Chemistry - A European Journal

Cover image for Vol. 19 Issue 7

February 11, 2013

Volume 19, Issue 7

Pages 2197–2554

  1. Cover Pictures

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Concept
    6. Communications
    7. Full Papers
    1. You have free access to this content
      Cover Picture: Cascade Syntheses Routes to the Centrocountins (Chem. Eur. J. 7/2013) (page 2197)

      Vincent Eschenbrenner-Lux, Dr. Heiko Dückert, Dr. Vivek Khedkar, Dipl.-Chem. Hanna Bruss, Prof. Dr. Herbert Waldmann and Dr. Kamal Kumar

      Version of Record online: 1 FEB 2013 | DOI: 10.1002/chem.201390017

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      The longest cascade reaction sequence known to date provides natural-product-inspired and biologically active centrocountins, or tetrahydroindoloquinolizines and related molecules. K. Kumar, H. Waldmann et al. unravel mechanistic insights into this long cascade reaction sequence in their Full Paper on page 2294 ff. by isolating and characterizing various intermediates and with control experiments. The cover picture shows a natural setup as a symbolic source of inspiration. As the reaction substrates in the pool of water flow in different streams, representing different cascade reaction sequences, they are progressively transformed into different intermediates before settling as a collection of products, the tetrahydro(indolo)quinolizine molecules.

    2. You have free access to this content
      Back Cover: Synthesis and Morphogenesis of Organic and Inorganic Polymers by Means of Biominerals and Biomimetic Materials (Chem. Eur. J. 7/2013) (page 2556)

      Misako Kijima, Dr. Yuya Oaki, Yurika Munekawa and Prof. Hiroaki Imai

      Version of Record online: 1 FEB 2013 | DOI: 10.1002/chem.201390020

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      Simultaneous synthesis and morphogenesis of polymer materials are achieved through the replication by using mesocrsytals in biological and biomimetic architectures as the host materials. Mesocrystalline structures have nanoscopic space within the interspace of the unit crystals. Introduction of monomers and subsequent polymerization in the nanospace affords the synthesis and morphogenesis of polymer materials. The polymer architectures are formed after dissolution of the original host mesocrystals. For more information see the Full Paper by Y. Oaki, H. Imai et al. on page 2284 ff.

  2. Graphical Abstract

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

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

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Concept
    6. Communications
    7. Full Papers
    1. Bond-Forming Transformations

      Stereoselective Multiple Bond-Forming Transformations (MBFTs): The Power of 1,2- and 1,3-Dicarbonyl Compounds (pages 2218–2231)

      Dr. Damien Bonne, Prof. Dr. Thierry Constantieux, Dr. Yoann Coquerel and Prof. Dr. Jean Rodriguez

      Version of Record online: 22 JAN 2013 | DOI: 10.1002/chem.201204018

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      The more the merrier: Owing to their multiple reactive centers, 1,2- and 1,3-dicarbonyl compounds are exceptional synthetic platforms that are particularly well adapted for multiple bond-forming transformations (MBFTs). Domino, multicomponent, and consecutive reactions with these powerful and densely functionalized building blocks have allowed the stereoselective preparation of very diverse and complex molecular architectures with the formation of up to six chemical bonds under efficient step- and atom-economical conditions.

  5. Communications

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

      [(η6-Praziquantel)Cr(CO)3] Derivatives with Remarkable In Vitro Anti-schistosomal Activity (pages 2232–2235)

      Dr. Malay Patra, Katrin Ingram, Vanessa Pierroz, Priv.-Doz. Dr. Stefano Ferrari, Priv.-Doz. Dr. Bernhard Spingler, Prof. Dr. Robin B. Gasser, Prof. Dr. Jennifer Keiser and Prof. Dr. Gilles Gasser

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201204291

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      The antischistosomal effect of two [(η6-praziquantel)Cr(CO)3] derivatives was investigated. The compounds (see figure: Cr purple, N blue, O red) were prepared in a one-step procedure from commercially available praziquantel. Both derivatives show a high in vitro activity against Schistosoma mansoni, a parasitic trematode, and only a minor cytotoxic effect on selected mammalian cell lines.

