Chemistry - A European Journal

Cover image for Vol. 11 Issue 12

June 6, 2005

Volume 11, Issue 12

Pages 3491–3783

    1. Cover Picture: Ligand Functionality as a Versatile Tool to Control the Assembly Behavior of Preformed Titania Nanocrystals (Chem. Eur. J. 12/2005) (page 3491)

      Julien Polleux, Nicola Pinna, Markus Antonietti, Christian Hess, Ute Wild, Robert Schlögl and Markus Niederberger

      Article first published online: 30 MAY 2005 | DOI: 10.1002/chem.200590036

      Fussy functionalized crystal faces of titania nanocrystals, represented by surface-functionalized octahedra in the cover picture, are found to spontaneously assemble into highly anisotropic nanostructures by means of oriented attachment in the [001] direction. M. Niederberger et al. describe the assembly behavior of preformed titania nanopowders in terms of the type of organic “assembler” molecule bound to the crystal surface in their article on page 3541 ff.

    2. Graphical Abstract: Chem. Eur. J. 12/2005 (pages 3492–3500)

      Article first published online: 30 MAY 2005 | DOI: 10.1002/chem.200590037

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      Alkylchlorotins Grafted to Cross-Linked Polystyrene Beads by a [BOND](CH2)n[BOND] Spacer (n=4, 6, 11): Selective, Clean and Recyclable Catalysts for Transesterification Reactions (page 3500)

      Carlos Camacho-Camacho, Monique Biesemans, Manu Van Poeck, Frédéric A. G. Mercier, Rudolph Willem, Karine Darriet-Jambert, Bernard Jousseaume, Thierry Toupance, Uwe Schneider and Ursula Gerigk

      Article first published online: 30 MAY 2005 | DOI: 10.1002/chem.200590038

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    5. Multicomponent Domino Processes Based on the Organocatalytic Generation of Conjugated Acetylides: Efficient Synthetic Manifolds for Diversity-Oriented Molecular Construction (pages 3502–3510)

      David Tejedor, David González-Cruz, Alicia Santos-Expósito, Jose Juan Marrero-Tellado, Pedro de Armas and Fernando García-Tellado

      Article first published online: 7 MAR 2005 | DOI: 10.1002/chem.200401267

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      Molecular complexity: Coupling two or more domino processes is a fast way to achieve molecular complexity. Efficient synthetic manifolds based on this concept have been developed for the one-pot, modular, and diversity-oriented construction of biologically relevant heterocycles (see scheme). Central to this methodology is the development of a novel set of multicomponent domino processes based on the organocatalytic generation of conjugated acetylides in the presence of aldehydes or activated ketones.

    6. Triple-Bond Covalent Radii (pages 3511–3520)

      Pekka Pyykkö, Sebastian Riedel and Michael Patzschke

      Article first published online: 14 APR 2005 | DOI: 10.1002/chem.200401299

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      Bond—Triple Bond! We present a set of triple-bond covalent radii for 81 elements on the basis of 324 experimental and theoretical data points (see plot). To our knowledge, this is the first comprehensive system of triple-bond covalent radii proposed.

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      Synthesis, X-ray Crystal Structures, and Gas Sorption Properties of Pillared Square Grid Nets Based on Paddle-Wheel Motifs: Implications for Hydrogen Storage in Porous Materials (pages 3521–3529)

      Hyungphil Chun, Danil N. Dybtsev, Hyunuk Kim and Kimoon Kim

      Article first published online: 11 MAR 2005 | DOI: 10.1002/chem.200401201

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      Similarities and differences exist in the structures and gas sorption behavior of highly porous metal–organic frameworks systematically modulated from a prototype based on a paddle-wheel-based three-dimensional net (see picture). The similarities and differences are used to draw a conclusion that might be useful for the development of efficient hydrogen-storage materials.

    8. Metal-Induced Chiral Folding of Depsipeptide Dendrimers (pages 3530–3540)

      Boris Buschhaus, Frank Hampel, Stefan Grimme and Andreas Hirsch

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401327

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      Diastereoselective folding of chiral dendrimers with known absolute configuration: Upon complexation of Cu2+ and Zn2+ ions, depsipeptide dendrimers containing an ethylenediaminetetraacetate-derived central cavity stereoselectively adopt a chiral folding motif. The absolute configuration of, for example, 1-CuCl2 around the core has been assigned by comparison of experimental and calculated CD spectra.

