Chemistry - A European Journal

Cover image for Vol. 12 Issue 8

March 1, 2006

Volume 12, Issue 8

Pages 2111–2395

    1. Cover Picture: Self-Assembled, Kinetically Locked, RuII-Based Metallomacrocyles: Physical, Structural, and Modeling Studies (Chem. Eur. J. 8/2006) (page 2111)

      Paul de Wolf, Phil Waywell, Matt Hanson, Sarah L. Heath, Anthony J. H. M. Meijer, Simon J. Teat and Jim A. Thomas

      Version of Record online: 21 FEB 2006 | DOI: 10.1002/chem.200690023

      A luminescent sensor for anions is described by J. A. Thomas, S. L. Heath, A. J. H. M. Meijer et al. on page 2188 ff. The sensor is composed of a heterometallic self-assembled macrocycle that has a palmate anion-binding pocket. Host–guest studies carried out in organic solvents reveal that the macrocycle functions as a luminescent sensor for anions, and the binding affinity and luminescent modulation are dependent on the structural nature and charge of the guest anion.

    2. From Dysfunction to Bis-function: On the Design and Applications of Functionalised Ionic Liquids (pages 2122–2130)

      Zhaofu Fei, Tilmann J. Geldbach, Dongbin Zhao and Paul J. Dyson

      Version of Record online: 6 SEP 2005 | DOI: 10.1002/chem.200500581

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      The pairing of functional cations and anions to form ionic liquids is unlimited and the potential of such ionic liquids has been recognised in a wide range of applications. For example, a hydroxy-functionalised imidazolium ionic liquid can be utilised for the synthesis of a pentapeptide, as illustrated here.

    3. Facile “Green” Synthesis, Characterization, and Catalytic Function of β-D-Glucose-Stabilized Au Nanocrystals (pages 2131–2138)

      Juncheng Liu, Gaowu Qin, Poovathinthodiyil Raveendran and Yukata Ikushima

      Version of Record online: 16 DEC 2005 | DOI: 10.1002/chem.200500925

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      Sugar-coated gold: Gold nanocrystals with an average diameter of 8.2 nm (SD=2.3 nm) could be synthesized and stabilized in an aqueous β-D-glucose dispersion under ambient conditions (see figure), and the as-prepared Au nanocrystals serve as an effective catalyst to activate the reduction of 4-nitrophenol in the presence of NaBH4.

      Corrected by:

      Corrigendum: Facile “Green” Synthesis, Characterization, and Catalytic Function of β-D-Glucose-Stabilized Au Nanocrystals

      Vol. 13, Issue 15, 4133, Version of Record online: 4 MAY 2007

    4. Orientational Control of Guest Molecules in an Organic Intercalation System by Host Polymer Tacticity (pages 2139–2146)

      Shinya Oshita and Akikazu Matsumoto

      Version of Record online: 7 FEB 2006 | DOI: 10.1002/chem.200500771

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      An organic intercalation system consisting of stereoregular poly(muconic acid)s and n-alkylamines as the host and guest, respectively, was investigated. The orientation of the guest molecules can be controlled by the stereoregularity of poly(muconic acid)s. The packing structure and conformation of the introduced alkylamines were determined by X-ray diffractions as well as IR and Raman spectroscopy (see figure).

    5. Co/CNF Catalysts Tailored by Controlling the Deposition of Metal Colloids onto CNFs: Preparation and Catalytic Properties (pages 2147–2151)

      Jieshan Qiu, Hongzhe Zhang, Changhai Liang, Jiawei Li and Zongbin Zhao

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/chem.200500960

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      Carbon-nanofiber-supported Co nanocomposites were prepared by means of a modified ethylene glycol (EG) process, in which the Co salts are reduced in EG and are subsequently deposited onto carbon nanofibers (see scheme).

