CNRS Coordination Chemistry

Toulouse, France

CNRS Coordination Chemistry

Toulouse, France
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Mignani S.,University of Paris Descartes | El Kazzouli S.,Institute of Nanomaterials and Nanotechnology | Bousmina M.,Hassan II Academy of science and Technology | Majoral J.-P.,CNRS Coordination Chemistry
Advanced Drug Delivery Reviews | Year: 2013

Drugs are introduced into the body by numerous routes such as enteral (oral, sublingual and rectum administration), parenteral (intravascular, intramuscular, subcutaneous and inhalation administration), or topical (skin and mucosal membranes). Each route has specific purposes, advantages and disadvantages. Today, the oral route remains the preferred one for different reasons such as ease and compliance by patients. Several nanoformulated drugs have been already approved by the FDA, such as Abelcet®, Doxil®, Abraxane® or Vivagel®(Starpharma) which is an anionic G4-poly(l-lysine)-type dendrimer showing potent topical vaginal microbicide activity. Numerous biochemical studies, as well as biological and pharmacological applications of both dendrimer based products (dendrimers as therapeutic compounds per se, like Vivagel®) and dendrimers as drug carriers (covalent conjugation or noncovalent encapsulation of drugs) were described. It is widely known that due to their outstanding physical and chemical properties, dendrimers afforded improvement of corresponding carried-drugs as dendrimer-drug complexes or conjugates (versus plain drug) such as biodistribution and pharmacokinetic behaviors. The purpose of this manuscript is to review the recent progresses of dendrimers as nanoscale drug delivery systems for the delivery of drugs using enteral, parenteral and topical routes. In particular, we focus our attention on the emerging and promising routes such as oral, transdermal, ocular and transmucosal routes using dendrimers as delivery systems. © 2013 Elsevier B.V.

Buchwalter P.,CNRS Coordination Chemistry | Rose J.,CNRS Coordination Chemistry | Braunstein P.,CNRS Coordination Chemistry
Chemical Reviews | Year: 2015

Multimetallic catalysis is based on the combined action of different metals in a chemical transformation. It has witnessed rapidly increasing developments during the past decades in numerous areas of chemistry. Almost inevitably, the exact nature of a catalytically (very) active species remains usually unknown due to its elusiveness, whether in homogeneous or in heterogeneous phases. When heterometallic clusters are used as precatalysts, it remains to be demonstrated whether they retain their integrity during the catalytic cycle, and one cannot claim without strong evidence that they are the actual catalysts. The strength of the metal-support interactions is also known to considerably influence the catalytic properties. In addition, the structure and composition of a surface will also strongly depend on the interacting substrates, and reconstructions and selective metal migration from the core to the surface, or vice versa, are well-known phenomena.

Hureau C.,CNRS Coordination Chemistry | Hureau C.,National Polytechnic Institute of Toulouse
Coordination Chemistry Reviews | Year: 2012

Metal ions, mainly copper, zinc and iron, have been involved in several processes associated with the etiology of Alzheimer disease (AD). Amyloid deposits found in AD patients' brains, known as senile plaques, are one of the morphological hallmarks of this neurodegenerative disorder. They are mostly constituted of aggregated and fibrillar forms of amyloid-β (Aβ) peptides but also contain high concentrations of metal ions (in the mM range). Because the Aβ peptide in its monomeric soluble form exist in healthy patients, step(s) in the process leading to the formation of the senile plaques is(are) key for the Aβ neurotoxicity. Aβ is obtained by specific cleavage of the Amyloid Precursor Protein (APP). Both Aβ peptides and APP contain metal ions binding sites and metal ions coordination may impact their intrinsic properties. For instance, in the case of Aβ peptides, metal ions modulate Aβ aggregation propensity and redox properties of redox active ions such as copper and iron are altered by binding to Aβ.The main objective of the present review is to give an overview of the structural evidence available nowadays concerning coordination to APP and Aβ peptides of redox active ions, i.e. copper(I/II) and iron(II/III). Copper(II) site in the so-called copper binding site of APP was determined by X-ray crystallography and is {Nimτ(His147)Nimπ(His151),PhO-(Tyr168),2Owater}. More recently, in APP, a copper(II) site made of four imidazole rings from His outside the copper binding domain was characterized by X-ray diffraction. Two copper(II) sites in Aβ co-exist at physiological pH, noted components I and II, where I (resp. II) is predominant at lower (resp. higher) pH. In I and II, the equatorial binding sites of copper(II) are {NH 2 (Asp1), CO (Asp1-Ala2), N im (His6), N im (His13 or His14),} and {NH 2 (Asp1), N - (Asp1-Ala2), CO (Ala2-Glu3), N im (His6 or His13 or His14)}, respectively. Copper(I) is linearly bound to Aβ via two imidazole rings from the His residues. Such highly different environments of copper in its two redox states impact the properties of the copper redox couple and will be briefly commented on in the present review. Regarding iron binding to APP and Aβ, preliminary data, which essentially show that iron(II) is the sole redox state able to interact with APP and Aβ, are described. © 2012 Elsevier B.V.

