Chemistry - A European Journal

Cover image for Chemistry - A European Journal

May 19, 2014

Volume 20, Issue 21

Pages 6197–6551

  1. Cover Pictures

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. You have free access to this content
      Cover Picture: A Glutathione-Activated Phthalocyanine-Based Photosensitizer for Photodynamic Therapy (Chem. Eur. J. 21/2014) (page 6197)

      Dr. Hui He, Prof. Pui-Chi Lo and Prof. Dennis K. P. Ng

      Article first published online: 14 MAY 2014 | DOI: 10.1002/chem.201490083

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      Smart photosensitizers that can be activated selectively by tumor-associated stimuli are of great potential for targeted photodynamic therapy. They can enhance the overall therapeutic outcome and reduce undesirable side effects. In their Communication on page 6241 ff., H. He, P.-C. Lo, and D. K. P. Ng report a simple, yet highly efficient, phthalocyanine-based photosensitizer. Its fluorescence emission and reactive oxygen species generation are greatly enhanced by glutathione, both in phosphate-buffered saline and inside cancer cells. The activation of this photosensitizer has also been demonstrated in tumor-bearing nude mice.

    2. You have free access to this content
      Back Cover: Vesicle Structures from Bolaamphiphilic Biosurfactants: Experimental and Molecular Dynamics Simulation Studies on the Effect of Unsaturation on Sophorolipid Self-Assemblies (Chem. Eur. J. 21/2014) (page 6556)

      Prabhu Dhasaiyan, Prithvi Raj Pandey, Nikunjkumar Visaveliya, Dr. Sudip Roy and Dr. B. L. V. Prasad

      Article first published online: 14 MAY 2014 | DOI: 10.1002/chem.201490086

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      Understanding the self-assembly of vesicles is important because they are involved in the construction of cell walls in some naturally occurring micro-organisms. In the Communication by S. Roy and B. L. V. Prasad et al. on page 6246 ff., experimental and molecular dynamics studies show that sophorolipids based on linolenic acid (which fit into the classification of asymmetric bolaamphiphilic lipids) self-assemble into giant-vesicle-type structures. The cell walls of these vesicles consist of a double bilayer wherein the molecules are arranged in a tail–head–head–tail manner in each bilayer.

  2. Cover Profile

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. You have free access to this content
      A Glutathione-Activated Phthalocyanine-Based Photosensitizer for Photodynamic Therapy (page 6201)

      Dr. Hui He, Prof. Pui-Chi Lo and Prof. Dennis K. P. Ng

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400433

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      The use of “smart” photosensitizers that can only be activated by tumor-associated stimuli can confine the cytotoxic effect at the tumor and spare the normal tissues” Read more about the story behind the cover in the Cover Profile and about the research itself on page 6241 ff. (DOI: 10.1002/chem.201400001).

  3. Graphical Abstract

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. Graphical Abstract: Chem. Eur. J. 21/2014 (pages 6202–6213)

      Article first published online: 14 MAY 2014 | DOI: 10.1002/chem.201490084

  4. Corrigendum

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. You have free access to this content
      Corrigendum: Aromatic Superhalogens (page 6213)

      Brandon Z. Child, Dr. Santanab Giri, Dr. Scott Gronert and Dr. Puru Jena

      Article first published online: 14 MAY 2014 | DOI: 10.1002/chem.201400437

      This article corrects:

      Aromatic Superhalogens

      Vol. 20, Issue 16, 4736–4745, Article first published online: 18 MAR 2014

  5. News

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
  6. Essay

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. Bond Order

      The Nature of the Fourth Bond in the Ground State of C2: The Quadruple Bond Conundrum (pages 6220–6232)

      Dr. David Danovich, Prof. Philippe C. Hiberty, Prof. Wei Wu, Prof. Henry S. Rzepa and Prof. Sason Shaik

      Article first published online: 29 APR 2014 | DOI: 10.1002/chem.201400356

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      The glass ceiling of triple bonding! This work provides an overview on the bonding conundrum in C2 and on the recent discussions regarding the proposal that it possesses a quadruple bond. It is shown that C2 is quadruply bonded by all reasonable measures, which include analyses of the impact of the 4th bond on the force constant, bond length, and stretching frequency, and a thermochemical derivation of the strength of the 4th bond. Thus C2 and its isoelectronic first-row diatomic species break the glass ceiling of triple bonding.

