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Showing papers in "Chemical Reviews in 2001"




Journal ArticleDOI

4,511 citations




Journal ArticleDOI
TL;DR: A detailed study of the structure of Perovskites and their properties in the context of a reducing Atmosphere andHydrogenation and Hydrogenolysis Reactions 2006 shows that the structure and properties of these minerals have changed little in the intervening years.
Abstract: II. Structure of Perovskites 1982 A. Crystal Structure 1982 B. Nonstoichiometry in Perovskites 1983 1. Oxygen Nonstoichiometry 1983 2. Cation Nonstoichiometry 1984 C. Physical Properties 1985 D. Adsorption Properties 1986 1. CO and NO Adsorption 1986 2. Oxygen Adsorption 1987 E. Specific Surface and Porosity 1987 F. Thermal Stability in a Reducing Atmosphere 1989 III. Acid−Base and Redox Properties 1990 A. Acidity and Basicity 1990 B. Redox Processes 1991 1. Kinetics and Mechanisms 1992 2. Reduction−Oxidation Cycles 1993 C. Ion Mobility 1993 1. Oxygen Transport 1993 2. Cation Transport 1994 IV. Heterogeneous Catalysis 1995 A. Oxidation Reactions 1995 1. CO Oxidation 1995 2. Oxidation of Hydrocarbons 1996 B. Pollution Abatement 2001 1. NOx Decomposition 2001 2. Exhaust Treatment 2002 3. Stability 2004 C. Hydrogenation and Hydrogenolysis Reactions 2004 1. Hydrogenation of Carbon Oxides 2004 2. Hydrogenation and Hydrogenolysis Reactions 2006

2,253 citations


Journal ArticleDOI
TL;DR: I. Foldamer Research 3910 A. Backbones Utilizing Bipyridine Segments 3944 1.
Abstract: III. Foldamer Research 3910 A. Overview 3910 B. Motivation 3910 C. Methods 3910 D. General Scope 3912 IV. Peptidomimetic Foldamers 3912 A. The R-Peptide Family 3913 1. Peptoids 3913 2. N,N-Linked Oligoureas 3914 3. Oligopyrrolinones 3915 4. Oxazolidin-2-ones 3916 5. Azatides and Azapeptides 3916 B. The â-Peptide Family 3917 1. â-Peptide Foldamers 3917 2. R-Aminoxy Acids 3937 3. Sulfur-Containing â-Peptide Analogues 3937 4. Hydrazino Peptides 3938 C. The γ-Peptide Family 3938 1. γ-Peptide Foldamers 3938 2. Other Members of the γ-Peptide Family 3941 D. The δ-Peptide Family 3941 1. Alkene-Based δ-Amino Acids 3941 2. Carbopeptoids 3941 V. Single-Stranded Abiotic Foldamers 3944 A. Overview 3944 B. Backbones Utilizing Bipyridine Segments 3944 1. Pyridine−Pyrimidines 3944 2. Pyridine−Pyrimidines with Hydrazal Linkers 3945

1,922 citations




Journal ArticleDOI
TL;DR: 4. Automated Interpretation of CID Spectra 282 5. Accurate Mass Tags 282 C. Protein Identification in Complex Mixtures 282 D. Analysis of Protein Expression 284 III.
Abstract: 4. Automated Interpretation of CID Spectra 282 5. Accurate Mass Tags 282 C. Protein Identification in Complex Mixtures 282 D. Analysis of Protein Expression 284 III. Proteomes and Post-Translational Modifications 285 A. Proteomes 285 1. The Analytical Challenge 285 2. Analysis of Protein−Protein Complexes 286 B. Post-Translational Modifications 286 1. Background 286 2. Detection and Purification of Phosphoproteins 288

