bluuebunny/crossref_metadata_2025 huggingface dataset:
Metallochaperones & Metal Ion Homeostasis
Authors: Culotta Valeria C.
Published: March 2006

There exists a large array of proteins that rely on metal ions such as copper and manganese for function and these so‐called metalloproteins are housed in diverse locations throughout the cell. It is imperative that each metalloprotein connects with the proper metal ion and also at the right time. How does this meeting of protein and metal occur in a specific and regulated fashion? The problem seems paramount when one considers the potentially toxic nature of metals. With the harm that metals can impose on biomolecules, these ions are never allowed to roam freely in the reactive form and, as such, the bioavailability of metals within cells is very limited. To overcome this problem, eukaryote cells have evolved with specific ‘metal trafficking pathways’ or designated routes a metal ion can follow once inside the cell. On one hand, the bulk of the metal may be subject to a dead fate involving sequestration by metal detoxification systems. On the other hand, a fraction of the metal destined for metalloproteins enters a trafficking pathway that involves both membrane transporters and ‘metal chaperones’ that directly insert the metal into the target metalloprotein. The bulk of current knowledge on metal chaperones and metal trafficking pathways has emerged from studies on copper and to a lesser degree on manganese. The work described herein focuses on paradigms developed for copper and manganese, with possible implications for other essential metals as well.
Metalloprotein Design & Engineering
Authors: Lu Yi
Published: March 2006

This review covers recent advances in metalloprotein design, with focus on different approaches to the design. Impressive progress has been made in designing metal‐binding sites in peptides, de novo designed proteins, and native protein scaffolds. The approach can be rational or combinatorial. Under rational design, redesigning an existing metal‐binding site to a new site with dramatically different structure and function complements well the design of new metal‐binding sites by revealing the role of specific residues responsible for a particular structural or functional feature of the metal‐binding site of interest. To create a new metal‐binding site, several approaches have been used, including design based on structural homology, by inspection, using automated computer search algorithms, or combination of the above approaches. In addition, modular approach by transplanting a conserved structural unit from one protein into another has also been shown to be effective. Design through combinatorial and evolution methods has also been successful as it requires little prior knowledge of the protein structure. Finally, introducing unnatural amino acids or nonnative metal ions/prosthetic groups to expand the repertoires of metalloproteins have been demonstrated. Successful examples of each of the approaches are given; advantages and disadvantages of the approaches are discussed; the outlook for future research is also presented.
Multi‐Heme Cytochromes & Enzymes
Authors: Pereira Inês A. C. , Xavier António V.
Published: March 2006

Multihemeccytochromes and enzymes are a diverse group of proteins having several hemesccovalently bound to the polypeptide chain that are either enzymes involved in redox chemistry or electron transfer proteins. Most known members of this group are associated with the respiratory chains of proteobacteria. These proteins are characterized by a low amino acid to heme ratio, bis‐histidinyl coordination (with a few exceptions), and low redox potentials of the hemes. The hemes are usually tightly packed in close contact, allowing very fast electron transfer. Despite the absence of overall sequence identity between proteins, the hemes are found in quite conserved structural motifs, which tend to be organized in diheme pairs that are either parallel or perpendicular to each other. From the structures available, two families can be recognized in terms of the heme structural arrangement: the cytochromec3family where the perpendicular motif is predominant, and the hydroxylamine oxidoreductase (HAO) family where the stacked parallel motif alternates with the perpendicular motifs. Other multiheme cytochromes for which the structure is not yet available may be part of novel structural families.
Semiconductor Nanocrystal Quantum Dots
Authors: Hollingsworth Jennifer A.
Published: March 2006

Semiconductor quantum dots (QDs) bridge the gap between cluster molecules and bulk materials. The boundaries between molecular, QD, and bulk regimes are not well defined and are strongly material dependent. However, a range from ∼100 to ∼10 000 atoms per particle can be considered as a rough estimate of sizes for which the nanocrystal regime occurs. The lower limit of this range is determined by the stability of the bulk crystalline structure with respect to isomerization into molecular structures. The upper limit corresponds to sizes for which energy level spacings approach thermal energy, kT. In this nanosize regime, the semiconductor energy‐ or band gap is dependent upon the particle size. This phenomenon is known as thequantum‐size effect, and it allows band‐gap‐dependent material properties to be tuned with particle size. Specifically, semiconductor absorption and emission wavelengths can be controllably blueshifted from their bulk semiconductor values over hundreds of nanometers.

