Chemistry - A European Journal

Cover image for Vol. 11 Issue 14

July 4, 2005

Volume 11, Issue 14

Pages 4043–4287

    1. Cover Picture: Structural and Binding Features of Cofacial Bis-Porphyrins with Calixarene Spacers: Pac-Man Porphyrins That Can Chew (Chem. Eur. J. 14/2005) (page 4043)

      Danica Jokic, Corinne Boudon, Grégory Pognon, Michel Bonin, Kurt J. Schenk, Maurice Gross and Jean Weiss

      Article first published online: 24 JUN 2005 | DOI: 10.1002/chem.200590045

      A new generation of cofacial bis-porphyrins has been synthesized based on the efficient combination of calixarene spacers and acetylenic porphyrin derivatives. In the Full Paper on page 4199 ff., M. Gross, J. Weiss et al. describe the synthesis and characterization (UV-visible and NMR spectroscopy and electrochemical studies) of pac-man-type porphyrins that adapt their shape to the size of bidentate guests.

    2. Graphical Abstract: Chem. Eur. J. 14/2005 (pages 4044–4051)

      Article first published online: 24 JUN 2005 | DOI: 10.1002/chem.200590046

    3. Photocontrollable Self-Assembly (pages 4054–4063)

      Shiki Yagai, Takashi Karatsu and Akihide Kitamura

      Article first published online: 7 MAR 2005 | DOI: 10.1002/chem.200401323

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      A smart supramolecular system may be created by introducing photoswitching molecules into self-assembling systems. This article reviews self-assembling systems that contain azobenzene, a reliable photoswitching molecule; the formation and/or dissociation of such self-assembled supramolecular structures can be controlled by light (an example is illustrated here).

    4. Highly Hydrated Cations: Deficiency, Mobility, and Coordination of Water in Crystalline Nonahydrated Scandium(III), Yttrium(III), and Lanthanoid(III) Trifluoromethanesulfonates (pages 4065–4077)

      Alireza Abbasi, Patric Lindqvist-Reis, Lars Eriksson, Dick Sandström, Sven Lidin, Ingmar Persson and Magnus Sandström

      Article first published online: 10 MAY 2005 | DOI: 10.1002/chem.200401339

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      Water on the move: Coordinated water molecules exchange positions in the series of nonahydrated trifluoromethanesulfonates [M(H2O)n](CF3SO3)3 (M=metal, see structure), and water deficiency occurs when the tricapped trigonal prism becomes too crowded for the smaller trivalent metal ions. The hydration number n increases with increasing ionic size for M=Sc, Lu, Yb, Tm and Er (n=8.0(1), 8.4(1), 8.7(1), 8.8(1) and 8.96(5), respectively).

    5. Self-Supported Heterogeneous Titanium Catalysts for Enantioselective Carbonyl–Ene and Sulfoxidation Reactions (pages 4078–4088)

      Xisheng Wang, Xingwang Wang, Hongchao Guo, Zheng Wang and Kuiling Ding

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200500239

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      “Self-supported” heterogeneous, chiral titanium catalysts demonstrated extremely high enantioselectivity and remarkable stability in the asymmetric catalysis of sulfoxidation (see scheme). These metal–ligand self-assemblies display the advantages of not only classical heterogeneous catalysts, such as easy recovery and simple recycling, but also of simple preparation, robust chiral structure, and high density of the catalytically active units.

    6. Cyanide-Bridged Vitamin B12–Cisplatin Conjugates (pages 4089–4095)

      Stefan Mundwiler, Bernhard Spingler, Philipp Kurz, Susanne Kunze and Roger Alberto

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200500117

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      Building bridges!cis-[PtCl(OH2)(NH3)2]+ coordinates to the cyano ligand of vitamin B12 (cyanocobalamin) to form a Co[BOND]C[TRIPLE BOND]N[BOND]Pt-bridged conjugate (1). The compound is stable in aqueous solution and has been characterized by X-ray crystallography. The remaining chloride can be exchanged by stronger coordinating ligands such as 2′-deoxyguanosine to yield B12–nucleoside conjugates.

    7. Spectroscopic Evidence for a Dinitrogen Complex of Gallium and Estimation of the Ga[BOND]N2 Bond Strength (pages 4096–4102)

      Hans-Jörg Himmel and Nicole Hebben

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200401297

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      The dinitrogen complex Ga⋅N2 is very weakly bonded. Resonance Raman spectroscopy (see spectrum) allows the experimental estimation of the fragmentation energy of this complex for the first time.