1,416 citations



Journal ArticleDOI
TL;DR: The goal of the "Opportunities for Catalysis Research in Carbon Management" workshop was to review within the context of greenhouse gas/carbon issues the current state of knowledge, barriers to further scientific and technological progress, and basic scientific research needs in the areas of H2 generation and utilization.
Abstract: There is increased recognition by the world’s scientific, industrial, and political communities that the concentrations of greenhouse gases in the earth’s atmosphere, particularly CO_2, are increasing. For example, recent studies of Antarctic ice cores to depths of over 3600 m, spanning over 420 000 years, indicate an 80 ppm increase in atmospheric CO_2 in the past 200 years (with most of this increase occurring in the past 50 years) compared to the previous 80 ppm increase that required 10 000 years.2 The 160 nation Framework Convention for Climate Change (FCCC) in Kyoto focused world attention on possible links between CO2 and future climate change and active discussion of these issues continues.3 In the United States, the PCAST report4 “Federal Energy Research and Development for the Challenges of the Twenty First Century” focused attention on the growing worldwide demand for energy and the need to move away from current fossil fuel utilization. According to the U.S. DOE Energy Information Administration,5 carbon emission from the transportation (air, ground, sea), industrial (heavy manufacturing, agriculture, construction, mining, chemicals, petroleum), buildings (internal heating, cooling, lighting), and electrical (power generation) sectors of the World economy amounted to ca. 1823 million metric tons (MMT) in 1990, with an estimated increase to 2466 MMT in 2008-2012 (Table 1).

Journal ArticleDOI
TL;DR: 1. Multifunctional Initiators.
Abstract: 1. Multifunctional Initiators. 3749 2. Multifunctional Linking Agents 3751 3. Use of Difunctional Monomers 3754 B. Star−Block Copolymers 3754 C. Functionalized Stars 3755 1. Functionalized Initiators 3755 2. Functionalized Terminating Agents 3756 D. Asymmetric Stars 3757 1. Molecular Weight Asymmetry 3757 2. Functional Group Asymmetry 3760 3. Topological Asymmetry 3761 E. Miktoarm Star Polymers 3761 1. Chlorosilane Method 3761 2. Divinylbenzene Method 3766 3. Diphenylethylene Derivative Method 3766 4. Synthesis of Miktoarm Stars by Other Methods 3770






Journal ArticleDOI
TL;DR: These studies on macromolecular chiral catalysts demonstrate that these materials are potentially very useful for practical applications and can also be preserved in the rigid and sterically regular polymer provided the catalytically active species of the monomer catalyst is not its aggregate.
Abstract: Because of the tremendous effort of a great number of researchers, the catalytic asymmetric dialkylzinc addition to aldehydes has become a mature method. Ligands of diverse structures have been obtained, and high enantioselectivity for all different types of aldehydes have been achieved. Among the representative excellent catalysts are compounds 1, 8, 120, 325, 352, and 360 discussed above. However, compared to the well-developed dialkylzinc addition, the catalytic asymmetric reactions of aryl-, vinyl-, and alkynylzinc reagents with aldehydes are still very much under developed. Although catalysts such as (S)-402 and 210 prepared by Pu and Bolm have shown good enantioselectivity for the reaction of diphenylzinc with certain aromatic and aliphatic aldehydes, the generality of these catalysts for other [formula: see text] arylzinc reagents have not been studied. The vinylzinc additions using ligands 1 and 412 reported by Oppolzer and Wipf were highly enantioselective for certain aromatic aldehydes but not as good for aliphatic aldehydes. Carreira discovered highly enantioselective alkynylzinc additions to aldehydes promoted by the chiral amino alcohol 415, but this process was not catalytic yet. Ishizaki achieved good enantioselectivity for the catalytic alkynylzinc addition to certain aldehydes by using compounds 160, but the enantioselectivity for simple linear aliphatic aldehydes was low. Another much less explored area is the organozinc addition to ketones. Yus and Fu showed very promising results by using ligands 381 and 406 for both dialkylzinc and diphenylzinc additions to ketones, but the scope of these reactions were still very limited. Therefore, more work is needed for the aryl-, vinyl-, and alkynylzinc additions and for the organozinc addition to ketones, although many good catalysts have been obtained for the dialkylzinc addition to aldehydes. Development of these reactions will allow the catalytic asymmetric synthesis of a great variety of functional chiral alcohols that are either the structural units or synthons of many important organic molecules as well as molecules of biological functions. Macromolecular chiral catalysts have become a very attractive research subject in recent years because these materials offer the advantages of simplified product isolation, easy recovery of the generally quite expensive chiral catalysts, and potential use for continuous production. Three types of macromolecules including flexible achiral polymers anchored with chiral catalysts, rigid and sterically regular main chain chiral polymers, and chiral dendrimers have been used for the asymmetric organozinc addition to aldehydes. Among these materials, the binaphthyl-based polymers such as (R)-451 developed by Pu have shown very high and general enantioselectivity. Study of the binaphthyl polymers in the asymmetric organozinc addition has demonstrated that it is possible to systematically modify the structure and function of the rigid and sterically regular polymer for the development of highly enantioselective polymer catalysts. The catalytic properties of highly enantioselective monomer catalysts can also be preserved in the rigid and sterically regular polymer provided the catalytically active species of the monomer catalyst is not its aggregate. The TADDOL-based polymers and dendrimers prepared by Seebach showed very high and stable enantioselectivity for the diethylzinc addition to benzaldehyde even after many cycles. These studies on macromolecular chiral catalysts demonstrate that these materials are potentially very useful for practical applications.


