Institut de Chimie de Strasbourg

Oxidative stress is known to play an important role in the pathogenesis of a number of diseases. In particular, it is linked to the etiology of Alzheimer's disease (AD), an age-related neurodegenerative disease and the most common cause of dementia in the elderly. Histopathological hallmarks of AD are intracellular neurofibrillary tangles and extracellular formation of senile plaques composed of the amyloid-beta peptide (Aβ) in aggregated form along with metal-ions such as copper, iron or zinc. Redox active metal ions, as for example copper, can catalyze the production of Reactive Oxygen Species (ROS) when bound to the amyloid-β (Aβ). The ROS thus produced, in particular the hydroxyl radical which is the most reactive one, may contribute to oxidative damage on both the Aβ peptide itself and on surrounding molecule (proteins, lipids, …). This review highlights the existing link between oxidative stress and AD, and the consequences towards the Aβ peptide and surrounding molecules in terms of oxidative damage. In addition, the implication of metal ions in AD, their interaction with the Aβ peptide and redox properties leading to ROS production are discussed, along with both in vitro and in vivo oxidation of the Aβ peptide, at the molecular level.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRu-, Rh-, and Pd-Catalyzed C−C Bond Formation Involving C−H Activation and Addition on Unsaturated Substrates: Reactions and Mechanistic AspectsVincent Ritleng, Claude Sirlin, and Michel PfefferView Author Information Laboratoire de Synthèses Métallo-Induites, UMR CNRS 7513 Université Louis Pasteur, 4, rue Blaise Pascal 67070 Strasbourg, France Cite this: Chem. Rev. 2002, 102, 5, 1731–1770Publication Date (Web):April 4, 2002Publication History Received13 October 2001Published online4 April 2002Published inissue 1 May 2002https://pubs.acs.org/doi/10.1021/cr0104330https://doi.org/10.1021/cr0104330research-articleACS PublicationsCopyright © 2002 American Chemical SocietyRequest reuse permissionsArticle Views23427Altmetric-Citations1854LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Addition reactions,Aromatic compounds,Catalysts,Hydrocarbons,Ligands Get e-Alerts

This recommendation proposes a definition for the term “halogen bond”, which designates a specific subset of the inter- and intramolecular interactions involving a halogen atom in a molecular entity.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTPhotoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and EfficacyPetr Klán*†‡, Tomáš Šolomek†‡, Christian G. Bochet§, Aurélien Blanc∥, Richard Givens⊥, Marina Rubina⊥, Vladimir Popik#, Alexey Kostikov#, and Jakob Wirz∇View Author Information† Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic‡ Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, Kamenice 3, 625 00 Brno, Czech Republic§ Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland∥ Institut de Chimie, University of Strasbourg, 4 rue Blaise Pascal, 67000 Strasbourg, France⊥ Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, 5010 Malott Hall, Lawrence, Kansas 66045, United States# Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States∇ Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland*E-mail: [email protected]. Phone: +420-54949-4856. Fax: +420-54949-2443.Cite this: Chem. Rev. 2013, 113, 1, 119–191Publication Date (Web):December 21, 2012Publication History Received29 April 2012Published online21 December 2012Published inissue 9 January 2013https://doi.org/10.1021/cr300177kCopyright © 2012 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views77851Altmetric-Citations1248LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (17 MB) Get e-AlertscloseSUBJECTS:Alcohols,Fluorescence,Irradiation,Organic compounds,Reaction products Get e-Alerts

