Chemistry - A European Journal

Cover image for Vol. 19 Issue 8

February 18, 2013

Volume 19, Issue 8

Pages 2557–2909

  1. Cover Pictures

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
    1. You have free access to this content
      Cover Picture: Structural Insights into the Trp-Cage Folding Intermediate Formation (Chem. Eur. J. 8/2013) (page 2557)

      Petra Rovó, Pál Stráner, Dr. András Láng, István Bartha, Kristóf Huszár, Prof. Dr. László Nyitray and Prof. Dr. András Perczel

      Article first published online: 11 FEB 2013 | DOI: 10.1002/chem.201390021

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      The folding energy landscape of the smallest protein, the 20-residue long Trp-cage, is more rugged than expected. Temperature-dependent NMR measurements revealed that at neutral pH the final step of the Trp-cage folding is a fast secondary structural rearrangement: the short α-helical G11–G15 segment of the intermediate (I) converts into a 310-helix and thus, the polypeptide adopts the most stable, folded (F) structure. At acidic pH the isomerization of the G11[BOND]P12 peptide bond slows down the folding process: two off-pathway intermediate unfolded states (U′ and U′′) emerge. These two states have no native-like structure and show elevated internal mobility. For more information see the Full Paper by A. Perczel et al. on page 2628 ff.

    2. You have free access to this content
      Back Cover: A Recyclable Trinuclear Bifunctional Catalyst Derived from a Tetraoxo Bis-Zn(salphen) Metalloligand (Chem. Eur. J. 8/2013) (page 2912)

      Dr. Martha V. Escárcega-Bobadilla, Dr. Marta Martínez Belmonte, Eddy Martin, Eduardo C. Escudero-Adán and Prof. Dr. Arjan W. Kleij

      Article first published online: 11 FEB 2013 | DOI: 10.1002/chem.201390024

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      Bifunctional, trinuclear complexes with high recycling potential in the synthesis of organic carbonates from oxiranes and carbon dioxide are described in the Full Paper on page 2641 ff. by A. W. Kleij et al. This supramolecular approach towards catalyst immobilization and recycling is highly promising, as demonstrated in a typical reaction that requires both Lewis acid and nucleophilic activation; the recycling potential of one of these complexes was found to be superior to the commonly used binary-type catalysts that comprise both (but separate) components

  2. Graphical Abstract

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Communications
    6. Full Papers
    1. Graphical Abstract: Chem. Eur. J. 8/2013 (pages 2560–2570)

      Article first published online: 11 FEB 2013 | DOI: 10.1002/chem.201390022

  3. News

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

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

      Mercury(II)-Catalyzed Cyclization of 2-Alkynylphenyl Alkyl Sulfoxides Provides 3-Acylbenzo[b]thiophenes (pages 2578–2581)

      Cheng-Han Lin, Dr. Chin-Chau Chen and Prof. Dr. Ming-Jung Wu

      Article first published online: 18 JAN 2013 | DOI: 10.1002/chem.201202704

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      Ring cyclization: A mercury-catalyzed cyclization reaction to provide 3-benzoylbenzo[b]thiophenes was achieved in good yields by treatment of 2-alkynylphenyl alkyl sulfoxides with mercury chloride and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in benzene heated at reflux for 24 h (see scheme).

    2. Dyes/Pigments

      Rational Design of New Thiazolo[BOND]Thiazole Dyes as Input Energy Units in Molecular Dyads (pages 2582–2588)

      Dr. Raymond Ziessel, Adela Nano, Elodie Heyer, Thomas Bura and Dr. Pascal Retailleau

      Article first published online: 11 JAN 2013 | DOI: 10.1002/chem.201203121

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      Bridge over troubled water: Highly fluorescent thiazolo[BOND]thiazole dyes with quantum yields of up to 60 % were prepared in a facile synthesis from dithiooxamide and various aldehydes. When adequately engineered, such dyes could be used as fluorescent bridges with other dyes. A sequence of highly efficient, intramolecular electronic-energy-transfer steps followed from selective illumination of the fluorescent centre in the molecular triads.