    8. Optically Active Oligomer Units in Aggregates of a Highly Unsaturated, Optically Inactive Carotenoid Phospholipid (pages 4103–4108)

      Bente Jeanette Foss, Hans-Richard Sliwka, Vassilia Partali, Christian Köpsel, Bernhard Mayer, Hans-Dieter Martin, Ferenc Zsila, Zsolt Bikadi and Miklos Simonyi

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200401191

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      Aggregation in water by the highly unsaturated (R)-lysophospholipid enantiomer 1, which is optically inactive in methanol, leads to intensive Cotton effects. The optical activity in the aggregates arises from small, helical constructed oligomeric primary units. The calculated octamer can be considered as the brick building up the supramolecular structure.

    9. Computational Study of Structures and Properties of Metallaboranes: Cobalt Bis(dicarbollide) (pages 4109–4120)

      Michael Bühl, Drahomír Hnyk and Jan Macháček

      Article first published online: 29 APR 2005 | DOI: 10.1002/chem.200401202

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      Virtually unexplored by modern computational methods, the large family of metallacarboranes awaits theoretical investigations. A detailed density functional study of one archetypical family member, namely, the cobalt bis(dicarbollide) anion (see picture), leads the way to applications of NMR chemical shift calculations to such species.

    10. Efficient Solid-Phase Synthesis of Peptide-Based Phosphine Ligands: Towards Combinatorial Libraries of Selective Transition Metal Catalysts (pages 4121–4131)

      Christian A. Christensen and Morten Meldal

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200500105

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      A plethora of beaded peptidophosphine palladium catalysts: Solid supported peptide scaffolds possessing either primary or secondary amines were readily synthesised from commercially available Fmoc-protected amino acids. Phosphine moieties were introduced by solid-phase phosphinomethylation of the free amines, immediately prior to the complexation with palladium(II). The resin bound palladium(II) complexes were applied in palladium catalysed asymmetric allylic substitution reactions, affording good yields and moderate enantioselectivity.

    11. An Efficient Three-Step Synthesis of Cyclopenta[b]pyrans via 2-Donor-Substituted Fischer Ethenylcarbenechromium Complexes (pages 4132–4148)

      Armin de Meijere, Heiko Schirmer, Frank Stein, Frank Funke, Michael Duetsch, Yao-Ting Wu, Mathias Noltemeyer, Thomas Belgardt and Burkhard Knieriem

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200500043

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      Pseudoazulenes, that is highly substituted cyclopenta[b]pyrans, are obtained in moderate to very good yields in the reaction of 2-donor-substituted Fischer chromiumcarbenes with alkynes, which proceeds with twofold insertion of the latter and subsequent intramolecular [4+2] cycloaddition (see scheme).

    12. Homochiral Conglomerates and Racemic Crystals in Two Dimensions: Tartaric Acid on Cu(110) (pages 4149–4154)

      Sara Romer, Bahar Behzadi, Roman Fasel and Karl-Heinz Ernst

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200400962

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      The local molecular adsorbate geometry determines the chiral intermolecular interactions on surfaces. Racemic tartaric acid undergoes lateral enantioselective self-separation into homochiral domains on a copper(110) surface if adsorbed as doubly deprotonated bitartrate. The singly deprotonated monotartrate species, on the other hand, crystallizes into a heterochiral two-dimensional lattice.

    13. Supramolecular Assemblies of a Series of 2-Arylbenzimidazoles at the Air/Water Interface: In Situ Coordination, Surface Architecture and Supramolecular Chirality (pages 4155–4162)

      Zongxia Guo, Jing Yuan, Yong Cui, Fei Chang, Wenhua Sun and Minghua Liu

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200401246

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      From achiral molecules to chiral supramolecular assemblies: A series of achiral benzimidazole derivatives, which have no alkyl chains, were found to form chiral supramolecular assemblies either at the air/water interface or through an in situ coordination with AgI ion at the air/aqueous AgNO3 interface (see scheme).

    14. Acid–Base and Metal-Ion Binding Properties of the RNA Dinucleotide Uridylyl-(5′[RIGHTWARDS ARROW]3′)-[5′]uridylate (pUpU3−) (pages 4163–4170)

      Bernd Knobloch, Danuta Suliga, Andrzej Okruszek and Roland K. O. Sigel

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200500013

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      Metal ions are key to ribozyme activity: Simultaneous coordination of a metal ion to neighboring phosphate groups (see figure) is a key feature of ribozyme structure and function. The ability of different metal ions to form such a macrochelate was quantified by using the dinucleotide pUpU3−. The results show that, for example, Mg2+ binds mainly in a monodentate and Pb2+ in a bidentate fashion.

    15. High Affinity, Sequence Specific DNA Binding by Synthetic Tripyrrole–Peptide Conjugates (pages 4171–4178)

      Juan B. Blanco, Olalla Vázquez, José Martínez-Costas, Luis Castedo and José L. Mascareñas

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200500010

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      Designed peptidic ligands which interact simultaneously in the DNA major and minor grooves (see scheme) recognize specific, relatively long sequences with high affinity.

