Chemistry - A European Journal

Cover image for Vol. 10 Issue 7

April 2, 2004

Volume 10, Issue 7

Pages 1579–1854

    1. Cover Picture: Pentacoordinate Nickel(II) Complexes Double Bridged by Phosphate Ester or Phosphinate Ligands: Spectroscopic, Structural, Kinetic, and Magnetic Studies (Chem. Eur. J. 7/2004) (page 1579)

      M. Dolores Santana, Gabriel García, A. Abel Lozano, Gregorio López, José Tudela, José Pérez, Luis García, Luis Lezama and Teófilo Rojo

      Article first published online: 24 MAR 2004 | DOI: 10.1002/chem.200490021

      The cover picture shows a representation of two pathways for the hydrolysis of phosphotriesters, which are represented by tris(phenyl)phosphate (TPP). The catalytic hydrolysis is represented by a novel bimetallic nickel(II) complex that contains a double phosphodiester bridge, prepared from the reaction of TPP with the hydroxo–nickel(II) complex [Ni(Me3[12]aneN3)(μ-OH)]2[PF6]2 (top right) The enzymatic hydrolysis (bottom left) is represented by the phosphotriesterase from Pseudomonas diminuta (PDB ID: 1EYW), a zinc-containing enzyme. The cover picture was created by A. Abel Lozano. For more details please see the article by G. García, M. D. Santana et al. on p. 1738ff.

    2. Inorganic Electrides (pages 1592–1596)

      Zhenyu Li, Jinlong Yang, J. G. Hou and Qingshi Zhu

      Article first published online: 29 JAN 2004 | DOI: 10.1002/chem.200305315

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      Itinerant electrons: A novel material—an “inorganic electride”—with a stoichiometic trapped or itinerant electron as anion is illustrated. Inorganic electrides are stable at room-temperature. The alkali metals in inorganic electrides form continuous zigzag chains along the narrow pore channels of zeolites and the released electrons are delocalized from the alkali metals.

    3. New Simulation Model of Multicomponent Crystal Growth And Inhibition (pages 1598–1605)

      Brent Wathen, Michael Kuiper, Virginia Walker and Zongchao Jia

      Article first published online: 29 JAN 2004 | DOI: 10.1002/chem.200305186

      Cool and calculating! A novel computational model for the study of crystal structures both on their own and in conjunction with inhibitor molecules is reported. This extended MC model has been applied to the study of antifreeze proteins (AFPs) and their effects on ice formation. The technique successfully models the AFP-induced ice-growth inhibition with concurrent changes to ice morphology that mimic experimental results.

    4. Design, Synthesis and Structural Investigations of a β-Peptide Forming a 314-Helix Stabilized by Electrostatic Interactions (pages 1607–1615)

      Magnus Rueping, Yogesh R. Mahajan, Bernhard Jaun and Dieter Seebach

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305571

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      Adequately designed β-peptides can be stabilized by electrostatic interactions which was shown with 1. The β3-heptapeptide was assembled by solid-phase synthesis from β3-homoarginine derivatives and investigated both in methanol and aqueous solutions using CD- and NMR-structural methods.

    5. Control of Hydrogen Bond Strengths through Push–Pull Effects Triggered by a Remote Reaction Center: A Theoretical Study (pages 1616–1624)

      Tsong-Song Hwang, Ning Juan, Hsing-Yin Chen, Cheng-Chung Chen, Shih-Jung Lo and Ito Chao

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305514

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      Remote control of binding is achieved by triggering the reaction center in a π-conjugated molecule (see scheme). Theoretical analysis shows why, in certain systems, the signal sent out by the reaction center does not die out with long distances.

    6. Synthesis and Antimalarial Activity of Trioxaquine Derivatives (pages 1625–1636)

      Odile Dechy-Cabaret, Françoise Benoit-Vical, Christophe Loup, Anne Robert, Heinz Gornitzka, Anne Bonhoure, Henri Vial, Jean-François Magnaval, Jean-Paul Séguéla and Bernard Meunier

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305576

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      A stable, nontoxic, and non-genotoxic antimalarial agent, compound 1 (DU1302 c), is a trioxaquine that was prepared from α-terpinene. It exhibited high antimalarial activity in vitro against Plasmodium falciparum, as well as in vivo activity after being orally administered to infected mice.