    3. Natural Products

      Total Synthesis of Gelsemiol (pages 2589–2591)

      Patrick Burch, Massimo Binaghi, Manuel Scherer, Corinna Wentzel, David Bossert, Dr. Luc Eberhardt, Dr. Markus Neuburger, Prof. Dr. Peter Scheiffele and Prof. Dr. Karl Gademann

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203746

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      Let it grow! The neuritogenic iridoid gelsemiol has been prepared in synthetic form by a radical cascade and skeletal rearrangement. This compound accelerates the differentiation of neurons and growth of neuritis (see scheme).

    4. Gold Catalysis

      Gold-Catalyzed Sequential Activation of Propargylic Carboxylates: A Facile Route to Benzoannulenes (pages 2592–2596)

      Prof. Chang Ho Oh, Ji Hee Kim, Bu Keun Oh, Jong Ryul Park and Ji Ho Lee

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201204091

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      A cascade reaction of 1-(2-(3-acetoxyprop-1-ynyl)phenyl)prop-2-ynyl acetate and its derivatives is catalyzed by gold to give the corresponding benzo[7]annulenes (see scheme) in excellent yields. A double activation of the gold catalyst toward two different propargylic carboxylates was proposed. Benzoannulenes were hydrolyzed to 8-hydroxybenzo[7]annulene-5-ones.

    5. Organocatalyzed Hydroamination

      Highly Enantioselective Intermolecular Hydroamination of Allylic Amines with Chiral Aldehydes as Tethering Catalysts (pages 2597–2601)

      Melissa J. MacDonald, Colin R. Hesp, Derek J. Schipper, Marc Pesant and Prof. André M. Beauchemin

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203462

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      Chirally LinkedIn: Chiral aldehydes are effective tethering catalysts for enantioselective intermolecular hydroamination, which provides access to vicinal diamine motifs in good yields and excellent enantioselectivities (see scheme). This work highlights simple chiral α-oxygenated aldehydes as effective organocatalysts capable of efficiently inducing asymmetry through transient intramolecularity.

    6. Light-Emitting Materials

      High-Efficiency Violet-Light-Emitting Materials Based on Phenanthro[9,10-d]imidazole (pages 2602–2605)

      Dr. Zhao Gao, Dr. Yulong Liu, Dr. Zhiming Wang , Dr. Fangzhong Shen, Dr. He Liu, Guannan Sun, Dr. Liang Yao, Dr. Ying Lv, Prof. Ping Lu and Prof. Yuguang Ma

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203335

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      Novel violet: The material M2 (see picture), which is based on phenanthro[9,10-d]imidazole and carbazole, has a narrow band in the electroluminescence emission spectrum that results in saturated violet-light emission. The CIE of a non-doped device can reach (0.166, 0.056) with an external efficiency of 3.02 %.

    7. Amide Activation

      Direct Room-Temperature Lactonisation of Alcohols and Ethers onto Amides: An “Amide Strategy” for Synthesis (pages 2606–2610)

      Viviana Valerio, Desislava Petkova, Claire Madelaine and Dr. Nuno Maulide

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203906

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      Last-minute deal: A direct lactonisation of ethers and alcohols onto amides that proceeds at room temperature under mild conditions is reported (see scheme). This allows the effective saving of up to two unproductive, sequential deprotection operations in synthetic sequences. Mechanistic studies are described, and a new “amide strategy” that exploits the dual robustness/late-stage selective activation properties of this functional group is outlined.

    8. C[BOND]C Bond Cleavage

      C[BOND]C Bond Cleavage of Zwitterionic Carboranes Promoted by a Half-Sandwich Iridium(III) Complex (pages 2611–2614)

      Dr. Zi-Jian Yao, Dr. Yue-Jian Lin, Dr. Zhen-Hua Li and Prof. Dr. Guo-Xin Jin

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203850

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      Open-and-shut case: The cage C[BOND]C bond cleavage of monosubstituted carborane derivatives at room temperature has now been achieved. This approach, which is facilitated by half-sandwich complexes, provides a facile and direct synthesis of pseudocloso metallacarboranes (see scheme; dots indicate carbon atoms).