    9. Ligand Functionality as a Versatile Tool to Control the Assembly Behavior of Preformed Titania Nanocrystals (pages 3541–3551)

      Julien Polleux, Nicola Pinna, Markus Antonietti, Christian Hess, Ute Wild, Robert Schlögl and Markus Niederberger

      Article first published online: 25 FEB 2005 | DOI: 10.1002/chem.200401050

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      Ligands allow links: Surface-functionalized anatase nanocrystals self-organize into different nanostructures upon redispersion in hot water. The ligand functionality on the surface of the nanoparticles determines the assembly behavior, allowing the controlled fabrication of highly anisotropic nanostructures. Experimental data suggest that the assembly is directed by specific desorption of the organic ligands from the {001} faces of the crystalline nanosized building blocks (see graphic).

    10. Borate-Catalyzed Reactions of Hydrogen Peroxide: Kinetics and Mechanism of the Oxidation of Organic Sulfides by Peroxoborates (pages 3552–3558)

      D. Martin Davies, Michael E. Deary, Kieran Quill and Robert A. Smith

      Article first published online: 13 APR 2005 | DOI: 10.1002/chem.200401209

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      It must be the water—there is something very unusual about peroxoborates. Compared with other hydroperoxides they are very much less selective than might be expected from their reactivity with nucleophilic sulfides (see scheme). Furthermore, they are very much more reactive than peroxoboric acid, HOOB(OH)2, which ought to be a better electrophile, since it is uncharged and the boron is electron-deficient.

    11. Atom-Type Assignment in Molecules and Clusters by Perturbation Theory—A Complement to X-ray Structure Analysis (pages 3559–3564)

      Florian Weigend and Claudia Schrodt

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200500028

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      There are nearly half a million possibilities to distribute 26 Ag and 18 In atoms to 44 atomic sites. As Ag and In are practically indistinguishable solely from X-ray data, complementary methods are necessary to find the correct distribution. From just one single DFT calculation and subsequent application of first-order perturbation theory, reasonable proposals for the distribution of atom types to atomic sites are possible in a simple and cheap way (see scheme).

    12. C-Linked Disaccharide Analogue of the Thomsen–Friedenreich (T)-Epitope α-O-Conjugated to L-Serine (pages 3565–3573)

      Loay Awad, Jens Riedner and Pierre Vogel

      Article first published online: 8 APR 2005 | DOI: 10.1002/chem.200401301

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      Sugar epitope mimetic: C-Linked disaccharide conjugates are necessary for artificial vaccines based on disaccharide and oligosaccharide epitopes. Epitope T is a tumor-associated antigen. An analogue (1) has been made and should be suitable for the construction of clusters by synthesis and further conjugation to immunogenic proteins.

    13. Isomeric Mono- and Bis[(phosphane)gold(I)] Thiocyanate Complexes (pages 3574–3582)

      Raphael J. F. Berger, Michael Patzschke, Daniel Schneider, Hubert Schmidbaur and Dage Sundholm

      Article first published online: 1 APR 2005 | DOI: 10.1002/chem.200400916

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      The combined effort of experimental and computational studies facilitates the structure assignment of three isomers in the reaction depicted. The dinuclear products, which are obtained from the reaction of SCN with two equivalents of [R3PAu]+, have been characterized by elemental analysis, IR and NMR spectroscopy, and mass spectrometry.

    14. Syntheses, Structures, Photoluminescence and Theoretical Studies of Xanthone in Crystalline Resorcinarene-Based Inclusion Complexes (pages 3583–3590)

      Shao-Liang Zheng and Philip Coppens

      Article first published online: 7 APR 2005 | DOI: 10.1002/chem.200500033

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      Crucial role of energy-level separation in energy transfer: The photophysical properties of two resorcinarene-based supramolecular phases containing monomeric and dimeric xanthone (shown here) are strongly dependent on the degree of aggregation of the guest molecules, with the second dimer-containing phase showing excimer emission.