Abstract A unified scale is recommended for reporting the NMR chemical shifts of all nuclei relative to the 1 H resonance of tetramethylsilane (TMS). The unified scale is designed to provide a precise ratio, Ξ , of the resonance frequency of a given nuclide to that of the primary reference, the 1H resonance of TMS in dilute solution (volume fraction, φ < 1%) in chloroform. Referencing procedures are discussed, including matters of practical application of the unified scale. Special attention is paid to recommended reference samples, and values of Ξ for secondary references on the unified scale are listed, many of which are the results of new measurements. Some earlier recommendations relating to the reporting of chemical shifts are endorsed. The chemical shift, δ , is redefined to avoid previous ambiguities but to leave practical usage unchanged. Relations between the unified scale and recently published recommendations for referencing in aqueous solutions (for specific use in biochemical work) are discussed, as well as the special effects of working in the solid state with magic-angle spinning. In all, nine new recommendations relating to chemical shifts are made. Standardized nuclear spin data are also presented in tabular form for the stable (and some unstable) isotopes of all elements with nonzero quantum numbers. The information given includes quantum numbers, isotopic abundances, magnetic moments, magnetogyric ratios and receptivities, together with quadrupole moments and line-width factors where appropriate.

Intersystem crossing (ISC), formally forbidden within nonrelativistic quantum theory, is the mechanism by which a molecule changes its spin state. It plays an important role in the excited state decay dynamics of many molecular systems and not just those containing heavy elements. In the simplest case, ISC is driven by direct spin-orbit coupling between two states of different multiplicities. This coupling is usually assumed to remain unchanged by vibrational motion. It is also often presumed that spin-allowed radiationless transitions, i.e. internal conversion, and the nonadiabatic coupling that drives them, can be considered separately from ISC and spin-orbit coupling owing to the vastly different time scales upon which these processes are assumed to occur. However, these assumptions are too restrictive. Indeed, the strong mixing brought about by the simultaneous presence of nonadiabatic and spin-orbit coupling means that often the spin, electronic, and vibrational dynamics cannot be described independently. Instead of considering a simple ladder of states, as depicted in a Jablonski diagram, one must consider the more complicated spin-vibronic levels. Despite the basic ideas being outlined in the 1960s, it is only with the advent of high-level theory and femtosecond spectroscopy that the importance of the spin-vibronic mechanism for ISC in both fundamental as well as applied research fields has been revealed with significant impact across chemistry, physics, and biology. In this review article, we present the theory and fundamental principles of the spin-vibronic mechanism for ISC. This is followed by empirical rules to estimate the rate of ISC within this regime. The most recent developments in experimental techniques, theoretical methods, and models for the spin-vibronic mechanism are discussed. These concepts are subsequently illustrated with examples, including the ISC mechanisms in transition metal complexes, small organic molecules, and organic chromophores.

