Chemistry - A European Journal

Cover image for Vol. 10 Issue 19

October 4, 2004

Volume 10, Issue 19

Pages 4651–4924

    1. Cover Picture: Expanded Utility of the Native Chemical Ligation Reaction (Chem. Eur. J. 19/2004) (page 4651)

      Dawn S. Y. Yeo, Rajavel Srinivasan, Grace Y. J. Chen and Shao Q. Yao

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/chem.200490064

      The cover picture shows the X-ray structure of Sce VMA intein from Saccharomyces cerevisiae in the background. This intein has been extensively modified to overexpress proteins that have a C-terminal thioester, which is the key component for the so-called "Native Chemical Ligation Reaction" shown in the foreground. More details could be found in the article by S. Q. Yao et al. on p. 4664 ff.

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      An Industrially Viable Catalyst System for Palladium-Catalyzed Telomerizations of 1,3-Butadiene with Alcohols (page 4661)

      Ralf Jackstell, Surendra Harkal, Haijun Jiao, Anke Spannenberg, Cornelia Borgmann, Dirk Röttger, Franz Nierlich, Mark Elliot, Stuart Niven, Kingsley Cavell, Oscar Navarro, Mihai S. Viciu, Steven P. Nolan and Matthias Beller

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/chem.200490066

    3. Expanded Utility of the Native Chemical Ligation Reaction (pages 4664–4672)

      Dawn S. Y. Yeo, Rajavel Srinivasan, Grace Y. J. Chen and Shao Q. Yao

      Version of Record online: 11 AUG 2004 | DOI: 10.1002/chem.200400414

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      Mixing DNA technology, protein splicing, and organic and chemoselective chemistry! In this article, we highlight recent progress in the applications of native chemical ligation reaction related to proteomics and chemical biology, namely, in vitro and in vivo protein biotinylation, protein microarray technologies for large-scale protein analysis, and live-cell bioimaging (see scheme).

    4. Nucleophilic De-coordination and Electrophilic Regeneration of “Hemilabile” Pincer-Type Complexes: Formation of Anionic Dialkyl, Diaryl, and Dihydride PtII Complexes Bearing No Stabilizing π-Acceptors (pages 4673–4684)

      Elena Poverenov, Mark Gandelman, Linda J. W. Shimon, Haim Rozenberg, Yehoshoa Ben-David and David Milstein

      Version of Record online: 20 AUG 2004 | DOI: 10.1002/chem.200400514

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      Long-armed ligands: The new “long-arm” hemilabile PCN-type ligand enables the formation of novel anionic dialkyl, diaryl, and dihydride platinum(II) complexes that do not bear stabilizing π-accepting ligands. These are formed by nucleophilic attack on [Pt(PCN)(R)] complexes, resulting in chelate-ring opening. The anionic complexes exhibit high nucleophilic reactivity with various electrophiles, upon which the pincer system is regenerated (see scheme).

    5. Enantioselective Hydrogenation of Alkenes with Iridium–PHOX Catalysts: A Kinetic Study of Anion Effects (pages 4685–4693)

      Sebastian P. Smidt, Nicole Zimmermann, Martin Studer and Andreas Pfaltz

      Version of Record online: 5 AUG 2004 | DOI: 10.1002/chem.200400284

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      Ir–PHOX complexes are remarkably active catalysts for the hydrogenation of unfunctionalized alkenes (see scheme). Turnover frequencies reach up to 5500 h−1, catalyst loadings can be decreased to as low as 0.02 mol %. A systematic study of anion effects is described here for the first time. A striking influence on both activity and productivity was found, with the following order in reaction rates for anions X: [Al{OC(CF3)3}4]>BArF>[B(C6F5)4]>PF6≫BF4>CF3SO3.