Semiconductor quantum dots (QDs) have been prepared by a variety of ‘physical’ and ‘chemical’ methods. Here, we review the synthetic chemistry of QDs prepared by colloidal chemical routes. These QDs, known as nanocrystal quantum dots (NQDs), comprise an inorganic core overcoated with a layer of organic ligand molecules. The organic capping provides electronic and chemical passivation of surface dangling bonds, prevents uncontrolled growth and agglomeration of the nanoparticles, and allows NQDs to be chemically manipulated like large molecules with solubility and reactivity determined by the identity of the surface ligand. In contrast, with substrate‐bound epitaxial QDs prepared by physical deposition methods (e.g. molecular beam epitaxy and metal‐organic chemical vapor deposition), NQDs are ‘freestanding.’ In this discussion, we concentrate on the most successful synthesis methods, where success is determined by high crystallinity, adequate surface passivation, solubility in nonpolar or polar solvents, and good size monodispersity. Size monodispersity is critical as it permits the study and, ultimately, the use of materials‐size‐effects to define novel electronic, optical, and structural materials properties. Further, we examine many of the most significant contributions in the areas of NQD chemical surface modification (organic and inorganic), particle shape control, and phase control.
Organic Synthesis Using Metal‐Mediated Coupling Reactions
Authors: Goodson Felix E. , Cichowicz Melissa B.
Published: March 2006

This article provides an overview of the cross‐coupling protocols most commonly used in organic synthesis. Particular emphasis is placed upon topics likely to be of interest to the inorganic chemist, namely, history, catalyst development, and mechanistic studies. While not a comprehensive review, this treatment is intended to provide the reader with a summary of some successful catalyst design strategies, methodological improvements, and mechanistic insights that have been achieved over the past 10 years.
Porous Inorganic Materials
Authors: Wang Xiqing , Bu Xianhui , Feng Pingyun
Published: March 2006

Porous inorganic materials cover a range of solids, both oxides and nonoxides, crystalline and amorphous, that have a pore size extending from about 3 Å to over 500 Å. Crystalline microporous materials such as zeolites have been known for over 200 years, and the research in the past decade has extended types of microporous materials from traditional oxides to chalcogenides and metal–organic frameworks. Efforts aimed toward developing new microporous materials that integrate uniform microporosity with other functionality have also led to promising results.

Periodically ordered mesoporous materials are a recent addition to the family of ordered inorganic porous materials. They can be made in the presence of organized assemblies of organic molecules (e.g. amines, cationic, anionic, or nonionic surfactants) or polymers (e.g. amphiphilic block copolymers). Micellar solutions, lyotropic liquid crystals, and microemulsions can all serve as structure‐directing agents during the cocondensation of inorganic precursors with organic species. A number of synthetic pathways have been developed for the preparation of mesoporous solids in a variety of chemical compositions including silica, organosilica, transition metal oxides, chalcogenides, and even elemental forms such as carbon and platinum. Much progress has also been made in the control of macroscopic morphologies (e.g. films, fibers, monoliths, and spheres). The pore geometry is closely related to the nature of the organic assemblies and other synthetic parameters and can be controlled to a certain degree to allow the synthesis of mesoporous materials with the desirable architecture and properties.

The past decade has also witnessed a rapid development in the synthesis of ordered macroporous materials and porous materials that are ordered at multiple‐length scales. Commonly used templates for the control of the macroscopic ordering include colloidal crystals such as latex or silica spheres and emulsion droplets. With the availability of a variety of inorganic porous materials, numerous applications are awaiting the exploration of materials researchers.
Self‐Assembled Inorganic Architectures
Authors: Bera Jitendra K. , Bacsa John , Dunbar Kim R.
Published: March 2006

The field of inorganic chemistry is witnessing an enormous growth period in the area of molecular self‐assembly. This review highlights key advances in this area with an emphasis on novel structures and the dynamic nature of inorganic self‐assembly reactions. Multidentate N‐heterocylic, cyanide, and carboxylate ligands are discussed in detail with respect to their use in the design of discrete structures, including molecular triangles, squares, pentagon, cubes, as well as polyhedra, oligomers, and polymers. Inorganic structures that employ metal–coordination and hydrogen bonds are also highlighted. The examples described herein illustrate the fact that the available binding sites and the topicity of the ligands along with the coordination requirements of metal ions are the key elements for building desired architectures. The role of intrinsic factors such as geometrical preferences of the metal ion as well as extrinsic factors such as the presence of a template in stabilizing a particular product are discussed. Recent progress in the rational design of functional materials vis‐à‐vis the manipulation of supramolecular chemistry is also covered in brief.
Hydrogen Bonding & Dihydrogen Bonding
Authors: Crabtree Robert H.
Published: March 2006

The review begins with the historical development of the area, notably Pauling's contribution. The current interest is in part related to the rise of supramolecular chemistry and molecular recognition, as well as the significance of hydrogen bonding in biology and biochemistry. Strong and weak cases are distinguished. A relationship with hypervalency is proposed, in which the bridging proton of a FHF anion is considered as hypervalent hydrogen. Dihydrogen bonding is considered the latest hydrogen bond type. Structural and spectroscopic aspects are discussed, together with applications. Hydrogen bonding in metal complexes is covered together with the distinction between hydrogen bonding and sigma complexation.
Carbon–Carbon & Carbon–Heteroatom Activation
Authors: Crabtree Robert H.
Published: March 2006

