Chemistry - A European Journal

Cover image for Vol. 19 Issue 4

January 21, 2013

Volume 19, Issue 4

Pages 1137–1510

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Communications
    7. Full Papers
    1. You have free access to this content
      Cover Picture: Development of Palladium Surface-Enriched Heteronuclear Au–Pd Nanoparticle Dehalogenation Catalysts in an Ionic Liquid (Chem. Eur. J. 4/2013) (page 1137)

      Dr. Xiao Yuan, Geng Sun, Hiroyuki Asakura, Prof. Tsunehiro Tanaka, Xi Chen, Dr. Yuan Yuan, Prof. Gabor Laurenczy, Prof. Yuan Kou, Prof. Paul J. Dyson and Prof. Ning Yan

      Version of Record online: 15 JAN 2013 | DOI: 10.1002/chem.201390007

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      Bimetallic Au–Pd nanoparticles were prepared in the functionalized ionic liquid [C2OHmim][NTf2] by the thermal decomposition of Pd(OAc)2 and Au(OAc)3. The Au atoms are mostly located in the NP core, leaving the Pd atoms enriched at the surface. Moreover, the Pd atoms are electropositive, which leads to high activity in catalytic dehalogenation reactions. The activity of the heteronuclear nanoparticles may be attributed to charge transfer from Pd to Au and consequently to more efficient reductive elimination. For more details, see the Full Paper by N. Yan et al. on page 1227 ff.

  2. Graphical Abstract

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

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

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Communications
    7. Full Papers
    1. Microwave Chemistry

      Developments in Direct C[BOND]H Arylation of (Hetero)Arenes under Microwave Irradiation (pages 1158–1168)

      Dr. Abhishek Sharma, Dipak Vacchani and Prof. Dr. Erik Van der Eycken

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201201868

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      Accelerated direct arylation: This Minireview describes the progress made in the development of direct C[BOND]H arylation approaches through the application of focused microwave irradiation. The synergistic combination of microwave-assisted techniques with the rapidly evolving domain of C[BOND]H arylation has opened new vistas in the efficient synthesis of a diverse array of biologically important (hetero)arenes (see scheme).

  5. Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Communications
    7. Full Papers
    1. Biomimetic Synthesis

      Synthesis of Difluorocatharanthine and Investigation of its Biomimetic Coupling with Vindoline (pages 1170–1173)

      Dr. Emerson Giovanelli, Dr. Lionel Moisan, Dr. Sébastien Leroux, Dr. Sébastien Comesse, Dr. Bernard Rousseau, Dr. Paul Hellier, Dr. Marc Nicolas and Dr. Eric Doris

      Version of Record online: 19 DEC 2012 | DOI: 10.1002/chem.201203577

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      The odd couple: The synthesis of 20,20-difluorocatharanthine starting from naturally occurring catharanthine is reported. The fluorinated catharanthine analogue was investigated as a potential precursor to dimeric Vinca alkaloids of the vinflunine family. However, the biomimetic coupling of difluorocatharanthine with vindoline led to unexpected products, the formation of which was rationalized (see scheme).

    2. Polyoxometalates

      Bifunctionalization of Polyoxometalates with Two Different Organoimido Ligands (pages 1174–1178)

      Dr. Chunlin Lv, Rao Naumaan Nasim Khan, Dr. Jin Zhang, Junjie Hu, Dr. Jian Hao and Prof. Dr. Yongge Wei

      Version of Record online: 19 DEC 2012 | DOI: 10.1002/chem.201203204

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      Doubly modified: Polyoxometalates can incorporate a large number of different functionalities in a way that mixes the ligands in a one-pot reaction. A class of mixed organoimido bifunctionalized hexamolybdates is presented that involves two different moieties L1 and L2, namely, differing aromatic, aromatic and aliphatic, and aliphatic moieties.

    3. Isomerization

      Rapid Nitrogen Inversion Pathway in the cis/trans Isomerization of Selenoxo Peptide Bonds (pages 1179–1183)

      Yun Huang, Dr. Günther Jahreis, Dr. Christian Lücke and Prof. Gunter Fischer

      Version of Record online: 11 DEC 2012 | DOI: 10.1002/chem.201203721

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      Two sides to a nitrogen: The cis to trans isomerization of selenoxo peptides in alkaline conditions is rationalized in terms of rapid nitrogen inversion of the tautomeric selenoimidate anion [C(Se)[DOUBLE BOND]N[BOND]] (see scheme), which increases the isomerization rate by about 30-fold as compared to the rotational pathway of the [CSe[BOND]NH[BOND]] form. The current work identifies the imino tautomer of a selenoxo peptide bond as a potential means to enhance oligopeptide backbone dynamics in a site-specific manner.