    9. Synthetic Methods

      Pronounced Solvent Effect on the Hydrostannylation of Propargylic Alcohol Derivatives with nBu3SnH/Et3B at Room Temperature (pages 2615–2618)

      Martins S. Oderinde and Prof. Michael G. Organ

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203405

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      The solvent is key: A general protocol is described for the hydrostannylation of propargyl alcohol derivatives at room temperature using Et3B/O2 as the promoter (see scheme). Rate and mechanistic studies point to a different autoxidation product of Et3B in THF than is observed in benzene, the typical solvent.

  5. Full Papers

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

      Remarkable Reinforcement of a Supramolecular Gel Constructed by Heteroditopic [18]Crown-6-Based Molecular Recognition (pages 2620–2627)

      Eunyoung Noh, Dr. Sunhong Park, Sunwoo Kang, Prof. Dr. Jin Yong Lee and Prof. Dr. Jong Hwa Jung

      Article first published online: 16 JAN 2013 | DOI: 10.1002/chem.201202710

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      Crown gels: A heteroditopic [18]crown-6-based ligand in the presence of Zn2+ can form gels with and without Cs+. Interestingly, the remarkable gelation reinforcement of the ligand is shown with Cs+ in the presence of Zn2+, which is due to the formation of a sandwich complex. According to DFT calculations, one of the Zn2+ ions is bound to two diazafluorenylimino moieties by a tetrahedral structure. In addition, one of the Cs+ ions is bound to two crown-rings (see picture).

    2. Protein Folding

      Structural Insights into the Trp-Cage Folding Intermediate Formation (pages 2628–2640)

      Petra Rovó, Pál Stráner, Dr. András Láng, István Bartha, Kristóf Huszár, Prof. Dr. László Nyitray and Prof. Dr. András Perczel

      Article first published online: 14 JAN 2013 | DOI: 10.1002/chem.201203764

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      Observing the invisible: The Trp-cage miniprotein folds in a multistate process into its native structure. Heteronuclear NMR spectroscopy studies combined with molecular dynamics simulations provide direct evidence for the 310- to α-helix rearrangement as an initial step during the unfolding. The G11[BOND]P12 peptide bond isomerization slows down the folding under acidic conditions (see figure; F=folded, I=intermediate, and U=unfolded structures).

    3. Bifunctional Catalysts

      A Recyclable Trinuclear Bifunctional Catalyst Derived from a Tetraoxo Bis-Zn(salphen) Metalloligand (pages 2641–2648)

      Dr. Martha V. Escárcega-Bobadilla, Dr. Marta Martínez Belmonte, Eddy Martin, Eduardo C. Escudero-Adán and Prof. Dr. Arjan W. Kleij

      Article first published online: 25 JAN 2013 | DOI: 10.1002/chem.201204132

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      A recyclable threesome: Highly stable supramolecular trinuclear complexes have been derived from a bis-Zn(salphen) metalloligand in almost quantitative yield and can act as bifunctional catalysts in the synthesis of organic carbonates from epoxides and CO2 under solvent-free conditions. These complexes have high recycling potential and can be used in up to five cycles without significant loss in substrate conversion and product yield.

    4. Fullerenes

      Quantum Chemical Insight of the Dimetallic Sulfide Endohedral Fullerene Sc2S@C70: Does It Possess the Conventional D5h Cage? (pages 2649–2654)

      Tao Yang, Prof. Dr. Xiang Zhao and Prof. Dr. Shigeru Nagase

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203388

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      Acting cagey: Through the use of quantum chemical calculations, an unconventional C70 cage structure, C2(7892), is found to survive in the form of the dimetallic sulfide endohedral fullerene Sc2S@C70 (see figure).