  7. Communications

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. Supramolecular Flow Chemistry

      Two-Dimensional Assembly Based on Flow Supramolecular Chemistry: Kinetic Control of Molecular Interactions Under Solvent Diffusion (pages 6234–6240)

      Prof. Dr. Munenori Numata and Tomohiro Kozawa

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201305006

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      Go with the flow: Self-assembly of porphyrin molecules can be controlled kinetically through a programmed solvent diffusion process in designed microflow spaces (see figure). Temporal solvent structures generated in the microflow were successfully transcribed into molecular architectures.

    2. Photosensitizers

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      A Glutathione-Activated Phthalocyanine-Based Photosensitizer for Photodynamic Therapy (pages 6241–6245)

      Dr. Hui He, Prof. Pui-Chi Lo and Prof. Dennis K. P. Ng

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400001

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      Light therapy: Fluorescence emission and reactive oxygen species generation are greatly enhanced in a molecular phthalocyanine-quencher system upon interaction with glutathione (see figure). Its activation has also been demonstrated in vivo.

    3. Lipid Self-Assembly

      Vesicle Structures from Bolaamphiphilic Biosurfactants: Experimental and Molecular Dynamics Simulation Studies on the Effect of Unsaturation on Sophorolipid Self-Assemblies (pages 6246–6250)

      Prabhu Dhasaiyan, Prithvi Raj Pandey, Nikunjkumar Visaveliya, Dr. Sudip Roy and Dr. B. L. V. Prasad

      Article first published online: 23 APR 2014 | DOI: 10.1002/chem.201304719

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      Giant vesicles from sophorolipids: Linolenic acid sophorolipids (LNSLs), a class of bolaamphiphilic glycolipids, self-assemble to form giant-vesicle-like structures. It is established that the walls of these vesicles consist of four molecules of LNSLs arranged in a tail–head–head–tail fashion, where the “tail” refers to the carboxylic acid group and the “head” to the sugar moieties.

    4. Synthesis

      Manganese(IV)-Mediated Hydroperoxyarylation of Alkenes with Aryl Hydrazines and Dioxygen from Air (pages 6251–6255)

      Stephanie Kindt, Dr. Hannelore Jasch and Prof. Dr. Markus R. Heinrich

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400064

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      The introduction of oxygen into a Meerwein arylation has been achieved with dioxygen from air as an oxygen-centered radical scavenger. The slow addition of the aryl hydrazine is key to aryl radical formation through oxidation with manganese dioxide; whereby, hydroperoxides were obtained from activated as well as non-activated alkenes.

    5. Paramagnetic NMR

      A Two-Armed Lanthanoid-Chelating Paramagnetic NMR Probe Linked to Proteins via Thioether Linkages (pages 6256–6258)

      Dr. Wei-Min Liu, Dr. Simon P. Skinner, Dr. Monika Timmer, Anneloes Blok, Dr. Mathias A. S. Hass, Dr. Dmitri V. Filippov, Dr. Mark Overhand and Prof. Dr. Marcellus Ubbink

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400257

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      A two-armed probe: α-Bromoacetamides are functionalised in a DOTA-like structure to form a new double-arm paramagnetic probe (see structure). This probe can be site-specifically attached to proteins and the ligation products are stable under reducing conditions. This probe creates a new avenue for studying biomolecules using paramagnetic NMR spectroscopy.

    6. Synthetic Methods

      Synthesis and Elaboration of All-cis-1,2,4,5-Tetrafluoro-3-Phenylcyclohexane: A Polar Cyclohexane Motif (pages 6259–6263)

      Dr. Alastair J. Durie, Dr. Tomoya Fujiwara, Rodrigo Cormanich, Prof. Michael Bühl, Prof. Alexandra M. Z. Slawin and Prof. David O'Hagan

      Article first published online: 16 APR 2014 | DOI: 10.1002/chem.201400354

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      A stereocontrolled synthesis of all-cis-1,2,4,5-tetrafluoro-3-phenylcyclohexane is developed as the first functionalised example of this polar cyclohexane motif. The dipolar nature of the cyclohexane ring is explored and the aryl ring is elaborated in different ways to demonstrate its versatility as a molecular building block (see figure).