Activation involves binding of the intact CC or CX bond to the metal followed by CC or CX bond cleavage. Both aspects are considered here. The activation of CC bonds is facilitated by an enforced close approach of the CC bond to the metal or by the presence of a strong driving force such as a strained ring starting material or aromatization during the reaction. The reactivity order is: sp–sp > sp2–sp2 > sp3–sp3. The activation of CX bonds occurs by a number of mechanistic pathways depending on the system. Halocarbon complexes of type RXM are often intermediates and can be isolated in favorable cases.
Main Group: Multiple Bonding
Authors: Robinson Gregory H.
Published: March 2006

This chapter summarizes the many quite remarkable discoveries that have been made in recent years regarding multiple bonding of the heavier main group elements. While the general concept of multiple bonding is well established and easily embraced in organic chemistry, this is not the case for much of organometallic chemistry. The criteria that are routinely employed to assign double and triple bond character in organic compounds, that is, bond distance and bond strength, are of little significance in many cases involving the heavier main group elements. For example, the EE (E = Sn or Pb) double bond is both longer and weaker than the corresponding EE single bond. This chapter will discuss such seminal discoveries as the syntheses of the first digallyne (GaGa), dibismuthene (BiBi), and disilyne (SiSi). Central to these breakthroughs is the incorporation of sterically demanding ligand systems, which both stabilize and inhibit decomposition pathways of the heavier main group atoms.
Copper Proteins with Type 2 Sites
Authors: McGuirl Michele A. , Dooley David M.
Published: March 2006

The copper enzymes covered in this article span a wide range in terms of both their structural and reactivity properties. Yet the copper centers in each share similar coordination geometries and have been designated ‘Type 2 (or II)’ copper proteins. Type 2 copper proteins lack the unique spectroscopic or magnetic signatures that typify the so‐called Type 1 and Type 3 copper proteins, and the unique tetranuclear cluster found in nitrous oxide reductase. Indeed, the basis for classifying proteins as Type 2 was that the EPR (Electron Paramagnetic Resonance) spectra of the oxidized (resting) forms of these proteins closely resembled the spectra of ‘normal’ tetragonal CuIIcomplexes, withg∥ > g⊥ > 2.00, andA∥ ≥ 120 G at X‐band. It was generally surmised that the coordination environments of the copper sites in such enzymes were unexceptional, with five‐ or six‐coordinate structures composed of N, O ligands. As is often the case in science, many fascinating and totally unexpected structural and chemical phenomena turned out to be concealed behind this deceptively ‘normal’ facade. Each of the Type 2 enzymes covered here (superoxide dismutase, amine oxidase, lysyl oxidase, galactose oxidase, dopamine‐β‐monooxygenase, peptidylglycine α‐hydroxylating monooxygenase, and quercetinase) displays unique active‐site properties. Elucidating and elaborating structure/function relationships for these enzymes has been greatly aided by the availability of high‐resolution crystal structures for one or more enzymes from each group. These have generally corroborated the fairly detailed structural models that were developed from extensive spectroscopic studies. At the same time, the 3D structures have revealed many surprising details of the active sites. Indeed, the roles of copper in these ‘normal’ Type 2 copper centers are more diverse than ever imagined.
Beryllium: Inorganic Chemistry
Authors: Keizer Timothy S. , McCleskey T. Mark
Published: March 2006

The speciation and molecular interactions of beryllium have remained relatively unexplored compared to most metals, despite its high toxicity and extensive use in industry. One reason for this fact is the difficulty in characterizing beryllium species in solution. Herein, the chemistry of beryllium, and its interaction with hydroxo, inorganic and organic ligands are discussed. The structure and formation of beryllium species are communicated with emphasis on the stability of species in solution.
Subvalent Compounds
Authors: Brothers Penelope J.
Published: March 2006

Subvalent compounds are those in which a main group element occurs in an oxidation state lower than its normal group oxidation state. Traditionally, these have been identified in solid‐state inorganic phases, but more recently there have been major advances in the preparation of stable, molecular compounds containing subvalent main group elements. This has occurred in some cases through the use of specially designed ligands able to stabilize low oxidation state species through electronic stabilization or steric protection using bulky substituents. Ingenious synthetic routes such as the preparation of solutions in organic solvents of metastable aluminum(I) and gallium(I) halides have allowed access to other novel species. Apart from a relatively small number of types of mononuclear complexes, most subvalent molecular compounds involve homoatomic element–element bonds in the form of rings, chains, and clusters. Many of these have unusual structural and electronic properties that challenge established, classical ideas of bonding and electronic structure. This discussion focuses on recent advances in the structure and chemistry of molecular subvalent compounds, with an emphasis on the groups 13 and 14 elements. In addition to mononuclear and simple homonuclear single‐bonded compounds, several classes of cluster compounds are examined, including electron‐precise, electron‐rich, and electron‐deficient clusters. The latter include the Zintl ions. A very new class of aluminum and gallium metalloid clusters containing metal–metal bonds unsupported by ligands represents species on the pathway to formation of the bulk metal. An area in which exciting developments have taken place in the last decade encompasses subvalent compounds that are heavier main group element analogs of alkenes and alkynes, and significant structural features and new bonding models for these are discussed.
Inorganic Ring Systems
Authors: Haiduc Ionel
Published: March 2006