    4. Spiro Compounds

      Catalytic Asymmetric Michael Addition/Cyclization of Isothiocyanato Oxindoles: Highly Efficient and Versatile Approach for the Synthesis of 3,2′-Pyrrolidinyl Mono- and Bi-spirooxindole Frameworks (pages 1184–1188)

      Yi-Ming Cao, Fang-Fang Shen, Fu-Ting Zhang and Prof. Dr. Rui Wang

      Version of Record online: 18 DEC 2012 | DOI: 10.1002/chem.201204114

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      A-spiro-ing to greatness: The catalytic asymmetric Michael addition/cyclization of isothiocyanato oxindoles has been realized. This versatile approach provides an easy and highly efficient way to access not only the enantioselective synthesis of 3,2′-pyrrolidinyl spirooxindole frameworks, but also the construction of enatiomerically enriched bi-spirooxindoles containing three contiguous stereocenters and two spiro-quaternary centers (see scheme).

    5. C[BOND]H Functionalization

      Facile Access to 3-Acylindoles through Palladium-Catalyzed Addition of Indoles to Nitriles: The One-Pot Synthesis of Indenoindolones (pages 1189–1193)

      Yuanhong Ma, Prof. Dr. Jingsong You and Dr. Feijie Song

      Version of Record online: 13 DEC 2012 | DOI: 10.1002/chem.201203354

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      Well-connected: The palladium-catalyzed addition of indoles to nitriles affords 3-acylindoles. The reaction proceeds with high selectivity, wide substrate scope, broadly available starting materials, and an operationally simple procedure. Combination with the palladium-catalyzed intramolecular oxidative coupling of 3-indolylarylketone gives access to indenoindolones in a one-pot synthesis.

    6. Photophysical Properties

      The Effect of the Substitution Position of Dibenzofuran on the Photophysical and Charge-Transport Properties of Host Materials for Phosphorescent Organic Light-Emitting Diodes (pages 1194–1198)

      Prof. Chil Won Lee, Jeong-A Seo, Prof. Myoung-Seon Gong and Prof. Jun Yeob Lee

      Version of Record online: 18 DEC 2012 | DOI: 10.1002/chem.201203778

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      A twist in the tail: The effect of varying the substitution position of dibenzofuran on its photophysical properties and organic light-emitting diode device performance was systematically investigated by synthesizing three compounds with 2-, 3- and 4-substitution patterns (see scheme). The proper selection of substitution position can control the photophysical properties and performance of the materials.

    7. Allylic Substitution

      Bidentate Hydroxyalkyl NHC Ligands for the Copper-Catalyzed Asymmetric Allylic Substitution of Allyl Phosphates with Grignard Reagents (pages 1199–1203)

      Magaly Magrez, Yann Le Guen, Dr. Olivier Baslé, Dr. Christophe Crévisy and Dr. Marc Mauduit

      Version of Record online: 19 DEC 2012 | DOI: 10.1002/chem.201203969

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      Demonstrating their potential: Bidentate alkoxy NHC ligands have been used in the copper-catalyzed asymmetric allylic alkylation of allyl phosphates with Grignard reagents (see scheme). The method provides access to tertiary and quaternary chiral centers with high regio- and enantioselectivity. The system is also applied to the synthesis of chiral E,E-dienes, a key structural motif prevalent in natural products.

    8. Reaction Mechanisms

      [3,3] Sigmatropic Rearrangement Versus [2+2] Cycloaddition: A DFT Investigation of Formal SN2′ Substitution of Imido Metal Complexes with Allylic Electrophiles (pages 1204–1208)

      Caihong Cheng, Danfeng Chen and Prof. Dr. Zhihong Wang

      Version of Record online: 19 DEC 2012 | DOI: 10.1002/chem.201203197

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      Is common sense always best? A DFT investigation of two SN2′ substitution reactions with different central metals (zirconium and titanium) and types of allylic sources revealed that in both cases, a [2+2]/retro-[2+2] pathway is energetically favorable. This is in contrast with the usually accepted [3,3] sigmatropic rearrangement mechanism (see picture; TMS=trimethylsilyl).

    9. Helical Coiling

      A PdII-Containing Self-Assembled Macrocyclic Host Induces Helical Coiling of Fatty Acids (pages 1209–1212)

      Prof. Dr. Choon Woo Lim, Hoa Thi Le, Gwun Soo Jung and Prof. Dr. Tae Woo Kim

      Version of Record online: 12 DEC 2012 | DOI: 10.1002/chem.201202947

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      Chain charmer: Fatty acids exhibit dynamic helical coiling in the presence of a PdII-containing self-assembled macrocycle (see scheme). The helical coiling, which was supported by molecular modeling, seems to be induced by hydrophobic interactions within the cavity.

