Chemistry - A European Journal

Cover image for Chemistry - A European Journal

May 10, 2013

Volume 19, Issue 20

Pages 6141–6506

  1. Cover Pictures

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
    1. You have free access to this content
      Cover Picture: Reversible Dimerization of Mononuclear Models of [Fe]-Hydrogenase (Chem. Eur. J. 20/2013) (page 6141)

      Dr. Bowen Hu, Prof. Dr. Dafa Chen and Prof. Dr. Xile Hu

      Article first published online: 2 MAY 2013 | DOI: 10.1002/chem.201390069

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      A unique bidentate pyridinol cofactor is to be found in [Fe]-hydrogenase. In their Communication on page 6221 ff., D. Chen, X. Hu, and B. Hu demonstrate the synthesis and reactivities of a series of mononuclear models, including the first five-coordinate complex with an alkyl thiolate ligand, that mimic the main structure of the [Fe]-hydrogenase active site. The equilibrium between these models and their dimeric components is also described.

    2. You have free access to this content
      Back Cover: Crystal Structures and Phase-Transition Dynamics of Cobaltocenium Salts with Bis(perfluoroalkylsulfonyl)amide Anions: Remarkable Odd–Even Effect of the Fluorocarbon Chains in the Anion (Chem. Eur. J. 20/2013) (page 6508)

      Prof. Dr. Tomoyuki Mochida, Yusuke Funasako, Dr. Takashi Inagaki, Meng-Jiao Li, Kotaro Asahara and Prof. Dr. Daisuke Kuwahara

      Article first published online: 2 MAY 2013 | DOI: 10.1002/chem.201390072

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      A remarkable odd–even effect in their crystal structures and melting entropies is observed for cobaltocenium salts with bis(perfluoroalkylsulfonyl)amide (CnF2n+1SO2)2N anions (n=0–4). In the salts with even n, the cations and anions are stacked alternately to form mixed columns, whereas the cations and anions form segregated columns in the salts with odd n. For more details on the structures and properties of these compounds see the Full Paper by T. Mochida et al. on page 6257 ff.

  2. Graphical Abstract

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
    1. Graphical Abstract: Chem. Eur. J. 20/2013 (pages 6144–6154)

      Article first published online: 2 MAY 2013 | DOI: 10.1002/chem.201390070

  3. News

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
  4. Review

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
    1. Molecular Recognition

      Artificial Allosteric Receptors (pages 6162–6196)

      Dipl.-Chem. Christopher Kremer and Prof. Dr. Arne Lützen

      Article first published online: 5 MAR 2013 | DOI: 10.1002/chem.201203814

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      Widely used: In biological systems, allosteric regulation is a widely used mechanism to control the function of proteins and enzymes. Inspired by this, a lot of effort has been made in supramolecular chemistry over the last 30 years to implement this concept into artificial systems to control functions such as molecular recognition, signal amplification, or even reactivity and catalysis, which are summarized here.

  5. Communications

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
    1. Rhodium Catalysis

      Rhodium(III)-Catalyzed Synthesis of Cinnolinium Salts from Azobenzenes and Alkynes: Application to the Synthesis of Indoles and Cinnolines (pages 6198–6202)

      Krishnamoorthy Muralirajan and Prof. Dr. Chien-Hong Cheng

      Article first published online: 15 APR 2013 | DOI: 10.1002/chem.201300922

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      Versatile salts: A new rhodium-catalyzed synthesis of cinnolinium salts from various azobenzenes and alkynes under air is described. These salts readily transform into three important classes of products, including indoles, indoloindoles, and cinnolines (see scheme).

    2. Macrocycles

      Synthesis of New Functionalized Calix[n]phyrin Macrocycles with Varied Ring Sizes by Using a Sterically Congested Dipyrromethane (pages 6203–6208)

      M.Sc. M. Hassan Beyzavi, Prof. Dr. Dieter Lentz, Prof. Dr. Hans-Ulrich Reissig and Dr. Arno Wiehe

      Article first published online: 20 MAR 2013 | DOI: 10.1002/chem.201300179

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      Congest and conjugate: The application of a sterically congested dipyrromethane in an acid-catalyzed [2+2+2] building-block approach was studied for the first time, resulting in the formation of two stable calix[6]phyrin(1.1.1.1.1.1) diastereomers (see scheme). The calix[n]phyrins were further functionalized at their pentafluorophenyl residues, allowing the first synthesis of a calix[4]phyrin(1.1.1.1) dimer.