    5. Graphene

      Halogenation of Graphene with Chlorine, Bromine, or Iodine by Exfoliation in a Halogen Atmosphere (pages 2655–2662)

      Hwee Ling Poh, Petr Šimek, Dr. Zdeněk Sofer and Prof. Martin Pumera

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201202972

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      Nanoarchitectonics: Halogenated graphenes have been prepared by thermal exfoliation in gaseous halogen atmospheres (see scheme) and their physical and chemical properties characterized. The results show that a direct relationship exists between the halogen atomic number and the properties of the halogenated graphenes.

    6. Coordination Chemistry

      Periodic Behavior of Lanthanide Coordination within Reverse Micelles (pages 2663–2675)

      Ross J. Ellis, Yannick Meridiano, Renato Chiarizia, Laurence Berthon, Julie Muller, Laurent Couston and Mark R. Antonio

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201202880

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      The combination of structural insights obtained from the ion-, molecule-, and aggregate-centric perspectives provides a unified view of the core architectures of reverse micelles formed in water-in-oil systems with an extractant of practicality in separation science (see figure). The effects of aqueous media on organic microemulsions are not subtle, showing variations of mono- and bidentate nitrate coordination to LnIII and hydration as well as mesoscale variations of micellar morphology.

    7. Clathrates

      Simulations of Guest Transport in Clathrates of Dianin’s Compound and Hydroquinone (pages 2676–2684)

      Alexandra Nemkevich, Prof. Mark A. Spackman and Prof. Ben Corry

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201202035

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      Flexible hosts make for independent guests: Molecular dynamics simulations of guest transport in clathrates of hydroquinone (HQ) and Dianin's compound show that each guest molecule moves independently through the pores (A[RIGHTWARDS ARROW]B[RIGHTWARDS ARROW]C in the figure) by exploiting the flexibility of the host lattice, rather than in a concerted fashion (A[RIGHTWARDS ARROW]C).

    8. Nanoparticles

      One-Step Synthesis of Small-Sized and Water-Soluble NaREF4 Upconversion Nanoparticles for In Vitro Cell Imaging and Drug Delivery (pages 2685–2694)

      Dr. Dongmei Yang, Dr. Yunlu Dai, Dr. Pingan Ma, Dr. Xiaojiao Kang, Dr. Ziyong Cheng, Dr. Chunxia Li and Prof. Jun Lin

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203634

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      RE ready to deliver: Small-sized and water-soluble NaREF4 (rare earth (RE)=Nd[BOND]Lu, Y) nanoparticles (NPs) were synthesized by an oil/water two-phase approach (see scheme). Hollow-structured NPs can be fabricated in situ by electron-beam lithography on solid NPs. The as-prepared hollow-structured NaLuF4:Yb3+, Er3+ can be used as an anticancer drug carrier to investigate their cytotoxic effect against HeLa cells. Furthermore, these NaLuF4:Yb3+, Er3+ NPs show bright-red emission, which can be used for upconversion cell imaging.

    9. Supramolecular Isomerism

      Guest-Triggered Supramolecular Isomerism in a Pillared-Layer Structure with Unusual Isomers of Paddle-Wheel Secondary Building Units by Reversible Single-Crystal-to-Single-Crystal Transformation (pages 2695–2702)

      In-Hyeok Park, Prof. Dr. Shim Sung Lee and Prof. Dr. Jagadese J. Vittal

      Article first published online: 9 JAN 2013 | DOI: 10.1002/chem.201203267

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      Reversible pedal motion: Solvent-induced supramolecular isomerism is reported in pillared-layer metal–organic frameworks containing unusual isomers of paddle-wheel structure and conformational isomers of the spacer ligand (see scheme). Solvent exchange occurs in a single-crystal-to-single-crystal (SCSC) manner.

    10. Phospholipids

      Structure and Dynamics of Molecular Rods in Membranes: Application of a Spin-Labeled Rod (pages 2703–2710)

      Christiane Grimm, Thomas Meyer, Dr. Sylvia Czapla, Dr. Jörg Nikolaus, Dr. Holger A. Scheidt, Dr. Alexander Vogel, Prof. Dr. Andreas Herrmann, Prof. Dr. Pablo Wessig, Prof. Dr. Daniel Huster and Dr. Peter Müller

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201202500

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      Membrane functionalization: The interaction of a spin-labeled rod with membranes is investigated. The rod is embedded in the membranes in a tilted orientation (see figure) to adjust for the varying hydrophobic thicknesses. By using cyclodextrins, the rod can be extracted/incorporated from/into the membranes. This will improve the future applications of rods in cellular systems as stable membrane-associated anchors for the functionalization of membrane surfaces.