Ligand design is becoming an increasingly important part of the synthetic activity in chemistry. This is of course because of the subtle control that ligands exert on the metal center to which they are coordinated. Ligands which contain significantly different chemical functionalities, such as hard and soft donors, are often called hybrid ligands and find increasing use in molecular chemistry. Although the interplay between electronic and steric properties has long been recognized as essential in determining the chemical or physical properties of a complex, predictions remain very difficult, not only because of the considerable diversity encountered within the Periodic Table-different metal centers will behave differently towards the same ligand and different ligands can completely modify the chemistry of a given metal-but also because of the small energy differences involved. New systems may-even through serendipity-allow the emergence of useful concepts that can gain general acceptance and help design molecular structures orientated towards a given property. The concept of ligand hemilability, which finds numerous illustrations with hybrid ligands, has gained increased acceptance and been found to be very useful in explaining the properties of metal complexes and in designing new systems for molecular activation, homogeneous catalysis, functional materials, or small-molecule sensing. In the field of homogeneous enantioselective catalysis, in which steric and/or electronic control of a metal-mediated process must occur in such a way that one stereoisomer is preferentially formed, ligands containing one or more chiral oxazoline units have been found to be very valuable for a wide range of metal-catalyzed reactions. The incorporation of oxazoline moieties in multifunctional ligands of increasing complexity makes such ligands good candidates to display hemilabile properties, which until recently, had not been documented in oxazoline chemistry. Herein, we briefly recall the definition and scope of hemilabile ligands, present the main classes of ligands containing one or more oxazoline moieties, with an emphasis on hybrid ligands, and finally explain why the combination of these two facets of ligand design appears particularly promising.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTMultimetallic Catalysis Based on Heterometallic Complexes and ClustersPaulin Buchwalter*, Jacky Rosé*, and Pierre Braunstein*View Author Information Laboratoire de Chimie de Coordination (UMR 7177 CNRS), Institut Le Bel - Université de Strasbourg, 4, rue Blaise Pascal F-67081, Strasbourg, France*Tel.: +33 3 68851308. E-mail: [email protected]*E-mail: [email protected]*E-mail: [email protected]Cite this: Chem. Rev. 2015, 115, 1, 28–126Publication Date (Web):December 29, 2014Publication History Received14 April 2014Published online29 December 2014Published inissue 14 January 2015https://pubs.acs.org/doi/10.1021/cr500208khttps://doi.org/10.1021/cr500208kreview-articleACS PublicationsCopyright © 2014 American Chemical SocietyRequest reuse permissionsArticle Views16019Altmetric-Citations650LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Catalysts,Cluster chemistry,Hydrocarbons,Hydrogenation,Selectivity Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransition Metal-Containing Rotaxanes and Catenanes in Motion: Toward Molecular Machines and MotorsJean-Pierre SauvageView Author Information Laboratoire de Chimie Organo-Minérale, UMR 7513 du CNRS, Université Louis Pasteur, Faculté de Chimie, 4, rue Blaise Pascal, 67070 Strasbourg Cedex, France Cite this: Acc. Chem. Res. 1998, 31, 10, 611–619Publication Date (Web):June 9, 1998Publication History Received20 November 1997Published online9 June 1998Published inissue 1 October 1998https://pubs.acs.org/doi/10.1021/ar960263rhttps://doi.org/10.1021/ar960263rresearch-articleACS PublicationsCopyright © 1998 American Chemical SocietyRequest reuse permissionsArticle Views4844Altmetric-Citations762LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Catenanes,Molecules,Rearrangement,Redox reactions,Rotaxanes Get e-Alerts

More than 40 antimicrobial peptides and proteins (AMPs) are expressed in the oral cavity. These AMPs have been organized into 6 functional groups, 1 of which, cationic AMPs, has received extensive attention in recent years for their promise as potential antibiotics. The goal of this review is to describe recent advances in our understanding of the diverse mechanisms of action of cationic AMPs and the bacterial resistance against these peptides. The recently developed peptide GL13K is used as an example to illustrate many of the discussed concepts. Cationic AMPs typically exhibit an amphipathic conformation, which allows increased interaction with negatively charged bacterial membranes. Peptides undergo changes in conformation and aggregation state in the presence of membranes; conversely, lipid conformation and packing can adapt to the presence of peptides. As a consequence, a single peptide can act through several mechanisms depending on the peptide's structure, the peptide:lipid ratio, and the properties of the lipid membrane. Accumulating evidence shows that in addition to acting at the cell membrane, AMPs may act on the cell wall, inhibit protein folding or enzyme activity, or act intracellularly. Therefore, once a peptide has reached the cell wall, cell membrane, or its internal target, the difference in mechanism of action on gram-negative and gram-positive bacteria may be less pronounced than formerly assumed. While AMPs should not cause widespread resistance due to their preferential attack on the cell membrane, in cases where specific protein targets are involved, the possibility exists for genetic mutations and bacterial resistance. Indeed, the potential clinical use of AMPs has raised the concern that resistance to therapeutic AMPs could be associated with resistance to endogenous host-defense peptides. Current evidence suggests that this is a rare event that can be overcome by subtle structural modifications of an AMP.

The Online Chemical Modeling Environment is a web-based platform that aims to automate and simplify the typical steps required for QSAR modeling. The platform consists of two major subsystems: the database of experimental measurements and the modeling framework. A user-contributed database contains a set of tools for easy input, search and modification of thousands of records. The OCHEM database is based on the wiki principle and focuses primarily on the quality and verifiability of the data. The database is tightly integrated with the modeling framework, which supports all the steps required to create a predictive model: data search, calculation and selection of a vast variety of molecular descriptors, application of machine learning methods, validation, analysis of the model and assessment of the applicability domain. As compared to other similar systems, OCHEM is not intended to re-implement the existing tools or models but rather to invite the original authors to contribute their results, make them publicly available, share them with other users and to become members of the growing research community. Our intention is to make OCHEM a widely used platform to perform the QSPR/QSAR studies online and share it with other users on the Web. The ultimate goal of OCHEM is collecting all possible chemoinformatics tools within one simple, reliable and user-friendly resource. The OCHEM is free for web users and it is available online at http://www.ochem.eu.