    6. A “Single-Sample Concept” (SSC): A New Approach to the Combinatorial Chemistry of Inorganic Materials (pages 4694–4702)

      Jürg Hulliger and Muhammad Aslam Awan

      Version of Record online: 12 AUG 2004 | DOI: 10.1002/chem.200400231

      Magnetic separation: A single-sample concept is presented which opens up a new route to a combinatorial ceramic synthesis that should provide access to the estimated upper limit of oxide materials, limited to N metallic compounds (N<61) and a maximum of q elements per compound (q≤6), to obtain magnetic and other properties. The new concept was applied in a search for magnetic iron oxides.

    7. Chiral Amplification in Macromolecular Helicity Assisted by Noncovalent Interaction with Achiral Amines and Memory of the Helical Chirality (pages 4703–4707)

      Kazuhide Morino, Nobuyuki Watase, Katsuhiro Maeda and Eiji Yashima

      Version of Record online: 5 AUG 2004 | DOI: 10.1002/chem.200400381

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      Singel-handed helix: The slight excess of the single-handed helical sense of poly[(4-carboxyphenyl)acetylene] induced by a small amount of an optically active amine was dramatically amplified by the co-addition of a bulky achiral amine to give the almost complete single-handed helix (see scheme). The amplified helical chirality was memorized by replacing the optically active amine and achiral amine with various achiral amines.

    8. Final Elucidation of the Absolute Configuration of the Signal Metabolite Hormaomycin (pages 4708–4717)

      Boris D. Zlatopolskiy, Karin Loscha, Petra Alvermann, Sergei I. Kozhushkov, Sergej V. Nikolaev, Axel Zeeck and Armin de Meijere

      Version of Record online: 20 AUG 2004 | DOI: 10.1002/chem.200400406

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      Final elucidation of the absolute configuration of hormaomycin 1 a has been accomplished by appropriate HPLC and HPLC/MS as well as feeding experiments with enantiomerically pure samples of the deuterium-labeled unique amino acids 3-(2′-nitrocyclopropyl)alanine and 4-(Z)-propenylproline. The latter were prepared for the first time and allowed one to unequivocally assign the hitherto unknown absolute configurations of the last four stereocenters in hormaomycin 1 a. As a bonus, some new information about the biosynthesis of this molecule has also been gathered.

    9. First Total Synthesis of Hormaomycin, a Naturally Occurring Depsipeptide with Interesting Biological Activities (pages 4718–4727)

      Boris D. Zlatopolskiy and Armin de Meijere

      Version of Record online: 28 JUL 2004 | DOI: 10.1002/chem.200400249

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      The first total synthesis of hormaomycin 1, a secondary metabolite from a Streptomyces griseoflavus strain with a wide spectrum of biological activities, is described. The 4-methylbenzyloxycarbonyl (MeZ) group was successfully applied for the first time as an acid-labile amino protective group in peptide synthesis.

    10. Highly Selective, Recyclable Epoxidation of Allylic Alcohols with Hydrogen Peroxide in Water Catalyzed by Dinuclear Peroxotungstate (pages 4728–4734)

      Keigo Kamata, Kazuya Yamaguchi and Noritaka Mizuno

      Version of Record online: 6 AUG 2004 | DOI: 10.1002/chem.200400352

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      The highly chemo-, regio-, and diastereoselective and stereospecific epoxidation of various allylic alcohols with only one equivalent of hydrogen peroxide in water can be efficiently catalyzed by a dinuclear peroxotungstate, K2[{W([DOUBLE BOND]O)(O2)2(H2O)}2(μ-O)]⋅2 H2O (see figure). The catalyst is easily recycled while maintaining the catalytic performance. The catalytic reaction mechanism is also discussed.

    11. Cooperative Near-IR to Visible Photon Upconversion in Yb3+-Doped MnCl2 and MnBr2: Comparison with a Series of Yb3+-Doped Mn2+ Halides (pages 4735–4741)

      Pascal Gerner, Christine Reinhard and Hans U. Güdel

      Version of Record online: 11 AUG 2004 | DOI: 10.1002/chem.200400282

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      Visible Mn2+luminescence after excitation of the Yb3+ around 10 000 cm−1 was observed for Yb3+-doped MnCl2 and MnBr2 (see figure). An upconversion mechanism based on exchange coupled Yb3+ and Mn2+ ions is proposed. We present the result of a systematic study on the upconversion properties of MnII halides with corner-, edge- (title compounds) and face-sharing bridging geometry.