    7. Low-Temperature Destruction of Carbon Tetrachloride over Lanthanide Oxide-Based Catalysts: From Destructive Adsorption to a Catalytic Reaction Cycle (pages 1637–1646)

      Pieter Van der Avert, Simon G. Podkolzin, Olga Manoilova, Hendrik de Winne and Bert M. Weckhuysen

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305442

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      Catalytic destruction of CCl4 in the presence of steam was investigated at 200–350 °C over a series of lanthanide (La, Ce, Pr, and Nd) and alkaline-earth metal (Mg, Ca, Sr, and Ba) oxide-based catalysts by kinetic experiments, various spectroscopic techniques and DFT calculations. For example, approach of a CCl4 molecule to the surface of La2O3 results in the elongation of a C[BOND]Cl bond, and the Cl gets a partial negative charge, while the hydrocarbon fragment becomes partially positively charged (see picture).

    8. Effect of Inorganic Anions on the Morphology and Structure of Magnesium Calcite (pages 1647–1656)

      Damir Kralj, Jasminka Kontrec, Ljerka Brečević, Giuseppe Falini and Vesna Nöthig-Laslo

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305313

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      The extent of incorporation of magnesium in the calcite crystal lattice depends on the type of co-anion present in the precipitation system. For the appropriate initial molar ratios ci(Mg2+)/ci(Ca2+), the magnesium content in calcite crystals decreases in the series Mg(OH)2>MgSO4>Mg(NO3)2>MgCl2, as illustrated.

    9. Silsesquioxane-Based Homogeneous and Heterogeneous Epoxidation Catalysts Developed by Using High-Speed Experimentation (pages 1657–1665)

      Paolo P. Pescarmona, Jan C. van der Waal and Thomas Maschmeyer

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305387

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      A high-speed experimentation exploration of the hydrolytic condensation of trichlorosilanes in highly polar solvents (see figure) has led to the identification of new silsesquioxane precursors for homogeneous and heterogeneous titanium catalysts active in the epoxidation of alkenes.

    10. Platinum Complexes of Naphthalene-1,8-dichalcogen and Related Polyaromatic Hydrocarbon Ligands (pages 1666–1676)

      Stephen M. Aucott, Heather L. Milton, Stuart D. Robertson, Alexandra M. Z. Slawin, Greg D. Walker and J. Derek Woollins

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305352

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      Unexplored ligands: Substituted naphthalene-1,8-dichalcogenoles are an unexplored class of ligands. A systematic series of novel platinum complexes have been prepared and characterised (see scheme).

    11. Reaction of Alkenes with Hydrogen Peroxide and Sodium Iodide: A Nonenzymatic Biogenic-Like Approach to Iodohydrins (pages 1677–1682)

      José Barluenga, María Marco-Arias, Francisco González-Bobes, Alfredo Ballesteros and José M. González

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305582

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      An acid rather than an enzyme as the active additive to trigger conversion of alkenes to iodohydrins by reaction with NaI and hydrogen peroxide in aqueous media (see scheme). This simple and efficient procedure is based on biomimetic considerations.

    12. First Systematic Investigation of C[BOND]H⋅⋅⋅Cl Hydrogen Bonding Using Inorganic Supramolecular Synthons: Lamellar, Stitched Stair-Case, Linked-Ladder, and Helical Structures (pages 1683–1690)

      V. Balamurugan, Maninder Singh Hundal and Rabindranath Mukherjee

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305701

      Remarkable ability for hydrogen bonding (primarily C[BOND]H⋅⋅⋅Cl; also C[BOND]H⋅⋅⋅O and O[BOND]H⋅⋅⋅Cl) and π–π stacking interactions is displayed by neutral MIICl2-containing coordination building blocks, varying in the type and denticity of heterocyclic N-donor ligands, metal ion (Co, Cu, Zn) and their geometry (tetrahedral, distorted square pyramidal/trigonal bipyramidal, and trans-octahedral). Such noncovalent interactions afford novel supramolecular architectures.

    13. Novel CuIII Bis-1,2-dichalcogenene Complexes with Tunable 3D Framework through Alkaline Cation Coordination: A Structural and Theoretical Study (pages 1691–1704)

      Xavi Ribas, João C. Dias, Jorge Morgado, Klaus Wurst, Elies Molins, Eliseo Ruiz, Manuel Almeida, Jaume Veciana and Concepció Rovira

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305422

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      A novel family of monoanionic CuIIIcomplexes of bis(pyrazine-1,2-dichalcogenene)ligands (picture, top left) is reported. The side-coordination capability of the pyrazine moieties towards alkali metal cations (dots in picture, right) was demonstrated to be a new tool for fine 3D tuning and crystal engineering of these and other systems. The innocence of the ligands was experimentally and theoretically addressed, by DFT calculations of MOs (picture, bottom left).