    15. Control of Helix Sense by Composition of Chiral–Achiral Copolymers of N-Propargylbenzamides (pages 3591–3598)

      Junichi Tabei, Masashi Shiotsuki, Takahiro Sato, Fumio Sanda and Toshio Masuda

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401009

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      Controlling the screw direction of a helical copolymer, formed from acetylenic monomers as shown, may in certain cases be possible by altering its composition of monomers.

    16. The Structure of Acrolein in a Liquid Crystal Phase (pages 3599–3608)

      Giorgio Celebre, Maria Concistrè, Giuseppina De Luca, Marcello Longeri, Giuseppe Pileio and James William Emsley

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401059

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      The structure and conformational equilibrium of acrolein in a liquid crystal phase have been studied by anisotropic and isotropic NMR techniques, also taking into account the corrections of molecular vibrations of flexible systems. The results obtained show a large prevalence of trans conformation (∼99 %). A comparison of those results with calculations and experiments in the gas phase, where the cis form seems to be more populated (∼4 %) than in the liquid crystal phase, was also performed.

    17. Molecular Conformation and Packing of Peptide β Hairpins in the Solid State: Structures of Two Synthetic Octapeptides Containing 1-Aminocycloalkane-1-Carboxylic Acid Residues at the i+2 Position of the β Turn (pages 3609–3620)

      Veldore Vidya Harini, Subrayashastry Aravinda, Rajkishor Rai, Narayanaswamy Shamala and Padmanabhan Balaram

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401124

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      The designed octapeptides Boc-Leu-Phe-Val-D-Pro-Ac6c-Leu-Phe-Val-OMe (1) and Boc-Leu-Phe-Val-D-Pro-Ac8c-Leu-Phe-Val-OMe (2) form β hairpins in the solid state with a central D-Pro-Acnc segment adopting a type II′ β-turn conformation (see figure). Two independent β-hairpins in the asymmetric unit are oriented in a nearly orthogonal manner resulting in a packing motif distinct from the commonly observed, flat β-sheet arrangement.

    18. Rhodium-Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC2H5 to Alkynes (pages 3621–3630)

      Ruimao Hua, Shun-ya Onozawa and Masato Tanaka

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401279

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      The novel high-yielding CO-retentive addition of ethoxalyl chloride to terminal alkynes proceeds efficiently in the presence of rhodium complexes (see scheme). The thermal stabilities of the intermediate ethoxalyl complexes to decarbonylation and reductive elimination are the key features for a successful catalysis.

    19. Strained, Stable 2-Aza-1-Phosphabicyclo[n.1.0]alkane and -alkene Fe(CO)4 Complexes with Dynamic Phosphinidene Behavior (pages 3631–3642)

      Mark L. G. Borst, Niels van der Riet, Renske H. Lemmens, Franciscus J. J. de Kanter, Marius Schakel, Andreas W. Ehlers, Allison M. Mills, Martin Lutz, Anthony L. Spek and Koop Lammertsma

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401249

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      Phosphinidene activity revealed! Disguised as simple phosphiranes, several stable phosphabicycloalkane–iron complexes show phosphinidene reactivity only when phenylacetylene is supplied as a substrate (see figure). The dynamic nature of these phosphirane iron complexes is beautifully shown by NMR analysis of an N-olefinic substituted phosphirane complex.

    20. Synthesis, Spectroscopic and Nonlinear Optical Properties of Multiple [60]Fullerene–Oligo(p-phenylene ethynylene) Hybrids (pages 3643–3658)

      Yuming Zhao, Yasuhiro Shirai, Aaron D. Slepkov, Long Cheng, Lawrence B. Alemany, Takashi Sasaki, Frank A. Hegmann and James M. Tour

      Article first published online: 7 APR 2005 | DOI: 10.1002/chem.200401198

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      Enhanced two-photon absorption could be achieved by incorporation of multiple fullerenes. In the ground state, the hybrid compounds show insignificant electronic communication between the oligomer and fullerene moieties. The synthesis of the multiple fullerene-terminated oligo(p-phenylene ethynylene) hybrids (see picture) has been performed through an in situ ethynylation protocol with satisfactory yields.