    2. Electrochemical Oxidation

      Facile Electrochemical Oxidation of Polyaromatic Hydrocarbons to Surface-Confined Redox-Active Quinone Species on a Multiwalled Carbon Nanotube Surface (pages 2236–2241)

      Palani Barathi and Annamalai Senthil Kumar

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203689

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      Polyaromatic hydrocarbon (PAH) oxidation: PAHs, which are considered major environmental pollutants, are carcinogenic, and cannot be electrochemically oxidized on conventional electrodes (gold, platinum, and glassy carbon), can be electrochemically oxidized on multiwalled carbon nanotube surfaces at a potential of 1 V versus Ag/AgCl at pH 7. This results in the formation of stable surface-confined quinone systems (see scheme; AN=anthracene; AQ=anthraquinone).

    3. Mesoporous Materials

      Electrochemical Deposition of Mesoporous Pt–Au Alloy Films in Aqueous Surfactant Solutions: Towards a Highly Sensitive Amperometric Glucose Sensor (pages 2242–2246)

      Dr. Cuiling Li, Dr. Hongjing Wang and Prof. Yusuke Yamauchi

      Version of Record online: 10 JAN 2013 | DOI: 10.1002/chem.201203378

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      Film star: The synthesis of mesoporous Pt–Au alloy films of varying composition by using a square-wave potential program is described. A Pt51Au49 alloy film exhibits superior performance for the detection of glucose than those reported previously. The activity was found to be strongly dependent on the synergistic effects of the mesoporous structure and the Pt–Au alloy surface.

    4. Porphyrins

      An Unsymmetrically π-Extended Porphyrin-Based Single-Crystal Field-Effect Transistor and Its Anisotropic Carrier-Transport Behavior (pages 2247–2251)

      Soojung Choi, Seung Hyun Chae, Dr. Mai Ha Hoang, Dr. Kyung Hwan Kim, Jung A Huh, Dr. Youngmee Kim, Prof. Sung-Jin Kim, Prof. Dong Hoon Choi and Prof. Suk Joong Lee

      Version of Record online: 27 DEC 2012 | DOI: 10.1002/chem.201202894

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      Anisotropic charge transport: Single-crystal organic field-effect transistor devices derived from aggregates of thiophene-appended porphyrins display very high mobility (0.27 cm2 V−1 s−1). This behavior is due to staircase stacking of the porphyrins with distances between layers of 3.17(7) Å. Furthermore, the charge-transport behavior is anisotropic owing to an anisotropic molecular arrangement in the single-crystal microplates.

    5. Cycloaddition Reactions

      Rhodium-Catalyzed [2+2+2] Cycloaddition of Oximes and Diynes To Give Pyridines (pages 2252–2255)

      Fen Xu, Chunxiang Wang, Dr. Dongping Wang, Dr. Xincheng Li and Prof. Dr. Boshun Wan

      Version of Record online: 27 DEC 2012 | DOI: 10.1002/chem.201203909

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      Oximes and diynes undergo efficient cycloaddition in the presence of a catalytic amount of a cationic rhodium(I)/dppf complex (see scheme). Spontaneous dehydration of the initially formed cycloadducts leads to the formation of a variety of substituted pyridines in moderate to good yields. The transformation could also be achieved in a one-pot procedure using aldehydes.

    6. C[BOND]C Bond Formation

      Palladium-Catalyzed Intermolecular Desulfinylative Cross-Coupling of Heteroaromatic Sulfinates (pages 2256–2260)

      Stéphane Sévigny and Prof. Dr. Pat Forgione

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201204201

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      Beauty lies in simplicity: An efficient and environmentally benign palladium-catalyzed protocol has been developed using a sulfinate as a nucleophilic coupling partner. The sulfinate position is arylated chemoselectively in very good yields. The bench-stable, non-hygroscopic heteroaromatic sulfinate salts rapidly undergo cross-coupling without the need of a co-catalyst, base, or additives (see scheme; mw=microwave).

    7. Cross-Coupling Reactions

      An Efficient Method for Sterically Demanding Suzuki–Miyaura Coupling Reactions (pages 2261–2265)

      Qing Zhao, Chengxi Li, Dr. Chris H. Senanayake and Prof. Dr. Wenjun Tang

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203898

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      An efficient method for sterically demanding Suzuki–Miyaura coupling reactions has been developed with two catalysts, Pd/BI-DIME (see scheme) and Pd/phenanthrene-based ligand. The Pd/BI-DIME catalyst facilitates the syntheses of extremely hindered biaryls bearing ortho-isopropyl substituents. The other catalyst is efficient for the synthesis of functionalized tetra-ortho-substituted biaryls at low catalyst loadings.