    7. Heterogeneous Catalysis

      Sustainable Heterogeneous Platinum Catalyst for Direct Methylation of Secondary Amines by Carbon Dioxide and Hydrogen (pages 6264–6267)

      Dr. Kenichi Kon, Dr. S. M. A. Hakim Siddiki, Wataru Onodera and Dr. Ken-ichi Shimizu

      Article first published online: 23 APR 2014 | DOI: 10.1002/chem.201400332

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      Over and over: A heterogeneous Pt catalyst for direct methylation of aromatic amines by CO2 and H2 with high reusability and an order of magnitude higher turnover number than previous catalysts has been demonstrated (see scheme).

    8. Aromatic Interactions

      Stabilisation of 2,6-Diarylpyridinium Cation by Through-Space Polar–π Interactions (pages 6268–6271)

      Joan Simó Padial, Dr. René de Gelder, Dr. Célia Fonseca Guerra, Prof. Dr. F. Matthias Bickelhaupt and Dr. Jasmin Mecinović

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201304462

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      The through-space polar–π interactions between pyridinium ion and the adjacent aromatic rings in 2,6-diarylpyridines affect the pKa values. Hammett analysis illustrates that the basicity of pyridines correlates well with the sigma values of the substituents at the para position of the flanking aryl rings (see figure).

    9. Mixed-Valent Compounds

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      Stable Mixed-Valent Radicals from Platinum(II) Complexes of a Bis(dioxolene) Ligand (pages 6272–6276)

      Dr. Jonathan J. Loughrey, Dr. Stephen Sproules, Prof. Eric J. L. McInnes, Prof. Michaele J. Hardie and Prof. Malcolm A. Halcrow

      Article first published online: 2 FEB 2014 | DOI: 10.1002/chem.201304848

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      Electron hopping: Diplatinum complexes, such as the one shown here, are readily oxidized to mixed-valent catechol/semiquinone radical species, some of which can be crystallized at room temperature. The dioxolene rings in the radical products are moderately strongly coupled by EPR and UV/Vis/NIR spectroscopies, despite being separated by saturated methylene spacers.

    10. Catalyst Reactivation

      UV-Assisted Removal of Inactive Peroxide Species for Sustained Epoxidation of Cyclooctene on Anatase TiO2 (pages 6277–6282)

      Dr. Changjun Yang, Dr. Xianjun Lang, Prof. Wanhong Ma, Prof. Chuncheng Chen, Prof. Hongwei Ji and Prof. Jincai Zhao

      Article first published online: 24 APR 2014 | DOI: 10.1002/chem.201400258

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      Light cleaning: In the epoxidation of cyclooctene with H2O2 on anatase TiO2, inert Ti-η2-peroxide species are produced and accumulate on the surface of TiO2, preventing sustainable epoxidation. UV-assisted clean-up of these inert surface species regenerates the active sites on TiO2 to resume the epoxidation process.

    11. Biomimetics

      Synthesis and Characterization of NiIIIN3S2 Complexes as Active Site Models for the Oxidized Form of Nickel Superoxide Dismutase (pages 6283–6286)

      Chien-Wei Chiang, Yun-Li Chu, Hong-Ling Chen, Ting-Shen Kuo and Prof. Way-Zen Lee

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201304543

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      SOD's law: Complexes [Ni(H2BARTPP)](ClO4)2 (R=Ph or iPr; see structure), supported by a pentadentate ligand H2BARTPP, were synthesized and oxidized to form NiIII species having a N3S2 coordination environment to mimic the active site of the oxidized form of NiSOD (NiSODox). DFT calculations reveal that the oxidized compound has an unpaired electron primarily located in the dinline image orbital of the NiIII center.

  8. Full Papers

    1. Top of page
    2. Cover Pictures
    3. Cover Profile
    4. Graphical Abstract
    5. Corrigendum
    6. News
    7. Essay
    8. Communications
    9. Full Papers
    1. Ionic Conductors

      Analysis of Dopant Atom Distribution and Quantification of Oxygen Vacancies on Individual Gd-Doped CeO2 Nanocrystals (pages 6288–6293)

      Dr. Daniel G. Stroppa, Prof. Cleocir J. Dalmaschio, Dr. Lothar Houben, Dr. Juri Barthel, Prof. Luciano A. Montoro, Prof. Edson R. Leite and Dr. Antonio J. Ramirez

      Article first published online: 14 MAY 2014 | DOI: 10.1002/chem.201400412

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      High-spatial-resolution electron energy-loss spectroscopy is applied to map the element distribution in CeO2 and Gd:CeO2 nanocrystals. An uneven Gd dopant distribution and an abnormal increase of O vacancies were detected on the doped system (see figure). These findings indicate a possible direction to enhance transport properties in ionic conductors.

