

    11. Establishing a Molecular Mechanism for the Beckmann Rearrangement of Oximes over Microporous Molecular Sieves (pages 2370–2373)

      Ana B. Fernández, Mercedes Boronat, Teresa Blasco and Avelino Corma

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462737

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      At least two possible pathways were found for the Beckmann rearrangement of acetophenone oxime to acetanilide over zeolite catalysts. In the first step, the N atom of the oxime is protonated over the Brønsted acid sites of an aluminum siliceous zeolite (see picture), but not over the silanol groups of a pure siliceous zeolite.

    12. Light-Driven Dynamic Pattern Formation (pages 2373–2376)

      Jaap J. D. de Jong, P. Ralph Hania, Audrius Pugžlys, Linda N. Lucas, Maaike de Loos, Richard M. Kellogg, Ben L. Feringa, Koos Duppen and Jan H. van Esch

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462500

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      The reversible photoconversion of self-assembling dithienylcyclopentene photochromic switches between an aggregated and nonaggregated state is manifest at the macroscopic level by a fully reversible sol–gel phase transition and results in spatially confined structure formation in an inhomogeneous optical field. The reversibility of aggregation is exploited in dynamic pattern formation (see images).

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      Metallophosphite-Induced Nucleophilic Acylation of α,β-Unsaturated Amides: Facilitated Catalysis by a Diastereoselective Retro [1,4] Brook Rearrangement (pages 2377–2379)

      Mary R. Nahm, Xin Linghu, Justin R. Potnick, Christopher M. Yates, Peter S. White and Jeffrey S. Johnson

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462795

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      Intermolecular alkene acylation reactions between acyl silanes and α,β-unsaturated amides with metallophosphite catalysis afford α-silyl-γ-ketoamides with high diastereoselectivities (see scheme). These can be converted into the corresponding γ-ketoamides and α-bromo-γ-ketoamides. Asymmetric catalysis of the acylation delivers the γ-ketoamide in the highest enantioselectivity yet reported for an intermolecular Stetter-type reaction.

    14. Palladium-Catalyzed Addition of Cyanoboranes to Alkynes: Regio- and Stereoselective Synthesis of α,β-Unsaturated β-Boryl Nitriles (pages 2380–2382)

      Michinori Suginome, Akihiko Yamamoto and Masahiro Murakami

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462961

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      Highly versatile intermediates are formed through the Pd-catalyzed cyanoboration of alkynes, which proceeds in a cis fashion. When 1-aryl alkynes are used, the corresponding α,β-unsaturated β-boryl nitriles are obtained regioselectively in good yields with the cyano group α to the aryl group. Suzuki–Miyaura coupling of the products leads to highly substituted α,β-unsaturated nitriles (see scheme).

    15. Effects of Bending Excitation on the Reaction of Chlorine Atoms with Methane (pages 2382–2385)

      Hans A. Bechtel, Jon P. Camden, Davida J. Ankeny Brown, Marion R. Martin, Richard N. Zare and Konstantin Vodopyanov

      Version of Record online: 14 MAR 2005 | DOI: 10.1002/anie.200462837

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      Bent up energy: Contrary to intuitive expectations, excitation of the low-frequency CH44=1) bending motion enhances the cross section for reaction with Cl atoms by a factor of two or more. This enhancement, which is constant over the collision energy range 0.12 eV to 0.26 eV, implies that shearing motion, in addition to stretching motion, can facilitate C[BOND]H bond cleavage in this direct abstraction reaction (see scheme; green Cl, purple C, gray H).

    16. Template-Dependent Morphogenesis of Oriented Calcite Crystals in the Presence of Magnesium Ions (pages 2386–2390)

      Yong-Jin Han, Laura M. Wysocki, Monica S. Thanawala, Theo Siegrist and Joanna Aizenberg

      Version of Record online: 28 FEB 2005 | DOI: 10.1002/anie.200462296

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      A potent crystallization strategy for the synthesis of homogeneous calcite crystals in a variety of morphological forms (see picture) from solutions containing Mg ions and using self-assembled monolayers as nucleation templates is reported. The approach is based on a new phenomenon – template-dependant crystal morphogensis.