    16. Electronic Structure, Spectra, and Magnetic Circular Dichroism of Cyclohexa-, Cyclohepta-, and Cyclooctapyrrole (pages 4179–4184)

      Alexander Gorski, Thomas Köhler, Daniel Seidel, Jeong Tae Lee, Grażyna Orzanowska, Jonathan L. Sessler and Jacek Waluk

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200401343

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      Symmetry does the trick! Electronic and spectral properties of three recently obtained expanded porphyrins can be predicted from symmetry considerations alone. The formal derivation of the three compounds from ideal perimeters is described.

    17. Use of Specific Functionalised Tips with STM: A New Identification Method of Ester Groups and Their Molecular Structure in Self-Assembled Overlayers (pages 4185–4190)

      Cedric Volcke, Priscilla Simonis, François Durant, Paul A. Thiry, Philippe Lambin, Christine Culot and Christophe Humbert

      Article first published online: 28 APR 2005 | DOI: 10.1002/chem.200401169

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      Contrast modification is revealed by the functionalisation of STM gold tips with different molecules. This technique is applied to identify an ester group position within a molecule in self-assembled layers at the liquid/solid interface (see picture).

    18. Two-Photon Absorption Properties of 2,6-Bis(styryl)anthracene Derivatives: Effects of Donor–Acceptor Substituents and the π Center (pages 4191–4198)

      Wen Jun Yang, Dae Young Kim, Mi-Yun Jeong, Hwan Myung Kim, Yun Kyoung Lee, Xingzhong Fang, Seung-Joon Jeon and Bong Rae Cho

      Article first published online: 29 APR 2005 | DOI: 10.1002/chem.200401134

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      2,6-Bis(styryl)anthracene derivatives (see figure) have been synthesized and shown to exhibit a large two-photon cross section in the peak absorptivity range of 1080–2490 GM at equation image=780–990 nm; values which are significantly larger than those of the corresponding 1,4-bis(p-dibutylaminostyryl)benzene derivatives.

    19. Structural and Binding Features of Cofacial Bis-Porphyrins with Calixarene Spacers: Pac-Man Porphyrins That Can Chew (pages 4199–4209)

      Danica Jokic, Corinne Boudon, Grégory Pognon, Michel Bonin, Kurt J. Schenk, Maurice Gross and Jean Weiss

      Article first published online: 29 APR 2005 | DOI: 10.1002/chem.200401225

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      Pac-man porphyrins can chew! Cofacial bis-porphyrins with flexible calix[4]arene spacers can adapt their size to the shape of a guest. They display an electrochemically induced pac-man-like chewing motion around bidentate guests such as diazabicyclo[2.2.2]octane (see picture).

    20. Synthesis of Enantiomerically Pure Cyclohex-2-en-1-ols: Development of Novel Multicomponent Reactions (pages 4210–4218)

      Dirk Strübing, Anett Kirschner, Helfried Neumann, Sandra Hübner, Stefan Klaus, Uwe T. Bornscheuer and Matthias Beller

      Article first published online: 29 APR 2005 | DOI: 10.1002/chem.200401258

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      Facile access to chiral cyclohexenols is achieved through a novel multicomponent reaction and subsequent enzyme-catalyzed kinetic resolution. Starting from aldehydes, dienophiles and carboxylic acid anhydrides or alcohols, the reaction sequence enables the selective synthesis of highly functionalized cyclohex-2-en-1-ols with high enantioselectivity (see scheme).

    21. Transition Metal Complexes Coordinated by an NAD(P)H Model Compound and their Enhanced Hydride-Donating Abilities in the Presence of a Base (pages 4219–4226)

      Atsuo Kobayashi, Hideo Konno, Kazuhiko Sakamoto, Akiko Sekine, Yuji Ohashi, Masashi Iida and Osamu Ishitani

      Article first published online: 2 MAY 2005 | DOI: 10.1002/chem.200401211

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      Deprotonation from the carbamoyl group on an NAD(P)H model (BNAH) occurs by coordination to the ruthenium(II) or rhenium(I) complex. The deprotonated BNAH–metal complexes have much stronger hydride donating abilities than “free” BNAH. The 1:1 adduct of the oxidized form BNA+ and the ruthenium(II) complex has been isolated for the first time (see scheme) and its structure was determined by X-ray crystallographic analysis.

    22. Utility of the Ammonia-Free Birch Reduction of Electron-Deficient Pyrroles: Total Synthesis of the 20S Proteasome Inhibitor, clasto-Lactacystin β-Lactone (pages 4227–4238)

      Timothy J. Donohoe, Herman O. Sintim, Leena Sisangia, Karl W. Ace, Paul M. Guyo, Andrew Cowley and John D. Harling

      Article first published online: 2 MAY 2005 | DOI: 10.1002/chem.200401119

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      A new synthesis of the 20S proteasome inhibitor clasto-lactacystin β-lactone is described. Our route to this important natural product involves the partial reduction of an electron deficient pyrrole as a key step and proceeds in just 13 steps and in 15 % overall yield.