    2. Electrochemistry

      Uniform Decoration of Vanadium Oxide Nanocrystals on Reduced Graphene-Oxide Balls by an Aerosol Process for Lithium-Ion Battery Cathode Material (pages 6294–6299)

      Seung Ho Choi and Prof. Yun Chan Kang

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201400134

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      Graphene-based ball: V2O5-decorated reduced-graphene balls and macroporous V2O5 powders were prepared by a spray-pyrolysis process. The V2O5-decorated reduced-graphene balls had higher initial charge and discharge capacities and better cycling and rate performances than the macroporous V2O5 powders (see figure).

    3. Phenothiazine-Based Dyes

      Molecular Engineering of Simple Phenothiazine-Based Dyes To Modulate Dye Aggregation, Charge Recombination, and Dye Regeneration in Highly Efficient Dye-Sensitized Solar Cells (pages 6300–6308)

      Dr. Yong Hua, Shuai Chang, Jian He, Caishun Zhang, Prof. Jianzhang Zhao, Dr. Tao Chen, Prof. Wai-Yeung Wong, Prof. Wai-Kwok Wong and Dr. Xunjin Zhu

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201304897

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      Shape sensitivity: A solar cell sensitized with a phenothiazine-based dye containing a bithiophene unit (TTP) as the electron donor has a high power conversion efficiency (PCE) of 7.87 %, whereas a related dye containing an ethylenedioxythiophene and thiophene unit (ETP) and that containing an ethylenedioxythiophene dimer (EEP) have much lower PCE values. The photovoltaic performance is sensitive to structural modifications (see picture).

    4. Pi Interactions

      Synthesis and Solid-State Structures of a Tetrathiafulvalene-Conjugated Bistetracene (pages 6309–6314)

      Masataka Yamashita, Dr. Daiki Kuzuhara, Prof. Dr. Naoki Aratani and Prof. Dr. Hiroko Yamada

      Article first published online: 11 APR 2014 | DOI: 10.1002/chem.201304997

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      High hole mobility: A tetrathiafulvalene (TTF)-conjugated bistetracene was synthesized and the molecular electronic structures, as well as the packing structures were characterized. A variety of crystal packing arrangements could be originated from the soft π linkage of TTF unit. The π-stacking structure affords large intermolecular orbital coupling of HOMOs, which is quite beneficial to enhance the charge-carrier mobility (see figure).

    5. Boron-Mediated Synthesis

      Designed Single-Step Synthesis, Structure, and Derivative Textural Properties of Well-Ordered Layered Penta-coordinate Silicon Alcoholate Complexes (pages 6315–6323)

      Dr. Xiansen Li, Dr. Vladimir K. Michaelis , Ta-Chung Ong , Dr. Stacey J. Smith, Prof. Robert G. Griffin  and Prof. Evelyn N. Wang

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400379

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      Mind the van der Waals gap! Well-ordered layered penta-coordinate silicon alcoholate was prepared by a new single-step transesterification mechanism (see scheme), the structure of which was elucidated with one single crystal directly acquired by a novel boron-mediated synthetic route; these complexes are very effective precursors for the facile preparation of high-surface-area amorphous silica powders.

    6. Metal-Free Catalysis

      Hybrid Nanocarbon as a Catalyst for Direct Dehydrogenation of Propane: Formation of an Active and Selective Core–Shell sp2/sp3 Nanocomposite Structure (pages 6324–6331)

      Dr. Rui Wang, Xiaoyan Sun, Dr. Bingsen Zhang, Dr. Xiaoying Sun and Prof. Dangsheng Su

      Article first published online: 16 APR 2014 | DOI: 10.1002/chem.201400018

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      Essential imperfections: The evolution of the surface state and catalytic performance of hybrid nanocarbon produced by high-temperature annealing of nanodiamond was investigated. The core–shell sp2/sp3 composite, comprised of a diamond core and a defective, curved graphene shell, exhibits superior catalytic activity that depends strongly on the high concentration of structural defects and high chemical reactivity of ketone-type groups (see figure).