    6. Versatile Coordination Chemistry towards Multifunctional Carbon Nanotube Nanohybrids (pages 2152–2161)

      Dirk M. Guldi, G. M. Aminur Rahman, Shuhui Qin, Maxim Tchoul, Warren T. Ford, Massimo Marcaccio, Demis Paolucci, Francesco Paolucci, Stéphane Campidelli and Maurizio Prato

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/chem.200500933

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      Grafted nanotubes: Complex formation of single-walled nanotubes grafted with poly(4-vinylpyridine) and zinc tetraphenylporphyrin through coordination provides a route to versatile donor–acceptor ensembles (see picture). Photoexcitation of the porphyrin chromophores is followed by a rapid and efficient intraensemble charge separation to generate a charge-separated state with a lifetime of the order of microseconds.

    7. Anchoring Dyes into Multidimensional Large-Pore Zeolites: A Prospective Use as Chromogenic Sensing Materials (pages 2162–2170)

      María Comes, M. Dolores Marcos, Ramón Martínez-Máñez, M. Carmen Millán, José Vicente Ros-Lis, Félix Sancenón, Juan Soto and Luis A. Villaescusa

      Version of Record online: 23 DEC 2005 | DOI: 10.1002/chem.200500932

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      A versatile protocol for anchoring dyes into the pores of multidimensional zeolites has been developed based on the inclusion of organic dye precursors in the synthesis gel. These dye–zeolite hosts are promising new sensor materials for the selective chromogenic sensing that discriminates by size/polarity of closely related guests through new solid-state supramolecular chemistry concepts (see picture).

    8. S,O-Acetals as Novel “Chiral Aldehyde” Equivalents (pages 2171–2187)

      Barry M. Trost, Matthew L. Crawley and Chul Bom Lee

      Version of Record online: 10 JAN 2006 | DOI: 10.1002/chem.200500919

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      High enantiomeric excess and single regioisomers of α-acetoxysulfones were obtained in AAA reactions of allylic geminal dicarboxylates with sodium benzenesulfinate (see scheme). The directing ability of this novel functional group was highlighted by a series of dihydroxylations.

    9. Self-Assembled, Kinetically Locked, RuII-Based Metallomacrocycles: Physical, Structural, and Modeling Studies (pages 2188–2195)

      Paul de Wolf, Phil Waywell, Matt Hanson, Sarah L. Heath, Anthony J. H. M. Meijer, Simon J. Teat and Jim A. Thomas

      Version of Record online: 19 DEC 2005 | DOI: 10.1002/chem.200500623

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      Playing jacks with anions: A hexafluorophosphate anion nestles in the palmate guest cavity (shown here) of a heterometallic self-assembled macrocyclic host that functions as a luminescent sensor for anions.

    10. Cyclic Quaternary Ammonium Ionic Liquids with Perfluoroalkyltrifluoroborates: Synthesis, Characterization, and Properties (pages 2196–2212)

      Zhi-Bin Zhou, Hajime Matsumoto and Kuniaki Tatsumi

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/chem.200500930

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      Cyclic quaternary ammonium ionic liquids with perfluoroalkyltrifluoroborates ([RFBF3], RF=CF3, C2F5, nC3F7, nC4F9; see picture) were synthesized and characterized. Their properties, such as phase transitions, thermal stability, density, viscosity, conductivity, and electrochemical windows, are significantly affected by the identity of the cation and anion, the variation of the side chain of the cation, and the change of the length of perfluoroalkyl (RF) in [RFBF3].

    11. Kinetic Energy Release of C70+ and Its Endohedral Cation N@C70+: Activation Energy for N Extrusion (pages 2213–2221)

      Baopeng Cao, Tikva Peres, Chava Lifshitz, R. James Cross and Martin Saunders

      Version of Record online: 13 JAN 2006 | DOI: 10.1002/chem.200501119

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      Extrusion of the endohedral N atom rather than loss of a C2 unit occurs in the unimolecular dissociation of N@C70+ (left) according to high-resolution mass-analyzed ion kinetic energy (MIKE) spectrometric data. The activation energy for N extrusion was determined from the kinetic energy release (KER), which in turn was obtained from the metastable-ion peak shape (right and inset, respectively), and the results support the proposal that the N atom escapes from the cage via an aza-bridged intermediate.