  6. Full Papers

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. News
    5. Minireview
    6. Communications
    7. Full Papers
    1. DNA Recognition

      Asymmetric Distyrylpyridinium Dyes as Red-Emitting Fluorescent Probes for Quadruplex DNA (pages 1214–1226)

      Xiao Xie, Bina Choi, Dr. Eric Largy, Dr. Régis Guillot, Dr. Anton Granzhan and Dr. Marie-Paule Teulade-Fichou

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203710

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      Shape matters: The asymmetric (2,4-disubstituted) distyrylpyrydinium dyes represent red-emitting “light-up” fluorescent probes selective for quadruplex DNA (see figure), whereas their symmetric (2,6-disubstituted) counterpart has no selectivity for quadruplex over duplex DNA.

    2. Nanoparticles

      Development of Palladium Surface-Enriched Heteronuclear Au–Pd Nanoparticle Dehalogenation Catalysts in an Ionic Liquid (pages 1227–1234)

      Dr. Xiao Yuan, Geng Sun, Hiroyuki Asakura, Prof. Tsunehiro Tanaka, Xi Chen, Dr. Yuan Yuan, Prof. Gabor Laurenczy, Prof. Yuan Kou, Prof. Paul J. Dyson and Prof. Ning Yan

      Version of Record online: 4 JAN 2013 | DOI: 10.1002/chem.201203605

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      The golden egg: Core–shell Au–Pd nanoparticles were prepared in the functionalized ionic liquid [C2OHmim][NTf2] (C2OHmim=1-(2′-hydroxyethyl)-3-methylimidazolium, TF=triflyl), thoroughly characterized, and found to be an excellent catalyst for dehalogenation reactions (see scheme).

    3. Rhodium

      Surface-Mediated Synthesis of Dimeric Rhodium Catalysts on MgO: Tracking Changes in the Nuclearity and Ligand Environment of the Catalytically Active Sites by X-ray Absorption and Infrared Spectroscopies (pages 1235–1245)

      Dicle Yardimci, Dr. Pedro Serna and Prof. Bruce C. Gates

      Version of Record online: 3 DEC 2012 | DOI: 10.1002/chem.201202514

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      Increasing activity: Increasing the nuclearity of an MgO-supported catalyst from one to two Rh atoms leads to a 58-fold increase in catalytic activity for ethylene hydrogenation (see figure). Changes in the nuclearity and ligand environment of the active sites are presented.

    4. Radical Ions

      A Heterobimetallic Approach To Stabilize the Elusive Disulfur Radical Trianion (“Subsulfide”) equation image (pages 1246–1253)

      Dr. Shenglai Yao, Dr. Peter Hrobárik, Dipl.-Chem. Florian Meier, Dipl.-Chem. Robert Rudolph, Dr. Eckhard Bill, Dr. Elisabeth Irran, Prof. Dr. Martin Kaupp and Prof. Dr. Matthias Driess

      Version of Record online: 18 DEC 2012 | DOI: 10.1002/chem.201203642

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      Disulfur ligand and nickel in difficulty: A unique heterobimetallic disulfur monoradical with a diamond-shaped {NiS2Pt} core has been synthesized. The results of DFT calculations as well as spectroscopic and structural features of the complex revealed that the bonding situation of the S2 ligand is between the elusive “half-bonded” S2 radical trianion (equation image) and two separated S2− ligands. Accordingly, the NiII center is partially oxidized, whereas the PtII site is redox innocent.

    5. Cubanes

      On the Controversial Fitting of Susceptibility Curves of Ferromagnetic CuII Cubanes: Insights from Theoretical Calculations (pages 1254–1261)

      Dr. Carmen J. Calzado

      Version of Record online: 12 DEC 2012 | DOI: 10.1002/chem.201203474

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      Alternative interpretations: Theoretical analysis of the electronic structure and magnetic coupling terms in CuII cubanes provides an alternative interpretation of the magnetic data that is more consistent with the structure and arrangement of the magnetic orbitals than the rationalization provided in experimental work (see figure; AF=antiferromagnetic). This study shows that it is possible to obtain similar fits with sets of parameters that represent different physical effects.