    17. Mechanism of the Norrish–Yang Photocyclization Reaction of an Alanine Derivative in the Singlet State: Origin of the Chiral-Memory Effect (pages 2390–2393)

      Adalgisa Sinicropi, Frédérique Barbosa, Riccardo Basosi, Bernd Giese and Massimo Olivucci

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200461898

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      Remember how it was …? A mechanistic explanation for the chiral-memory effect in Norrish–Yang photoreactions has been obtained by computing the reaction pathway (see figure) at the ab initio level. The results show that both the ultrafast excited-state decay, which occurs at a conical intersection (CI), and the specific hydrogen-bonded structure of the primary diradical intermediate determine the high stereoselectivity of the reaction.

    18. Highly Enantioselective Catalytic Conjugate Addition of N-Heterocycles to α,β-Unsaturated Ketones and Imides (pages 2393–2397)

      Mark Gandelman and Eric N. Jacobsen

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200463058

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      New nucleophiles in the arena of asymmetric catalysis, fused and nonfused N-heterocycles undergo conjugate addition to unsaturated imides and enones in the presence of a chiral [(salen)AlIII] complex with generally high enantioselectivities (see scheme; salen=N,N′-bis(salicylaldehydo)ethylenediamine).

    19. Synthesis of Medium- and Large-Sized Lactones in an Aqueous–Organic Biphasic System (pages 2397–2400)

      Hidenori Kinoshita, Hiroshi Shinokubo and Koichiro Oshima

      Version of Record online: 16 MAR 2005 | DOI: 10.1002/anie.200462677

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      Saving solvent: An aqueous–ethyl acetate biphasic system allows an efficient synthesis of medium- and large-sized lactones by an intramolecular Tsuji–Trost reaction (see scheme, n=1–5). The macrocyclization protocol does not require a large quantity of solvents or a slow-addition technique.

    20. Class Assignment of Sequence-Unrelated Members of Enzyme Superfamilies by Activity-Based Protein Profiling (pages 2400–2403)

      Nadim Jessani, Jason A. Young, Sandra L. Diaz, Matthew P. Patricelli, Ajit Varki and Benjamin F. Cravatt

      Version of Record online: 14 MAR 2005 | DOI: 10.1002/anie.200463098

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      No longer in a class of its own: By using a gel-free platform for activity-based protein profiling (ABPP; see figure), it was shown that the enzyme sialic acid 9-O-acetylesterase (SAE), which shares no sequence homology with other enzymes, is a member of the serine hydrolase superfamily. The site of fluorophosphonate labeling in SAE was identified as serine 127; this residue is essential for catalytic activity.

    21. Stable, Soluble Beryllium Aluminum Citrate Complexes Inspired by the Emerald Mineral Structure (pages 2403–2406)

      Timothy S. Keizer, Brian L. Scott, Nancy N. Sauer and T. Mark McCleskey

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462531

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      A gem of a structure: A mixed-metal species with a structure very similar to the beryl structure found in nature is the 1:1:2 title complex (see structure). Its core structure contains a ring of alternating Al and Be atoms bridged by the aliphatic hydroxy group of the citric acid. A 1:1:1 complex isolated from phosphate buffer has a larger cluster structure consisting of six Al–Be–citrate species linked by bridging phosphate groups.

    22. Reversible Transformation of Two Diphenylphosphanido Ligands into the Neutral Tetraphenyldiphosphane Ligand (pages 2407–2410)

      Juan Forniés, Consuelo Fortuño, Susana Ibáñez, Antonio Martín, Athanasios C. Tsipis and Constantinos A. Tsipis

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462498

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      From a theoretical prediction to an experimental finding: Oxidation of two bridging diphenylphosphanido ligands to a neutral tetraphenyldiphosphane is predicted theoretically and achieved experimentally in a trinuclear Pt2Pd complex (see scheme, RF=C6F5, P*=PPh2).

