Angewandte Chemie International Edition

Cover image for Vol. 43 Issue 46

November 26, 2004

Volume 43, Issue 46

Pages 6219–6389

    1. Cover Picture: A Molybdenum Crown Cluster Forms Discrete Inorganic–Organic Nanocomposites with Metalloporphyrins (Angew. Chem. Int. Ed. 46/2004) (page 6219)

      Akihiko Tsuda, Eri Hirahara, Yeong-Sang Kim, Hiroyuki Tanaka, Tomoji Kawai and Takuzo Aida

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200490163

      A generous host describes the fully inorganic doughnut-shaped polyoxometalate crown cluster illustrated in the cover picture which has a 2.3-nm-wide and 1.3-nm-deep nanoscopic cavity and serves as a novel host for three metalloporphyrin molecules that contain 3- or 4-aminophenyl groups. A. Tsuda, T. Kawai, T. Aida, and co-workers describe in their Communication on page 6327 ff. how this new organic/inorganic hybrid complex forms through multiple hydrogen-bonding interactions.

    2. Handbook of Proteomic Methods. By P. Michael Conn. (pages 6235–6236)

      Evelyn W. Wang and Matthew S. Bogyo

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200385103

    3. Pyrrole Syntheses by Multicomponent Coupling Reactions (pages 6238–6241)

      Geneviève Balme

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461073

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      Versatile strategies of multicomponent coupling reactions to synthesize variously substituted pyrroles 1 are summarized. These heterocycles are important targets as molecules in their own right, for their pharmacological properties, as well as intermediates for more elaborate syntheses.

    4. Endohedral Zintl Ions: Intermetalloid Clusters (pages 6242–6247)

      Thomas F. Fässler and Stephan D. Hoffmann

      Version of Record online: 26 OCT 2004 | DOI: 10.1002/anie.200460427

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      The close race between Zintl ions and fullerides has gone into the second round, initialized by the synthesis of the soluble endohedral cluster [Pt@Pb12]2− (see picture, left). The structural characterization of an anion with almost ideal icosahedral symmetry illustrates that many heteroatomic clusters observed in the gas phase can, indeed, be regarded as endohedral clusters.

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      Controlled Microwave Heating in Modern Organic Synthesis (pages 6250–6284)

      C. Oliver Kappe

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200400655

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      Out of the kitchen into the laboratory: Direct heating by microwave irradiation (see picture) in many cases enables synthesis to be carried out in a fraction of the time required with conventional heating techniques. The use of microwave heating in organic synthesis is growing rapidly and the advantages not only include faster reaction times, but also higher product yields, cleaner reactions, better controllability, and reproducibility.

    6. A Route to the Synthesis of Trivalent Transition-Metal Porous Carboxylates with Trimeric Secondary Building Units (pages 6285–6289)

      Christian Serre, Franck Millange, Suzy Surblé and Gérard Férey

      Version of Record online: 7 SEP 2004 | DOI: 10.1002/anie.200454250

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      Prefabricated construction techniques: A solvothermal route involving iron(III) trimeric secondary building units has been developed. Two new open-framework iron (III) dicarboxylates have been characterized from X-ray powder diffraction studies. Their 3D structures are built up from trimers of iron polyhedra related through dicarboxylates, thus creating cationic frameworks with 1D pore systems filled with solvent molecules and anions (see example).

    7. Hybrid Organic–Inorganic Frameworks: Routes for Computational Design and Structure Prediction (pages 6290–6296)

      Caroline Mellot-Draznieks, Julien Dutour and Gérard Férey

      Version of Record online: 3 SEP 2004 | DOI: 10.1002/anie.200454251

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      Structure prediction of hybrid organic–inorganic frameworks is now computationally possible. The employed method embraces the concept of hybrid framework through the automated assembly of predefined organic and inorganic building units in 3D space. Crystal structures of hybrid candidates are predicted (space group, cell parameters, atomic positions; see picture), together with an estimate of their lattice energies.