    6. DNA Recognition

      Tailored Host–Guest Lipidic Cubic Phases: A Protocell Model Exhibiting Nucleic Acid Recognition (pages 1262–1267)

      Dr. Marek Komisarski, Dr. Yazmin M. Osornio, Prof. Jay S. Siegel and Prof. Ehud M. Landau

      Version of Record online: 12 DEC 2012 | DOI: 10.1002/chem.201203372

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      Modeling job: A synthetically tailored host–guest lipidic cubic phase comprising monoolein and an oleolipid–nucleic acid conjugate can perform efficient DNA recognition and sequestration, and is proposed as a protocell model (see figure). A lipid polymorph that is stable in bulk water over a large temperature range offers an alternative to metastable micelle and vesicular models. Such hybrid systems also show promise as functional bioengineering materials.

    7. Nitrogen Heterocycles

      A New Series of C-6 Unsubstituted Tetrahydropyrimidines: Convenient One-Pot Chemoselective Synthesis, Aggregation-Induced and Size-Independent Emission Characteristics (pages 1268–1280)

      Dr. Qiuhua Zhu, Lan Huang, Dr. Zhipeng Chen, Sichao Zheng, Longyun Lv, Dr. Zhibo Zhu, Prof. Derong Cao, Prof. Huanfeng Jiang and Prof. Shuwen Liu

      Version of Record online: 29 NOV 2012 | DOI: 10.1002/chem.201203012

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      Blue and green: A new series of C-6 unsubstituted tetrahydropyrimidines (6) was synthesized through urea-catalyzed five-component reactions (5CRs). Compounds 6 emit blue/green fluorescence in aggregates with ΦF up to 93 %, but no fluorescence in solution. One of the 5CR products, 6aa, exhibits two types of aggregates (bf- and gf-aggregates), the formation of which is tuned by external conditions. Compound 6aa shows unusual size-independent emission characteristics (see figure).

    8. Nanoparticles

      Mechanism and Cellular Kinetic Studies of the Enhancement of Antioxidant Activity by Using Surface-Functionalized Gold Nanoparticles (pages 1281–1287)

      Dr. Libo Du, Siqingaowa Suo, Guangqing Wang, Dr. Hongying Jia, Prof. Dr. Ke Jian Liu, Prof. Dr. Baolu Zhao and Prof. Dr. Yang Liu

      Version of Record online: 11 DEC 2012 | DOI: 10.1002/chem.201203506

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      Au antioxidant boost: New, antioxidant salvianic acid A (SA)-coated gold nanoparticles (Au@PEG3SA) were synthesized based on a layer-by-layer self-assembly method. Radical-scavenging experiments with a 2,2-diphenyl-1-picryhydrazyl (DPPH) radical revealed that the rate constant for the reaction of Au@PEG3SA with the DPPH radical is about nine times greater than that for SA. Moreover, the kinetics of the protective effects of Au@PEG3SA not only applies to macrophage cells, but also to C. elegans (see figure).

    9. Conformation Analysis

      Conformational Analysis of δ-Lactones by DFT Calculations: The Parent Compound and its Monomethyl and Selected Dimethyl Derivatives (pages 1288–1302)

      Dipl.-Chem. Fabian Weber and Prof. Dr. Reinhard Brückner

      Version of Record online: 7 JAN 2013 | DOI: 10.1002/chem.201202988

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      Static and dynamic stereochemistry of unsubstituted δ-valerolactone, all monomethylated δ-lactones, and all nongeminally dimethylated δ-lactones was explored theoretically. The lowest threshold conformational interconversion pathways were scanned and visualized in appealingly intuitive yet unprecedented diagrams (see figure).

    10. Water Splitting

      Charge-Neutral Amidinate-Containing Iridium Complexes Capable of Efficient Photocatalytic Water Reduction (pages 1303–1310)

      Dr. Zhen-Tao Yu, Yong-Jun Yuan, Jian-Guang Cai and Prof. Dr. Zhi-Gang Zou

      Version of Record online: 23 NOV 2012 | DOI: 10.1002/chem.201203029

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      The photoreduction of water to hydrogen has been carried out using two charge-neutral iridium complexes. The photophysical properties, electrochemical behaviours and emission quenching properties of these newly designed species have been investigated. In concert with the catalyst [Co(bpy)3]2+, members of this new class of complexes enable the photocatalytic generation of hydrogen from mixed aqueous solutions via an oxidative quenching pathway (see figure).