    12. Isostructurality, Polymorphism and Mechanical Properties of Some Hexahalogenated Benzenes: The Nature of Halogen⋅⋅⋅Halogen Interactions (pages 2222–2234)

      C. Malla Reddy, Michael T. Kirchner, Ravi C. Gundakaram, K. Anantha Padmanabhan and Gautam R. Desiraju

      Version of Record online: 29 DEC 2005 | DOI: 10.1002/chem.200500983

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      Crystals of hexahalogenated benzenes undergo bending and shearing deformations (see figure), which enable an evaluation of the halogen⋅⋅⋅halogen interactions in these solids. It was found that these interactions in the monoclinic group are nonspecific, whereas in the triclinic group some interactions are anisotropic, chemically specific and crystal-structure directing.

    13. Both Spacer Length and Parity Influence the Thermal and Light-Induced Properties of Iron(II) α,ω-Bis(tetrazole-1-yl)alkane Coordination Polymers (pages 2235–2243)

      Alina Absmeier, Matthias Bartel, Chiara Carbonera, Guy N. L. Jameson, Peter Weinberger, Andrea Caneschi, Kurt Mereiter, Jean-François Létard and Wolfgang Linert

      Version of Record online: 9 DEC 2005 | DOI: 10.1002/chem.200500941

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      A question of parity and the number of carbon atoms in the alkane spacers are the keys to the thermal spin-crossover temperature, T1/2, of [μ-tris-{1,n-bis(tetrazol-1-yl)alkane-N4,N4′}iron(II)] bis(perchlorate) coordination polymers ([Fe(nditz)3](ClO4)2]; n=4–9; see picture).

    14. Pyrazole Complexes as Anion Receptors (pages 2244–2251)

      Sonia Nieto, Julio Pérez, Lucía Riera, Víctor Riera and Daniel Miguel

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/chem.200500913

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      Cationicfac-tris(pyrazole) rhenium complexes act as anion receptors. Crystal structures of the nitrate (see picture) and acetone adducts reveal hydrogen bonding between the guest and the N[BOND]H groups of two pyrazole moieties, as well as an opening of the N-Re-N angle subtended for the involved pyrazoles ligands.

    15. Bond Orders between Molecular Fragments (pages 2252–2262)

      Adam J. Bridgeman and Christopher J. Empson

      Version of Record online: 27 DEC 2005 | DOI: 10.1002/chem.200500909

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      Bond orders and valency are key chemical concepts that focus on diatomic and atomic properties. This paper describes a new approach for the analysis of the results of high or low-level molecular-orbital calculations. The approach is illustrated using examples drawn from organometallic chemistry (see picture).

    16. Photophysical Studies of Anion-Induced Colorimetric Response and Amplified Fluorescence Quenching in Dipyrrolylquinoxaline-Containing Conjugated Polymers (pages 2263–2269)

      Cheng-Yang Wu, Min-Shen Chen, Chih-An Lin, Su-Ching Lin and Shih-Sheng Sun

      Version of Record online: 19 DEC 2005 | DOI: 10.1002/chem.200500804

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      Is the deprotonation or hydrogen bonding responsible for colorimetric response and fluorescence quenching in dipyrrolylquinoxaline (DPQ)-based anion sensors? We have found that the colorimetric responses and fluorescence quenching in the presence of fluoride or pyrophosphate are indeed the result of deprotonation of the N-H proton. The anion-induced deprotonation generates low-energy, non-fluorescent trapping sites and is responsible for the signal amplification through rapid exciton migration along the polymeric backbone.