    8. Sandwich Compounds

      Synthesis, Structure, and Single-Molecule Magnetic Properties of Rare-Earth Sandwich Complexes with Mixed Phthalocyanine and Schiff Base Ligands (pages 2266–2270)

      Hailong Wang, Wei Cao, Prof. Tao Liu, Prof. Chunying Duan and Prof. Jianzhuang Jiang

      Version of Record online: 27 DEC 2012 | DOI: 10.1002/chem.201203912

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      Double- and quadruple-decker complexes of rare-earth metals with mixed phthalocyanine and Schiff base ligands have been synthesized and structurally and magnetically characterized. These complexes (see picture: Dy pink, Ca green, N blue, C black) extend the scope of sandwich-type tetrapyrrole-based rare-earth molecular materials.

    9. Gels

      Cross-Linked Helically Chiral Poly-(γ-benzyl-L-glutamate) as Enantiodiscriminating Alignment Medium (pages 2271–2274)

      Dipl.-Ing. Tobias Montag and Prof. Dr. Christina M. Thiele

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201202554

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      The best of both worlds: By crosslinking poly-(γ-benzyl-L-glutamate) (PBLG), an alignment medium, which combines the scalability of cross-linked polymer gels (strain-induced-alignment media) with the enantiodiscriminating properties of helically chiral PBLG, was obtained. Spectra of excellent quality and residual dipolar couplings (RDCs) of the perfect size can be obtained for small organic compounds (see scheme; Bn=benzyl).

  6. Full Papers

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

      Nitrogen-Doped Carbon Dots: A Facile and General Preparation Method, Photoluminescence Investigation, and Imaging Applications (pages 2276–2283)

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

      Version of Record online: 15 JAN 2013 | DOI: 10.1002/chem.201203641

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      Going dotty: A facile and general strategy involving the carbonization of precursors and their subsequent extraction with solvents is proposed for the preparation of nitrogen-doped carbon dots (N-Cdots) with multicolor emission (see figure). The emission mechanism of the Cdots was studied. Multicolor photoluminescence was validated in living cell systems.

    2. Biomimetic Synthesis

      Synthesis and Morphogenesis of Organic and Inorganic Polymers by Means of Biominerals and Biomimetic Materials (pages 2284–2293)

      Misako Kijima, Dr. Yuya Oaki, Yurika Munekawa and Prof. Hiroaki Imai

      Version of Record online: 22 JAN 2013 | DOI: 10.1002/chem.201203088

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      Morphology replication: Simultaneous synthesis and morphogenesis of polymer materials is achieved by the use of host materials from nanoscopic to macroscopic scales. The morphologies of the original host materials can be replicated to the polymer materials.

    3. Domino Reactions

      Cascade Syntheses Routes to the Centrocountins (pages 2294–2304)

      Vincent Eschenbrenner-Lux, Dr. Heiko Dückert, Dr. Vivek Khedkar, Dipl.-Chem. Hanna Bruss, Prof. Dr. Herbert Waldmann and Dr. Kamal Kumar

      Version of Record online: 14 JAN 2013 | DOI: 10.1002/chem.201203714

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      Rolling transformations! Various cascade synthesis routes that employ easily accessible substrates and provide efficient access to diverse tetrahydroquinolizines are disclosed (see figure). Mechanistic insights into the long cascade process that gives centrocountins are also presented.

    4. Ab Initio Calculations

      Isomerization Energy Decomposition Analysis for Highly Ionic Systems: Case Study of Starlike E5Li7+ Clusters (pages 2305–2310)

      Maryel Contreras, Dr. Edison Osorio, Franklin Ferraro, Gustavo Puga, Prof. Kelling J. Donald, Jason G. Harrison, Prof. Gabriel Merino and Prof. William Tiznado

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203329

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      Structural analysis: The combination of lithium and Group 14 elements is shown to prefer one of two distinct E5Li7+ clusters (E = C, Si, Ge, Sn, and Pb) depending on the identity of E, and the preferences are rationalized on the basis of a simple isomerization energy decomposition scheme (see figure).