    23. Fully Plastic Actuator through Layer-by-Layer Casting with Ionic-Liquid-Based Bucky Gel (pages 2410–2413)

      Takanori Fukushima, Kinji Asaka, Atsuko Kosaka and Takuzo Aida

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462318

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      Liquid films: Ionic liquids containing dispersed single-walled carbon nanotubes (bucky gels), allow the first layer-by-layer casting fabrication of a fully plastic actuator. This actuator adopts a simple three-layered configuration of soft electrodes and electrolyte layers (see picture) and can operate in air at low voltages.

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      Room-Temperature Swern Oxidations by Using a Microscale Flow System (pages 2413–2416)

      Tatsuya Kawaguchi, Hiroyuki Miyata, Kikuo Ataka, Kazuhiro Mae and Jun-ichi Yoshida

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462466

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      Residence time controlled reaction: The Swern oxidation of alcohols has been accomplished by using a microscale flow system, consisting of micromixers and microscale tube reactors (see schematic representation; DMSO=dimethylsulfoxide, TFAA=trifluoroacetic anhydride), at higher temperatures (−20 to 20 °C) than those for conventional macroscale batch systems (−50 °C or below).

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      Building Blocks for 2D Molecule-Based Magnets: The Diruthenium Tetrapivalate Monocation [RuII/III2(O2CtBu)4]+ (pages 2416–2419)

      Thomas E. Vos and Joel S. Miller

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462546

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      Networking: In contrast to 3D structured [Ru2(O2CR)4]3[MIII(CN)6] (M=Cr, Fe, Co) in which R=Me, 2D layered network structures form when R=tBu (see structure orange Ru, dark blue Cr, light blue N, red O, black C). The magnetic properties of 2D materials are investigated to further understand the magnetostructural relationship of 2D extended networks, and why the 2D material magnetically orders at higher temperatures than the 3D structured magnets.

    26. Self-Assembly and Cross-Linking of Bionanoparticles at Liquid–Liquid Interfaces (pages 2420–2426)

      Justin T. Russell, Yao Lin, Alexander Böker, Long Su, Philippe Carl, Heiko Zettl, Jinbo He, Kevin Sill, Ravisubhash Tangirala, Todd Emrick, Kenneth Littrell, Pappannan Thiyagarajan, David Cookson, Andreas Fery, Qian Wang and Thomas P. Russell

      Version of Record online: 1 APR 2005 | DOI: 10.1002/anie.200462653

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      Bionanoparticles, such as the cowpea mosaic virus, can stabilize oil droplets in aqueous solutions by self-assembly at liquid interfaces. Subsequent cross-linking of the bionanoparticles transforms the assemblies into robust membranes that have covalent inter-bionanoparticle connections. The resulting membranes are nanoscopically thin sheets (see SANS image (SANS=small-angle neutron scattering)), which were examined by fluorescent labeling.

    27. A Novel Fluorescent Dye with Strong, Anisotropic Solid-State Fluorescence, Small Stokes Shift, and High Photostability (pages 2427–2428)

      Heinz Langhals, Oswald Krotz, Kurt Polborn and Peter Mayer

      Version of Record online: 16 MAR 2005 | DOI: 10.1002/anie.200461610

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      A refrigerator when the light is on. In leaflets of 1 (0.1×50×50 μm3) the large planes display a strong, anisotropic solid-state fluorescence. Owing to its small Stokes shift, this perylene dye may have potential for cooling with light.