    11. Enzymes

      Enzyme Entrapped in Polymer-Modified Nanopores: The Effects of Macromolecular Crowding and Surface Hydrophobicity (pages 2711–2719)

      Jia Liu, Juan Peng, Shuai Shen, Qianru Jin, Prof. Dr. Can Li and Prof. Dr. Qihua Yang

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203833

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      Entrapment: The effects of macromolecular crowding and surface hydrophobicity on the properties of an immobilized enzyme were explored by accommodating lipase into a series of mesoporous silicas that contained various amounts of inert poly(methacrylate) (PMA) covalently anchored inside the nanopores.

    12. Hydroformylations

      Bis(phosphite) Ligands with Distal Regulation: Application in Rhodium-mediated Asymmetric Hydroformylations (pages 2720–2725)

      Ignasi Mon, Dr. D. Amilan Jose and Prof. Anton Vidal-Ferran

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203677

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      Adaptive hydroformylators: Small amounts of achiral polyethyleneoxy binders are employed to enhance the enantioselectivity in the hydroformylation of an array of diversely substituted alkenes (see scheme). The enantioselectivity was increased by up to 62 % ee (for vinyl acetate).

    13. Z-Selective Ring-Closing Metathesis

      Efficient and Selective Formation of Macrocyclic Disubstituted Z Alkenes by Ring-Closing Metathesis (RCM) Reactions Catalyzed by Mo- or W-Based Monoaryloxide Pyrrolide (MAP) Complexes: Applications to Total Syntheses of Epilachnene, Yuzu Lactone, Ambrettolide, Epothilone C, and Nakadomarin A (pages 2726–2740)

      Dr. Chenbo Wang, Miao Yu, Andrew F. Kyle, Dr. Pavol Jakubec, Prof. Darren J. Dixon, Prof. Richard R. Schrock and Prof. Amir H. Hoveyda

      Article first published online: 23 JAN 2013 | DOI: 10.1002/chem.201204045

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      Z macrocyclic alkenes of all shapes: A general method for catalytic ring-closing (RCM) metathesis reactions that afford many types of macrocyclic alkenes with high Z selectivity is now available. Mo- and W-based catalysts, by delivering unprecedented levels of efficiency and stereoselectivity, lead to near doubling of yields in cases where previous systems afford an equal mixture of typically inseparable olefin isomers. Utility is illustrated through total synthesis of five natural products.

    14. N Ligands

      Synchronizing Steric and Electronic Effects in {RuII(NNNN,P)} Complexes: The Catalytic Dehydrative Alkylation of Anilines by Using Alcohols as a Case Study (pages 2741–2748)

      Dipl.-Chem. Daniel Weickmann, Dr. Wolfgang Frey and Prof. Dr. Bernd Plietker

      Article first published online: 4 JAN 2013 | DOI: 10.1002/chem.201203285

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      Structure–activity relationships: New hexacoordinated {RuII(NNNN,P)} complexes proved to be potent catalyst for the alkylation of amines with alcohols. Evaluation of their catalytic activity in relation to their electronic properties (redox potentials and HOMO energies) revealed an optimum catalyst structure, which showed strong chemoselectivity for the monoalkylation of aromatic amines with primary alcohols (see scheme).

    15. Pd-Catalysed Sulfination

      Sulfination by Using Pd-PEPPSI Complexes: Studies into Precatalyst Activation, Cationic and Solvent Effects and the Role of Butoxide Base (pages 2749–2756)

      Mahmoud Sayah, Dr. Alan J. Lough and Prof. Michael G. Organ

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203142

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      On activation duty: The activation of PEPPSI precatalysts has been evaluated in the sulfination of aryl halides (see figure). Substitution of the two chlorides on Pd with two sulfides occurs immediately, even at low temperature, and it is this species that is reduced and enters the catalytic cycle. The butoxide base is involved in precatalyst activation and maintaining a healthy level of active catalyst to ensure high catalytic performance. Examination of the cation of the sulfide salt and solvent dielectric revealed that solubility is very important to the success of this transformation.