Transition-metal-containing rotaxanes can behave as linear motors at the molecular level. The molecules are set into motion either by an electrochemical reaction or using a chemical signal. In a first example, a simple rotaxane is described that consists of a ring threaded by a two-coordination-site axle. The ring contains a bidentate ligand, coordinated to a copper center. The axle incorporates both a bidentate and a terdentate ligand. By oxidizing or reducing the copper center to Cu(II) or Cu(I) respectively, the ring glides from a given position on the axle to another position and vice versa. By generalizing the concept to a rotaxane dimer, whose synthesis involves a quantitative double-threading reaction triggered by copper(I) complexation, a molecular assembly reminiscent of a muscle is constructed. By exchanging the two metal centers of the complex (copper(I)/zinc(II)), a large-amplitude movement is generated, which corresponds to a contraction/stretching process. The copper(I)-containing rotaxane dimer is in a stretched situation (overall length approximately 8 nm), whereas the zinc(II) complexed compound is contracted (length approximately 6.5 nm). The stretching/contraction process is reversible and it is hoped that, in the future, other types of signals can be used (electrochemical or light pulse) to trigger the motion.

Protein misfolding and aggregation is observed in many amyloidogenic diseases affecting either the central nervous system or a variety of peripheral tissues. Structural and dynamic characterization of all species along the pathways from monomers to fibrils is challenging by experimental and computational means because they involve intrinsically disordered proteins in most diseases. Yet understanding how amyloid species become toxic is the challenge in developing a treatment for these diseases. Here we review what computer, in vitro, in vivo, and pharmacological experiments tell us about the accumulation and deposition of the oligomers of the (Aβ, tau), α-synuclein, IAPP, and superoxide dismutase 1 proteins, which have been the mainstream concept underlying Alzheimer’s disease (AD), Parkinson’s disease (PD), type II diabetes (T2D), and amyotrophic lateral sclerosis (ALS) research, respectively, for many years.

The authors report the implementation of a simple one-step method for obtaining an infinite-order two-component (IOTC) relativistic Hamiltonian using matrix algebra. They apply the IOTC Hamiltonian to calculations of excitation and ionization energies as well as electric and magnetic properties of the radon atom. The results are compared to corresponding calculations using identical basis sets and based on the four-component Dirac-Coulomb Hamiltonian as well as Douglas-Kroll-Hess and zeroth-order regular approximation Hamiltonians, all implemented in the DIRAC program package, thus allowing a comprehensive comparison of relativistic Hamiltonians within the finite basis approximation.

Copper(I)-induced template synthesis produces a linear rotaxane dimer capable of undergoing contraction and stretching motions of large amplitude under the action of a chemical stimulus (see scheme). The process is reminiscent of those observed in natural muscles.

Many spinel cobaltite oxides meet the requirement for a wide range of electrochemical reactions. These materials have largely been investigated as electrocatalysts for the oxygen evolution reaction (OER) or oxygen reduction reaction (ORR). The objective of this article is to summarize the studies available in the literature on electrochemical and electrocatalytic properties of cobaltite spinel oxides towards the OER and ORR in alkaline media. The main focus of this review is on the recent investigations dealing with the performance of Co3O4 and Co-based spinel oxides as the oxygen electrodes in the light of the earlier published work.

Recent years have seen the rapid development of a new field of palladium catalysis in organic synthesis. This chemistry takes place outside the usually encountered Pd(0)/Pd(II) cycles. It is characterized by the presence of strong oxidants, which prevent further palladium(II)-promoted reactions at a given point of the catalytic cycle by selective metal oxidation. The resulting higher-oxidation-state palladium complexes have been used to develop a series of new synthetic transformations that cannnot be realized within conventional palladium catalysis. This type of catalysis by palladium in a higher oxidation state is of significant synthetic potential.