    3. Nucleophilic Addition

      Generation of CF3-Containing Epoxides and Aziridines by Visible-Light-Driven Trifluoromethylation of Allylic Alcohols and Amines (pages 6209–6212)

      Eunjin Kim, Sungkyu Choi, Heejeong Kim and Prof. Dr. Eun Jin Cho

      Article first published online: 28 MAR 2013 | DOI: 10.1002/chem.201300564

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      Radical reactions! Efficient methods for the generation of CF3-containing epoxides and aziridines have been developed (see scheme). A variety of allylic alcohols and allylic amines were transformed into the corresponding epoxides and aziridines by using [Ru(bpy)3]Cl2 (bpy=2,2′-bipyridine), CF3I, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (or N,N,N′,N′-tetramethylethylenediamine, TMEDA) under visible-light irradiation.

    4. Asymmetric Synthesis

      Catalytic Enantioselective Formal Hetero-Diels–Alder Reactions of Enones with Isatins to Give Spirooxindole Tetrahydropyranones (pages 6213–6216)

      Dr. Hai-Lei Cui and Prof. Dr. Fujie Tanaka

      Article first published online: 4 APR 2013 | DOI: 10.1002/chem.201300595

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      Organocatalytic formal hetero-Diels–Alder reactions of enones with isatins, which gave highly enantiomerically enriched functionalized spirooxindole tetrahydropyranones via an enamine-based mechanism, were developed. The catalyst systems were identified by a screen of combinations of amines, acids, and additives. With the identified catalyst systems, various spirooxindole tetrahydropyranones were synthesized in high yields with high diastereo- and enantioselectivities (see scheme).

    5. Nanoparticles

      Fabrication of Magnetic Yolk–Shell Nanocatalysts with Spatially Resolved Functionalities and High Activity for Nitrobenzene Hydrogenation (pages 6217–6220)

      Qiang Sun, Chun-Zao Guo, Dr. Guang-Hui Wang, Prof. Dr. Wen-Cui Li, Hans-Josef Bongard and Prof. Dr. An-Hui Lu

      Article first published online: 27 MAR 2013 | DOI: 10.1002/chem.201300307

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      In cracking from: Highly engineered bifunctional yolk–shell nanocatalysts with tailored structural configuration, that is, hollow carbon spheres as the matrix, entrapped magnetite nanoparticles in the core, and in situ formed and highly dispersed noble metal nanoparticles within the carbon shells as active catalytic sites, were prepared. These nanocatalysts show high activity, reusability, and good magnetic separation properties.

    6. Enzyme Models

      Reversible Dimerization of Mononuclear Models of [Fe]-Hydrogenase (pages 6221–6224)

      Dr. Bowen Hu, Prof. Dr. Dafa Chen and Prof. Dr. Xile Hu

      Article first published online: 10 APR 2013 | DOI: 10.1002/chem.201300495

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      Enzyme models on the catwalk! A series of new model complexes of the active site of [Fe]-hydrogenase have been synthesized and characterized. These complexes are monomeric in solution, but dimeric in the solid state.

    7. Synthetic Methods

      Cobalt-Catalyzed Electrophilic Amination of Arylzincs with N-Chloroamines (pages 6225–6229)

      Xin Qian, Zailu Yu, Dr. Audrey Auffrant and Dr. Corinne Gosmini

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201300229

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      Roles reversed: An efficient cobalt-catalyzed electrophilic amination of arylzinc reagents has been achieved. A variety of functionalized arylzincs and N-chloroamines were coupled under mild conditions (see scheme). Both secondary and tertiary arylamines were obtained in moderate to excellent yields.

    8. Heterocycle Synthesis

      A Convenient Palladium-Catalyzed Carbonylative Synthesis of 2-Aminbenzoxazinones from 2-Bromoanilines and Isocyanates (pages 6230–6233)

      Dr. Xiao-Feng Wu, Dr. Muhammad Sharif, Khurram Shoaib, Dr. Helfried Neumann, Dr. Anahit Pews-Davtyan, Prof. Peter Langer and Prof. Matthias Beller

      Article first published online: 20 MAR 2013 | DOI: 10.1002/chem.201300537

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      Mon ami(ne)! A general and convenient methodology for 2-aminobenzoxazinone synthesis has been developed (see scheme). Readily available 2-bromoanilines and isocyanates were used as substrates and various products have been prepared in good yields. Notably, [Mo(CO)6] as a solid CO source was applied instead of gas.