    28. A Cobaltocenium–Peptide Bioconjugate Shows Enhanced Cellular Uptake and Directed Nuclear Delivery (pages 2429–2432)

      Fozia Noor, Annette Wüstholz, Ralf Kinscherf and Nils Metzler-Nolte

      Version of Record online: 3 MAR 2005 | DOI: 10.1002/anie.200462519

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      The key to the cells: The N-terminal organometallic complex shown greatly improves cellular uptake of a bioconjugate containing the NLS peptide (NLS=nuclear localization sequence) and cobaltocenium carboxylic acid. Nuclear localization of this novel organometallic bioconjugate in HepG2 cells is demonstrated by live-cell fluorescence microscopy (see picture). FITC=fluorescein isothiocyanate.

    29. In-Plane Bishomoaromaticity in Tetranitrogen Dianions: Solid-State, Solution, and Electronic Structures (pages 2433–2437)

      Jens Geier, Hansjörg Grützmacher, Kai Exner and Horst Prinzbach

      Version of Record online: 14 MAR 2005 | DOI: 10.1002/anie.200462126

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      Na4N8cuboctahedra containing nearly planar N4 polygons make up, in the solid state as well as in solution, the core of the dimer structures of remarkably persistent bishomoaromatic dianions, which are generated by reduction of preoriented bisdiazenes by sodium. As to the nature of the transannular N[BOND]N interactions (dN-N= 2.5–2.8 Å) quantum chemical calculations disclose long bonds.

    30. CdSe/ZnS Nanocrystals with Dye-Functionalized Polymer Ligands Containing Many Anchor Groups (pages 2437–2440)

      Inga Potapova, Ralf Mruk, Christian Hübner, Rudolf Zentel, Thomas Basché and Alf Mews

      Version of Record online: 17 MAR 2005 | DOI: 10.1002/anie.200462236

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      Something to fret about: Luminescent semiconductor nanocrystals are covered with polymeric ligands which form many bonds to the nanocrystal (NC) and increase their solubility. The ligands are decorated with an organic dye molecule (see picture) so that the electronic interaction in individual nanocrystal–dye complexes can be investigated by fluorescence resonance energy transfer (FRET) experiments. The results show many factors influence the FRET results.

    31. High-Resolution Solid-State NMR Spectroscopy of the Prion Protein HET-s in Its Amyloid Conformation (pages 2441–2444)

      Ansgar B. Siemer, Christiane Ritter, Matthias Ernst, Roland Riek and Beat H. Meier

      Version of Record online: 16 MAR 2005 | DOI: 10.1002/anie.200462952

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      Partly present, partly absent: The solid-state NMR spectra (figure, right side) of the amyloid form of the HET-s prion protein (EM image at left) show the resonances for 43 residues with high resolution, whereas 29 residues give no observable NMR signals. A possible explanation could be that the protein structure consists of both highly ordered and strongly disordered domains.

    32. Modular Diamino- and Dioxophosphine Oxides and Chlorides as Ligands for Transition-Metal-Catalyzed C[BOND]C and C[BOND]N Couplings with Aryl Chlorides (pages 2444–2447)

      Lutz Ackermann and Robert Born

      Version of Record online: 16 MAR 2005 | DOI: 10.1002/anie.200462371

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      Air-stable diamino- and dioxophosphine oxides were used as ligands in palladium-catalyzed Suzuki reactions of aryl chlorides. Additionally, a diaminophosphine chloride was applied to palladium- and nickel-catalyzed C[BOND]C and C[BOND]N bond-forming reactions.

    33. 3D-Hybrid Networks with Controllable Electrical Conductivity from the Electrochemical Deposition of Terthiophene-Functionalized Polyphenylene Dendrimers (pages 2447–2451)

      Hermann John, Roland Bauer, Pamela Espindola, Prashant Sonar, Jürgen Heinze and Klaus Müllen

      Version of Record online: 10 MAR 2005 | DOI: 10.1002/anie.200462378

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      Unusual conductivity effects: Suitably functionalized dendrimers (see picture) are capable of forming truly covalent three-dimensional networks with remarkably high conductivity on electrochemical doping. Depending on the charging level of the electroactive components used as building blocks for the dendrimer core and the perimeter, two separated regimes of electrical conductivity can be observed.

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