    5. Reaction Mechanisms

      Inner Workings of a Cinchona Alkaloid Catalyzed Oxa-Michael Cyclization: Evidence for a Concerted Hydrogen-Bond-Network Mechanism (pages 2311–2321)

      Prof. Dr. Lukas Hintermann, Dr. Jens Ackerstaff and Dr. Florian Boeck

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203505

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      Secret of cyclization: The cinchona alkaloid catalyzed asymmetric oxa-Michael cyclization of 2′-hydroxyphenyl-2-butenoates to benzodihydrofurans proceeds by a highly enantio- and diastereoselective syn-specific addition mode (see scheme). Transition-state activation of the carbonyl group by hydrogen bonding to the catalyst is excluded. This represents a clear-cut demonstration of the importance of concerted hydrogen-bond network mechanisms in cinchona-based asymmetric organocatalysis.

    6. Noble Gases

      C5Li7+ and O2Li5+ as Noble-Gas-Trapping Agents (pages 2322–2329)

      Sudip Pan, Maryel Contreras, Jonathan Romero, Prof. Andres Reyes, Prof. Pratim K. Chattaraj and Prof. Gabriel Merino

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203245

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      Caught in a trap: Ab initio and density functional studies reveal that the Li centers of star-shaped C5Li7+ clusters and O2Li5+ super-alkali clusters can bind noble gas (Ng) atoms effectively (see figure).

    7. Cyclitols

      Generation of Molecular Complexity from Cyclooctatetraene: Preparation of Optically Active Protected Aminocycloheptitols and Bicyclo[4.4.1]undecatriene (pages 2330–2336)

      Mohamed F. El-Mansy, Dr. Anobick Sar, Dr. Sergey Lindeman and Dr. William A. Donaldson

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203754

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      And the cycloheptitol is… The racemic [(6-cycloheptadienyl)Fe(CO)3]+ cation, prepared from cyclooctatetraene, reacts with a variety of carbon and heteroatom nucleophiles to afford (1,6-disubstituted heptadiene)FeCO3 complexes. Decomplexation and further synthetic manipulation leads to the optically active aminocycloheptitols (−)-1 and (+)-1 in 15.7 and 12.2 % overall yields from cyclooctatetraene (see scheme). TBDPS=tert-butyldiphenylsilyl, Phth=phthalate.

    8. Hydroboration

      Syntheses and Characterization of New Vinyl-Borylene Complexes by the Hydroboration of Alkynes with [(μ3-BH)(Cp*RuCO)2(μ-CO)Fe(CO)3] (pages 2337–2343)

      Dr. Shubhankar Kumar Bose, Dipak Kumar Roy, Pritam Shankhari, K. Yuvaraj, Bijan Mondal, Amrita Sikder and Prof. Sundargopal Ghosh

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203627

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      Unique metal–borylene complexes: Photolysis of a triply bridged borylene complex [(μ3-BH)(Cp*RuCO)2(μ-CO)Fe(CO)3] (Cp*=η5-C5Me5) with various internal alkynes led to hydroboration yielding new vinyl-borylene complexes (see figure). A plausible mechanism has been proposed for the formation of vinyl-borylene complexes, which is supported by density functional theory (DFT) methods.

    9. Nucleic Acid Delivery

      Phospholipid–Detergent Conjugates as Novel Tools for siRNA Delivery (pages 2344–2355)

      Dr. Philippe Pierrat, Dr. Gilles Laverny, Dr. Gaëlle Creusat, Dr. Patrick Wehrung, Dr. Jean-Marc Strub, Dr. Alain VanDorsselaer, Prof. Françoise Pons, Dr. Guy Zuber and Dr. Luc Lebeau

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203071

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      Bioresponsive deciduous-charge cationic lipids: Biodegradable 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)–Triton X-100 covalent conjugates were designed to assist nucleic acid delivery into cells. The bioresponsive cationic amphiphiles are degraded under different pH values or an enzymatic stimulus, thus triggering both nucleic acid decomplexation and formation of Triton X-100, which may help the cytosolic delivery of small interfering RNA (siRNA) through endosome membrane destabilization (see figure).