    9. Asymmetric Catalysis

      Enantioselective Relay Catalytic Cascade Intramolecular Hydrosiloxylation and Mukaiyama Aldol Reaction (pages 6234–6238)

      Pu-Sheng Wang, Kang-Nan Li, Xiao-Le Zhou, Dr. Xiang Wu, Dr. Zhi-Yong Han, Rui Guo and Prof. Dr. Liu-Zhu Gong

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201300702

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      Cascading chemistry! The first practical relay catalytic cascade intramolecular hydrosiloxylation of arylacetylene and asymmetric Mukaiyama aldol reaction has been established to give synthetically useful products in high yields and with excellent ee (see scheme).

    10. Heterocycles

      A General Method to Diverse Cinnolines and Cinnolinium Salts (pages 6239–6244)

      Dr. Dongbing Zhao, Qian Wu, Xiaolei Huang, Dr. Feijie Song, Taiyong Lv and Prof. Dr. Jingsong You

      Article first published online: 28 MAR 2013 | DOI: 10.1002/chem.201300155

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      Rhodium catalysis: A highly efficient and general method has been established to prepare cinnolines, cinnolinium salts, and polycyclic cinnolinium salts through the rhodium(III)-catalyzed oxidative C[BOND]H activation/cyclization of azo compounds with alkynes (see scheme). Key features of this methodology include the unprecedented capacity to create both cinnoline and cinnolinium frameworks.

  6. Full Papers

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Review
    6. Communications
    7. Full Papers
    1. Threading Intercalators

      Bridging Ligand Length Controls AT Selectivity and Enantioselectivity of Binuclear Ruthenium Threading Intercalators (pages 6246–6256)

      Johan R. Johansson, Yubo Wang, Dr. Mattias P. Eng, Prof. Nina Kann, Prof. Per Lincoln and Dr. Johanna Andersson

      Article first published online: 9 APR 2013 | DOI: 10.1002/chem.201300483

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      Threading into DNA: Elongation of the bridging ligand of binuclear ruthenium threading intercalators increases the binding affinity but decreases the AT selectivity (see figure). The length of the bridging ligand also controls the enantioselectivity of the threading interaction, with increasing preference for the ΔΔ enantiomer as the distance between the ruthenium centres increases.

    2. Odd–Even Effects

      Crystal Structures and Phase-Transition Dynamics of Cobaltocenium Salts with Bis(perfluoroalkylsulfonyl)amide Anions: Remarkable Odd–Even Effect of the Fluorocarbon Chains in the Anion (pages 6257–6264)

      Prof. Dr. Tomoyuki Mochida, Yusuke Funasako, Dr. Takashi Inagaki, Meng-Jiao Li, Kotaro Asahara and Prof. Dr. Daisuke Kuwahara

      Article first published online: 9 APR 2013 | DOI: 10.1002/chem.201300186

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      Odds and evens: Cobaltocenium salts with (CnF2n+1SO2)2N anions (n=0–4) exhibit a remarkable odd–even effect of the fluorocarbon chains in the anion on their phase-change entropies from crystal to melt and crystal structures. In the salts with even n, the cation and the anion are stacked alternately to form mixed columns in the solid state, whereas the cations and anions form segregated columns in the salts with odd n (see figure). These salts exhibit phase transitions in the solid state, accompanied by order–disorder of the anions at low temperature.

    3. Graphene

      In Situ Synthesis and Nonvolatile Rewritable-Memory Effect of Polyaniline-Functionalized Graphene Oxide (pages 6265–6273)

      Dr. Bin Zhang, Prof. Dr. Yu Chen, Prof. Dr. Yujie Ren, Li-Qun Xu, Dr. Gang Liu, Prof. Dr. En-Tang Kang, Cheng Wang, Prof. Dr. Chun-Xiang Zhu and Prof. Dr. Koon-Gee Neoh

      Article first published online: 13 MAR 2013 | DOI: 10.1002/chem.201203940

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      Making memories: A new polyaniline (PANI)-functionalized graphene oxide (GO-PANI) was prepared through the in situ oxidative graft polymerization of aniline on the surface of GO (see figure). An indium tin oxide (ITO)/GO-PANI/Al device exhibits bistable electrical conductivity switching behavior and nonvolatile rewritable-memory effects, with an ON/OFF current ratio in excess of 104.