    7. NMR Spectroscopy

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      Fast Proton Exchange in Histidine: Measurement of Rate Constants through Indirect Detection by NMR Spectroscopy (pages 6332–6338)

      Akansha Ashvani Sehgal, Dr. Luminita Duma, Prof. Geoffrey Bodenhausen and Dr. Philippe Pelupessy

      Article first published online: 9 APR 2014 | DOI: 10.1002/chem.201304992

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      Seeking the invisible: The protons attached to the N atoms of histidine in an aqueous solution have hitherto escaped detection owing to the very fast exchange of these protons with the solvent. The exchange rate constants along with the one-bond scalar couplings and chemical shifts of these elusive protons have been determined for a pH range in which the three N nuclei are protonated (see figure).

    8. Chemosensors

      Highly Selective Detection of Nerve-Agent Simulants with BODIPY Dyes (pages 6339–6347)

      Andrea Barba-Bon, Prof. Ana M. Costero, Prof. Salvador Gil, Prof. Anthony Harriman and Dr. Félix Sancenón

      Article first published online: 3 APR 2014 | DOI: 10.1002/chem.201304475

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      For all to see: Two new boron dipyrromethene (BODIPY) derivatives have been synthesized and used as naked-eye colorimetric and fluorescence probes for the detection of nerve-agent simulants (see picture; DCNP=diethylcyanophosphonate, DFP=diisopropylfluorophosphate). Selectivity to nerve-agent simulants versus acidic media has been achieved. Two portable chemosensor kits have been used in real-time monitoring.

    9. Prebiotic Chemistry

      Unearthing the Mechanism of Prebiotic Nitrile Bond Reduction in Hydrogen Cyanide through a Curious Association of Two Molecular Radical Anions (pages 6348–6357)

      Ambar Banerjee, Gaurab Ganguly, Ravi Tripathi, Dr. Nisanth N. Nair and Dr. Ankan Paul

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201304627

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      Where like attracts like: Theoretical studies show that the prebiotic reduction of the nitrile bond in HCN is initiated through the formation of a dipole anion (see figure, PCET=proton-coupled electron transfer). This is followed by association of two doublet [HCN] radical anions leading to the formation of a transient singlet dianion species. Subsequently, a proton-coupled electron transfer occurs within the dianion electron trap effecting the reduction of HCN.

    10. Molecular Motors

      4,4′-Bipyridine as a Unidirectional Switching Unit for a Molecular Pushing Motor (pages 6358–6365)

      Christine Kallweit, Prof. Dr. Gebhard Haberhauer and Sascha Woitschetzki

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201304166

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      Motor drive: The combination of the intrinsic chirality of a 4,4′-bipyridine with a metal-ion-induced switching principle leads to a metal-ion-induced chirality switch that can also be used as a basic unit for a molecular pushing motor. Rotation around the C[BOND]C bond axis of the bipyridine, which is linked to a cyclic imidazole peptide, leads to switching between P and M isomers (see scheme).

    11. Graphene

      Cytotoxicity Profile of Highly Hydrogenated Graphene (pages 6366–6373)

      Elaine Lay Khim Chng, Prof. Zdeněk Sofer and Prof. Martin Pumera

      Article first published online: 7 APR 2014 | DOI: 10.1002/chem.201304911

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      Toxic avenger: Highly hydrogenated graphene (HHG) was discovered to be cytotoxic towards A549 cells across a wide range of concentrations tested, and at the same time it is much more cytotoxic than graphene oxide (see figure). It is hypothesized that the hydrophobic nature as a result of the saturated carbon bonds in HHG plays a key role in its cytotoxicity.

    12. Organic Synthesis

      Oxygenated Metabolites of n-3 Polyunsaturated Fatty Acids as Potential Oxidative Stress Biomarkers: Total Synthesis of 8-F3t-IsoP, 10-F4t-NeuroP and [D4]-10-F4t-NeuroP (pages 6374–6380)

      Dr. Alexandre Guy, Dr. Camille Oger, Dr. Johannes Heppekausen, Dr. Cinzia Signorini, Claudio De Felice, Prof. Alois Fürstner, Dr. Thierry Durand and Dr. Jean-Marie Galano

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400380

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      Three for the price of one! Two strategies, Caruso coupling or ring-closing alkyne metathesis (RCAM), enabled the synthesis of 8-F3t-IsoP and 10-F4t-NeuroP and its deuterated derivative from acetylenic intermediate A (see scheme). Such compounds represent potential biomarkers of neuronal oxidative stress.