Journal ArticleDOI
TL;DR: 2. Thiol Oxidation to Disulfides 3007 3. Epoxidation of Alkenes 3007 4.Oxidation of Bromide 3008 5. Oxidation of Mercaptoethanol by Dioxygen 3008 V.
Abstract: 2. Thiol Oxidation to Disulfides 3007 3. Epoxidation of Alkenes 3007 4. Oxidation of Bromide 3008 5. Oxidation of Mercaptoethanol by Dioxygen 3008 V. Particle−Dendrimer Assemblies 3008 1. Hydrogenation 3008 2. Heck Reaction 3010 3. Anodic Oxidation of Ethanol 3010 VI. Redox Catalysis 3010 1. Anodic Oxygen Reduction 3010 2. Cathodic Reduction of CO2 to CO 3010 3. Ferrocenes as Redox Mediators for Glucose Oxidation 3010



Journal ArticleDOI
TL;DR: The chiral architectures from macromolecular building blocks were discussed and the conformational dynamics of the helicity and their effect on the physical properties of the polymers and the induction of helicity in the polymer chain were elaborated.
Abstract: The chiral architectures from macromolecular building blocks were discussed. The conformational dynamics of the helicity and their effect on the (photo)physical properties of the polymers and the induction of helicity in the polymer chain were elaborated. The influence of kinetics on the macromolecular secondary structure and the use of multiple interactions in the hierarchical organization of macromolecules to well-defined supramolecular assemblied were also examined.