    4. Supramolecular Chemistry

      An Imine-Based Molecular Cage with Distinct Binding Sites for Small and Large Alkali Metal Cations (pages 6274–6281)

      Clément Schouwey, Dr. Rosario Scopelliti and Prof. Kay Severin

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201300098

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      Selective M+ binding: A new imine-based cage has been synthesized that acts as a tritopic receptor by binding small alkali metal cations (Li+, Na+) on the outside and large alkali metal cations (Rb+, Cs+) on the inside of the cage (see figure). Association constants were determined for various alkali metal salts and a negative heterotopic cooperative effect between two different binding sites was observed.

    5. Sensors

      Reduced Carbon Dots versus Oxidized Carbon Dots: Photo- and Electrochemiluminescence Investigations for Selected Applications (pages 6282–6288)

      Yang Xu, Ming Wu, Prof. Dr. Xi-Zeng Feng, Prof. Dr. Xue-Bo Yin, Prof. Xi-Wen He and Prof. Yu-Kui Zhang

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201204372

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      Joining the Cdots: Two kinds of carbon dots (Cdots), with different oxidation levels, were successfully prepared through a carbogenic and then extraction or oxidation process. Their photoluminescence (PL) and electrochemiluminescence (ECL) properties were carefully studied for selected applications in cell imaging and metal-ion detection (see figure; CB=conduction band, VB=valence band).

    6. Density Functional Calculations

      A DFT Study on the Mechanism of the Cycloaddition Reaction of CO2 to Epoxides Catalyzed by Zn(Salphen) Complexes (pages 6289–6298)

      Fernando Castro-Gómez, Giovanni Salassa, Prof. Dr. Arjan W. Kleij and Prof. Dr. Carles Bo

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201203985

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      Breaking down barriers: The reaction mechanism for the Zn(salphen)/NBu4X (X=Br, I) mediated cycloaddition of CO2 to six different epoxides affording cyclic carbonate products has been explored in detail by DFT calculations (see figure). The epoxide ring-opening process is a function of the substrate, and for all studied cases the CO2 insertion and ring-closing steps show significantly higher barriers and are rate limiting. The combined results should allow the design and application of more efficient catalysts for organic carbonate formation.

    7. Dendrimers

      A Versatile Methodology for the Controlled Synthesis of Photoluminescent High-Boron-Content Dendrimers (pages 6299–6312)

      Dr. Arántzazu González-Campo, Albert Ferrer-Ugalde, Prof. Clara Viñas, Prof. Francesc Teixidor, Prof. Reijo Sillanpää, Jesús Rodríguez-Romero, Dr. Rosa Santillan, Dr. Norberto Farfán and Dr. Rosario Núñez

      Article first published online: 11 MAR 2013 | DOI: 10.1002/chem.201203771

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      B between dendrimers: High-boron-content dendrimers are prepared by nucleophilic substitution or hydrosilylation reactions to incorporate a different number of carborane clusters. The introduction of an alkyl spacer between the fluorescent core and the boron cages enables the isolation of the nucleus from the clusters. Neutral and anionic compounds exhibit photoluminescent properties depending on the nature of the clusters and the substituent (see figure).

    8. Host–Guest Systems

      Wide-Ranging Host Capability of a PdII-Linked M2L4 Molecular Capsule with an Anthracene Shell (pages 6313–6320)

      Norifumi Kishi, Dr. Zhiou Li, Dr. Yoshihisa Sei, Prof. Dr. Munetaka Akita, Dr. Kenji Yoza, Prof. Dr. Jay S. Siegel and Dr. Michito Yoshizawa

      Article first published online: 18 MAR 2013 | DOI: 10.1002/chem.201204010

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      An accommodating host: A PdII-linked M2L4 molecular capsule was capable of encapsulating various neutral molecules in quantitative yields. The formation of the host–guest complexes was confirmed by NMR spectroscopy and ESI-TOF MS studies as well as single-crystal X-ray analyses. Detailed studies of the host capability of the PdII-linked capsule revealed that spherical, planar, and bowl-shaped molecules (see figure) were encapsulated in the large spherical cavity, giving rise to 1:1 and 1:2 host–guest complexes, respectively.