    13. VOC Capture

      Enhanced Formaldehyde-Vapor Adsorption Capacity of Polymeric Amine-Incorporated Aminosilicas (pages 6381–6390)

      Dr. Akihiro Nomura and Prof. Dr. Christopher W. Jones

      Article first published online: 3 APR 2014 | DOI: 10.1002/chem.201304954

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      Volatile organic compounds: Polymeric amine-incorporated porous silicas (aminosilicas) adsorb toxic airborne formaldehyde. The adsorption capacity increases along with the amine loading until the polymeric amines completely fill the silica pores, achieving four times higher adsorption capacity than the previous aminosilicas constructed from aminosilanes (see figure).

    14. Helical Structures

      Synthesis and Structures of N-Alkyl-1,13-dimethoxychromeno- [2,3,4-kl]acridinium Salts: The Missing Azaoxa[4]helicenium (pages 6391–6400)

      Dr. Thomas Just Sørensen, Dr. Anders Ø. Madsen and Prof. Dr. Bo W. Laursen

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400082

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      Last but not least! The last of the azaoxa[4]helicenium ions has been synthesised and studied in detail. It is found to be a potent red dye, a stable cation and a structure that can be perturbed depending on the nature of the substituent on the nitrogen atom (see figure).

    15. Energetic Materials

      Dense Energetic Nitraminofurazanes (pages 6401–6411)

      Dennis Fischer, Prof. Dr. Thomas M. Klapötke, Marius Reymann and Dr. Jörg Stierstorfer

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201400362

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      Safety, performance, and practicality are the key demands on new energetic materials. More than 40 new nitraminobifurazanes were synthesized and characterized with respect to potential energetic use in explosives, propellants and pyrotechnics (see figure).

    16. Host–Guest Systems

      Synthesis and Electronic Properties of 1,2-Hemisquarimines and Their Encapsulation in a Cucurbit[7]uril Host (pages 6412–6420)

      Christian C. De Filippo, Dr. Hao Tang, Luca Ravotto, Dr. Giacomo Bergamini, Dr. Patrizio Salice, Dr. Miriam Mba, Prof. Paola Ceroni, Prof. Elena Galoppini and Prof. Michele Maggini

      Article first published online: 3 APR 2014 | DOI: 10.1002/chem.201400039

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      Be square! 1,2-Hemiquarimines (see figure), with one unsubstituted or derivatized phenylimine group, can be synthesized from the corresponding 1,2-squaraine. The interesting photophysical and redox characteristics of these dyes make them useful candidates for charge transfer and sensitization studies.

    17. CO Binding

      The Coordination Chemistry of Pentafluorophenylphosphino Pincer Ligands to Platinum and Palladium (pages 6421–6432)

      Dr. Bradley G. Anderson and Prof. John L. Spencer

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201304398

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      Back and forth: The electron-poor P(C6F5)2 donor group was incorporated into the PCP pincer ligand motif to generate a range of poorly donating ligands. Palladium carbonyl complexes of these ligands demonstrated the ability to reversibly bind CO, with the ease of CO displacement increasing with increasing ν(CO) values (see figure). These ligands also displayed a reluctance to undergo metallation on Pt or Pd, which led to the formation of rare examples of cis,trans-dimers.

    18. Photophysics

      A Theoretical Investigation into the Luminescent Properties of d8-Transition-Metal Complexes with Tetradentate Schiff Base Ligands (pages 6433–6443)

      Dr. Glenna So Ming Tong, Dr. Pui Keong Chow, Dr. Wai-Pong To, Prof. Wai-Ming Kwok and Prof. Chi-Ming Che

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201304375

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      Low, but not ignored: Low-frequency normal modes are usually not considered to be important in determining nonradiative decay rates because they are not effective energy acceptors. The importance of these low-frequency normal modes in estimating knr by using a convolution approach is highlighted (see figure).