    8. A Hybrid Solid with Giant Pores Prepared by a Combination of Targeted Chemistry, Simulation, and Powder Diffraction (pages 6296–6301)

      Gérard Férey, Christian Serre, Caroline Mellot-Draznieks, Franck Millange, Suzy Surblé, Julien Dutour and Irène Margiolaki

      Version of Record online: 30 AUG 2004 | DOI: 10.1002/anie.200460592

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      A perfect combination: The association of a chromium(III) trimeric building unit and 1,3,5-benzenetricarboxylate led to the powdered solid MIL-100. Simulations provided a crystal structure solution, which matched the experimental powder XRD pattern. This unique simulation/diffraction combination allowed the structure determination of a giant-pore solid with a zeotype architecture, built up from hybrid supertetrahedra (see picture).

    9. Chemical Control of Valence Tautomerism of Nickel(II) Semiquinone and Nickel(III) Catecholate States (pages 6301–6303)

      Hideki Ohtsu and Koji Tanaka

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460023

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      Fine-tuning the N-donor ability of a bidentate aminopyridyl ligand facilitated the selective synthesis of complexes 1 (no methyl substituent) and 2 (with a methyl substituent) which possess valence tautomeric nickel(II) semiquinonato and nickel(III) catecholato frameworks, respectively.

    10. Metallic Nanomagnets Randomly Dispersed in Spherical Colloids: Toward a Universal Route for the Preparation of Colloidal Composites Containing Nanoparticles (pages 6304–6307)

      Pedro Tartaj, Teresita González-Carreño, Maria L. Ferrer and Carlos J. Serna

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460830

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      Small world: Metallic nanomagnets (MNMs) dispersed in spherical colloids can be prepared by the aerosol evaporation of an aqueous sol containing mineralized ferritin and a colloidal matrix precursor (see picture). Essential to the success of the method is the template effect provided by ferritin.

    11. Dipeptides as Microporous Materials (pages 6308–6311)

      Dmitriy V. Soldatov, Igor L. Moudrakovski and John A. Ripmeester

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460952

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      Robust porous frameworks are formed by the dipeptides L-Ala-L-Val (see structure) and L-Val-L-Ala that have a high capacity and selectivity for gas sorption. The dipeptides assemble through hydrogen bonds as a 61 helix to form channels with average diameters of 5.13 and 4.90 Å, respectively.

    12. Are NMR-Derived Model Structures for β-Peptides Representative for the Ensemble of Structures Adopted in Solution? (pages 6312–6316)

      Alice Glättli and Wilfred F. van Gunsteren

      Version of Record online: 2 NOV 2004 | DOI: 10.1002/anie.200460384

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      The data fit, but the structures are different. Two methods for the interpretation of NMR data of a β-hexapeptide are compared. While the simulated annealing procedure suggests the formation of a (P)-28-helix, unrestrained molecular dynamics simulations indicate that the NMR data can also be described by a much broader ensemble of conformations, in which (P)-2.512-helical structures are prominent (see diagram).

    13. Large Lattice Responses in a Mixed-Valence Prussian Blue Analogue Owing to Electronic and Spin Transitions Induced by X-ray Irradiation (pages 6316–6319)

      Serena Margadonna, Kosmas Prassides and Andrew N. Fitch

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460603

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      Illuminating phase changes: Absorption of X-ray photons induces reversible internal charge-transfer processes in the mixed-valence Mn/Fe cyanide Rb0.7MnII1.15[FeIII(CN)6]⋅2 H2O over a broad temperature range. Both continuous and abrupt phase transformations can be triggered (see scheme; HS=high spin, LS=low spin) and because the X-rays simultaneously probe the structural properties of the material, the resulting phase diagram can be elucidated in detail.