    9. Coordination Modes

      Post-Synthetic Monovalent Central-Metal Exchange, Specific I2 Sensing, and Polymerization of a Catalytic [3×3] Grid of [CuII5CuI4L6]⋅(I)2⋅13 H2O (pages 6321–6328)

      Yi Han, Nicholas F. Chilton, Ming Li, Chao Huang, Prof. Hong Xu, Prof. Hongwei Hou, Boujemaa Moubaraki, Stuart K. Langley, Prof. Stuart R. Batten, Prof. Yaoting Fan and Prof. Keith S. Murray

      Article first published online: 20 MAR 2013 | DOI: 10.1002/chem.201204115

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      Fast off the grid: A predesigned grid, [CuII5CuI4L6](I)213 H2O (1), was extended into a 3D 1[{CuII5CuI8L6}{μ-[CuI3(CN)6]}22 CH3CN] network that showed the unprecedented coexistence of all five coordination geometries of copper. Grid 1 also displayed monovalent central-metal exchange of CuI for AgI for the first time, as well as tri-iodide formation in the crystalline state (see figure).

    10. Phase Transfer

      Reversible Phase Transfer of Luminescent ZnO Quantum Dots between Polar and Nonpolar Media (pages 6329–6333)

      Chengbo Zhang, Dr. Keyan Li, Dr. Shuyan Song and Prof. Dongfeng Xue

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201203236

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      A quick switch: The structure and optical properties of ZnO QDs are retained during fast and reversible phase transfer between polar and nonpolar media (see figure). This process is based on Pearson's hard and soft (Lewis) acid and base (HSAB) theory and the principle that similar substances are more likely to be dissolved by each other.

    11. Hyperpolarized Fluorine

      Parahydrogen-Induced Polarization Transfer to 19F in Perfluorocarbons for 19F NMR Spectroscopy and MRI (pages 6334–6339)

      Dr. Markus Plaumann, Dr. Ute Bommerich, Dipl.-Phys. Thomas Trantzschel, Dipl.-Ing. Denise Lego, Dipl.-Chem. Sonja Dillenberger, Dipl.-Chem. Grit Sauer, Prof. Dr. Joachim Bargon, Prof. Dr. Gerd Buntkowsky and Prof. Dr. Johannes Bernarding

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201203455

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      Fluorinated substances are important in chemistry and the life sciences. In a new approach, parahydrogen-induced polarization (PHIP) is applied to enhance 19F MR signals of (perfluoro-n-hexyl)ethene and (perfluoro-n-hexyl)ethane. This allows 19F MR imaging of hyperpolarized linear semifluorinated alkenes (see picture). Unexpectedly, the end-standing CF3 group exhibits the highest amount of polarization despite the negligible coupling to the added protons.

    12. Photosensitizers

      Tricyclometalated Iridium Complexes as Highly Stable Photosensitizers for Light-Induced Hydrogen Evolution (pages 6340–6349)

      Yong-Jun Yuan, Dr. Zhen-Tao Yu, Hong-Lin Gao, Prof. Dr. Zhi-Gang Zou, Dr. Chao Zheng and Prof. Dr. Wei Huang

      Article first published online: 20 MAR 2013 | DOI: 10.1002/chem.201300146

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      Not watered down: Neutral tricyclometalated IrIII complexes were synthesized for visible-light-induced H2 production with [Co(bpy)3]2+ (bpy=2,2′-bipyridine) and triethanolamine (TEOA; see figure). These complexes showed superior stability during the photocatalytic reaction.

    13. Titanocene Complexes

      Synthesis and Structures of ansa-Titanocene Complexes with Diatomic Bridging Units for Overall Water Splitting (pages 6350–6357)

      Monty Kessler, Dr. Sven Hansen, Christian Godemann, Dr. Anke Spannenberg and Dr. Torsten Beweries

      Article first published online: 27 MAR 2013 | DOI: 10.1002/chem.201300223

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      Titanocenes at work: A series of new ansa-titanocene bis(trimethylsilyl)acetylene complexes can be prepared from the corresponding dichloride complexes. Reactions with water yield the well-known structural motif of dihydroxido complexes as well as titanocene silanolate–alkenyl complexes. The former are interesting compounds for the investigation of the elemental steps of overall water splitting (see scheme).