    10. Sandwich Complexes

      Gold(I) and Silver(I) Complexes of Diphosphacyclobutadiene Cobaltate Sandwich Anions (pages 2356–2369)

      Jennifer Malberg, Thomas Wiegand, Prof. Dr. Hellmut Eckert, Dr. Michael Bodensteiner and Prof. Dr. Robert Wolf

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203606

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      Complexing cobaltates: The first gold(I) and silver(I) complexes of anionic diphosphacyclobutadiene cobaltates show a variety of structures. Monomeric phosphane adducts, “ate complexes”, and coordination polymers have been isolated and structurally characterized. Multinuclear solid-state NMR spectroscopy proved to be an excellent tool to study the structure and connectivity of these new coordination compounds (see figure).

    11. Liquid Crystals

      Design and Synthesis of a New Family of Fluorinated Liquid Crystals (pages 2370–2383)

      Prof. Dr. Valentine G. Nenajdenko, Dr. Aleksey A. Goldberg, Dr. Vasily M. Muzalevskiy, Prof. Dr. Elizabeth S. Balenkova and Dr. Aleksey V. Shastin

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203315

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      Clear as liquid crystal: A flexible three-step pathway to the new family of CF2CF2S-bridged alkanes and CF2S- and CF2O-bridged alkenes and alkynes was elaborated, starting from 1,2-dibromoethane. Simplicity of the reaction procedures, high universality, and liquid crystalline characteristics of the compound are attractive features of the method proposed, which provides opportunities for the synthesis of new liquid crystals (see scheme).

    12. Nanotubes

      Microenvironment Effects in Electrocatalysis: Ionic-Liquid-Like Coating on Carbon Nanotubes Enhances the Pd-Electrocatalytic Alcohol Oxidation (pages 2384–2391)

      Shuwen Li, Zhengping Dong, Honglei Yang, Shujing Guo, Galian Gou, Ren Ren, Zhejun Zhu, Prof. Jun Jin and Jiantai Ma

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203686

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      IL overachiever: A new ionic liquid (IL)-coated carbon nanotube (CNT) catalyst exhibited higher electrocatalytic activity, better tolerance, and electrochemical stability than the Pd nanoparticles (NPs) immobilized on CNTs (see figure); this is ascribed to the effects of the IL, a larger electrochemically active surface area (ECSA), and greater processing performance. The strategy of IL functionalization of CNTs could be available to prepare other carbonaceous carrier supports.

    13. Catalysis

      Synthesis of 2′-Deoxy-1′-homo-N-nucleosides with Anti-Influenza Activity by Catalytic Methyltrioxorhenium (MTO)/H2O2 Oxyfunctionalization (pages 2392–2404)

      Prof. Dr. Raffaele Saladino, Dr. Veronica Neri, Dr. Paola Checconi, Dr. Ignacio Celestino, Dr. Lucia Nencioni, Prof. Dr. Anna Teresa Palamara and Dr. Marcello Crucianelli

      Version of Record online: 6 DEC 2012 | DOI: 10.1002/chem.201201285

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      Antiviral activity: Under either homogeneous or heterogeneous catalytic conditions, the high reactivity of the methyltrioxorhenium (MTO)/H2O2 oxidative system allowed the synthesis of new 1′-homo-N-nucleoside derivatives through a selective oxyfunctionalization of the heterocyclic ring and of the N-heteroatom moiety (see scheme). Many of the modified nucleosides have been shown to be active against the influenza A virus.

    14. Transition-Metal Catalysis

      Asymmetric Hydrogenation Using Rhodium Complexes Generated from Mixtures of Monodentate Neutral and Anionic Phosphorus Ligands (pages 2405–2415)

      Dr. Dominik J. Frank, Dr. Axel Franzke and Prof. Dr. Andreas Pfaltz

      Version of Record online: 27 DEC 2012 | DOI: 10.1002/chem.201202408

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      Charge effects and hydrogen bonding favor the formation of rhodium hetero bis-ligand complexes from mixtures of neutral and anionic monodentate phosphorus ligands. The combination of a neutral phosphoric acid diester as a hydrogen donor and an anionic phosphoramidite as a hydrogen acceptor gives very high enantioselectivities in Rh-catalyzed hydrogenation reactions, thus exceeding the ee values of the corresponding homo bis-ligand complexes (see scheme).