    19. Carbohydrates

      Two-Step Functionalization of Oligosaccharides Using Glycosyl Iodide and Trimethylene Oxide and Its Applications to Multivalent Glycoconjugates (pages 6444–6454)

      Hsiao-Wu Hsieh, Dr. Ryan A. Davis, Jessica A. Hoch and Prof. Dr. Jacquelyn Gervay-Hague

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201400024

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      A two-step methodology for the conjugation of per-O-acetylated oligosaccharides to functionalized linkers, which can be used for various displays, is described. Oligosaccharides were converted to glycosyl iodides and activated with I2, forming reactive donors, which were subsequently trapped with trimethylene oxide (TMO), forming iodopropyl conjugates. Conversion into the corresponding azide followed by copper-catalyzed azide–alkyne cycloaddition afforded multivalent glycoconjugates of Gb3 for further investigation as anti-cancer therapeutics (see scheme).

    20. Sensors

      A Highly Fluorescent Metallosalalen-Based Chiral Cage for Enantioselective Recognition and Sensing (pages 6455–6461)

      Jinqiao Dong, Yanfang Zhou, Fangwei Zhang and Prof. Yong Cui

      Article first published online: 7 APR 2014 | DOI: 10.1002/chem.201304606

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      Cage-based chiral sensor: A highly fluorescent coordination cage [Zn8L4I8] can be prepared from enantiopure pyridyl-functionalized metallosalalen units (L). The cage has an amphiphilic helical cavity decorated with chiral NH functionalities and supramolecular interactions generate a 3D polycage network interconnected by pentahedral cages formed by adjacent pentamers (see graphic). The fluorescence of the cage is greatly enhanced either in solution or in the solid state in the presence of enantiomeric saccharides or amines, respectively, with significant enantioselectivity factors.

    21. Self-Assembly

      Influence of the Alkyl Chain Length on the Self-Assembly of Amphiphilic Iron Complexes: An Analysis of X-ray Structures (pages 6462–6473)

      Stephan Schlamp, Dr. Peter Thoma and Prof. Dr. Birgit Weber

      Article first published online: 7 APR 2014 | DOI: 10.1002/chem.201304653

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      Looking ahead: Based on the X-ray structures of 15 amphiphilic iron complexes the self-assembly parameter, sap, is introduced, providing the ability to predict when lipid-layer-like structures are observed (see figure). This was used for the crystallisation of a complex with two C22 alkyl chains and can also be applied to other systems.

    22. Confined Nanoreactors

      Assembly of a Nanoreactor System with Confined Magnetite Core and Shell for Enhanced Fenton-Like Catalysis (pages 6474–6481)

      Dr. Tao Zeng, Dr. Xiaole Zhang, Saihua Wang, Yurong Ma, Hongyun Niu and Prof. Yaqi Cai

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201304221

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      An unconventional shell: A novel yolk–shell nanostructure in which both the core and the shell are composed of magnetite (designated as yolk-like Fe3O4@Fe3O4/C) functions as a nanoreactor for the Fenton-like reaction, displaying enhanced catalytic activity compared with conventional solid catalysts (see figure).

    23. Ionic Liquids

      A Roadmap to Uranium Ionic Liquids: Anti-Crystal Engineering (pages 6482–6493)

      Damla Yaprak, Dr. Eike T. Spielberg, Dr. Tobias Bäcker, Mark Richter, Dr. Bert Mallick, Prof. Dr. Axel Klein and Prof. Dr. Anja-Verena Mudring

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201303333

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      IL effects: Eight tris(N,N-dialkyldithiocarbamato)uranylates (see scheme) are synthesized as salts of 1-butyl-3-methylimidazolium to study the impact of structural variations on the thermal behavior. Room-temperature ionic liquids are obtained with highly asymmetric ligands. Combining low melting points, stable complex formation, and hydrophobicity, these materials qualify for nuclear fuel purification and recovery.

    24. Fluorophores

      Azacyanines of the Pyrrolopyrrole Series (pages 6494–6504)

      Timo Marks, Prof. Dr. Ewald Daltrozzo and Prof. Dr. Andreas Zumbusch

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201304235

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      Brightly shining red: The synthesis of pyrrolopyrrole–azacyanines as a new class of long-wavelength-absorbing fluorophores (see figure) is discussed. The boron complexes are especially thermally and photochemically stable fluorescent dyes with strong absorption and fluorescence emissions around 700 nm. The photophysics of the compounds are also discussed and conclusions are drawn about the correlation between molecular structure and optical properties.

