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Le Bideau F.,University Paris - Sud | Dagorne S.,CNRS Strasbourg Institute of Chemistry
Chemical Reviews | Year: 2013

Access to functionalized steroids via metal-mediated homogeneous catalysis lies outside the scope of the present contribution, except when the corresponding discrete transition-metal-functionalized substituted steroids have been isolated. This area has already been comprehensively reviewed elsewhere. Owing to its availability in the cold series, rhenium was also used as a model for technetium in that context. Though the transposition to the radioactive series could not be achieved, this nevertheless allowed access to new species and provided information about their affinities for the studied receptors or their lipophilicities. Nevertheless, substituted cyclopentadienes typically exhibit a limited stability, and besides, their characterization is complicated by their existence as a mixture of isomers. In contrast, fulvenes are easier to synthesize and handle due to their better stability. Moreover, access to a wide variety of cyclopentadienyl metals may be achieved upon varying the reaction conditions and reagents involved.


Bellemin-Laponnaz S.,CNRS Institute of Genetics and of Molecular and Cellular Biology | Bellemin-Laponnaz S.,University of Strasbourg | Dagorne S.,CNRS Strasbourg Institute of Chemistry
Chemical Reviews | Year: 2014

Early transition metal N-Heterocyclic carbenes (NHC) complexes in catalysis remain a field to be explored and developed taking advantage of the robustness/stability imparted to the resulting metal-based catalytically active components. Recent and promising reports on the use of early transition metal NHC complexes in homogeneous catalysis include, most notably, their ability to effectively mediate ketone hydrosilylation, olefin/cyclic esters polymerization, and olefin hydroamination reactions. Recent developments in carbene lithium compounds includevthe isolation and structural characterization of Li+ adductsvbearing abnormal NHCs. In related studies on anionic NHCs, Lavallo and co-workers visolated and characterized a number of Li salts of carborane-containing NHC anions starting from a formally monoanionic carborane N-functionalized imidazolium salt as the protio ligand. Other examples of lithium and potassium NHC compounds have been reported and typically include polydentate ligands incorporating a carbene ligand with an anionic functional group and variously functionalized monodentate NHC ligands.


Salnikov E.S.,CNRS Strasbourg Institute of Chemistry | Bechinger B.,CNRS Strasbourg Institute of Chemistry
Biophysical Journal | Year: 2011

To gain further insight into the antimicrobial activities of cationic linear peptides, we investigated the topology of each of two peptides, PGLa and magainin 2, in oriented phospholipid bilayers in the presence and absence of the other peptide and as a function of the membrane lipid composition. Whereas proton-decoupled 15N solid-state NMR spectroscopy indicates that magainin 2 exhibits stable in-plane alignments under all conditions investigated, PGLa adopts a number of different membrane topologies with considerable variations in tilt angle. Hydrophobic thickness is an important parameter that modulates the alignment of PGLa. In equimolar mixtures of PGLa and magainin 2, the former adopts transmembrane orientations in dimyristoyl-, but not 1-palmitoyl-2-oleoyl- , phospholipid bilayers, whereas magainin 2 remains associated with the surface in all cases. These results have important consequences for the mechanistic models explaining synergistic activities of the peptide mixtures and will be discussed. The ensemble of data suggests that the thinning of the dimyristoyl membranes caused by magainin 2 tips the topological equilibrium of PGLa toward a membrane-inserted configuration. Therefore, lipid-mediated interactions play a fundamental role in determining the topology of membrane peptides and proteins and thereby, possibly, in regulating their activities as well. © 2011 by the Biophysical Society.


Semeril D.,CNRS Strasbourg Institute of Chemistry | Matt D.,CNRS Strasbourg Institute of Chemistry
Coordination Chemistry Reviews | Year: 2014

The goal of this review is twofold: (a) to provide synthetic methodology for the preparation of P(III)- and P(V)-functionalised calix[. n]arenes and resorcin[4]arenes; (b) to give an up-to-date overview of catalytic applications of these ligands. © 2014 Elsevier B.V.


Durot S.,CNRS Strasbourg Institute of Chemistry | Taesch J.,CNRS Strasbourg Institute of Chemistry | Heitz V.,CNRS Strasbourg Institute of Chemistry
Chemical Reviews | Year: 2014

An overview of the synthesis and applications of molecular containers containing more than one porphyrin in their framework and enclosing a three-dimensional (3D) cavity is presented. Multiporphyrinic molecular cages held together by more than two linkers are considered in the review, as these multiple linkers restrict or prevent free rotation of the porphyrin derivatives and in such molecular architectures an internal 3D void space exists. The synthesis of covalent multiporphyrinic cages requires an important effort in the case of a stepwise synthesis which starts with the preparation of a functionalized porphyrin ready to cyclize.