    15. Asymmetric Catalysis

      A New Modular Phosphite-Pyridine Ligand Library for Asymmetric Pd-Catalyzed Allylic Substitution Reactions: A Study of the Key Pd-π-Allyl Intermediates (pages 2416–2432)

      Dr. Javier Mazuela, Dr. Oscar Pàmies and Prof. Montserrat Diéguez

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203365

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      A library of phosphite-pyridine ligands has been successfully applied in the Pd-catalyzed allylic substitution reactions of several di- and trisubstituted substrates by using a wide range of C, N, and O nucleophiles. By carefully selecting the ligand components, high regio- and enantioselectivities (up to >99 % ee) and good activities have been achieved (see scheme). The NMR studies on the Pd-π-allyl intermediates provide a deeper understanding of the effect of ligand parameters on the origin of enantioselectivity.

    16. Doped Nanocrystals

      Ionic-Liquid-Assisted Synthesis of Uniform Fluorinated B/C-Codoped TiO2 Nanocrystals and Their Enhanced Visible-Light Photocatalytic Activity (pages 2433–2441)

      Jiaguo Yu, Qin Li, Shengwei Liu and Mietek Jaroniec

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201202778

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      Photoactive nanocrystals: Fluorinated B/C-codoped anatase TiO2 nanocrystals (TIL) were prepared by using the ionic liquid BMIM+BF4 as a dopant source and structure-controlling agent. The crystals were then calcined at various temperatures. The crystals had high visible-light photocatalytic activity (see figure for the level of visible-light absorption as a function of calcination temperature) toward the degradation of rhodamine dyes.

    17. Peptidomimetics

      A Modular Synthesis of Teraryl-Based α-Helix Mimetics, Part 1: Synthesis of Core Fragments with Two Electronically Differentiated Leaving Groups (pages 2442–2449)

      Dr. Martin Peters, Melanie Trobe, Dipl.-Chem. Hao Tan, Dr. Rolf Kleineweischede and Prof. Dr. Rolf Breinbauer

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203005

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      Turn on: Teraryl-based α-helix mimetics can be effectively produced by sequential Suzuki coupling of a central core fragment featuring electronically differentiated leaving groups with aryl boronic pinacol esters (see scheme; dppf=1,1′-bis(diphenylphosphino)ferrocene, DME=dimethoxyethane, Pin=pinacol, Tf=trifluoromethanesulfonyl). With a set of only 2×18 building blocks, all permutations of α-helix mimetics can be produced.

    18. A Modular Synthesis of Teraryl-Based α-Helix Mimetics, Part 2: Synthesis of 5-Pyridine Boronic Acid Pinacol Ester Building Blocks with Amino Acid Side Chains in 3-Position (pages 2450–2456)

      Dr. Martin Peters, Melanie Trobe and Prof. Dr. Rolf Breinbauer

      Version of Record online: 23 DEC 2012 | DOI: 10.1002/chem.201203006

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      Tune in: The chemical orthogonality of Knochel's Grignard chemistry enables the synthesis of 3-substituted 5-pyridine-boronic esters with amino acid side chains, which can be used for convenient assembly of teraryl-based α-helix peptide mimetics by Suzuki coupling (see scheme; dppf=1,1′-bis(diphenylphosphino)ferrocene, DME= dimethoxyethane, Tf=trifluoromethanesulfonyl).

    19. Self-Assembly

      Hierarchical Self-Assembly of a Biomimetic Light-Harvesting Antenna Based on DNA G-Quadruplexes (pages 2457–2461)

      Dr. Núria Sancho Oltra, Dr. Wesley R. Browne and Dr. Gerard Roelfes

      Version of Record online: 27 DEC 2012 | DOI: 10.1002/chem.201202550

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      A new organization: A new and versatile supramolecular approach to the assembly of a functional artificial light-harvesting system based on DNA G-quadruplexes is presented (see figure). The key advantages of the G-quadruplex-based concept include its modular nature and the ease of assembly, which allow rapid structural variation and optimization.