    12. Understanding the Nature of the Molecular Mechanisms Associated with the Competitive Lewis Acid Catalyzed [4+2] and [4+3] Cycloadditions between Arylidenoxazolone Systems and Cyclopentadiene: A DFT Analysis (pages 4742–4749)

      Manuel Arnó, M. Teresa Picher, Luis R. Domingo and Juan Andrés

      Version of Record online: 10 AUG 2004 | DOI: 10.1002/chem.200400277

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      The mechanism of the cycloaddition reaction between aryliden-5(4H)-oxazolone and cyclopentadiene in the presence of the Lewis acid catalyst AlH3, to obtain the corresponding [4+2] and [4+3] cycloadducts, is studied through DFT calculations. The [4+3] cycloaddition is a stepwise process that is initiated by a Friedel–Crafts-type addition of the electrophilically activated carbonyl group of 1 to cyclopentadiene. The second step is a cyclization of the corresponding zwitterionic intermediate IN1 to yield the corresponding [4+3] cycloadduct (see scheme).

    13. Highly Effective Sulfated Zirconia Nanocatalysts Grown out of Colloidal Silica at High Temperature (pages 4750–4754)

      Guangshan Zhu, Ce Wang, Yahong Zhang, Na Guo, Yiyang Zhao, Runwei Wang, Shilun Qiu, Yen Wei and Ray H. Baughman

      Version of Record online: 10 AUG 2004 | DOI: 10.1002/chem.200400288

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      More from the world of nanocatalysts: A sol–gel process is presented in which nano units of catalysts are formed in the matrix of a colloidal carrier with assistance of a cross-linking agent and then grow out of the carrier at high temperatures. A binary nanocatalyst (JML-1: a TEM image is shown here) that consists of a silica nanoparticle core and a sulfated zirconia (SZ) nanocrystal shell is demonstrated to be a highly effective catalyst.

    14. MoF6 and WF6: Nonrigid Molecules? (pages 4755–4762)

      Gustavo Santiso Quiñones, Gerhard Hägele and Konrad Seppelt

      Version of Record online: 13 AUG 2004 | DOI: 10.1002/chem.200400095

      New insight into the structures of MoF6, WF6, and their derivatives, CF3[BOND]CH2[BOND]O[BOND]MoF5, CF3[BOND]CH2[BOND]O[BOND]F5, C6F5[BOND]O[BOND]MoF5, C6F5[BOND]O[BOND]WF5, and (CF3)3C[BOND]O[BOND]WF5 is provided by DFT calculations and dynamic 19F NMR spectroscopy.

    15. Enantioselective Self-Assembly of Bimetallic [MnII (Δ)-CrIII(C2O4)3] and [MnII (Λ)-CrIII(C2O4)3] Layered Anionic Networks Templated by the Optically Active (Rp)- and (Sp)-[1-CH2N(n-C3H7)3-2-CH3[BOND]C5H3Fe[BOND]C5H5]+ Ions (pages 4763–4769)

      Michel Gruselle, René Thouvenot, Bernard Malézieux, Cyrille Train, Patrick Gredin, Tatiana V. Demeschik, Ludmila L. Troitskaya and Viatcheslav I. Sokolov

      Version of Record online: 10 AUG 2004 | DOI: 10.1002/chem.200305760

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      Optically active 2D oxalate-based Mn–Cr magnets can be obtained by utilizing intermolecular interactions occurring during the formation of specific diastereomeric ion pairs in solution in the reaction of planar chiral 1,2-disubstituted ferrocenic ammonium cations, such as (Rp)- and (Sp)-[1-CH2NR3–2-CH3-C5H3Fe-C5H5]+ (R=CH3, C2H5, n-C3H7, n-C4H9), in the presence of the (Δ)-(tris(tetrachlorobenzenediolato)phosphate(V) anion), [(Δ)-Trisphat] (see picture).