Inorganic rings of various types can be formed as a result of the broad range of bond types available. Cyclic structures formed by self‐assembly of molecular building units (tectons) are discussed in terms of supramolecular chemistry concepts. The formation of covalent rings can be understood in terms of combining various fragments (synthons) in which the central atoms can display various oxidation states, coordination numbers, and geometries, leading to a broad structural diversity of cyclic structures for a given composition of the ring skeleton (as illustrated for P2N2and Si2N2rings).
Current Developments in Optical Data Storage with Organic Dyes
Authors: Mustroph Heinz , Stollenwerk Manfred , Bressau Volker
Published: March 2006

The main motivation for the development of digital data storage has been the improvement in play‐back quality and the increase in storage capacity. In 1982 Philips and Sony introduced the first technically and economically successful system based on this—the compact disc (CD) and a compatible player. A very broad diversity of optical data recording formats are available today, and a difference is drawn between prerecorded, recordable, and rewritable media. This Review gives an overview of the systems used, the main features of production, and then concentrates on the properties of the organic dyes that are used in recordable systems. Dyestuffs chemistry has gained the reputation of having become a mature field of activity. Is this prejudice or a justified swan song for dyestuffs chemistry? When applications in optical data storage are considered, it is evident that even today progresses such as CD‐R and DVD/R would not be feasible without functional dyes.
Helical twists of collagen model peptides
Authors: Okuyama Kenji , Wu Guanghan , Jiravanichanun Nattha , Hongo Chizuru , Noguchi Keiichi
Published: March 2006

Average helical twists were calculated by the method of Sugeta and Miyazawa (Biopolymers 1967, 5, 673–679) for all of the collagen model peptides analyzed to date. Calculation of the helical twists of all triplets in each peptide strand provided novel insights for several model peptides. In the (Pro‐Pro‐Gly)n (n = 9 and 10), the helical twists showed cyclic fluctuations between 40 and 65° with a 20 Å period, suggesting that their molecular conformations were close enough to the ideal 7/2‐helix to show the helical repeat of 20 Å. Rather small helical twists in the guest regions of IBP in complex and T3‐785 were attributed to the interaction with Integrin I domain and a relaxed conformation caused by three consecutive triplets lacking imino acid residues, respectively. Although most of the triplets used in this study were imino acid–rich triplets, helical twists were scattered in a wide range from 30 to 70° with an overall average of 52.6°. This distribution of helical twists indicated a strong preference for the 7/2‐helical conformation (51.4°) rather than the 10/3‐helical model (36°). © 2006 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 84: 421–432, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Effect of medium sugar source on the production of retroviral vectors for gene therapy
Authors: Coroadinha A.S. , Ribeiro J. , Roldão A. , Cruz P.E. , Alves P.M. , Merten O.‐W. , Carrondo M.J.T.
Published: March 2006

The production of gene therapy retroviral vectors presents many difficulties, mainly due to vector instability and low cell productivities hampering the attainment of high titers of infectious viral vectors. The objective of this work is to increase the production titers of retroviral vectors by manipulating the sugar carbon sources used in bioreaction. Four sugars were tested (glucose, galactose, sorbitol, and fructose) on an established Moloney murine leukemia virus (MoMLV) producer cell line. Galactose and sorbitol did not support cell growth or vector production. Glucose supplemented at 25 mM supported the highest cell growth; however, the use of glucose or fructose at 83 and 140 mM have shown to improve the infectious vector titer three to fourfold. The reasons for the titer improvements were further analyzed and, although, the cell‐specific productivity in viral transgene RNA and reverse transcriptase were augmented 5‐ and 6‐fold for glucose at 140 mM and 14‐ and 16‐fold for fructose at 140 mM, comparing with glucose at 25 mM, these increases did not seem sufficient to account for the 14‐ (140 mM glucose) and 32‐ (140 mM fructose) fold increment obtained for the infectious particles‐specific productivity. Further accounting the enhancement in the titers was the improvement in the viral stability, the half‐life of the vectors was enhanced by 30–60%. This resulted in a product quality with a superior ratio of infectious to total particles, thus reducing the most problematic contaminant in the production of retroviral vectors, non‐infectious retroviral particles. © 2006 Wiley Periodicals, Inc.
Comparison of two immunomagnetic separation technologies to deplete T cells from human blood samples
Authors: Lara Oscar , Tong Xiaodong , Zborowski Maciej , Farag Sherif S. , Chalmers Jeffrey J.
Published: March 2006