    20. Boron

      The Hydride-Ion Affinity of Borenium Cations and Their Propensity to Activate H2 in Frustrated Lewis Pairs (pages 2462–2466)

      Dr. Ewan R. Clark, Alessandro Del Grosso and Dr. Michael J. Ingleson

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203318

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      DFT and experimental studies indicated that [Cl2B(2,6-lutidine)]+ has a greater hydride-ion affinity (HIA) than B(C6F5)3. Heating the frustrated Lewis pair formed from [Cl2B(2,6-lutidine)]+ and P(mesityl)3 under H2 resulted in activation of H2 and deprotonation of lutidine to form the boracycle [(CH2{NC5H3Me})BCl2] (see scheme).

    21. Cycloaddition

      Diastereoselective Access to Polyoxygenated Polycyclic Spirolactones through a Rhodium-Catalyzed [3+2] Cycloaddition Reaction: Experimental and Theoretical Studies (pages 2467–2477)

      Fabien Rodier, Michel Rajzmann, Dr. Jean-Luc Parrain, Dr. Gaëlle Chouraqui and Dr. Laurent Commeiras

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203155

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      A rapid regio- and diastereoselective access to functionalized rigid polycyclic systems that contain a spiro[6.4] moiety through a Rh-catalyzed [3+2] cycloaddition is described (see scheme). A theoretical treatment rationalized the empirical observations.

    22. Click Chemistry

      Synthesis and Thermoreversible Gelation Properties of Main-Chain Poly(pyridine-2,6-dicarboxamide-triazole)s (pages 2478–2486)

      Sui-Lung Yim, Prof. Hak-Fun Chow, Prof. Man-Chor Chan, Prof. Chi-Ming Che and Dr. Kam-Hung Low

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201203684

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      Supramolecular chemistry: The presence of an intramolecular hydrogen-bonding pyridine-2,6-dicarboxamide unit inside a diacetylene monomer promoted its AABB click copolymerization efficiency with a diazide by reducing the amount of low molecular weight oligomers; this structural motif also conferred excellent thermoreversible gelating properties to the resulting poly(amide-triazole) compound (see scheme).

    23. Scorpionate Ligands

      S-Alkylation of Soft Scorpionates (pages 2487–2495)

      Rajeev Rajasekharan-Nair, Dean Moore, Dr. Kirsten Chalmers, Dr. Dawn Wallace, Louise M. Diamond, Lisa Darby, Dr. David R. Armstrong, Dr. John Reglinski and Dr. Mark D. Spicer

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201202314

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      Alkylation reactions of soft scorpionates (see figure) are not universally successful. DFT analysis of these reactions indicates that the outcome is driven by kinetic factors. Di[aquo-μ-aquohydrotris(mercaptobenzothiazolyl)boratosodium] has been structurally characterized. The analysis of the species involved in these reactions shows that the B[BOND]N bond of soft scorpionates is weak.

    24. Immunoassays

      Anodic-Stripping Voltammetric Immunoassay for Ultrasensitive Detection of Low-Abundance Proteins Using Quantum Dot Aggregated Hollow Microspheres (pages 2496–2503)

      Dr. Bing Zhang, Prof. Dianping Tang, Prof. Irina Yu. Goryacheva, Prof. Reinhard Niessner and Prof. Dietmar Knopp

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203131

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      A sandwich-type immunoassay for ultrasensitive detection of low-abundance proteins was developed by using mAb2-functionalized quantum dot aggregated hollow microspheres (QDHMS), as tags on an mAb1-functionalized magnetic-bead (MB)-based platform. In the immunoassay, square-wave anodic-stripping voltammetric (SWASV) detection of Cd released under acidic conditions from the coupled QDs was conducted.

    25. Donor–Acceptor Systems

      Tetrathiafulvalene[BOND]Benzothiadiazoles as Redox-Tunable Donor–Acceptor Systems: Synthesis and Photophysical Study (pages 2504–2514)

      Dr. Flavia Pop, Anneliese Amacher, Dr. Narcis Avarvari, Dr. Jie Ding, Dr. Latevi Max Lawson Daku, Prof.  Andreas Hauser, Marius Koch, Jürg Hauser, Dr. Shi-Xia Liu and Prof. Silvio Decurtins

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201202742

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      To give and receive: Covalently linked or fused tetrathiafulvalene[BOND]benzothiadiazole (TTF[BOND]BTD) systems, with planar solid-state structures, show intramolecular charge transfer (ICT), as confirmed both experimentally and theoretically, and fluorescence properties that are modulated by the oxidation state of TTF, as demonstrated by photophysical studies (see figure).