    14. Design of a Conformation-Sensitive Xenon-Binding Cavity in the Ribose-Binding Protein (pages 6320–6322)

      Thomas J. Lowery, Seth M. Rubin, E. Janette Ruiz, Alexander Pines and David E. Wemmer

      Version of Record online: 11 OCT 2004 | DOI: 10.1002/anie.200460629

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      129Xe NMR spectroscopy meets protein engineering: NMR spectroscopy with laser-polarized 129Xe can be used to report protein conformations only if a protein has a conformationally sensitive xenon-binding cavity. However, many proteins lack such reporter sites. A straightforward design process is used to engineer a xenon-binding cavity into the ribose-binding protein (see picture) that allows the 129Xe NMR spectroscopic report of protein conformation and ligand binding.

    15. cRGD-Functionalized Polymer Micelles for Targeted Doxorubicin Delivery (pages 6323–6327)

      Norased Nasongkla, Xintao Shuai, Hua Ai, Brent D. Weinberg, John Pink, David A. Boothman and Jinming Gao

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460800

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      Targeting micelles: Cyclic pentapeptide cRGDfK (red triangles), which targets integrin αvβ3, was conjugated to the outer shell of doxorubicin-loaded (red hexagons) polymeric micelles by using a post-micelle modification method. The modified micelles significantly enhanced their internalization (up to 30-fold) by receptor-mediated endocytosis in tumor endothelial cells overexpressing the αvβ3 receptor.

    16. A Molybdenum Crown Cluster Forms Discrete Inorganic–Organic Nanocomposites with Metalloporphyrins (pages 6327–6331)

      Akihiko Tsuda, Eri Hirahara, Yeong-Sang Kim, Hiroyuki Tanaka, Tomoji Kawai and Takuzo Aida

      Version of Record online: 23 SEP 2004 | DOI: 10.1002/anie.200460990

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      Filled doughnuts: Molybdenum crown cluster MC accommodates up to three molecules of aminophenyl-substituted metalloporphyrins through hydrogen-bonding interactions, to form discrete inorganic–organic nanocomposite materials (see picture; blue polyhedra=MC, space-filling model=metalloporphyrin). Ultrahigh-vacuum scanning tunneling microscopy, in conjunction with scanning tunneling spectroscopy, at 80 K confirms the formation of the inclusion complex.

    17. Solid-Phase Synthesis of Styryl Dyes and their Application as Amyloid Sensors (pages 6331–6335)

      Qian Li, Jun-Seok Lee, Chanki Ha, Chan Beum Park, Guang Yang, Wen Biao Gan and Young-Tae Chang

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461600

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      The combinatorial approach: A library of fluorescent styryl dyes (320 compounds) was prepared by solid-phase chemistry. The dyes were screened for their detection of amyloid aggregates, which are associated with diseases such as Alzheimer's, and two of the 320 compounds screened, 2C40 and 2E10, showed promise as brain-imaging agents (see microscopy image).

    18. Improving Quantum Efficiencies of Siloles and Silole-Derived Butadiene Chromophores through Structural Tuning (pages 6336–6338)

      Andrew J. Boydston and Brian L. Pagenkopf

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461844

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      A brighter future for siloles. Luminescent silole chromophores with the highest quantum efficiencies reported for a fully substituted monomeric silole are generated by altering the steric properties of the substituent groups. Treatment of 1,1-dimethylsiloles with Bu4NF (TBAF) in THF rapidly gives stereospecific desilylation at room temperature (see scheme). Intense solid-state photoluminescence is observed in thin films of the silole fluorophores.

    19. A Reductive-Aggregation Route to [Mn12O12(OMe)2(O2CPh)16(H2O)2]2− Single-Molecule Magnets Related to the [Mn12] Family (pages 6338–6342)

      Anastasios J. Tasiopoulos, Wolfgang Wernsdorfer, Khalil A. Abboud and George Christou

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461551

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      Axes of power: Jahn–Teller isomerism (that is, Jahn–Teller distortion along different axes) accounts for the presence of both faster and slower relaxing magnetization dynamics of the title compound (see core structure; blue Mn, red O, gray C), which is a single-molecule magnet (SMM). The new compound is a structural variant of the [Mn12] family of SMMs and is prepared by a reductive aggregation of [MnO4] in a mixture of MeOH/PhCO2H.