    21. Diversity Oriented Synthesis of Hispanane-like Terpene Derivatives from (R)-(+)-Sclareolide (pages 3659–3667)

      María C. de la Torre, Isabel García and Miguel A. Sierra

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401220

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      A highly versatile and structurally diverse approach has been developed in the synthesis of hispanane and hispanane-like derivatives by using (R)-(+)-sclareolide as the starting material (see scheme). The approach is achieved by changing either the aromatic moiety or the stereochemistry on key intermediates.

    22. Copolymerization of Cyclohexene Oxide with CO2 by Using Intramolecular Dinuclear Zinc Catalysts (pages 3668–3678)

      Youli Xiao, Zheng Wang and Kuiling Ding

      Article first published online: 13 APR 2005 | DOI: 10.1002/chem.200401159

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      Practical catalysts: Copolymerization of cyclohexene oxide takes place with CO2 at only 1 atm pressure in the presence of an intramolecular dinuclear zinc catalyst (shown here) to afford a completely alternating poly(cyclohexene carbonate) in excellent yield and chemoselectivity.

    23. Intervalence Charge Transfer (IVCT) in Ruthenium Dinuclear and Trinuclear Assemblies Containing the Bridging Ligand HAT {1,4,5,8,9,12-hexaazatriphenylene} (pages 3679–3688)

      Deanna M. D'Alessandro and F. Richard Keene

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401038

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      Mixed-valence forms of the meso (ΔΛ) and rac (ΔΔ/ΛΛ) diastereoisomers of [{Ru(bpy)2}2(μ-hat)]n+ and the homochiral (Δ33) and heterochiral (Δ2Λ/Λ2Δ; shown) diastereoisomers of trinuclear [{Ru(bpy)2}3(μ-hat)]n+ {hat=1,4,5,8,9,12-hexaazatriphenylene; bpy=2,2′-bipyridine} were investigated in terms of their IVCT properties. The results reveal a marked dependence of intramolecular electron transfer on the stereochemical identity, nuclearity and oxidation state of the assemblies. The unusual spectroscopic and electrochemical behaviour is indicative of strong metal–metal coupling.

    24. Discovery of Powerful Uranyl Ligands from Efficient Synthesis and Screening (pages 3689–3697)

      Marcin Sawicki, Jean-Michel Siaugue, Christophe Jacopin, Christophe Moulin, Théodorine Bailly, Ramon Burgada, Stéphane Meunier, Paul Baret, Jean-Louis Pierre and Frédéric Taran

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401056

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      A dye compound allows the high-throughput screening of uranyl ligands even by simple visualization by the naked eye. 96 candidate ligands were screened and the results highlighted (see figure) the remarkable uranium-binding properties of ligands bearing bis-phosphonate moieties.

    25. Heteroditopic Ligand Accommodating a Fused Phenanthroline and a Schiff Base Cavity as Molecular Spacer in the Study of Electron and Energy Transfer (pages 3698–3710)

      Yann Pellegrin, Annamaria Quaranta, Pierre Dorlet, Marie France Charlot, Winfried Leibl and Ally Aukauloo

      Article first published online: 5 APR 2005 | DOI: 10.1002/chem.200401064

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      A remarkably long-lived charge-separated state (lifetime ca. 30 μs) was observed for the Ru complex of a heteroditopic ligand containing a phenanthroline and a Schiff base cavity. Intramolecular electron transfer was confirmed for the Ru-only complex in the presence of methyl viologen dication (MV2+), while fast energy quenching is proposed for the dinuclear Ru/Cu complex (see scheme). Density functional calculations helped to disentangle the electronic properties of the constituent units of these supramolecular systems.

    26. Photoinduced Processes within Compact Dyads Based on Triphenylpyridinium-Functionalized Bipyridyl Complexes of Ruthenium(II) (pages 3711–3727)

      Philippe P. Lainé, Ilaria Ciofini, Philippe Ochsenbein, Edmond Amouyal, Carlo Adamo and Fethi Bedioui

      Article first published online: 8 APR 2005 | DOI: 10.1002/chem.200401150

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      The ability of compact dyads, P-(θ1)-A, made of a photosensitizer (P) directly linked to an electron acceptor (A), to undergo intramolecular photoinduced electron transfer processes is investigated (see scheme). Formation of a charge-separated state is examined as a function of the degree of conjugation of P with A. The derived possibility of a conformational control (θ1) of the emission properties of P within *[P-(θ1)-A] is discussed.