    11. Bioimaging

      Rational Design of an “OFF–ON” Phosphorescent Chemodosimeter Based on an Iridium(III) Complex and Its Application for Time-Resolved Luminescent Detection and Bioimaging of Cysteine and Homocysteine (pages 1311–1319)

      Yan Tang, Hui-Ran Yang, Hui-Bin Sun, Prof. Shu-Juan Liu, Jing-Xia Wang, Prof. Qiang Zhao, Dr. Xiang-Mei Liu, Dr. Wen-Juan Xu, Prof. Sheng-Biao Li and Prof. Wei Huang

      Version of Record online: 19 DEC 2012 | DOI: 10.1002/chem.201203137

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      Seeing sense: An excellent “OFF–ON” phosphorescent chemodosimeter for sensing cysteine (Cys) and homocysteine (Hcy) with high selectivity and naked-eye detection based on an IrIII complex has been developed (see scheme). The time-resolved luminescent assay of this probe for sensing Cys was achieved by using the long emission lifetime of phosphorescence, which can eliminate interference from short-lived background fluorescence and improve the signal-to-noise ratio. The probe has been used for the bioimaging of changes in Cys/Hcy concentration in living cells.

    12. Photocatalysis

      A Theoretical Study on the Mechanism of Photocatalytic Oxygen Evolution on BiVO4 in Aqueous Solution (pages 1320–1326)

      Jingxiu Yang , Donge Wang , Dr. Xin Zhou and Prof. Dr. Can Li

      Version of Record online: 3 DEC 2012 | DOI: 10.1002/chem.201202365

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      The photocatalytic O2 evolution activity of monoclinic BiVO4 single crystals depends on the degree of exposure of the (010) facets. Hence, geometric structure, optical properties, electronic structure, water adsorption, and the complete O2 evolution free-energy profiles (see figure) on different surfaces were investigated by DFT calculations. Owing to the combined effects of the above-mentioned factors, different facets exhibit quite different photocatalytic activities.

    13. Alkane Functionalization

      Functionalization of Non-activated C[BOND]H Bonds of Alkanes: An Effective and Recyclable Catalytic System Based on Fluorinated Silver Catalysts and Solvents (pages 1327–1334)

      M. Ángeles Fuentes, Dr. Bianca K. Muñoz, Kane Jacob, Dr. Laure Vendier, Dr. Ana Caballero, Prof. Michel Etienne and Prof. Pedro J. Pérez

      Version of Record online: 29 NOV 2012 | DOI: 10.1002/chem.201203566

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      Flawless fluorous: Silver complexes with perfluorinated ligands efficiently catalyze the functionalization of alkanes by insertion of CHCO2Et from N2CHCO2Et (see scheme). The use of a fluorous phase enabled the separation and reuse of the catalyst several times without loss of its catalytic properties.

    14. Heterogeneous Catalysis

      Tuning the Surface Chemistry of Pd by Atomic C and H: A Microscopic Picture (pages 1335–1345)

      Dr. Hristiyan A. Aleksandrov, Dr. Francesc Viñes, Wiebke Ludwig, Dr. Swetlana Schauermann and Prof. Dr. Konstantin M. Neyman

      Version of Record online: 23 NOV 2012 | DOI: 10.1002/chem.201201106

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      A detailed and unified view on the interactions of H and C species with Pd nanoparticles provides indispensable insight into their catalytic properties. For instance, the migration of surface H atoms that densely cover Pd nanoparticles into the subsurface area is facilitated by the presence of subsurface atomic C, which destabilizes nearby H atoms (see figure).

    15. Mesoporous Materials

      Enzyme-Responsive Silica Mesoporous Supports Capped with Azopyridinium Salts for Controlled Delivery Applications (pages 1346–1356)

      Núria Mas, Alessandro Agostini, Dr. Laura Mondragón, Dr. Andrea Bernardos, Dr. Félix Sancenón, Dr. M. Dolores Marcos, Prof. Ramón Martínez-Máñez, Prof. Ana M. Costero, Prof. Salvador Gil, Prof. Matilde Merino-Sanjuán, Prof. Pedro Amorós, Dr. Mar Orzáez and Prof. Enrique Pérez-Payá

      Version of Record online: 7 DEC 2012 | DOI: 10.1002/chem.201202740

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      Command and deliver: A new capped silica mesoporous material for on-command delivery applications has been designed based on a MCM-41-like support loaded with Rhodamine B and capped with an azopyridine derivative. This material is able to release the entrapped cargo in the presence of indigenous intestinal microflora enzymes (such as reductases and esterases; see figure). Nanoparticles capped with azopyridine and loaded with camptothecin were also prepared and used as delivery nanodevices in HeLa cells.