    16. Charge Transfer

      Organic Photovoltaic Devices Based on a New Class of Oligothienylenevinylene Derivatives as Donor Materials (pages 2757–2767)

      Eric Chi-Ho Kwok, Daniel Ping-Kuen Tsang, Prof. Mei-Yee Chan and Prof. Vivian Wing-Wah Yam

      Article first published online: 4 JAN 2013 | DOI: 10.1002/chem.201202403

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      Class act: A new class of low-optical-bandgap donor–acceptor-containing oligothienylenevinylenes (OTVs) that show intense charge-transfer absorption in the visible region has been synthesized and characterized for photovoltaic applications. With fullerene as the acceptor, bilayer organic photovoltaic devices with high open-circuit voltages have been demonstrated (see figure).

    17. Supramolecular Chemistry

      Coordination-Driven Switching of a Preorganized and Cooperative Calix[4]pyrrole Receptor (pages 2768–2775)

      Steffen Bähring, Gunnar Olsen, Prof. Dr. Paul C. Stein, Prof. Dr. Jacob Kongsted and Prof. Dr. Kent A. Nielsen

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203319

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      Zinc's a turn on! The molecular recognition of an asymmetric tetrathiafulvalene (TTF)–calix[4]pyrrole receptor can be reversibly switched between positive and negative cooperativity, when binding 1,3,5-trinitrobenzene (TNB), by chemical stimuli in the form of ZnII (see figure). An intramolecular complexation promotes a preorganized receptor with an increased affinity for TNB with a 237-fold increase in the first complexation (K1).

    18. Main Group Catalysts

      Magnesium Catalysis of Imine Hydroboration (pages 2776–2783)

      Dr. Merle Arrowsmith, Prof. Michael S. Hill and Dr. Gabriele Kociok-Köhn

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203190

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      Double-dipping catalyst: The heteroleptic magnesium alkyl complex [CH{C(Me)NDipp}2MgnBu] (Dipp=2,6-iPr2C6H3) is reported as a highly efficient precatalyst for the hydroboration of aldimines and ketamines with pinacolborane (see scheme).

    19. Homogeneous Catalysis

      Cyclohydroamination of Aminoalkenes Catalyzed by Disilazide Alkaline-Earth Metal Complexes: Reactivity Patterns and Deactivation Pathways (pages 2784–2802)

      Dr. Bo Liu, Dr. Thierry Roisnel, Prof. Dr. Jean-François Carpentier and Dr. Yann Sarazin

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203562

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      Playing a role: Phenolate and β-diketiminate disilazide complexes of the large alkaline-earth metals (Ca, Sr, and Ba) have been employed as competent catalysts for the cyclohydroamination of terminal aminoalkenes (see scheme). Trends regarding the catalytic activity of these complexes have been established and allow the discrimination between metal, ligand framework, and amido groups. A specific deactivation pathway has been identified, and several model compounds have been used for stoichiometric investigations.

    20. Materials Science

      Structures of Uncharacterised Polymorphs of Gallium Oxide from Total Neutron Diffraction (pages 2803–2813)

      Helen Y. Playford, Dr. Alex C. Hannon, Dr. Emma R. Barney and Prof. Richard I. Walton

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203359

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      To morph or not to morph? Three polymorphs of Ga2O3 with inherently disordered crystal structures and a gallium oxyhydroxide have structures based on close-packed oxide layers with partial filling of octahedral (circles) and tetrahedral (squares) interstitial sites. The relationship between these materials is reported, along with synthetic routes to these apparently simple solids that have potential in a variety of applications.