    14. Mesoporous Materials

      Synthesis, Bifunctionalization, and Remarkable Adsorption Performance of Benzene-Bridged Periodic Mesoporous Organosilicas Functionalized with High Loadings of Carboxylic Acids (pages 6358–6367)

      Dr. Hao-Yiang Wu, Prof. Fa-Kuen Shieh, Prof. Hsien-Ming Kao, Yi-Wen Chen, Dr. Juti Rani Deka, Shih-Hsiang Liao and Prof. Kevin C.-W. Wu

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201204400

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      Functionalization matters! Highly ordered benzene-bridged periodic mesoporous silicas with extremely high loadings (up to 80 mol %) of COOH groups have been synthesized and used as adsorbents for the removal of methylene blue (MB) and the delivery of an anticancer drug, doxorubicin (DOX). These materials exhibited high adsorption capacities, rapid adsorption rates for methylene blue removal, and an excellent loading/release profile for doxorubicin.

    15. Sensors

      A New Dual-Signalling Electrochemical Sensing Strategy Based on Competitive Host–Guest Interaction of a β-Cyclodextrin/Poly(N-acetylaniline)/Graphene-Modified Electrode: Sensitive Electrochemical Determination of Organic Pollutants (pages 6368–6373)

      Gangbing Zhu, Liang Wu, Xia Zhang, Wei Liu, Xiaohua Zhang and Prof. Dr. Jinhua Chen

      Article first published online: 20 MAR 2013 | DOI: 10.1002/chem.201204635

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      Talking electro-sense: Based on the competitive host–guest interaction between a β-cyclodextrin (β-CD)/poly(N-acetylaniline) (PNAANI)/electrogenerated-graphene (EG) film and probing or target molecules, a new dual-signalling electrochemical sensing method has been developed for the sensitive and selective determination of organic pollutants (see figure; GC=glassy carbon electrode, RhB=rhodamine B, 1-AP=1-aminopyrene).

    16. Ligand Effects

      K⋅⋅⋅F/O Interactions Bridge Copper(I) Fluorinated Alkoxide Complexes and Facilitate Dioxygen Activation (pages 6374–6384)

      Dr. June S. Lum, Dr. Laleh Tahsini, Prof. Dr. James A. Golen, Dr. Curtis Moore, Prof. Dr. Arnold L. Rheingold and Prof. Dr. Linda H. Doerrer

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201204275

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      By the power of O2: CuI complexes with fluorinated alkoxide ligands have been prepared and their reactivity with O2 studied. These species can react with O2 in a Cu-concentration-dependent manner to form 2:1 and 3:1 Cu/O2 species (see scheme). Intramolecular hydroxylation of ligand C[BOND]H bonds and oxo transfer to CO2 are observed.

    17. Organic Light-Emitting Diodes

      Luminescent Platinum(II) Complexes of 1,3-Bis(N-alkylbenzimidazol- 2′-yl)benzene-Type Ligands with Potential Applications in Efficient Organic Light-Emitting Diodes (pages 6385–6397)

      Elizabeth Suk-Hang Lam, Daniel Ping-Kuen Tsang, Dr. Wai Han Lam, Dr. Anthony Yiu-Yan Tam, Dr. Mei-Yee Chan, Prof. Dr. Wing-Tak Wong and Prof. Dr. Vivian Wing-Wah Yam

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201203290

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      Promising OLED candidates: Cyclometalated PtII complexes have exhibited bright emission. Efficient organic light-emitting diodes (OLEDs) with high current and external quantum efficiencies, as well as solution-processable white OLEDs, have been fabricated (see figure; EQE=external quantum efficiency).

    18. Natural Products

      Illicium Sesquiterpenes: Divergent Synthetic Strategy and Neurotrophic Activity Studies (pages 6398–6408)

      Dr. Lynnie Trzoss, Dr. Jing Xu, Michelle H. Lacoske, Prof. Dr. William C. Mobley and Prof. Dr. Emmanuel A. Theodorakis

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201300198

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      Enantioselective synthesis: A unified strategy toward the synthesis of several illicium natural products is reported (see scheme). Key steps include an enantioselective Robinson annulation reaction and a one-pot oxidative lactonization cascade. The synthetic strategy allows access to various potent analogues. Structure–activity studies revealed that the C-10 stereocenter significantly affected the neurotrophic activity.

    19. Imaging Agents

      Targeted Tumor Computed Tomography Imaging Using Low-Generation Dendrimer-Stabilized Gold Nanoparticles (pages 6409–6416)

      Hui Liu, Yanhong Xu, Shihui Wen, Qian Chen, Dr. Linfeng Zheng, Prof. Mingwu Shen, Prof. Jinglong Zhao, Prof. Guixiang Zhang and Prof. Xiangyang Shi

      Article first published online: 15 MAR 2013 | DOI: 10.1002/chem.201204612

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      Dart of gold: Low-generation poly(amidoamine) dendrimer-stabilized gold nanoparticles (Au DSNPs) formed by a hydrothermal approach can be functionalized with folic acid with good stability and biocompatibility in a given concentration range. The formed functional Au DSNPs are able to be used as contrast agents for in vitro and in vivo targeted CT imaging of cancer cells (see CT image).