    27. Palladium(0)-Catalyzed Tandem Cyclization of Allenenes: Direct Construction of Tricyclic Heterocycles through Aromatic C[BOND]H Activation (pages 3728–3741)

      Hiroaki Ohno, Kumiko Miyamura, Tsuyoshi Mizutani, Yoichi Kadoh, Yusuke Takeoka, Hisao Hamaguchi and Tetsuaki Tanaka

      Article first published online: 7 APR 2005 | DOI: 10.1002/chem.200500050

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      Tandem cycling: Palladium(0)-catalyzed tandem cyclization of allenenes with an aryl halide (ArX) afforded tri- or tetracyclic heterocycles through insertion of [ArPdIIX] into the allenic moiety, intramolecular carbopalladation, and aromatic C[BOND]H activation (see scheme; Ar=phenyl, thienyl, furyl, indolyl, pyridyl, etc.).

    28. Design of Organic Semiconductors: Tuning the Electronic Properties of π-Conjugated Oligothiophenes with the 3,4-Ethylenedioxythiophene (EDOT) Building Block (pages 3742–3752)

      Mathieu Turbiez, Pierre Frère, Magali Allain, Christine Videlot, Jörg Ackermann and Jean Roncali

      Article first published online: 14 APR 2005 | DOI: 10.1002/chem.200401058

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      A new series of hybrid EDOT-thiophene oligomers varying in number and position of the 3,4-ethylenedioxythiophene (EDOT) units has been synthesized and characterized. The structure–property relationships were studied, and the influence of the number and position of the EDOT groups on the structure and electronic properties of the π-conjugated system is discussed. For example, the picture shows the UV/Vis absorption spectra of the three alternating oligomers depicted on the left.

    29. Excitation-Energy Migration in Self-Assembled Cyclic Zinc(II)–Porphyrin Arrays: A Close Mimicry of a Natural Light-Harvesting System (pages 3753–3761)

      In-Wook Hwang, Mira Park, Tae Kyu Ahn, Zin Seok Yoon, Dah Mee Ko, Dongho Kim, Fuyuki Ito, Yukihide Ishibashi, Sazzadur R. Khan, Yutaka Nagasawa, Hiroshi Miyasaka, Chusaku Ikeda, Ryoichi Takahashi, Kazuya Ogawa, Akiharu Satake and Yoshiaki Kobuke

      Article first published online: 13 APR 2005 | DOI: 10.1002/chem.200500069

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      Energy-hopping systems: The excitation-energy-hopping (EEH) times within two-dimensional cyclic zinc(II)–porphyrin arrays (illustrated here) were deduced by modeling the EEH process based on the anisotropy depolarization as well as the exciton–exciton annihilation dynamics.

    30. Structure–Property Correlations in Solid Solutions of (CuI)8P12−xAsx, 2.4≤x≤6.6 (pages 3762–3772)

      Buddhimathie Jayasekera, Stephanie L. Brock, Andy Y. H. Lo, Robert W. Schurko and Gholam-Abbas Nazri

      Article first published online: 13 APR 2005 | DOI: 10.1002/chem.200400727

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      The solubility limit of arsenic in polymeric phosphorus: A series of (CuI)8P12−xAsx phases is formed by the partial substitution of arsenic into the neutral chains of phosphorus in (CuI)8P12. The As shows clear site preferences, as reflected in the nonlinearity in the Vegard's law plot (see graph), and up to 60 % As can be adopted into the polymer.

    31. Nanotubes from Isomeric Dibenzoylmethane Molecules (pages 3773–3778)

      Liyun Zhao, Wensheng Yang, Yi Luo, Tianyou Zhai, Guangjin Zhang and Jiannian Yao

      Article first published online: 13 APR 2005 | DOI: 10.1002/chem.200401265

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      Narrow nanotubes fluoresce nicely! Organic nanotubes of various diameters were fabricated from isomeric dibenzoylmethane (DBM) by using the template-based method (see figure). As the diameters of the nanotubes decreased, the observed fluorescence emission was remarkably enhanced. This is due to the corresponding increased ratio of the enol isomers of DBM.

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      Preview: Chem. Eur. J. 12/2005 (page 3783)

      Article first published online: 30 MAY 2005 | DOI: 10.1002/chem.200590039