    23. Affinity Interactions between Phenylboronic Acid-Carrying Self-Assembled Monolayers and Flavin Adenine Dinucleotide or Horseradish Peroxidase (pages 4239–4246)

      Songqin Liu, Ulla Wollenberger, Jan Halámek, Eik Leupold, Walter Stöcklein, Axel Warsinke and Frieder W. Scheller

      Article first published online: 29 APR 2005 | DOI: 10.1002/chem.200400827

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      The affinities of glycated molecules to boronate-carrying monolayers provides a method for their recognition. Conjugates of 3-aminophenylboronic acid and 3,3′-dithiodipropionic acid or 11-mercaptoundecanoic acid were prepared and self-assembled on gold surfaces. The affinity interaction of flavin adenine dinucleotide and horseradish peroxidase and phenylboronic acid monolayers on gold was investigated using voltammetric and microgravimetric methods.

    24. Simple Synthesis of Aminoquinoline/Ethylaniline Copolymer Semiconducting Nanoparticles (pages 4247–4256)

      Xin-Gui Li, Yi-Min Hua and Mei-Rong Huang

      Article first published online: 4 MAY 2005 | DOI: 10.1002/chem.200401140

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      A significant dependence of the polymerization yield, structure, and properties of the 8-aminoquinoline (AQ)/2-ethylaniline (EA) copolymer particles on AQ/EA ratio and polymerization conditions has been observed (see figure). Surprisingly, AQ homopolymerization and AQ/EA (50:50) copolymerization can simply afford nano-ellipsoids. A simple method for the synthesis of semiconducting pure polymer nanoparticles by introducing a charged AQ unit in the absence of stabilizer or sulfonic substituent on the monomers is first established.

    25. Absolute Configuration of C2-Symmetric Spiroselenurane: 3,3,3′,3′-Tetramethyl-1,1′-spirobi[3 H,2,1]Benzoxaselenole (pages 4257–4262)

      Ana G. Petrovic, Prasad L. Polavarapu, Jozef Drabowicz, Yingru Zhang, Oliver J. McConnell and Helmut Duddeck

      Article first published online: 2 MAY 2005 | DOI: 10.1002/chem.200401331

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      Configuration with confidence! The absolute configuration and predominant stereoisomer of 3,3,3′,3′-tetramethyl-1,1′-spirobi[3 H,2,1]benzoxaselenole have been determined by using three different chiroptical spectroscopic methods. This molecule exists as a trans isomer (see figure) and its S enantiomer exhibits negative optical rotation at 589 nm in CH2Cl2.

    26. Novel Phthalocyaninatobis(alkylcarboxylato)silicon(IV) Compounds: NMR Data and X-ray Structures To Study the Spacing Provided by Long Hydrocarbon Tails That Enhance Their Solubility (pages 4263–4273)

      Jose L. Sosa-Sánchez, Arturo Sosa-Sánchez, Norberto Farfán, Luis S. Zamudio-Rivera, Gerson López-Mendoza, Javier Pérez Flores and Hiram I. Beltrán

      Article first published online: 2 MAY 2005 | DOI: 10.1002/chem.200500003

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      Up to the sixth methylenic group is influenced by the strong anisotropic currents of the phthalocyanine macrocycles in trans-PcSi[O2C(CH2)nCH3]2. The correlation between the 1H NMR chemical shifts and the position of the corresponding carbon atoms in the tail (see picture) reveals that the dicarboxylate substituents exhibit spacer-like behaviour that enhances the solubility of the macrocycle.

    27. The Photochemistry of 4-Chlorophenol in Water Revisited: The Effect of Cyclodextrins on Cation and Carbene Reactions (pages 4274–4282)

      Ilse Manet, Sandra Monti, Pietro Bortolus, Maurizio Fagnoni and Angelo Albini

      Article first published online: 29 APR 2005 | DOI: 10.1002/chem.200401227

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      Chloride loss from the triplet state to yield the aryl cation in protolytic equilibrium with 4-oxocyclohexadienylidene occurs during the photolysis of 4-chlorophenol in water. The role of the former intermediate is proved by trapping with a π nucleophile, allyl alcohol. In the presence of cyclodextrins, neither alkene nor oxygen trapping operates and reduction to phenol is the only process.

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      Preview: Chem. Eur. J. 14/2005 (page 4287)

      Article first published online: 24 JUN 2005 | DOI: 10.1002/chem.200590047

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