    20. Multicomponent Reactions

      A Multiple Multicomponent Approach to Chimeric Peptide–Peptoid Podands (pages 6417–6428)

      Dr. Daniel G. Rivera, Fredy León, Odette Concepción, Fidel E. Morales and Prof. Dr. Ludger A. Wessjohann

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201201591

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      Fast track to podands: The rapid and highly versatile assembly of podands with linear or branched oligopeptidic arms can be achieved in one pot through multiple Ugi reactions involving a variety of flexible or preorganizing core moieties (see figure).

    21. Reaction Mechanisms

      The Aza-Morita–Baylis–Hillman Reaction: A Mechanistic and Kinetic Study (pages 6429–6434)

      Dr. Christoph Lindner, Dr. Yinghao Liu, Prof. Konstantin Karaghiosoff, Dr. Boris Maryasin and Prof. Hendrik Zipse

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201204006

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      Examining the aza-MBH: The aza-Morita–Baylis–Hillman (aza-MBH) reaction has been studied in a variety of solvents, with a selection of imine substrates, and with various combinations of PPh3 and para-nitrophenol as the catalyst system (see scheme). The measured kinetic data indicates that the effects of solvent and protic co-catalyst are strongly interdependent. 31P NMR spectroscopy and quantum chemical studies support a mechanistic model that involves the reversible protonation of zwitterionic intermediates in the catalytic cycle.

    22. Lewis Base Catalysis

      Annelated Pyridines as Highly Nucleophilic and Lewis Basic Catalysts for Acylation Reactions (pages 6435–6442)

      Raman Tandon, Teresa Unzner, Dr. Tobias A. Nigst, Dr. Nicolas De Rycke, Dr. Peter Mayer, Dr. Bernd Wendt, Dr. Olivier R. P. David and Prof. Dr. Hendrik Zipse

      Article first published online: 15 MAR 2013 | DOI: 10.1002/chem.201204452

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      A special relationship: Highly nucleophilic and Lewis basic derivatives of 9-azajulolidine have been synthesized and a good correlation between Lewis basicity and nucleophilicity has been obtained. The catalytic performance of these compounds in acylation reactions of sterically hindered alcohols is found to be more complex and quantitative prediction of reaction rates requires a three-component quantitative structure–activity relationship (QSAR) model including Lewis basicity, structural, and charge distribution parameters (see figure).

    23. Visible-Light Catalysis

      A Highly Efficient and Selective Aerobic Cross-Dehydrogenative-Coupling Reaction Photocatalyzed by a Platinum(II) Terpyridyl Complex (pages 6443–6450)

      Jian-Ji Zhong, Qing-Yuan Meng, Ge-Xia Wang, Dr. Qiang Liu, Dr. Bin Chen, Dr. Ke Feng, Prof. Dr. Chen-Ho Tung and Prof. Dr. Li-Zhu Wu

      Article first published online: 15 MAR 2013 | DOI: 10.1002/chem.201204572

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      Illuminating the complex: An efficient and selective approach for a visible-light-induced aerobic cross-dehydrogenative-coupling (CDC) reaction has been achieved by using a catalytic amount of a platinum(II) complex (1; see scheme). A spectroscopic study and product analysis revealed that a photoinduced electron-transfer from N-phenyltetrahydroisoquinoline to complex 1 and subsequent formation of a superoxide radical anion are responsible for the clean and facile transformation.

    24. Supercapacitor Structures

      Structural Engineering for High Energy and Voltage Output Supercapacitors (pages 6451–6458)

      Jing Xu, Hui Wu, Chen Xu, Hongtao Huang, Dr. Linfeng Lu, Prof. Guqiao Ding, Dr. Huili Wang, Prof. Dongfang Liu, Prof. Guozhen Shen, Prof. Dongdong Li and Prof. Xiaoyuan Chen

      Article first published online: 20 MAR 2013 | DOI: 10.1002/chem.201204571

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      Cloth's got the power! The structural engineering of supercapacitors for high-areal energy and voltage output is presented. Several layers of textile loaded with active materials were laminated to construct individual electrodes, which enabled fold-increased areal capacitance and energy density. Ten unit cells with solid-state electrolyte were stacked together to form a tandem device with a 10 V output (see figure).