    20. A Purely Organic Molecular Metal Based on a Hydrogen-Bonded Charge-Transfer Complex: Crystal Structure and Electronic Properties of TTF-Imidazole–p-Chloranil (pages 6343–6346)

      Tsuyoshi Murata, Yasushi Morita, Kozo Fukui, Kazunobu Sato, Daisuke Shiomi, Takeji Takui, Mitsuhiko Maesato, Hideki Yamochi, Gunzi Saito and Kazuhiro Nakasuji

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460801

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      Modification of tetrathiafulvalene with an imidazolyl substituent as a hydrogen-bond donor allows the generation of a hydrogen-bonded 2:1 charge-transfer complex with chloranil. This complex forms a three-dimensional network with columnar stacking of each component and multiple S⋅⋅⋅S interactions (see picture). This strongly hydrogen-bonded purely organic conducting material is the first to display metallic behavior.

    21. Photoswitchable Organic Nanoparticles and a Polymer Film Employing Multifunctional Molecules with Enhanced Fluorescence Emission and Bistable Photochromism (pages 6346–6350)

      Seon-Jeong Lim, Byeong-Kwan An, Sang Don Jung, Myung-Ae Chung and Soo Young Park

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461172

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      Get turned on: Fluorescent photochromic organic nanoparticles (FPONs) of 1 (see picture) show a strongly enhanced fluorescence emission with increasing concentration and bistable photochromism. High-contrast on/off fluorescence switching has been successfully implemented in size-tuned FPONs of 1 and also in a photo-rewritable polymer film highly loaded with 1.

    22. Macroscopic Spinning Chirality Memorized in Spin-Coated Films of Spatially Designed Dendritic Zinc Porphyrin J-Aggregates (pages 6350–6355)

      Tatsuya Yamaguchi, Tatsumi Kimura, Hiro Matsuda and Takuzo Aida

      Version of Record online: 12 NOV 2004 | DOI: 10.1002/anie.200461431

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      Supramolecular polymerization of dendritic zinc porphyrins with two carboxylic acid functionalities leads to the formation of J-aggregates through multipoint π-stacking interactions. Spin-coating of the J-aggregate solutions gives optically active films, whose sense of chirality can be selected by the spinning direction (see picture). The chiroptical memory is thermally stable up to the melting temperatures of the spin-coated films.

    23. Optimization Of “Wired” Enzyme O2-Electroreduction Catalyst Compositions by Scanning Electrochemical Microscopy (pages 6355–6357)

      José L. Fernández, Nicolas Mano, Adam Heller and Allen J. Bard

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461528

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      Rapid screening: For optimizing the weight fraction of enzyme in enzyme electrodes, the scanning electrochemical microscopy (SECM) screening method described gives results (see picture) in good agreement with those obtained by the traditional rotating-disk-electrode method but in one tenth of the time and with a reduction in the amount of polymer and enzyme required by a factor of 100 000.

    24. Asymmetric Synthesis of Highly Substituted β-Lactones by Nucleophile-Catalyzed [2+2] Cycloadditions of Disubstituted Ketenes with Aldehydes (pages 6358–6360)

      Jonathan E. Wilson and Gregory C. Fu

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460698

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      α,α-Disubstituted β-lactones can be obtained by the cycloaddition of the corresponding ketenes with aldehydes (see scheme). For the first time, a chiral PPY derivative, 1, serves as an efficient catalyst for the asymmetric synthesis of β-lactones (PPY=4-pyrrolidin-1-ylpyridine). To date, this is the only catalyst that is effective for enantioselective cycloadditions of disubstituted ketenes with aldehydes.

    25. Large-Scale Synthesis of Micrometer-Scale Single-Crystalline Au Plates of Nanometer Thickness by a Wet-Chemical Route (pages 6360–6363)

      Xuping Sun, Shaojun Dong and Erkang Wang

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461013

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      The chemical reduction of H[AuCl4] with ortho-phenylenediamine in aqueous media at room temperature and ambient pressure allows the synthesis of Au nanoplates with lengths of several micrometers (see SEM image). The as-prepared nanoplates are single crystals with a preferential growth direction along the Au (111) plane and mainly hexagonal in shape.