    25. Organic Synthesis

      You have full text access to this OnlineOpen article
      Carbamoyl Radical-Mediated Synthesis and Semipinacol Rearrangement of β-Lactam Diols (pages 6505–6517)

      Dr. Marie Betou, Dr. Louise Male, Prof. Jonathan W. Steed and Dr. Richard S. Grainger

      Article first published online: 7 APR 2014 | DOI: 10.1002/chem.201304982

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      Let the phosphorane take the strain: Cyclic activation is key to achieving high yields in the semipinacol rearrangement of fused β-lactam diols to keto-bridged bicyclic amides, with cyclic phosphoranes proving particularly effective. Functionalized β-lactams are readily obtained through a tandem 4-exo-trig carbamoyl radical cyclization, with the dithiocarbamate group providing the synthetic handle for diol incorporation (see scheme).

    26. Electrochemistry

      Ruthenoarenes versus Phenol Derivatives as Axial Linkers for Subporphyrazine Dimers and Trimers (pages 6518–6525)

      Dr. Esmeralda Caballero, Dr. Carlos Romero-Nieto, Volker Strauß, Dr. M. Salomé Rodríguez-Morgade, Prof. Dirk M. Guldi, Prof. Jonathan L. Sessler and Prof. Tomás Torres

      Article first published online: 7 APR 2014 | DOI: 10.1002/chem.201304622

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      Making a connection: Cyclopentadienylruthenium π-coordination to the axial phenolic substituent that functions to link individual subporphyrazine (SubPz) subunits in dimers and trimers serves to modify the interactions between the macrocyclic constituents (see figure). The ground and excited states of the SubPz dimers and trimers of this study reflect the nature of the bridging spacer, with the extent of inter-subunit coupling being relatively increased in the case of the ruthenoarene bridged systems.

    27. Asymmetric Catalysis

      Ureidopeptide-Based Brønsted Bases: Design, Synthesis and Application to the Catalytic Enantioselective Synthesis of β-Amino Nitriles from (Arylsulfonyl)acetonitriles (pages 6526–6531)

      Dr. Saioa Diosdado, Dr. Rosa López and Prof. Dr. Claudio Palomo

      Article first published online: 15 APR 2014 | DOI: 10.1002/chem.201304877

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      Learning from peptides: A concise route for the catalytic enantioselective synthesis of β-amino nitriles has been achieved by using ureidopeptide-based Brønsted bases as catalysts in the Mannich reaction of N-Boc imines and (arylsulfonyl)acetonitriles (see scheme; Boc=tert-butoxycarbonyl, napht=naphthyl, TMS=trimethylsilyl).

    28. C[BOND]H Activation

      Substrate-Dependent H/D Kinetic Isotope Effects and the Role of the Di(μ-oxo)diiron(IV) Core in Soluble Methane Monooxygenase: A Theoretical Study (pages 6532–6541)

      Binh Khanh Mai and Yongho Kim

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201303466

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      Very large kinetic isotope effects (KIEs) were observed for the H-transfer of CH4 and CH3CN in the C[BOND]H activation by soluble methane monooxygenase; however, a relatively small KIE was observed for CH3NO2. Variational transition-state-theory calculations including tunneling revealed that the diverse KIE values originated mostly from substrate-dependent tunneling (see figure). The H-transfer dynamics and the role of the diiron core depend on the substrates.

    29. Dehydrogenation

      Metal–Ligand Cooperation on a Diruthenium Platform: Selective Imine Formation through Acceptorless Dehydrogenative Coupling of Alcohols with Amines (pages 6542–6551)

      Biswajit Saha, S. M. Wahidur Rahaman, Prosenjit Daw, Gargi Sengupta and Prof. Jitendra K. Bera

      Article first published online: 8 APR 2014 | DOI: 10.1002/chem.201304403

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      Ligand lends a hand: Metal–hydroxy/hydroxide and metal–metal cooperation is demonstrated for acceptorless dehydrogenation of alcohols to give aldehydes. The ligand architecture ensures rapid extrusion of the aldehyde from the metal core, resulting in the formation of the corresponding imine as the sole coupled product with amines (see scheme; DABCO=1,4-diazabicyclo[2.2.2]octane).

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