Daniel C.,CNRS Strasbourg Institute of Chemistry
Coordination Chemistry Reviews | Year: 2015

Methodological aspects are highlighted in connection to three important theoretical issues in the field of transition metal complexes photochemistry and photophysics: (i) accuracy of electronic absorption spectra calculation and their interpretation; (ii) photo-induced isomerization and ultra-fast intersystem crossing processes in rhenium (I) α-diimine complexes; (iii) environment effects on absorption spectroscopy and photophysics of ruthenium (II) polypyridyl complexes. The results of recent applications provide an illustration of the role of spin-orbit coupling and environment effects in the photochemistry and photophysics of transition metal complexes and point to the limits of the methods for specific problems, such as accuracy, long-range charge-transfer excited states and biological environment modeling. © 2014 Elsevier B.V.


Dagorne S.,CNRS Strasbourg Institute of Chemistry | Fliedel C.,New University of Lisbon
Topics in Organometallic Chemistry | Year: 2013

This chapter highlights the most recent and representative results on the use of organoaluminum compounds in polymerization catalysis with a special emphasis on discrete Al-incorporating catalysts. The first part of this contribution summarizes recent and noteworthy developments on well-defined Al-based initiators for the controlled (and stereocontrolled) polymerization of various monomers including isobutene, styrene, epoxides, methyl methacrylate, cyclic esters, and cyclic carbonates. The second part discusses the latest significant advances on the synthesis and structural characterization of polynuclear organoaluminum/transition (and f-block) metal complexes relevant to Ziegler-Natta-type catalysis. Graphical Abstract: © Springer-Verlag Berlin Heidelberg 2012.


Gramage-Doria R.,CNRS Strasbourg Institute of Chemistry | Armspach D.,CNRS Strasbourg Institute of Chemistry | Matt D.,CNRS Strasbourg Institute of Chemistry
Coordination Chemistry Reviews | Year: 2013

Although quite common in nature, notably in metalloenzymes, the coordination of transition metals within a confined three dimensional environment has long been hampered by the lack of molecular receptors that may force ligand binding to take place internally. However, an increasing number of appropriate cavity-shaped molecules has become available over the years. Their modification with donor atoms has led to metalloreceptors that can not only bind substrates inside a well-defined hollow space, but which can also promote transformations of the confined guests. This article gives an overview of transition metal complexes capable of directing the binding of exogeneous ligands inside a molecular cavity. Special emphasis is placed on the stabilisation of unusual coordination modes and geometries as well as the role of the cavity in catalysis and metal-assisted molecular recognition. © 2012 Elsevier B.V.


Bianco A.,CNRS Strasbourg Institute of Chemistry
Angewandte Chemie - International Edition | Year: 2013

Graphene is considered the future revolutionary material. For its development, it is of fundamental importance to evaluate the safety profile and the impact on health. Graphene is part of a bigger family which has been identified as the graphene family nanomaterials (GFNs). Clarifying the existence of multiple graphene forms allows better understanding the differences between the components and eventually correlating their biological effects to the physicochemical characteristics of each structure. Some invitro and invivo studies clearly showed no particular risks, while others have indicated that GFNs might become health hazards. This Minireview critically discusses the recent studies on the toxicity of GFNs to provide some perspective on the possible risks to their future development in materials and biomedical sciences. Two sides of the coin: Graphene is part of a bigger family identified as the graphene family nanomaterials (GFNs). For their development, it is important to evaluate the safety profiles and impacts on health. Some studies clearly show no particular risks exist and others indicate that GFNs might become health hazards. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Loison A.,CNRS Strasbourg Institute of Chemistry
Astrobiology | Year: 2010

Laboratory experiments carried out under plausible prebiotic conditions (under conditions that might have occurred at primitive deep-sea hydrothermal vents) in water and involving constituents that occur in the vicinity of submarine hydrothermal vents (e.g., CO, H(2)S, NiS) have disclosed an iterative Ni-catalyzed pathway of C-C bond formation. This pathway leads from CO to various organic molecules that comprise, notably, thiols, alkylmono- and disulfides, carboxylic acids, and related thioesters containing up to four carbon atoms. Furthermore, similar experiments with organic compounds containing various functionalities, such as thiols, carboxylic acids, thioesters, and alcohols, gave clues to the mechanisms of this novel synthetic process in which reduced metal species, in particular Ni(0), appear to be the key catalysts. Moreover, the formation of aldehydes (and ketones) as labile intermediates via a hydroformylation-related process proved to be at the core of the chain elongation process. Since this process can potentially lead to organic compounds with any chain length, it could have played a significant role in the prebiotic formation of lipidic amphiphilic molecules such as fatty acids, potential precursors of membrane constituents.

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