    16. Peptidyl–RNA Conjugates

      Efficient Access to Peptidyl-RNA Conjugates for Picomolar Inhibition of Non-ribosomal FemXWv Aminoacyl Transferase (pages 1357–1363)

      Dr. Matthieu Fonvielle , Dénia Mellal , Delphine Patin, Maxime Lecerf, Dr. Didier Blanot, Dr. Ahmed Bouhss, Dr. Marco Santarem, Dr. Dominique Mengin-Lecreulx, Dr. Matthieu Sollogoub, Dr. Michel Arthur and Dr. Mélanie Ethève-Quelquejeu

      Version of Record online: 29 NOV 2012 | DOI: 10.1002/chem.201201999

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      Conjugation of complex biomolecules: Peptidyl–RNA conjugates have various applications to study the ribosome and enzymes participating in tRNA-dependent pathways such as Fem transferases in peptidoglycan synthesis. Here, a convergent route for synthesis of peptidyl–RNAs based on Huisgen–Sharpless cycloaddition for the final ligation step is developed (see figure). Both moieties of the peptidyl–RNA conjugate contribute to high-affinity binding to FemX, providing a picomolar inhibitor.

    17. Inhibitors

      Macrocyclic Mechanism-Based Inhibitor for Neuraminidases (pages 1364–1372)

      Dr. Hirokazu Kai, Dr. Hiroshi Hinou, Dr. Kentaro Naruchi, Dr. Takahiko Matsushita and Prof. Shin-Ichiro Nishimura

      Version of Record online: 11 DEC 2012 | DOI: 10.1002/chem.201200859

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      Setting the trap: A macrocyclic mechanism-based inhibitor that inhibits neuraminidases (NAs) irreversibly was designed and evaluated (see scheme). As expected, NAs having small kcat values, such as those from Influenza virus, Vibrio cholerae, and Trypanosoma cruzi, were inhibited irreversibly. However, Salmonella typhimurium NA, which has an extremely high kcat, was not affected irreversibly by the inhibitor.

    18. Organogelators

      Immobilization of Styrene-Substituted 1,3,4-Oxadiazoles into Thermoreversible Luminescent Organogels and Their Unexpected Photocatalyzed Rearrangement (pages 1373–1384)

      Dr. Frédéric Dumur, Dr. Emmanuel Contal, Dr. Guillaume Wantz, Dr. Trang N. T. Phan, Prof. Denis Bertin and Dr. Didier Gigmes

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201202246

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      Organogel rearrangement: A series of styrene-substituted 1,3,4-oxadiazoles has been designed and investigated as new low-molecular-weight organogelators (see scheme). Interestingly, UV irradiation of the gels caused a rearrangement of the immobilized 1,3,4-oxadiazoles bearing a styrene moiety by a tandem [4+2] and [3+2] cascade reaction.

    19. Electrophosphorescence

      Elevating the Triplet Energy Levels of Dibenzofuran-Based Ambipolar Phosphine Oxide Hosts for Ultralow-Voltage-Driven Efficient Blue Electrophosphorescence: From D[BOND]A to D[BOND]π[BOND]A Systems (pages 1385–1396)

      Chunmiao Han, Zhensong Zhang, Dr. Hui Xu, Jing Li, Prof. Yi Zhao, Prof. Pengfei Yan and Prof. Shiyong Liu

      Version of Record online: 11 DEC 2012 | DOI: 10.1002/chem.201203719

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      I'm blue, D[BOND]A ba dee: A series of donor (D)–π–acceptor (A)-type phosphine oxide hosts (DBFxPOPhCzn) were designed and synthesized. The π spacer between the carbazolyl and dibenzofuran moieties elevated the first triplet energy levels (T1) to about 3.0 eV. Phosphorescent blue-light-emitting diodes (PHOLEDs) based on DBFxPOPhCzn not only inherited the ultralow driving voltages, but also had much-improved efficiencies.

    20. Metal Fluorides

      Matrix Infrared Spectroscopy and Quantum-Chemical Calculations for the Coinage-Metal Fluorides: Comparisons of Ar[BOND]AuF, Ne[BOND]AuF, and Molecules MF2 and MF3 (pages 1397–1409)

      Prof. Xuefeng Wang, Prof. Lester Andrews, Dipl.Chem. Felix Brosi and Dr. Sebastian Riedel

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201203306

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      To coin a phrase: Experiments in solid neon and argon under cryogenic conditions led to the formation and characterization of MF2 and MF3 molecules (M=Au, Ag, Cu), NgAuF complexes (Ng=Ne, Ar), and AuF5 (see figure), whilst also providing evidence for the formation of Au2F6. IR spectra were in excellent agreement with state-of-the-art quantum-chemical calculations.