    14. Synthesis and Photochemistry of a New Class of Photocleavable Protein Cross-linking Reagents (pages 1705–1710)

      Lilia Milanesi, Gavin D. Reid, Godfrey S. Beddard, Christopher A. Hunter and Jonathan P. Waltho

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305405

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      A new optical trigger: A new series of photocleavable protein cross-linking reagents based on bis(maleimide) derivatives of diaryl disulfides have been synthesised. They have been functionalised with cysteine and transient absorption spectra for the photolysis reaction have been recorded by using the pump-probe technique with a time resolution of 100 femtoseconds (see scheme).

    15. Dynamic Combinatorial Carbohydrate Libraries: Probing the Binding Site of the Concanavalin A Lectin (pages 1711–1715)

      Olof Ramström, Sophie Lohmann, Taridaporn Bunyapaiboonsri and Jean-Marie Lehn

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305551

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      Work with nature! Dynamic combinatorial carbohydrate libraries can easily be generated by acylhydrazone interchange from a range of carbohydrate aldehydes and structural hydrazide elements. In the present study, such libraries were used to probe carbohydrate–lectin interactions by using Concanavalin A as a target species. The libraries allowed the efficient identification of the structural features required for binding to Concanavalin A and the selection of a tritopic mannoside as a strong binder (see picture).

    16. Realization of Unusual Ligand Binding Motifs in Metalated Container Molecules: Synthesis, Structures, and Magnetic Properties of the Complexes [(LMe)Ni2(μ-L′)]n+ with L′=NO3, NO2, N3, N2H4, Pyridazine, Phthalazine, Pyrazolate, and Benzoate (pages 1716–1728)

      Julia Hausmann, Marco H. Klingele, Vasile Lozan, Gunther Steinfeld, Dieter Siebert, Yves Journaux, Jean Jacques Girerd and Berthold Kersting

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305705

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      Accommodating capsules! The capability of the dinuclear complex fragment [(LMe)Ni2]2+ to accommodate a range of small molecules L′ in its bowl-shaped cavity is demonstrated herein (see picture). Owing to the confined environment in the binding pocket only one of possible coordination modes of L′ is realized. The coligands influence many properties of the dinuclear complex fragment, such as complex stability, redox potential, and spin ground state.

    17. tBuP(NH2)2—A Reactive Synthon for the Synthesis of Molecular Imidophosphinates of Group 13 Metals (pages 1729–1737)

      T. Bauer, S. Schulz, M. Nieger and I. Krossing

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305530

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      Step by step: Reactions of tBuP(NH2)2 with Group 13 trialkyls MR3 (M=Al, Ga, In; R=Me, tBu) proceed stepwise with the formation of aminophosphane and iminophosphorane adducts and finally yield heterocyclic metallonitridophosphinates (see structure). The proposed reaction pathway was verified by variable-temperature NMR investigations and quantum-chemical calculations.

    18. Pentacoordinate Nickel(II) Complexes Double Bridged by Phosphate Ester or Phosphinate Ligands: Spectroscopic, Structural, Kinetic, and Magnetic Studies (pages 1738–1746)

      M. Dolores Santana, Gabriel García, A. Abel Lozano, Gregorio López, José Tudela, José Pérez, Luis García, Luis Lezama and Teófilo Rojo

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305367

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      Bridging the gap: The bis(phosphatediester)-bridged and phosphinate-bridged complexes were prepared from the hydroxo complex [{Ni([12]aneN3)(μ-OH)}2](PF6)2 (see scheme). The eight-membered rings defined by the nickel atoms and the bridging ligands display different conformations, and the magnetic-exchange pathways involve the phosphate/phosphinate bridges (Ni[BOND]O[BOND]P[BOND]O[BOND]Ni); these favour antiferromagnetic interactions. The kinetics for the hydrolysis of TNP (tris(4-nitrophenyl)phosphate) with the dinuclear nickel(II) hydroxo complex was studied by UV-visible spectroscopy.