    26. High-Mobility Air-Stable n-Type Semiconductors with Processing Versatility: Dicyanoperylene-3,4:9,10-bis(dicarboximides) (pages 6363–6366)

      Brooks A. Jones, Michael J. Ahrens, Myung-Han Yoon, Antonio Facchetti, Tobin J. Marks and Michael R. Wasielewski

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461324

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      Taking up the semiconducting baton: Organic field-effect transistors fabricated with a new class of extremely electron-deficient cyanated perylene diimides are air-stable and exhibit n-type mobilities as high as 0.64 cm2 V−1 s−1 (see scheme). Devices can be fabricated from vapor-deposited and solution-cast films as well as top- and bottom-contact electrode configurations.

    27. An Iridium Difluoroketene Complex: Synthesis and Isolation (pages 6366–6369)

      Joseph G. Cordaro, Herman van Halbeek and Robert G. Bergman

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461402

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      Deprotonation of the trifluoroacyl hydride complex 1 with tert-butyllithium leads to difluoroketene adduct 2. Coordination of the difluoroketene to iridium through the C[BOND]C bond is confirmed by X-ray diffraction (see scheme). This complex is the first isolated and characterized dihaloketene complex and provides the only structural data for difluoroketene.

    28. Polymer–Monomer Pairs as a Reaction System for the Synthesis of Magnetic Fe3O4–Polymer Hybrid Hollow Nanospheres (pages 6369–6372)

      Yin Ding, Yong Hu, Xiqun Jiang, Leyang Zhang and Changzheng Yang

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460408

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      Magnetic hollow Fe3O4–polymer hybrid nanospheres (see figure) were prepared by adding Fe3O4 nanoparticles to an aqueous solution of polymer–monomer pairs composed of a cationic polymer (chitosan) and an anionic monomer (acrylic acid), followed by polymerization of acrylic acid and selective crosslinking of chitosan at the end of the polymerization.

    29. Pd-Catalyzed Amination of Nucleoside Arylsulfonates to yield N6-Aryl-2,6-Diaminopurine Nucleosides (pages 6372–6377)

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

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200460782

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      Substituents on both the nucleoside arylsulfonate as well as the aryl amine component have a significant impact on their coupling to form 2,6-diaminopurine-2′-deoxyribonucleosides (see scheme). A systematic study of ligands for the Pd catalysts in amination and C[BOND]C cross-coupling reactions gives insight into the structural elements that lead to effective catalysis.

    30. In Situ Magnetic Resonance Investigation of Styrene Oxidation over TS-1 Zeolites (pages 6377–6381)

      Jianqin Zhuang, Gang Yang, Ding Ma, Xijie Lan, Xiumei Liu, Xiuwen Han, Xinhe Bao and Ulrich Mueller

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461113

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      Competing reactions, not consecutive processes, are the oxidation of styrene to styrene epoxide and the formation of phenylacetaldehyde (PADH). In situ NMR and EPR spectroscopic analysis of styrene oxidation on TS-1 zeolite (see picture) demonstrated that Brønsted acid sites provide the active centers needed to transform an intermediate hemiacetal species into PADH.

    31. A Bis(thiophosphinoyl)methanediide Palladium Complex: Coordinated Dianion or Nucleophilic Carbene Complex? (pages 6382–6385)

      Thibault Cantat, Nicolas Mézailles, Louis Ricard, Yves Jean and Pascal Le Floch

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200461392

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      A question of identity: A palladium complex featuring a carbenic S,C,S-based pincer ligand is reported (see scheme). DFT calculations show that, unlike classical carbene complexes, coordination occurs through donation from a d orbital at the metal into the empty np orbital of the carbene fragment, with the nσ orbital essentially acting as a nonbonding orbital. The complex is shown to have nucleophilic character.

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      Preview: Angew. Chem. Int. Ed. 46/2004 (page 6389)

      Version of Record online: 23 NOV 2004 | DOI: 10.1002/anie.200490165