Weak attractive interactions between closed shell metal ions have been increasingly studied in the last few years and are generally designated as metallophilic interactions. They are best evidenced in the solid state where structural data obtained by X-ray diffraction provide precise information about the distance between the metals involved. The strength of such metal-metal interactions has been compared to that of hydrogen bonding (ca. 7-11 kcal mol(-1)) and is clearly sufficient to bring about novel bonding and structural features and confer interesting physical properties such as luminescence, polychromism, magnetism or one-dimensional electrical conductivity. The Cu(I)-Cu(I), Ag(I)-Ag(I) and Au(I)-Au(I) interactions have been increasingly observed and the latter have certainly been the most studied. Early qualitative analyses of the aurophilic attraction focused on Au-Au bonding originating from 6s, 6p and 5d orbital mixing. Numerous theoretical studies on metallophilic interactions continue to be carried out at various levels of sophistication which take into account relativistic and correlation effects to describe these van der Waals-type interactions. In this critical review, we would like to focus on the synthesis and structures of heterometallic clusters of the transition metals in which intra- rather than intermolecular d(10)-d(10) interactions are at work, in order to limit the role of packing effects. We wish to provide the reader with a comparative overview of the metal core structures resulting from or favoring metallophilic interactions but do not intend to provide a comprehensive coverage of the literature. We will first examine heterometallic clusters displaying homometallic and then heterometallic d(10)-d(10) interactions. Although the focus of this review is on d(10)-d(10) interactions involving metals from the group 11, we shall also briefly examine for comparison some complexes displaying intramolecular d(10)-d(10) interactions involving metals from other groups (188 references).

Abstract Ultrathin metal–organic framework (MOF) nanosheets (NSs) offer potential for many applications, but the synthetic strategies are largely limited to top‐down, low‐yield exfoliation methods. Herein, Ni–M–MOF (M=Fe, Al, Co, Mn, Zn, and Cd) NSs are reported with a thickness of only several atomic layers, prepared by a large‐scale, bottom‐up solvothermal method. The solvent mixture of N,N‐dimethylacetamide and water plays key role in controlling the formation of these two‐dimensional MOF NSs. The MOF NSs can be directly used as efficient electrocatalysts for the oxygen evolution reaction, in which the Ni–Fe–MOF NSs deliver a current density of 10 mA cm−2 at a low overpotential of 221 mV with a small Tafel slope of 56.0 mV dec−1, and exhibit excellent stability for at least 20 h without obvious activity decay. Density functional theory calculations on the energy barriers for OER occurring at different metal sites confirm that Fe is the active site for OER at Ni–Fe–MOF NSs.

Abstract Metal–organic frameworks (MOFs), which consist of central metal nodes and organic linkers, constitute a fast growing class of crystalline porous materials with excellent application potential. Herein, a series of Mn‐based multimetallic MOF (bimetallic and trimetallic MIL‐100) nano‐octahedra are prepared by a facile one‐pot synthetic strategy. The types and proportions of the incorporated elements can be tuned while retaining the original topological structure. The introduction of other metal ions is verified at the atomic level by combining X‐ray absorption fine structure experiments and theoretical calculations. Furthermore, these multimetallic Mn‐based MIL‐100 nano‐octahedra are utilized as sulfur hosts to prepare cathodes for Li–S batteries. The MnNi‐MIL‐100@S cathode exhibits the best Li–S battery performance among all reported MIL‐100@S composite cathode materials, with a reversible capacity of ≈708.8 mAh g −1 after 200 cycles. The synthetic strategy described herein is utilized to incorporate metal ions into the MOF architecture, of which the parent monometallic MOF nano‐octahedra cannot be prepared directly, thus rationally generating novel multimetallic MOFs. Importantly, the strategy also allows for the general synthesis and study of various micro‐/nanoscale MOFs in the energy storage field.