    26. Sensors

      Highly Sensitive and Selective Spectroscopic Detection of Mercury(II) in Water by Using Pyridylporphyrin–DNA Conjugates (pages 2515–2522)

      Jung Kyu Choi, Gevorg Sargsyan, Amanda M. Olive and Prof. Milan Balaz

      Version of Record online: 13 DEC 2012 | DOI: 10.1002/chem.201202461

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      Dark H(u)g: Mercury(II) quenches the emission of pyridylporphyrin–DNA conjugates (see figure), which allows its detection in water in the presence of other heavy metals. The effect of chemical structure, number of nucleotides, and porphyrin metalation on the sensitivity and selectivity of detection is explored. The results indicate that porphyrin, rather than thymine, plays a crucial role in mercury(II) sensing.

    27. Nanocomposites

      Ag/AgBr/Co–Ni–NO3 Layered Double Hydroxide Nanocomposites with Highly Adsorptive and Photocatalytic Properties (pages 2523–2530)

      Hai Fan, Jianying Zhu, Jianchao Sun, Shenxiang Zhang and Prof. Shiyun Ai

      Version of Record online: 28 DEC 2012 | DOI: 10.1002/chem.201203408

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      Anchored on sheets: Bifunctional Ag/AgBr/Co–Ni–NO3 layered double hydroxide (LDH) nanocomposites with Ag/AgBr nanoparticles highly dispersed on Co–Ni–NO3 LDH sheets were prepared by a facile anion-exchange precipitation method, in which AgNO3 solution was added to a suspension of Co–Ni–Br LDH. They show high adsorption capacity and visible-light-driven photocatalytic activity towards organic pollutants. The figure shows SEM images of Co–Ni–NO3 LDH sheets without (A) and with Ag/AgBr nanoparticles (B).

    28. Sandwich Complexes

      Alkaline Earth Metal Ion Induced Coil–Helix–Coil Transition of Lysine–Coumarin–Azacrown Hybrid Foldamers with OFF–OFF–ON Fluorescence Switching (pages 2531–2538)

      Dr. Yu-Chen Lin and Prof. Dr. Chao-Tsen Chen

      Version of Record online: 28 NOV 2012 | DOI: 10.1002/chem.201202998

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      Switching off the helix: An alkaline earth metal ion responsive and fluorescence-detectable foldamer (OPLM8) has been designed and synthesized. Variation of the chelator-to-metal-ion ratio resulted in the assembly and disassembly of sandwich complexes between fluoroionophores with i, i+4 spacing on the peptide backbone, leading to the formation and collapse of the helical structure, and was probed by “OFF–OFF–ON” fluorescence switching (see graphic).

    29. Natural Products

      Collective Total Synthesis of Englerin A and B, Orientalol E and F, and Oxyphyllol: Application of the Organocatalytic [4+3] Cycloaddition Reaction (pages 2539–2547)

      Jie Wang, Shu-Guang Chen, Prof. Dr. Bing-Feng Sun, Prof. Guo-Qiang Lin and Prof. Yong-Jia Shang

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203467

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      Total synthesis: The concise collective total synthesis of englerin A and B, orientalol E and F, and oxyphyllol has been accomplished in 10–15 steps, with the total synthesis of orientalol E and oxyphyllol being achieved for the first time (see scheme).

    30. Cycloaddition

      Fine-Tuning the Reactivity and Stability by Systematic Ligand Variations in CpCoI Complexes as Catalysts for [2+2+2] Cycloaddition Reactions (pages 2548–2554)

      Indre Thiel, Dr. Haijun Jiao, Dr. Anke Spannenberg and Dr. Marko Hapke

      Version of Record online: 18 DEC 2012 | DOI: 10.1002/chem.201202946

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      Directed symbiosis: By fusing two different catalysts, new CpCoI complexes that contain the combined properties assigned to both original complexes were developed (see scheme). These unique catalysts were rather stable yet possess high activity at relatively mild conditions in the [2+2+2] cycloaddition reaction for the synthesis of pyridine derivatives.