    21. Lanthanoid Coordination Chemistry

      Synthesis, Structures and Reactivity of Lanthanoid(II) Formamidinates of Varying Steric Bulk (pages 1410–1420)

      Prof. Dr. Marcus L. Cole, Prof. Dr. Glen B. Deacon, Dr. Craig M. Forsyth, Prof. Dr. Peter C. Junk, Dr. Kristina Konstas, Dr. Jun Wang, Henry Bittig and Daniel Werner

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201202861

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      New reactive divalent lanthanoid formamidinates (see figure) have been prepared by redox transmetallation/protolysis reactions and their involvement in C[BOND]X (X=F, Cl, Br) activation reactions has been studied.

    22. Mesoporous Silica Nanoparticles

      Selective Anchoring of GdIII Chelates on the External Surface of Organo-Modified Mesoporous Silica Nanoparticles: A New Chemical Strategy To Enhance Relaxivity (pages 1421–1428)

      Dr. Fabio Carniato, Dr. Lorenzo Tei, Dr. Aldo Arrais, Prof. Leonardo Marchese and Prof. Mauro Botta

      Version of Record online: 11 DEC 2012 | DOI: 10.1002/chem.201202670

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      Anchors away! Selective anchoring of Gd–DOTA-like (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complexes on the external surface of organo-modified mesoporous silica nanoparticles, followed by extraction of the surfactant molecules and chemical modification of the surface, results in a porous paramagnetic nanosystem of outstanding relaxivity (see figure).

    23. Click Chemistry

      A Click Approach to Polymetallic Chromium(0) and Tungsten(0) Fischer-Carbene Complexes and Their Use in the Synthesis of Functionalized Polymetallic Metal[BOND]Carbene Complexes (pages 1429–1435)

      Beatriz Baeza, Prof. Luis Casarrubios and Prof. Miguel A. Sierra

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201202328

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      Stone the Cr0s: Alkynylamino Cr0 and W0 Fischer carbenes reacted with di-/tri-/tetra-azides in a Cu-catalyzed 1,3-dipolar cycloaddition reaction to afford polymetallic Cr0 and W0 (Fischer)-carbene complexes. This versatile method affords structures with a high level of symmetry.

    24. Conformation Analysis

      How the Generalized Anomeric Effect Influences the Conformational Preference (pages 1436–1444)

      Changwei Wang, Dr. Zhenhua Chen, Prof. Dr. Wei Wu and Prof. Dr. Yirong Mo

      Version of Record online: 5 DEC 2012 | DOI: 10.1002/chem.201203429

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      Pressure to conform: The block-localized wavefunction (BLW) method is employed to explore the origin of the generalized anomeric effect. For systems such as methoxymethyl fluoride or chloride, both the steric and hyperconjugation effects contribute to the conformational preferences (see figure). However, for most systems including methanediol, methanediamine, aminomethanol, and dimethoxymethane, the hyperconjugative interactions play a negative role, and the steric effect is solely responsible for the generalized anomeric effect.

    25. Cage Compounds

      Self-Assembled Tetragonal Prismatic Molecular Cage Highly Selective for Anionic π Guests (pages 1445–1456)

      Cristina García-Simón, Marc Garcia-Borràs, Dr. Laura Gómez, Dr. Isaac Garcia-Bosch, Dr. Sílvia Osuna, Prof. Marcel Swart, Dr. Josep M. Luis, Prof. Concepció Rovira, Prof. Manuel Almeida, Dr. Inhar Imaz, Prof. Daniel Maspoch, Dr. Miquel Costas and Dr. Xavi Ribas

      Version of Record online: 4 DEC 2012 | DOI: 10.1002/chem.201203376

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      Host–guest in a nanocage: A Pd-carboxylate self-assembled nanocage with two porphyrin moieties has been spectroscopically and structurally characterized, and shows very high affinity for anionic π-guest molecules (see figure). The subtle parameters controlling the host–guest interaction are widely discussed by means of spectroscopic and computational experiments, and fine tuning of the physical properties of the guest has been achieved.

    26. Single-Molecule Magnets

      Influence of Peripheral Substitution on the Magnetic Behavior of Single-Ion Magnets Based on Homo- and Heteroleptic TbIII Bis(phthalocyaninate) (pages 1457–1465)

      Carolina R. Ganivet, Dr. Beatriz Ballesteros, Dr. Gema de la Torre, Dr. Juan M. Clemente-Juan, Prof. Eugenio Coronado and Prof. Tomás Torres

      Version of Record online: 29 NOV 2012 | DOI: 10.1002/chem.201202600

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      Tb-thumping: Homo- and heteroleptic TbIII bis(phthalocyaninate)s were characterized as single-molecule magnets. Electron-donor groups on one of the ligands show higher blocking temperatures and effective barriers than their homoleptic analogues. A heteroleptic [TbIII(Pc)(Pc′)] complex with one octa(tert-butylphenoxy)-substituted phthalocyanine exhibited the highest reported effective barrier and blocking temperature for single-molecule magnets.