    21. Amphiphiles

      Highly Efficient Synthesis of Globular (Bola)amphiphilic [5:1]Hexakisadducts of C60 (pages 2814–2825)

      Frank Hörmann, Dr. Michael Brettreich, Wolfgang Donaubauer, Dr. Frank Hampel and Prof. Dr. Andreas Hirsch

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201203863

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      Testing the water: Globular (bola)amphiphilic mixed [5:1]hexakisadducts have been synthesized from C2v-symmetrical fullerene pentakisadducts with high efficiency (see figure). Due to the pH-dependent charge state, these hexakisadducts show interesting solubility properties in water.

    22. NMR Spectroscopy

      An Investigation of 1:1 Adducts of Gallium Trihalides with Triarylphosphines by Solid-State 69/71Ga and 31P NMR Spectroscopy (pages 2826–2838)

      Dr. Fu Chen, Dr. Guibin Ma, Dr. Guy M. Bernard, Prof. Roderick E. Wasylishen, Prof. Ronald G. Cavell, Dr. Robert McDonald and Dr. Michael J. Ferguson

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201202954

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      Spying on nuclear secrets: Several 1:1 gallium trihalide triarlyphosphine adducts have been investigated by solid-state gallium and phosphorus NMR spectroscopy (see figure), complemented with density functional theory calculations and X-ray crystallography. By using 31P as a “spy”, information about the Ga nuclei not available from 69/71Ga NMR spectroscopy has been obtained, including the sign of the nuclear quadrupolar coupling.

    23. Nanoparticles

      Popcorn-Shaped Magnetic Core–Plasmonic Shell Multifunctional Nanoparticles for the Targeted Magnetic Separation and Enrichment, Label-Free SERS Imaging, and Photothermal Destruction of Multidrug-Resistant Bacteria (pages 2839–2847)

      Zhen Fan, Dr. Dulal Senapati, Sadia Afrin Khan, Dr. Anant Kumar Singh, Prof. Ashton Hamme, Dr. Brian Yust, Prof. Dhiraj Sardar and Prof. Paresh Chandra Ray

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201202948

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      Golden nano-popcorn: For the first time, the synthesis of a multifunctional popcorn-shaped iron magnetic core–gold plasmonic shell nanoparticle and its use in targeted magnetic separation, SERS imaging, and the photothermal destruction of multidrug-resistant (MDR) Salmonella has been described (see figure).

    24. Bioengineering

      Polyoxometalates as a Novel Class of Artificial Proteases: Selective Hydrolysis of Lysozyme under Physiological pH and Temperature Promoted by a Cerium(IV) Keggin-Type Polyoxometalate (pages 2848–2858)

      Karen Stroobants, Eva Moelants, Hong Giang T. Ly, Prof. Dr. Paul Proost, Prof. Dr. Kristin Bartik and Prof. Dr. Tatjana N. Parac-Vogt

      Article first published online: 9 JAN 2013 | DOI: 10.1002/chem.201203020

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      It's a snip! Hen-egg-white lysozyme (HEWL) is specifically hydrolyzed at the Trp28–Val29 and Asn44–Arg45 peptide bonds in the presence of a Keggin-type [Ce(α-PW11O39)2]10− polyoxometalate (1) at pH 7.4 and 37 °C (see figure). The reactivity of 1 towards a range of dipeptides was also examined and the calculated reaction rates were comparable to those observed for the hydrolysis of HEWL.

    25. Biocatalysis

      Chemoenzymatic Synthesis of All Four Diastereomers of 2,6-Disubstituted Piperidines through Stereoselective Monoamination of 1,5-Diketones (pages 2859–2865)

      Dr. Robert C. Simon, Dr. Ferdinand Zepeck and Prof. Dr. Wolfgang Kroutil

      Article first published online: 4 JAN 2013 | DOI: 10.1002/chem.201202793

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      Being selective: By applying either an S- or R-stereoselective ω-transaminase, the (S)- or (R)-Δ1-piperideines were accessible through regioselective monoamination of 1,5-diketones (see scheme). Diastereoselective reduction of the optically pure Δ1-piperideines gave access to all four diastereomers of 2,6-dialkylpiperidines.