Journal ArticleDOI
TL;DR: The most recently synthesized rod-coil copolymers and their supramolecular structures are highlighted, which shows that rod segments can endow various functionalities such as photophysical and electrochemical properties to the supramolescular materials.
Abstract: One of the fascinating subjects in areas such as materials science, nanochemistry, and biomimetic chemistry is concerned with the creation of supramolecular architectures with well-defined shapes and functions. Self-assembly of molecules through noncovalent forces including hydrophobic and hydrophilic effects, electrostatic interactions, hydrogen bonding, microphase segregation, and shape effects has the great potential for creating such supramolecular structures.1-5 An example is provided by rodlike macromolecules whose solutions and melts exhibit liquid crystalline phases such as nematic and/or layered smectic structures with the molecules arranged with their long axes nearly parallel to each other.6,7 The main factor governing the geometry of the supramolecular structures in the liquid crystalline phase is the anisotropic aggregation of the molecules. In contrast, coil-coil diblock molecules consisting of different immiscible segments exhibit a wide range of microphase-separated supramolecular structures with curved interfaces in addition to layered structures.8-11 This phase behavior is mainly due to the mutual repulsion of the dissimilar blocks and the packing constraints imposed by the connectivity of each block. The covalent linkage of these different classes of molecules to a single linear polymer chain (rod-coil copolymer) can produce a novel class of self-assembling materials since the molecules share certain general characteristics of diblock molecules and rodlike liquid crystalline molecules.12-15 The difference in chain rigidity of stiff rodlike and flexible coillike block is expected to greatly affect the details of molecular packing and thus the nature of thermodynamically stable supramolecular structures. This rod-coil molecular architecture imparts microphase separation of the rod and coil blocks into ordered periodic structures even at very low molecular weights relative to flexible block copolymers due to the high stiffness difference between the blocks. As a consequence, the rod-coil copolymer forms supramolecular structures with dimensions as small as few nanometers, which are not common in microphaseseparated flexible block copolymers.16 The supramolecular structures of rod-coil polymers arise from a combination of organizing forces including the mutual repulsion of the dissimilar blocks and the packing constraints imposed by the connectivity of each block, and the tendency of the rod block to form orientational order. Apart from the wide range of different supramolecular structures in nanoscale dimensions, another unique characteristic is that rod segments can endow various functionalities such as photophysical and electrochemical properties to the supramolecular materials. Many of the syntheses of rod-coil diblock and triblock copolymers as well as their interesting supramolecular structures and the intriguing properties of rod-coil copolymers are discussed in excellent books and reviews that have been published by several experts in the field.16-19 Here, we do not want to present a complete overview on reported rod-coil copolymers. Instead, we have highlighted the most recently synthesized rod-coil copolymers and their supramolecular structures.

Journal ArticleDOI
TL;DR: In this paper, a review of high-resolution X-ray emission and Xray absorption spectroscopy is presented, where the focus is on the 3D transition-metal systems.
Abstract: In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption process. Section II discusses 1s X-ray absorption, i.e., the K edges, and section III deals with 2p X-ray absorption, the L edges. X-ray emission is discussed in, respectively, the L edges. X-ray emission is discussed in, respec-tively, and section V on 2p3s and 2p3d X-ray emission. Section VI focuses on magnetic dichroism effects, and in section VII selective X-ray absorption experiments are discussed. To limit the scope of this review paper, many related topics (for example, EELS, XPS, and resonant photoemission, phonon-oriented inelastic X-ray scat-tering, and X-ray microscopy) will not be discussed. In addition, many aspects of X-ray absorption, such as reflection experiments, diffraction absorption fine structure, and related experiments, will remain untouched. EXAFS will be discussed very briefly, and its X-ray emission analogue EXEFS 69,71 will not be discussed.




Journal ArticleDOI
TL;DR: Microbial polymers are synthesized from renewable low-cost feedstocks, and the polymerizations operate under mild process conditions with minimal environmental impact, providing products that, when disposed, can degrade to nontoxic products.
Abstract: In nature, living organisms are constantly producing different macromolecules for their metabolic needs. These macromolecules, such as polysaccharides, polynucleotides, proteins, or polyesters, are essential to organism survival. Their synthesis generally involves in vivo enzyme-catalyzed chaingrowth polymerization reactions of activated monomers, which are generally formed within the cells by complex metabolic processes. Because of their diversity and renewability, microbial polymers such as polysaccharides, bacterial polyhydroxyalkanoates (1) and polyanions such as poly(γ-glutamic acid) (2) have received increasing attention as candidates for industrial applications. In many cases, microorganisms carry out polymer syntheses that are impractical or impossible to accomplish with conventional chemistry. Thus, microbial catalysts enable the production of materials that might otherwise be unavailable. Microbial polymers are synthesized from renewable low-cost feedstocks, and the polymerizations operate under mild process conditions with minimal environmental impact. In addition, microbial polymers provide products that, when disposed, can degrade to nontoxic products.