    16. Synergic Binding of Carbon Monoxide and Cyanide to the FeMo Cofactor of Nitrogenase: Relic Chemistry of an Ancient Enzyme? (pages 4770–4776)

      Christopher J. Pickett, Kylie A. Vincent, Saad K. Ibrahim, Carol A. Gormal, Barry E. Smith, Shirley A. Fairhurst and Stephen P. Best

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400382

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      The iron–molybdenum cofactor of nitrogenase: Electrochemical, FTIR-spectroelectrochemical and EPR spectroscopy reveal cyanide binding to oxidised and a new superoxidised state of the cofactor (see picture) and a synergic binding of CO and CN to its semireduced and oxidised forms. This chemistry may be a relic of an earlier role of the cluster in a cyanide-metabolising enzyme.

    17. Theory and Experiment in Concert: Templated Synthesis of Amide Rotaxanes, Catenanes, and Knots (pages 4777–4789)

      Christoph A. Schalley, Werner Reckien, Sigrid Peyerimhoff, Bilge Baytekin and Fritz Vögtle

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400365

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      Theoretically tied up in knots! In line with the available experimental data, theory gives a detailed insight into the template effects operative in the formation of amidic rotaxanes and catenanes. The synthesis of the trefoil dodecaamide knot (see figure) proceeds through a closely analogous template mechanism, which probably involves the formation of a hydrogen-bond-stabilized helical loop as an intermediate.

    18. Enantioselective Cyanosilylation of Ketones by a Catalytic Double-Activation Method with an Aluminium Complex and an N-Oxide (pages 4790–4797)

      Fu-Xue Chen, Hui Zhou, Xiaohua Liu, Bo Qin, Xiaoming Feng, Guolin Zhang and Yaozhong Jiang

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400506

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      By means of double-activation catalysis a successful enantioselective addition of TMSCN to ketones could be obtained. Through the use of salen–Al complex (0.1–0.5 mol %) and N-oxides (0.05–0.25 mol %), ketones were converted into the corresponding cyanohydrin O-TMS ethers with excellent yields (80–99 %) and enantioselectivities (up to 94 % ee for aromatic ketones, and up to 90 % ee for aliphatic ones). Mechanistically, it is proposed that the salen–Al complex acts as a Lewis acid to activate the ketone and the N-oxide as a Lewis base to activate TMSCN (see scheme).

    19. Synthesis and Biological Evaluation of a Lipid A Derivative That Contains an Aminogluconate Moiety (pages 4798–4807)

      Balaji Santhanam, Margreet A. Wolfert, James N. Moore and Geert-Jan Boons

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400376

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      Lessons from lipopolysaccharides: A highly convergent strategy for the synthesis of several derivatives of the lipid A of Rhizobium sin-1 has been developed. The synthetic derivatives are 2-aminogluconate 1 and 2-aminogluconolactone 2, both of which lack C-3 acylation. Based on a comparison of the biological responses of the synthetic lipid A derivatives with those of the R. sin-1 lipopolysaccharide (LPS) and lipid A, conclusions can be drawn about the structural features that are important for antagonization of enteric LPS-induced cytokine production.

    20. Revealing the Configuration and Crystal Packing of Organic Compounds by Solid-State NMR Spectroscopy: Methoxycarbonylurea, a Case Study (pages 4808–4816)

      Sven Macholl, Frank Börner and Gerd Buntkowsky

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400191

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      Dipolar solid-state NMR spectroscopy is a method for determining the structure of, for example, poorly crystallizing or amorphous organic compounds. Our strategy was based on precise REDOR measurements of selected C[BOND]N distances in methoxycarbonylurea (see picture). Isotope dilution experiments and numerical simulations of ISn spin systems have been employed to distinguish between intra- and intermolecular C[BOND]N distances, thereby facilitating the molecular modeling of the configuration and packing of molecules: a step towards “solid state NMR crystallography”.