The objective of this study was to compare the performance of two immunomagnetic separation technologies to deplete T cells from buffy coats of human blood. Specifically, two versions of the commercial MACS® Technology: MiniMACS and SuperMACS, and a prototype, flow‐through system, the QMS, were evaluated. Peripheral blood mononuclear leukocytes (PBL) were isolated from buffy coats and an immunomagnetic separation of CD3+ cells was conducted using company and optimized labeling protocols. To mimic peripheral blood containing bone marrow purged hematopoietic stem cells, HSC, CD34 expressing‐cells (KG1a) were spiked into PBL prior to T‐cell depletion once optimized depletion conditions were determined. Once the labeling protocol was optimized, the MiniMACS system performed well by producing a highly enriched CD3+ fraction, and a respectable level of depletion of T cells and recovery of KG1a cells in the depleted fraction; an average log10 depletion of T cells of 2.88 ± 0.17 and an average recovery of the KG1a cells of 60.8 ± 5.94% (n = 14). The performance of the SuperMACS system was very similar with an average log10 depletion of T cells of 2.89 ± 0.22 and an average recovery of KG1a of 63.1 ± 8.55% (n = 10). In contrast, the QMS system produced an average log10 depletion of T cells of 3.98 ± 0.33 (n = 16) with a corresponding average recovery of 57.9 ± 16.6% of the spiked CD34+ cells. The aforementioned QMS performance values were obtained using sorting speeds ranging from 2.5 × 104 to 1.7 × 105 cells per second. It is suggested that the lack of a 100% recovery of the unlabeled KG1a cells is the result of a previously reported “drafting” phenomena which pulls unlabeled cells in the direction of the magnetically labeled cells thereby resulting in loss of the unlabeled cells. © 2006 Wiley Periodicals, Inc.
Self‐Organizing Properties of Monosubstituted Sucrose Fatty Acid Esters: The Effects of Chain Length and Unsaturation
Authors: Molinier Valérie , Kouwer Paul J. J. , Fitremann Juliette , Bouchu Alain , Mackenzie Grahame , Queneau Yves , Goodby John W.
Published: March 2006

Three families of mono‐substituted sucrose fatty acid esters were prepared by enzymatic and classical synthetic procedures, and their self‐assembly and self‐organizational properties were investigated by thermal polarised light microscopy, differential scanning calorimetry and X‐ray diffraction. The properties were evaluated as a function of the fatty acid chain length. For the lower homologues of the series columnar liquid‐crystalline stacking structures were found, whereas for the higher homologues, lamellar phases predominated. A model for the columnar stacking arrangement, consisting of a unique arrangement of the molecules which could lead to the creation of multiple internal ion channels between the hydrophobic interior and the hydrophilic exterior of the columns, is suggested.
A Pyrazolato‐Bridged Dinuclear Platinum(II) Complex Induces Only Minor Distortions upon DNA‐Binding
Authors: Teletchéa Stéphane , Komeda Seiji , Teuben Jan‐Maarten , Elizondo‐Riojas Miguel‐Angel , Reedijk Jan , Kozelka Jiří
Published: March 2006

The cytotoxic, pyrazolato‐bridged dinuclear platinum(II) complex [(cis‐{Pt(NH3)2})2(μ‐OH)(μ‐pz)]2+ (pz=pyrazolate) has been found to cross‐link two adjacent guanines of a double‐stranded DNA decamer without destabilizing the duplex and without changing the directionality of the helix axis. A 1H NMR study of the oligonucleotide d(CTCTG*G*TCTC)‐d(GAGACCAGAG), cross‐linked at the two G* guanines by [(cis‐{Pt(NH3)2})2(μ‐pz)]3+, and molecular dynamics simulations of the explicitly solvated duplex were performed to characterize the structural details of the adduct. The dinuclear platinum cross‐link unwinds the helix by approximately 15°, that is, to a similar extent as the widely used antitumor drug cisplatin, but, in contrast to the latter, induces no significant bend in the helix axis. The Watson–Crick base‐pairing remains intact, and the melting temperature of the duplex is unaffected by the cross‐link. The helical twist is considerably reduced between the two platinated bases, as becomes manifest in an unusually short sequential H1′–H1′ distance. This unwinding also affects the sugar ring of the guanosine in the 3′‐position to the cross‐link, which presents an N⇌S equilibrium. This is the first cytotoxic platinum complex that has been successfully designed by envisioning the structural consequences of its binding to DNA.
Orientational Effect of Aryl Groups on 77Se NMR Chemical Shifts: Experimental and Theoretical Investigations
Authors: Nakanishi Waro , Hayashi Satoko , Shimizu Daisuke , Hada Masahiko
Published: March 2006