    19. Probing Ionic Association on Metal Oxide Clusters by Pulsed Field Gradient NMR Spectroscopy: The Example of Sn12–Oxo Clusters (pages 1747–1751)

      François Ribot, Virginie Escax, José C. Martins, Monique Biesemans, Laurent Ghys, Ingrid Verbruggen and Rudolph Willem

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305604

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      Preferential ion pairing: The possibility to individually monitor the diffusion coefficient of multiple anionic and cationic species in mixtures allows us to evidence ion exchange. Thus when [(BuSn)12O14(OH)6](PTS)2 (PTS=p-toluenesulfonate) is mixed with two equivalents of [NMe4]Ph2PO2, PTS is displaced by Ph2PO2 (see scheme). This example clearly illustrates the potential of pulsed field gradient 1H NMR spectroscopy in inorganic/organometallic chemistry, to follow preferential ion pairing in multi-ion systems at the level of each individually charged species.

    20. Ring-Closure Reactions through Intramolecular Displacement of the Phenylselenonyl Group by Nitrogen Nucleophiles: A New Stereospecific Synthesis of N-Tosyl and N-Benzoyl-1,3-oxazolidin-2-ones from β-Hydroxyalkyl Phenyl Selenides (pages 1752–1764)

      Marcello Tiecco, Lorenzo Testaferri, Andrea Temperini, Luana Bagnoli, Francesca Marini and Claudio Santi

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305497

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      A stereospecific intramolecular nucleophilic substitution of the selenonyl group by the nitrogen atom of the carbamate in a ring-closure reaction (see scheme; R=Ts or Bz) is the key step in the stereospecific synthesis of 5- and 4,5-substituted-1,3-oxazolidin-2-ones from β-hydroxyalkyl phenyl selenides.

    21. Reactivity of Molybdenum and Rhenium Hydroxo-Carbonyl Complexes toward Organic Electrophiles (pages 1765–1777)

      Luciano Cuesta, Darío C. Gerbino, Eva Hevia, Dolores Morales, M. Elena Navarro Clemente, Julio Pérez, Lucía Riera, Víctor Riera, Daniel Miguel, Ignacio del Río and Santiago García-Granda

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305577

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      The hydroxo complexes of Groups 6 and 7 [Mo(OH)(η3-C3H4[BOND]Me-2)(CO)2(phen)] and [Re(OH)(CO)3(N[BOND]N)] (N[BOND]N=bipy, Me2[BOND]bipy) react with a variety of unsaturated organic electrophiles to yield the corresponding products of insertion into either the M[BOND]O or O[BOND]H bond. In addition, when the electrophile is dimethylacetylenedicarboxylate (DMAD), the activation of a carbonyl ligand gave rise to a cyclic hydroxycarbene (see scheme).

    22. Titanocene-Catalyzed Cascade Cyclization of Epoxypolyprenes: Straightforward Synthesis of Terpenoids by Free-Radical Chemistry (pages 1778–1788)

      José Justicia, Antonio Rosales, Elena Buñuel, Juan L. Oller-López, Mónica Valdivia, Ali Haïdour, J. Enrique Oltra, Alejandro F. Barrero, Diego J. Cárdenas and Juan M. Cuerva

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305647

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      The total synthesis of a wide range of complex terpenoid skeletons, including monocyclic, bicyclic, and tricyclic natural products, is facilitated by employing a novel reaction cascade based on the combination of biomimetic strategies with titanocene catalysis. For example, the titanocene-catalyzed radical cyclization of 2,3-oxidosqualene mainly gave malabaricatrienes (see scheme). Mechanistically the reaction presumably occurs via discrete carbon-centered radicals.

    23. Homogeneous Catalysts Supported on Soluble Polymers: Biphasic Suzuki–Miyaura Coupling of Aryl Chlorides Using Phase-Tagged Palladium–Phosphine Catalysts (pages 1789–1797)

      Markus an der Heiden and Herbert Plenio

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305562

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      Phase-tagged palladium–phosphine catalysts for Suzuki coupling: Soluble, polymeric catalysts for aryl chloride coupling are recycled efficiently by applying a biphasic reaction protocol. One catalyst batch can be used for numerous coupling reactions with almost constant activity (TOF). A typical ligand used in these studies is shown.