    21. Machinable Long PVP-Stabilized Silver Nanowires (pages 4817–4821)

      Peng Jiang, Shun-Yu Li, Si-Shen Xie, Yan Gao and Li Song

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400318

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      Bending wires! Silver nanowires capped by PVP molecules with a diameter range from 150 to 200 nm and length range from 50 to 100 μm have a fivefold-twinned structure bound by five {1 0 0} wall planes and two spearlike ends around five {1 1 1} facets. They can be intentionally bent into various angles and shapes (see SEM image illustrated here), demonstrating excellent mechanical stability under room temperature conditions.

    22. Reactions of Hydrated Electrons (H2O)n with Carbon Dioxide and Molecular Oxygen: Hydration of the CO2 and O2 Ions (pages 4822–4830)

      O. Petru Balaj, Chi-Kit Siu, Iulia Balteanu, Martin K. Beyer and Vladimir E. Bondybey

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400416

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      Both CO2and O2can act as electron scavengers and form hydrated molecular anions upon collisions with gas-phase hydrated electrons. While O2 is a stable anion, stabilization of CO2 is achieved by the presence of solvent molecules; five H2O molecules form a cyclic pentamer with four of them interacting with CO2 (see picture).

    23. New Amphiphilic Silicon(IV) Phthalocyanines as Efficient Photosensitizers for Photodynamic Therapy: Synthesis, Photophysical Properties, and in vitro Photodynamic Activities (pages 4831–4838)

      Pui-Chi Lo, Jian-Dong Huang, Diana Y. Y. Cheng, Elaine Y. M. Chan, Wing-Ping Fong, Wing-Hung Ko and Dennis K. P. Ng

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400462

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      Fluorescing phthalocyanines: A new series of silicon(IV) phthalocyanines substituted axially with one or two 1,3-bis(dimethylamino)-2-propoxy group(s) and two of their methylated derivatives have been synthesized. They are highly potent against HepG2 human hepatocarcinoma cells and J774 mouse macrophage cells with IC50 values down to 0.02 μM. As revealed by fluorescence microscopy, compound 1 shows a high and selective affinity to the mitochondria of HepG2 cells.

    24. Synthesis and Stereochemical Properties of Chiral Square Complexes of Iron(II) (pages 4839–4845)

      Thomas Bark, Alexander von Zelewsky, Dmitrij Rappoport, Markus Neuburger, Silvia Schaffner, Jérôme Lacour and Jonathan Jodry

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400399

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      Interwoven squares: A chiral, interwoven square complex, the X-ray structure of which is depicted below, was obtained from L1 and Fe2+ ions and was resolved with antimonyltartrate. The properties of the pure enantiomer were investigated by CD and NMR spectroscopy, but also theoretically by time-dependent DFT. A similar complex was obtained directly in a stereochemically pure form, when a chiral derivative of L1 was used.

    25. Influence of DNA Structure on the Reactivity of the Guanine Radical Cation (pages 4846–4852)

      Francesco Luigi Gervasio, Alessandro Laio, Marcella Iannuzzi and Michele Parrinello

      Version of Record online: 20 AUG 2004 | DOI: 10.1002/chem.200400171

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      The first steps of oxidative damage in double helical DNA by the guanine radical cation are investigated. We found that the rate limiting step is the water protolysis and that the local environment plays a role in considerably lowering the barrier (1). Once the 8-hydroxy-7,8-dihydroguanyl radical intermediate is formed, it is stabilized by a reprotonation of guanine N1 (2).