    25. Click Chemistry

      Synthesis and Redox and Photophysical Properties of Benzodifuran–Spiropyran Ensembles (pages 6459–6466)

      Hui Li, Dr. Jie Ding, Songjie Chen, Dr. Christoph Beyer, Dr. Shi-Xia Liu, Prof. Hans-Achim Wagenknecht, Prof. Andreas Hauser and Prof. Silvio Decurtins

      Article first published online: 13 MAR 2013 | DOI: 10.1002/chem.201204043

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      Photoswitching: Two benzodifuran-coupled spiropyran (SP) systems were obtained by Huisgen–Meldal–Sharpless click chemistry. Their electrochemical and photophysical properties were investigated with regard to the regulation of light-induced electron- and energy-transfer processes (see figure). The observed acceleration of the ring-closing reaction upon irradiation at 366 nm accounts for the low merocyanine (MC) fractions in their photostationary states.

    26. Bond Theory

      Comparative Study of Phosphine and N-Heterocyclic Carbene Stabilized Group 13 Adducts [L(EH3)] and [L2(E2Hn)] (pages 6467–6479)

      Dipl.-Chem. Nicole Holzmann, Dr. Andreas Stasch, Prof. Cameron Jones and Prof. Gernot Frenking

      Article first published online: 19 MAR 2013 | DOI: 10.1002/chem.201203679

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      Checking the bonds: Quantum chemical calculations show that the multibond character of Group 13 donor–acceptor complexes [L2(E2Hn)] depends on atom E and on the nature of the ligand L (see scheme).

    27. Catalytic Nanoparticles

      Strong Morphological Effect of Mn3O4 Nanocrystallites on the Catalytic Activity of Mn3O4 and Au/Mn3O4 in Benzene Combustion (pages 6480–6487)

      Dr. Zhao-Yang Fei, Bo Sun, Liang Zhao, Prof. Wei-Jie Ji and Prof. Chak-Tong Au

      Article first published online: 22 MAR 2013 | DOI: 10.1002/chem.201204112

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      Shape matters: Mn3O4 nanocrystallites of three distinct morphologies and the corresponding Au/Mn3O4 nanocomposites are synthesized in a controlled manner and tested in benzene oxidation. The activities of Mn3O4 facets (103)≈(200)>(101) and Au-Mn3O4 interfaces Au/(200)≈Au/(103)>Au/(101) are derived. The interaction between electronically modified Au clusters and specific facets of Mn3O4 polyhedrons brings about the unique interfacial synergism responsible for the enhanced performance (see figure).

    28. Prebiotic Chemistry

      A New Route for the Prebiotic Synthesis of Nucleobases and Hydantoins in Water/Ice Solutions Involving the Photochemistry of Acetylene (pages 6488–6497)

      Dr. César Menor-Salván and Margarita R. Marín-Yaseli

      Article first published online: 27 MAR 2013 | DOI: 10.1002/chem.201204313

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      Greatness from small beginnings: The ultraviolet irradiation of a urea solution subjected to freeze–thaw cycles under an acetylene atmosphere leads to the formation of pyrimidines, purines, and hydantoin (see scheme). This work describes the possible pathways to different nitrogen heterocycles from these precursors. This reaction completes the model of the abiotic origin of nucleobases in our solar system and on prebiotic Earth.

    29. Supramolecular Chemistry

      Self-Sorting of Four Organic Molecules into a Heterowheel Polypseudorotaxane (pages 6498–6506)

      Dr. Liang Li, Dr. Heng-Yi Zhang, Jin Zhao, Nan Li and Prof. Dr. Yu Liu

      Article first published online: 15 MAR 2013 | DOI: 10.1002/chem.201204583

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      Self-sufficient: Complexion of naphthyl-bridged bis(α-cyclodextrin), N,N′-dioctyl-4,4′-bipyridinium, cucurbit[8]uril (CB[8]), and 2,6-dihydroxynaphthalene leads to the exclusive formation of the purple supramolecular heterowheel polypseudorotaxane (see figure). The heterowheel polypseudorotaxane is a thermodynamically stable self-sorted product, and consists of two different macrocycles with hydrophobic, ion–dipole, and charge-transfer interactions.

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