    24. Synthesis and Structures of the First Cationic Perfluoroaryllanthanoid(II) Complexes (pages 1798–1804)

      Glen B. Deacon and Craig M. Forsyth

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200306010

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      A one-pot reaction provides a simple route to novel tetraphenylborate salts of organolanthanoid(II) cations [Ln(C6F5)(thf)n]+ (e.g. 1). These organolanthanoid(II) cations show remarkable stability, even forming part of a fortuitously isolated mixed-valent cation/anion pair (e.g. 2).

    25. Density Functional Calculations on the Conversion of Azide and Carbon Monoxide to Isocyanate and Dinitrogen by a Nickel to Sulfur Rebound Mechanism (pages 1805–1814)

      Yubo Fan and Michael B. Hall

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200304840

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      A three-step mechanism is predicted for the reaction between CO and [Ni(N3)(′S3′)] (′S32−=bis(2-mercaptophenyl)sulfide (2−)) based on DFT (B3 LYP & BP86) calculations: 1) reaction with CO generates a pseudo “square-pyramidal” complex; 2) CO inserts into the Ni[BOND]N bond (1) and the apical Ni[BOND]S bond rebounds as the nickel forms a square-planar intermediate 2; 3) in a one-step process N2 leaves as the remaining N atom and carbonyl rearrange to produce [Ni(NCO)(′S3′)].

    26. A New Multifunctional Ferrocenyl-Substituted Ferrocenophane Derivative: Optical and Electronic Properties and Selective Recognition of Mg2+ Ions (pages 1815–1826)

      Juan Luis Lopez, Alberto Tárraga, Arturo Espinosa, M. Desamparados Velasco, Pedro Molina, Vega Lloveras, José Vidal-Gancedo, Concepció Rovira, Jaume Veciana, David J. Evans and K. Wurst

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305394

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      An electrosensor for magnesium: The structural characteristics of the novel ferrocenophane (illustrated here) prepared have proved to be of special interest in the study of intramolecular electron transfer, as a specific electrosensor for Mg2+ and as a model for explaining the special stability of α-ferrocenylcarbenium ions.

    27. Reactions of Copper(II) Salts with 3{5}-tert-Butylpyrazole: Double-Cubane Complexes with Bound Exogenous Anions, and a Novel Pyrazole Coordination Mode (pages 1827–1837)

      Xiaoming Liu, Judith A. McAllister, Marcelo P. de Miranda, Eric J. L. McInnes, Colin A. Kilner and Malcolm A. Halcrow

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305613

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      A double-cubane heptacopper core surrounded by a belt of six X ions is present in the compounds [{Cu3(HpztBu)63-X)(μ3-OH)3}2Cu]X6 (X[DOUBLE BOND]Cl, Br, or NO3 (see structure)). These are associated with the cluster core through a combination of very long axial Cu⋅⋅⋅X interactions, hydrogen bonding and hydrophobic interactions. Spin frustration results in the seven Cu spins coalescing into three mutually independent spin systems in their magnetic ground state.

    28. A Systematic Investigation into the Mechanism of the Reaction Between CF3 Radicals and CO/O2 (pages 1838–1844)

      Maximiliano A. Burgos Paci and Gustavo A. Argüello

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200305480

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      Cool, radical discoveries! The combined action of ab initio IR predicted spectra of isotopomers and selective use of isotope-labeled reagents allowed the complete elucidation of the mechanism shown in the scheme (CF3 radicals in the presence of CO and O2). This led to the conclusion that acyloxy radicals can be substantially stabilized at temperatures close to 0 °C.

    29. Growing ZnO Crystals on Magnetite Nanoparticles (pages 1845–1850)

      Rachel Turgeman, Shay Tirosh and Aharon Gedanken

      Article first published online: 16 MAR 2004 | DOI: 10.1002/chem.200306022

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      Hollowed ZnO hexagons of 0.15 μm width and 0.5 μm length filled with functionaliazed Fe3O4 nanoparticles were grown from a supersaturated solution of Zn(NO3)2 seeded with the magnetic nanoparticles. HR-TEM (high-resolution transmission electron microscopy) and selected-area EDS (energy-dispersive spectroscopy) show that the nanoparticles are homogenously spread in the ZnO tubes. Zeta potential measurements show that the surfactants induced the directional growth of the ZnO crystals. The figure shows an HR-SEM (high-resolution scanning electron microscopy) micrograph of the ZnO crystals that were grown on the magnetite nanoparticles.

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      Preview: Chem. Eur. J. 7/2004 (page 1854)

      Article first published online: 24 MAR 2004 | DOI: 10.1002/chem.200490023