    17. New Cyanine–Oligonucleotide Conjugates: Relationships between Chemical Structures and Properties (pages 2270–2281)

      Rémy Lartia and Ulysse Asseline

      Version of Record online: 18 JAN 2006 | DOI: 10.1002/chem.200500908

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      Fluorescent oligonucleotide probes: Thiocyanine, quinocyanine, and thiazole orange isomers were attached through either the quinoline or the benzothiazole nucleus to different positions of an oligonucleotide chain. Parameters, such as base-pair neighbors, stereochemical configuration at the phosphorus atom, and the position of attachment of the linker to the cyanines (see picture) were studied. The duplex stability observed on hybridization of the conjugates with the target sequence and fluorescence changes confirmed the influence of the conjugate structures on their properties.

    18. Synthesis and Some Properties of Binuclear Ruthenocenes Bridged by Oligoynes: Formation of Bis(cyclopentadienylidene)cumulene Diruthenium Complexes in the Two-Electron Oxidation (pages 2282–2292)

      Masaru Sato, Yusuke Kubota, Yasushi Kawata, Takashi Fujihara, Kei Unoura and Aiko Oyama

      Version of Record online: 12 DEC 2005 | DOI: 10.1002/chem.200500926

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      Bridging chains: Oxidation potential of the oligoyne-bridged binuclear ruthenocenes, [Rc*(C[TRIPLE BOND]C)nRc*] (n=1–4), showed an anodic shift with increasing n. The two-electron-oxidized species were isolated and characterized as bis(cyclopentadienylidene)cumulene diruthenium complexes for n=1–3. The spin coupling is weakened with the elongation of the bridging chain.

    19. Fine Tuning of the Oxidation Locus, and Electron Transfer, in Nickel Complexes of Pro-Radical Ligands (pages 2293–2302)

      Olaf Rotthaus, Olivier Jarjayes, Fabrice Thomas, Christian Philouze, Carlos Perez Del Valle, Eric Saint-Aman and Jean-Louis Pierre

      Version of Record online: 21 DEC 2005 | DOI: 10.1002/chem.200500915

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      Modulation of the ligand field during the one-electron oxidation of square-planar nickel(II) Schiff base derived complexes (see picture) allows the formation of either of the valence tautomers, namely the phenoxyl nickel(II) or phenolatonickel(III) species.

    20. Novel 2,1,3-Benzothiadiazole-Based Red-Fluorescent Dyes with Enhanced Two-Photon Absorption Cross-Sections (pages 2303–2317)

      Shin-ichiro Kato, Taisuke Matsumoto, Motoyuki Shigeiwa, Hideki Gorohmaru, Shuuichi Maeda, Tsutomu Ishi-i and Shuntaro Mataka

      Version of Record online: 19 DEC 2005 | DOI: 10.1002/chem.200500921

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      Attractive red fluorescence is observed by near-IR irradiation of two-photon absorbing materials, which are composed of an electron-accepting benzothiadiazole ring and electron-donating amino groups. The two-photon-induced red emission presented can be applied to biological fluorescence imaging with versatile advantages, increase of penetration depth in tissue, and less photodamage.

    21. Asymmetric Hydrogenation of Imines and Olefins Using Phosphine-Oxazoline Iridium Complexes as Catalysts (pages 2318–2328)

      Anna Trifonova, Jarle S. Diesen and Pher G. Andersson

      Version of Record online: 19 DEC 2005 | DOI: 10.1002/chem.200500942

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      Complex chemistry! The synthesis of a new class of chiral phosphine-oxazolines and their application as ligands in iridium-catalyzed hydrogenations is described. Acyclic aromatic N-aryl imines and unfunctionalized olefins were reduced with conversions and enantiomeric excesses up to 99 %.

    22. π Topology and Spin Alignment in Unique Photoexcited Triplet and Quintet States Arising from Four Unpaired Electrons of an Organic Spin System (pages 2329–2336)

      Yoshio Teki, Tetuya Toichi and Satoru Nakajima

      Version of Record online: 22 DEC 2005 | DOI: 10.1002/chem.200500981

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      Photoinduced spin alignment and unique photoexcited states of 1 are reported. The two radical moieties interact very weakly in the ground state. By photoirradiation, a novel lowest photoexcited triplet (S=1) state arising from four unpaired electrons with a low-lying quintet (S=2) photoexcited state were detected. The D value of the triplet state is reduced by antiferromagnetic spin alignment between two radical spins through the excited triplet spin coupler.