The orientational effect of p‐YC6H4 (Ar) on δ(Se) is elucidated for ArSeR, based on experimental and theoretical investigations. The effect is examined in the cases in which SeCR in ArSeR is either in the Ar plane (pl) or is perpendicular to the plane (pd). 9‐(Arylselanyl)anthracenes (1) and 1‐(arylselanyl)anthraquionones (2) are employed to establish the effect in pl and pd, respectively. Large upfield shifts are observed for Y=NMe2, OMe, and Me, and large downfield shifts for Y=COOEt, CN, and NO2 in 1, relative to Y=H, as is expected. Large upfield shifts are brought by Y=NMe2, OMe, Me, F, Cl, and Br, and downfield shifts by Y=CN and NO2 in 2, relative to Y=H, with a negligible shift by Y=COOEt. Absolute magnetic shielding tensors of Se (σ(Se)) are calculated for ArSeR (R=H, Me, and Ph), assuming pl and pd, based on the DFT‐GIAO method. Observed characters are well explained by the total σ(Se). Paramagnetic terms (σp(Se)) are governed by (σp(Se)xx+σp(Se)yy), in which the direction of np(Se) (constructed by 4pz(Se)) is set to the z axis. The main interaction in pl is the np(Se)–π(C6H4)–pz(Y) type. The Y dependence in pl occurs through admixtures of 4pz(Se) in π(SeC6H4Y) and π*(SeC6H4Y), modified by the conjugation, with 4px(Se) and 4py(Se) in σ(CSeX) and σ*(CSeX) (X=H or C) under a magnetic field. The main interaction in pd is the σ(CSeX)–π(C6H4)–px(Y) type, in which SeX is nearly on the x axis. The Y dependence in pd mainly arises from admixtures of 4pz(Se) in np(Se) with 4px(Se) and 4py(Se) in modified σ*(CSeX), since np(Se) is filled with electrons. It is demonstrated that the effect of Y on σp(Se) in the pl conformation is the same regardless of whether Y is an electron‐donor or electron‐acceptor, whereas for pd conformations the effect is greater when Y is an electron donor, as observed in 1 and 2, respectively. Contributions of each molecular orbital and each transition on σp(Se) are evaluated, which enables us to recognize and visualize the effect clearly.
Conformational, Concomitant Polymorphs of 4,4‐Diphenyl‐2,5‐cyclohexadienone: Conformation and Lattice Energy Compensation in the Kinetic and Thermodynamic Forms
Authors: Roy Saikat , Banerjee Rahul , Nangia Ashwini , Kruger Gert J.
Published: March 2006

4,4‐Diphenyl‐2,5‐cyclohexadienone (1) crystallized as four conformational polymorphs and a record number of 19 crystallographically independent molecules have been characterized by low‐temperature X‐ray diffraction: form A (P21, Z′=1), form B (P$\bar 1$, Z′=4), form C (P$\bar 1$, Z′=12), and form D (Pbca, Z′=2). We have now confirmed by variable‐temperature powder X‐ray diffraction that form A is the thermodynamic polymorph and B is the kinetic form of the enantiotropic system A–D. Differences in the packing of the molecules in these polymorphs result from different acidic CH donors approaching the CO acceptor in CH⋅⋅⋅O chains and in synthons I–III, depending on the molecular conformation. The strength of the CH⋅⋅⋅O interaction in a particular structure correlates with the number of symmetry‐independent conformations (Z′) in that polymorph, that is, a short CH⋅⋅⋅O interaction leads to a high Z′ value. Molecular conformation (Econf) and lattice energy (Ulatt) contributions compensate each other in crystal structures A, B, and D resulting in very similar total energies: Etotal of the stable form A=1.22 kcal mol−1, the metastable form B=1.49 kcal mol−1, and form D=1.98 kcal mol−1. Disappeared polymorph C is postulated as a high‐Z′, high‐energy precursor of kinetic form B. Thermodynamic form A matches with the third lowest energy frame based on the value of Ulatt determined in the crystal structure prediction (Cerius2, COMPASS) by full‐body minimization. Re‐ranking the calculated frames on consideration of both Econf (Spartan 04) and Ulatt energies gives a perfect match of frame #1 with stable structure A. Diphenylquinone 1 is an experimental benchmark used to validate accurate crystal structure energies of the kinetic and thermodynamic polymorphs separated by <0.3 kcal mol−1 (∼1.3 kJ mol−1).
A Dynamic Tricopper Double Helicate
Authors: Hutin Marie , Frantz Richard , Nitschke Jonathan R.
Published: March 2006