    26. Photocatalysis

      Facile Synthesis of Thermal- and Photostable Titania with Paramagnetic Oxygen Vacancies for Visible-Light Photocatalysis (pages 2866–2873)

      Dr. Xiaoxin Zou, Jikai Liu, Juan Su, Fan Zuo, Prof. Jiesheng Chen and Prof. Pingyun Feng

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201202833

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      Photocatalysis: Developing visible-light-responsive TiO2 materials is a necessary prerequisite for effective utilization of sunlight. A novel dopant-free TiO2 photocatalyst (Vo.-TiO2), which embodies a large number of paramagnetic oxygen vacancies, exhibits satisfactory thermal- and photostability, and superior visible-light photocatalytic activity for H2 evolution (115 μmol h−1 g−1) from water with methanol as sacrificial reagent (λ>400 nm).

    27. N-Heterocyclic Carbenes

      Theory of the Formation and Decomposition of N-Heterocyclic Aminooxycarbenes through Metal-Assisted [2+3]-Dipolar Cycloaddition/Retro-Cycloaddition (pages 2874–2888)

      Alexander S. Novikov, Dr. Maxim L. Kuznetsov and Prof. Armando J. L. Pombeiro

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203098

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      Going in circles: The theoretical background of the formation of N-heterocyclic aminooxycarbenes through a metal-assisted [2+3]-cycloaddition of nitrones to isocyanides and of their decomposition to imines and isocyanates is discussed (see scheme).

    28. Nanostructures

      Facile Synthesis and Thermoelectric Properties of Self-assembled Bi2Te3 One-Dimensional Nanorod Bundles (pages 2889–2894)

      Dr. Shuyan Song, Jipeng Fu, Xiyan Li, Wei Gao and Prof. Hongjie Zhang

      Article first published online: 7 JAN 2013 | DOI: 10.1002/chem.201203437

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      Nano-hot-rods: A simplified chemical process to synthesize pure Bi2Te3 nanorod bundles was developed, and the formation of Bi2Te3 nucleation, the growth of Bi2Te3 nanostructures, and the process of self-assembly were investigated (see figure). The enhancement of the thermal conductivity has been demonstrated and compared to that of thermoelectric materials.

    29. Aldol Reaction

      Syntheses of 2-Keto-3-deoxy-D-xylonate and 2-Keto-3-deoxy-L-arabinonate as Stereochemical Probes for Demonstrating the Metabolic Promiscuity of Sulfolobus solfataricus Towards D-Xylose and L-Arabinose (pages 2895–2902)

      Robert M. Archer, Dr. Sylvain F. Royer, William Mahy, Dr. Caroline L. Winn, Prof. Michael J. Danson and Dr. Steven D. Bull

      Article first published online: 11 JAN 2013 | DOI: 10.1002/chem.201203489

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      A promiscuous aldolase: The enantiomers 2-keto-3-deoxy-D-xylonate (D-KDX) and 2-keto-3-deoxy-L-arabinonate (L-KDA) are good substrates for the 2-keto-3-deoxy-D-gluconate aldolase from the archaeon Sulfolobus solfataricus, thus confirming that S. solfataricus employs a metabolically promiscuous pathway to catabolise the C5-sugars D-xylose and L-arabinose (see scheme).

    30. Fluorescent probe

      A Triazatruxene-Based Glycocluster as a Fluorescent Sensor for Concanavalin A (pages 2903–2909)

      Dr. Ke-Rang Wang, Yue-Qing Wang, Hong-Wei An, Jin-Chao Zhang and Prof. Dr. Xiao-Liu Li

      Article first published online: 10 JAN 2013 | DOI: 10.1002/chem.201200905

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      Multivalent glycocluster: A novel triazatruxene-based fluorescent sensor (1) for concanavalin A (Con A), based on specific binding interactions, has been designed and synthesized. Its binding constant with Con A was found to be two orders of magnitude higher than those of monovalent mannose ligands. Most interestingly, a fluorescence enhancement of the triazatruxene-based glycocluster was observed upon binding with Con A because of hydrophobic interactions involving sites close to the triazatruxene moiety (see figure).

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