    26. Boron–Diindomethene (BDI) Dyes and Their Tetrahydrobicyclo Precursors—en Route to a New Class of Highly Emissive Fluorophores for the Red Spectral Range (pages 4853–4871)

      Zhen Shen, Holger Röhr, Knut Rurack, Hidemitsu Uno, Monika Spieles, Burkhard Schulz, Günter Reck and Noboru Ono

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400173

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      Fluorescent molecular sensors: A new class of intensively absorbing and strongly fluorescing boron–diindomethene dyes (an example is shown here) for the red spectral range is introduced. The facile synthesis, modular architecture, and perpendicular arrangement of the functional subunits of the dyes allow the specific design of electron-transfer-active fluorescent molecular sensors or switches for various functional (receptor) units.

    27. Facile Access to Redox-Active C2-Bridged Complexes with Half-Sandwich Manganese End Groups (pages 4872–4885)

      Sohrab Kheradmandan, Koushik Venkatesan, Olivier Blacque, Helmut W. Schmalle and Heinz Berke

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400143

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      A singlet/triplet spin equilibrium (see scheme) is exhibited by the C2-bridged half-sandwich complex [(MeC5H4)(dmpe)MnC2Mn(dmpe)(C5H4Me)] (1). In addition, the mixed valent monocation 1+ is paramagnetic, while the dication 12+ is diamagnetic; this stresses the fact that the manganese centers are electronically strongly coupled. The interesting electronic properties exhibited by these complexes makes them promising candidates for the purpose of molecular electronics.

    28. Brønsted Acidic Ionic Liquids and Their Zwitterions: Synthesis, Characterization and pKa Determination (pages 4886–4893)

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

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400145

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      Novel, essentially chloride-free Brønsted acidic ionic liquids have been synthesized via their corresponding zwitterions. These acidic salts exhibit melting points as low as −61 °C and could thus serve as reaction media. The crystal structures of the precursors indicate extensive hydrogen bonding, as illustrated.

    29. Diverted Total Synthesis and Biological Evaluation of Gambierol Analogues: Elucidation of Crucial Structural Elements for Potent Toxicity (pages 4894–4909)

      Haruhiko Fuwa, Noriko Kainuma, Kazuo Tachibana, Chihiro Tsukano, Masayuki Satake and Makoto Sasaki

      Version of Record online: 17 AUG 2004 | DOI: 10.1002/chem.200400355

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      The first systematic structure–activity relationship (SAR) study of gambierol, a complex polycyclic ether neurotoxin (see figure), is described. Diverted total synthesis and biological evaluation of a series of gambierol analogues revealed the importance of the C28[DOUBLE BOND]C29 double bond and the length of the unsaturated side chain for potent toxicity.

    30. Mesostructured Silica Tubes and Rods by Templating Porous Membranes (pages 4910–4914)

      Zhijian Liang and Andrei S. Susha

      Version of Record online: 18 AUG 2004 | DOI: 10.1002/chem.200400005

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      Mesostructured silica tubes (see picture) and rods were prepared by deposition of prehydrolysed silica sol with surfactant into the cylindrical pores of polycarbonate (PC) membrane templates, followed by calcination to remove the surfactant and template. The method affords a uniform control of the morphologies of the mesostructured materials by the membrane templates used.

    31. Retention of Configuration in the Nucleophilic Substitution Reactions of Some Nine-Membered Ansa Derivatives of Cyclotriphosphazatriene (pages 4915–4920)

      Serap Beşli, Simon J. Coles, David B. Davies, Michael B. Hursthouse, Hanife İbişoǧlu, Adem Kılıç and Robert A. Shaw

      Version of Record online: 20 AUG 2004 | DOI: 10.1002/chem.200400311

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      X-ray crystallography provides evidence of retention of configuration in nucleophilic substitution reactions of two different types of cyclophosphazene derivatives (see example) containing nine-membered ansa rings that are relatively rigid, which suggests that this mechanism may be less rare than considered previously.

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      Preview: Chem. Eur. J. 19/2004 (page 4924)

      Version of Record online: 22 SEP 2004 | DOI: 10.1002/chem.200490067