The reaction between 8‐aminoquinoline, 1,10‐phenantholine‐2,9‐dicarbaldehyde, and copper(I) tetrafluoroborate gave a quantitative yield of a tricopper double helicate. The presence of dynamic covalent imine (CN) bonds allowed this assembly to participate in two reactions not previously known in helicate chemistry: 1) It could be prepared through subcomponent substitution from a dicopper double helicate that contained aniline residues. An electron‐poor aniline was quantitatively displaced; a more electron‐rich aniline competed effectively with the aminoquinoline, setting up an equilibrium between dicopper and tricopper helicates that could be displaced towards the tricopper through the addition of further copper(I). 2) Both dicopper and tricopper helicates could be prepared simultaneously from a mixture of phenanthroline dialdehyde, aniline, and aminoquinoline, which contained all possible imine condensation products in equilibrium. Following the addition of copper(I), thermodynamic equilibration on both covalent and coordinative levels eliminated all partially‐formed and mixed imine ligands from the mixture, leaving the helicates as exclusive products.
On the Structure and Chemical Bonding of Tri‐Tungsten Oxide Clusters W3On‐ and W3On (n = 7—10): W3O8 as a Potential Molecular Model for O‐Deficient Defect Sites in Tungsten Oxides
Authors: Huang Xin , Zhai Hua‐Jin , Li Jun , Wang Lai‐Sheng
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Syntheses, Structure, and Bonding of Rb14(Mg1‐xInx)30. A Nonstoichiometric Phase with an Unusual Substitution in the Anion Framework.
Authors: Li Bin , Corbett John D.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Hydride Ion as a Two‐Electron Donor in a Nanoporous Crystalline Semiconductor 12CaO×7Al2O3.
Authors: Hayashi Katsuro , Sushko Peter V. , Shluger Alexander L. , Hirano Masahiro , Hosono Hideo
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Chemical Vapor Transport of Solid Solutions. Part 26. Formation of Mixed Phases and Chemical Vapor Transport in the Systems TiS2/NbS2, TiSe2/NbSe2, NbS2/TaS2 and NbSe2/TaSe2.
Authors: Hotje U. , Wartchow R. , Binnewies M.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Electrochemical and Spectroscopic Studies of the Chloro and Oxochloro Complex Formation of Nb(V) and Ta(V) in NaCl—AlCl3 Melts.
Authors: von Barner J. H. , Bjerrum N. J.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis and Characterization of Two Open‐Framework Germanates Containing Double Four‐Ring Building Units.
Authors: Lin Zhi‐En , Zheng Shou‐Tian , Yang Guo‐Yu
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
V4S9Br4: A Novel High‐Spin Vanadium Cluster Thiobromide with Square‐Planar Metal Core.
Authors: Mironov Yuri V. , Yarovoi Spartak S. , Naumov Dmitry Y. , Kozlova Svetlana G. , Ikorsky Vladimir N. , Kremer Reinhard K. , Simon Arndt , Fedorov Vladimir E.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A New Preparative Approach to HgPbP14 Structure Type Materials: Crystal Structure of Cu0.73(1)Sn1.27(1)P14 and Characterization of M1‐xSn1+xP14 (M: Cu, Ag) and AgSbP14.
Authors: Lange Stefan , Sebastian C. Peter , Nilges Tom
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis, Structure, and Magnetic Properties of Sr2NiOsO6 and Ca2NiOsO6: Two New Osmium‐Containing Double Perovskites.
Authors: Macquart Rene , Kim Seung‐Joo , Gemmill William R. , Stalick Judith K. , Lee Yongjae , Vogt Tom , zur Loye Hans‐Conrad
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Al‐Catalyzed Enantioselective Alkylation of α‐Ketoesters by Dialkylzinc Reagents. Enhancement of Enantioselectivity and Reactivity by an Achiral Lewis Base Additive.
Authors: Wieland Laura C. , Deng Hongbo , Snapper Marc L. , Hoveyda Amir H.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Asymmetric Multicomponent Domino Reactions and Highly Enantioselective Conjugated Addition of Thiols to α,β‐Unsaturated Aldehydes.
Authors: Marigo Mauro , Schulte Tobias , Franzen Johan , Joergensen Karl Anker
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Asymmetric Organocatalysis with Novel Chiral Thiourea Derivatives: Bifunctional Catalysts for the Strecker and Nitro‐Michael Reactions.
Authors: Tsogoeva Svetlana B. , Yalalov Denis A. , Hateley Martin J. , Weckbecker Christoph , Huthmacher Klaus
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Asymmetric Direct Vinylogous Michael Reaction of Activated Alkenes to Nitroolefins Catalyzed by Modified Cinchona Alkaloids.
Authors: Xue Dong , Chen Ying‐Chun , Wang Qi‐Wei , Cun Ling‐Feng , Zhu Jin , Deng Jin‐Gen
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Diastereoselective Synthesis of Five‐ and Seven‐Membered Rings by [2 + 2 + 1], [3 + 2], [3 + 2 + 2], and [4 + 3] Carbocyclization Reactions of β‐Substituted (Alkenyl)(methoxy)carbene Complexes with Methyl Ketone Lithium Enolates.
Authors: Barluenga Jose , Alonso Jorge , Fananas Francisco J.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
One‐Pot Synthesis of New Imidazo[1,2‐a]pyridine and Imidazo[1,2‐a]pyrimidine Derivatives.