    27. Asymmetric Synthesis

      Copper-Free Asymmetric Allylic Alkylation with a Grignard Reagent: Design of the Ligand and Mechanistic Studies (pages 1466–1475)

      David Grassi, Dr. Chrysanthi Dolka, Dr. Olivier Jackowski and Prof. Alexandre Alexakis

      Version of Record online: 6 DEC 2012 | DOI: 10.1002/chem.201202318

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      A new way to AAA: The Cu-free asymmetric allylic alkylation (AAA) with Grignard reagents on allyl bromide derivatives, catalysed by N-heterocyclic carbenes (NHC), is reported (see scheme). This new synthesis gave good enantioselectivities with good to excellent γ regioselectivities, particularly for the formation of quaternary chiral centres. Several new NHCs were tested and mechanistic studies by NMR spectropscopic analysis led to the discovery of the catalytically active species.

    28. Bridging Ligands

      Impact of the Synergistic Collaboration of Oligothiophene Bridges and Ruthenium Complexes on the Optical Properties of Dumbbell-Shaped Compounds (pages 1476–1488)

      Dr. Rubén D. Costa, Dr. Juan Aragó, Prof. Dr. Enrique Ortí, Dr. Ted M. Pappenfus, Prof. Dr. Kent R. Mann, Dr. Katarzyna Matczyszyn, Prof. Dr. Marek Samoc, Dr. José L. Zafra, Prof. Dr. Juan T. López Navarrete and Prof. Dr. Juan Casado

      Version of Record online: 3 DEC 2012 | DOI: 10.1002/chem.201202456

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      Dumb and dumbbell: The linear and nonlinear optical properties of dumbbell-shaped compounds, which were formed by two end-capping RuII complexes and an oligothiophene bridge, were modulated by changing the length of the bridge. The luminescence from the Ru complexes disappeared on increasing the number of thiophene rings, owing to quenching by the low-energy triplet of the bridge. Nonlinear absorption increased with the length of the bridge.

    29. Donor–Acceptor Systems

      You have full text access to this OnlineOpen article
      Synthesis and Characterization of Redox-Active Charge-Transfer Complexes with 2,3,5,6-Tetracyanopyridine (TCNPy) for the Photogeneration of Pyridinium Radicals (pages 1489–1495)

      Eva Wöß, Dr. Uwe Monkowius and Prof. Dr. Günther Knör

      Version of Record online: 11 DEC 2012 | DOI: 10.1002/chem.201201915

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      Pyridine photoreduction: The heteroaromatic polynitrile system 2,3,5,6-tetracyanopyridine (TCNPy) is introduced as an attractive electron acceptor for the formation of deeply colored charge-transfer complexes. Possible light-induced strategies for the formation of pyridinium radicals, which involve direct optical electron transfer coupled to a protonation step, are discussed for different types of donor–acceptor pairs (see scheme).

    30. Gold(I) Catalysis

      Gold(I)-Catalyzed Aminohalogenation of Fluorinated N′-Aryl-N-Propargyl Amidines for the Synthesis of Imidazole Derivatives under Mild Conditions (pages 1496–1501)

      Dr Shan Li, Zhengke Li, Yafen Yuan, Yajun Li, Lisi Zhang and Prof. Dr. Yongming Wu

      Version of Record online: 19 DEC 2012 | DOI: 10.1002/chem.201202402

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      Golden(I): Under gold(I) catalysis, propargyl amidines were converted into 5-fluoromethyl imidazoles in the presence of Selectfluor. Treatment with N-iodosuccinimide afforded imidazole-5-carbaldehydes as the final product (see scheme).

    31. Polyrotaxanes

      Main-Chain Linear Polyrotaxanes: Synthesis, Characterization, and Conformational Modulation (pages 1502–1510)

      Dr. Ji-Min Han, Yong-Hong Zhang, Xiao-Ye Wang, Prof. Chen-Jiang Liu, Dr. Jie-Yu Wang and Prof. Jian Pei

      Version of Record online: 30 NOV 2012 | DOI: 10.1002/chem.201203165

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      Having a ball: Functional main-chain linear polyrotaxanes P1 and P2 were synthesized through strong DB24C8/DBA interactions and click chemistry. P1 polymers were rigid rods, whereas P2 polymers were flexible and much easier to mold into ball-shaped particles. The anion-induced ET enhancement and base-driven molecular-shuttle process confirmed that electrostatic interactions were crucial for the assembly of polyrotaxanes P1 and P2.

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