    23. Biomolecule-Assisted Synthesis and Electrochemical Hydrogen Storage of Porous Spongelike Ni3S2 Nanostructures Grown Directly on Nickel Foils (pages 2337–2342)

      Bin Zhang, Xingchen Ye, Wei Dai, Weiyi Hou and Yi Xie

      Version of Record online: 3 JAN 2006 | DOI: 10.1002/chem.200501005

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      Porous nanomaterials: Nanothread-based porous spongelike Ni3S2 nanostructures (see image), which can store hydrogen electrochemically with a capacity of 380 mAh g−1, were synthesized directly on Ni foil by using a simple biomolecule-assisted method. Other novel Ni3S2 nanostructures were also fabricated on the Ni substrate by varying the experimental parameters. The capacity of hydrogen storage depended on the morphology of the nanostructures.

    24. Characterization and Catalytic-Hydrogenation Behavior of SiO2-Embedded Nanoscopic Pd, Au, and Pd–Au Alloy Colloids (pages 2343–2357)

      Vasile I. Pârvulescu, Viorica Pârvulescu, Uwe Endruschat, George Filoti, Friedrich E. Wagner, Christian Kübel and Ryan Richards

      Version of Record online: 27 DEC 2005 | DOI: 10.1002/chem.200500971

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      Alloying Pd with Au in bimetallic nanoclusters leads to improved activity, and most importantly, to an improved selectivity. The combination of the two metals (see picture) is also shown to result in catalysts with very high tolerance to poisons, as is evidenced for the hydrogenation of styrene in the presence of thiophene. The method of nanocluster preparation and embedding in silica is crucial for the activity of these catalysts.

    25. Electrochemistry and Photophysics of Donor-Substituted Triarylboranes: Symmetry Breaking in Ground and Excited State (pages 2358–2370)

      Rainer Stahl, Christoph Lambert, Conrad Kaiser, Rüdiger Wortmann and Ruth Jakober

      Version of Record online: 20 DEC 2005 | DOI: 10.1002/chem.200500948

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      A star-shaped, carbazole-substituted triarylborane (see picture) and its 1D model compounds are studied by cyclic voltammetry, UV/Vis absorption and fluorescence spectroscopy, and electro-optical absorption measurements. The results prove that the ground-state symmetry of the parent borane is lower than D3.

    26. Scope and Mechanism of the PdII-Catalyzed Arylation/Carboalkoxylation of Unactivated Olefins with Indoles (pages 2371–2382)

      Cong Liu and Ross A. Widenhoefer

      Version of Record online: 17 JAN 2006 | DOI: 10.1002/chem.200500787

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      Polycyclic indoles are formed in good yield with high regioselectivity (see scheme) by treatment of 2- and 3-alkenyl indoles with a catalytic amount of [PdCl2(CH3CN)2] (5 mol %) and a stoichiometric amount of CuCl2 (3 equiv) in methanol under CO (1 atm) at room temperature.

    27. Near Monodisperse TiO2 Nanoparticles and Nanorods (pages 2383–2391)

      Xiao-Lin Li, Qing Peng, Jia-Xiang Yi, Xun Wang and Yadong Li

      Version of Record online: 23 DEC 2005 | DOI: 10.1002/chem.200500893

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      Well-controlled solvothermal reactions yield highly crystalline, near monodisperse, and redispersible TiO2 nanoparticles, nanorods, and their metal-doped (Sn4+, Fe3+, Co2+, Ni2+, etc.) derivates (see figure). The reaction mechanisms and formation processes of the products are discussed.

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      Preview: Chem. Eur. J. 8/2006 (page 2395)

      Version of Record online: 21 FEB 2006 | DOI: 10.1002/chem.200690025