Authors: Georgescu Florentina , Georgescu Emilian , Draghici Constantin , Iuhas Paula C. , Filip Petru I.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Novel Nitrogen‐Containing Chelating Ligands from Aziridines — Preparation, Coordination Studies, and Catalytic Application in the Cyclopropanation of Styrene.
Authors: Krasnova Larissa B. , Yudin Andrei K.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Kumada Coupling of Aryl and Vinyl Tosylates under Mild Conditions.
Authors: Limmert Michael E. , Roy Amy H. , Hartwig John F.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Quinolinium Fluorochromate: An Efficient and Convenient Reagent for Oxidative Cleavage of Thioacetals to Their Parent Carbonyl Compounds.
Authors: Tajbakhsh Mahmood , Alimohammadi Kamal , Ramzanian‐Lehmali Farhad , Barghamadi Mohamad , Shakeri Alireza
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Four‐Component Pd‐Catalyzed Cascade/Ring Closing Metathesis. Synthesis of Heterocyclic Enones.
Authors: Grigg Ronald , Martin William , Morris James , Sridharan Visuvanathar
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Sulfur Dioxide Mediated One‐Pot, Four‐Component Synthesis of Polyfunctional Sulfones and Sulfonamides, Including Medium‐Ring Cyclic Derivatives.
Authors: Bouchez Laure C. , Turks Maris , Dubbaka Srinivas Reddy , Fonquerne Freddy , Craita Cotinica , Laclef Sylvain , Vogel Pierre
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
β Elimination of a Phosphonate Group from an Alkoxyl Radical — Intramolecular Acylation Using Acylphosphonate Derivatives as Carbonyl Group Acceptors.
Authors: Cho Chang Ho , Kim Sunggak
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
[12]Annulynes.
Authors: Gard Matthew N. , Kiesewetter Matthew K. , Reiter Richard C. , Stevenson Cheryl D.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Regioselective Nitration of N,N‐Dialkylanilines Using Cerium(IV) Ammonium Nitrate in Acetonitrile.
Authors: Yang Xianghua , Xi Chanjuan , Jiang Yanfeng
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A Powerful Broensted Acid Catalyst for the Organocatalytic Asymmetric Transfer Hydrogenation of Imines.
Authors: Hoffmann Sebastian , Seayad Abdul Majeed , List Benjamin
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A Novel Ruthenium Catalyzed Deracemization of Alcohols.
Authors: Adair Gareth R. A. , Williams Jonathan M. J.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis, Structure Determination, and Hydroformylation Activity of N‐Heterocyclic Carbene Complexes of Rhodium.
Authors: Chen Austin C. , Allen Daryl P. , Crudden Cathleen M. , Wang Ruiyao , Decken Andreas
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Asymmetric Phase Transfer Catalyzed Glycolate Alkylation: Investigation of the Scope, and Application to the Synthesis of (‐)‐Ragaglitazar.
Authors: Andrus Merritt B. , Hicken Erik J. , Stephens Jeffrey C. , Bedke D. Karl
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Ruthenium‐Catalyzed Asymmetric Hydrogenation of α‐ and β‐Keto Esters in Ionic Liquids Using Chiral P‐Phos Ligand.
Authors: Lam Kim Hung , Xu Lijin , Feng Lichun , Ruan Jiwu , Fan Qinghua , Chan Albert S. C.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Mild and Reversible Dehydration of Primary Amides with PdCl2 in Aqueous Acetonitrile.
Authors: Maffioli Sonia I. , Marzorati Ettore , Marazzi Alessandra
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A Convenient Procedure for Palladium‐Catalyzed Cyanation Using a Unique Bidentate Phosphorus Ligand.
Authors: Jensen Rader S. , Gajare Anil S. , Toyota Kozo , Yoshifuji Masaaki , Ozawa Fumiyuki
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Asymmetric Synthesis of α‐ and α,β‐Substituted β‐Alkoxycarbonyl Sulfonates.
Authors: Enders Dieter , Adelbrecht Jean‐Claude , Harnying Wacharee
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Highly Selective Photo‐Catalytic Dimerization of α‐Methylstyrene by a Novel Palladium Complex with Photosensitizing Ruthenium(II) Polypyridyl Moiety.
Authors: Inagaki Akiko , Edure Shinichi , Yatsuda Shinichi , Akita Munetaka
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Acid‐Catalyzed ortho‐Alkylation of Anilines with Styrenes: An Improved Route to Chiral Anilines with Bulky Substituents.
Authors: Cherian Anna E. , Domski Gregory J. , Rose Jeffrey M. , Lobkovsky Emil B. , Coates Geoffrey W.
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Palladium‐Catalyzed Cross‐Coupling of Baylis—Hillman Acetate Adducts with Organosilanes.
Authors: Kabalka George W. , Dong Gang , Venkataiah Bollu , Chen Chunlan
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Gold‐Catalyzed Cycloisomerization of o‐Alkynylbenzaldehydes with a Pendant Unsaturated Bond: [3 + 2] Cycloaddition of Gold‐Bound 1,3‐Dipolar Species with Dipolarophiles.
Authors: Kim Nakjoong , Kim Yeongmi , Park Wooram , Sung Dokyung , Gupta Aruna Kumar , Oh Chang Ho
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Cyclohexenones as Michael Acceptors in the Staunton—Weinreb Annulation: A Simple Stannane Modification for the Synthesis of Polycyclic Systems.
Authors: Hill Bryan , Rodrigo Russell
Published: March 2006

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.