Dognon J.-P.,CNRS Coordination Chemistry
Coordination Chemistry Reviews | Year: 2014

The chemical bonding in actinide compounds is usually analyzed by inspecting the shape and the occupation of the orbitals or by calculating bond orders which are based on orbital overlap and occupation numbers. However, this may not give a definite answer because the choice of the partitioning method may strongly influence the result leading sometimes to qualitatively different answers. This review highlights that the joint and complementary tools such as charge, orbital, quantum chemical topology and energy decomposition analyses are very powerful to understand chemical bonding in the field of actinide chemistry. However, understanding the actinide-ligand bond is not straightforward and requires caution in the use of these methods. This review is illustrated through applications to newly discovered bent actinocene compounds and actinide endohedral clusters fulfilling a 32-electron rule. © 2013 Elsevier B.V.

Meunier B.,CNRS Coordination Chemistry
Angewandte Chemie - International Edition | Year: 2012

A bright future for small molecules: Drugs based on molecules made by chemists are far from old-fashioned. Although biopharmaceuticals developed during the last two decades may have caught the public's imagination, traditional drugs remain a strong force in the pharmaceutical industry. Effective, inexpensive small-molecule drugs are crucial in fighting diseases and maintaining cost-effective health care. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lavigne G.,CNRS Coordination Chemistry
Angewandte Chemie - International Edition | Year: 2012

The selective redistribution of hydrocarbon chains C (n) on a polyhydrido triruthenium cyclopentadienyl complex (see scheme; Rured spheres) involves a repeated sequence of face-to-face C-H group transfers (A to C) through the open cluster B, followed by individual concerted skeletal rearrangements on the two faces (C to A'). This process is just one of several spectacular examples illustrating the power of a molecular polymetallic system. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pitie M.,CNRS Coordination Chemistry | Pratviel G.,Toulouse 1 University Capitole
Chemical Reviews | Year: 2010

A study was conducted to demonstrate activation of DNA carbon-hydrogen bonds by metal complexes. It was demonstrated that active species, formed by activation of O 2 or H 2O 2 with metal complexes was divided into three categories. The most commonly used metals in the field of oxygen activation and DNA damage were iron, copper, and manganese. It was also demonstrated that a triple helix strategy was necessary when sequence selective oxidation of a DNA duplex target was desired. Proteins were found to be alternative macromolecules that were able to selectively target large DNA sequences apart from oligonucleotides. A final strategy for targeting a metal complex to bind DNA consisted of the preparation of conjugates with agents able to form a covalent linkage with DNA.

Poli R.,CNRS Coordination Chemistry
European Journal of Inorganic Chemistry | Year: 2011

The reactions engaged by organic radicals with transition-metal complexes are reviewed with a particular focus on how they can interplay with and affect the results of radical polymerization. Radicals can either add to a metal centre to establish metal-carbon bonds, abstract an atom or group, be abstracted by an atom or group, undergo associative exchange, transfer a β-H atom or add to existing ligands in the metal coordination sphere. Reversibility is key for certain controlled polymerization methods. The various ways in which metal complexes can play a role in radical polymerization lead to atom-transfer radical polymerization (ATRP), organometallic-mediated radical polymerization by either reversible termination (OMRP-RT) or degenerative transfer (OMRP-DT) and chain-transfer-catalysed radical polymerization (CTCRP). Radicals react with transition-metal complexes in many different ways. The type of reaction, when reversible, is relevant to the outcome of metal-mediated radical polymerizations. This article analyses all these reactivity patterns and their relevance to radical polymerization processes, attempting to identify trends and principles of general use. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA.

Thuery P.,CNRS Coordination Chemistry
Crystal Growth and Design | Year: 2012

The crystal structures of the complexes formed under hydrothermal conditions by uranyl ions with 4-aminobenzoic (HL1), 4-amino-3-methylbenzoic (HL2), 4-(aminomethyl)benzoic (HL3), and 3-amino-5-hydroxybenzoic (HL4) acids, in the presence of cucurbit[6]uril (CB6), have been determined. These ligands have been chosen because, in their zwitterionic form, they display both a metal-complexing carboxylate group and an ammonium group able to associate with CB6 through ion-dipole and hydrogen bonding interactions. The complexes [H 2NMe 2] 2[(UO 2) 2(L1) 2O(OH)(H 2O)] 2•CB6•15H 2O (1) and [H 2NMe 2] 2[(UO 2) 2(L2) 2O(OH)(H 2O)] 2•CB6• 17H 2O (2) were obtained in the presence of dimethylformamide, which gives dimethylammonium ions in situ. The latter are held at the CB6 portals, while the tetranuclear uranyl complex with the aminobenzoate anions is not bound to CB6. The neutral, ammonium-containing form of the ligand is present in [UO 2(HL3)(OH)(HCOO)(H 2O)] 2•2CB6•2DMF•14H 2O (3), in which the di(μ 2-hydroxo)-bridged, dinuclear uranyl complex displays two diverging, monodentate HL3 ligands. The latter are associated with two CB6 molecules to give a dumbbell-shaped supramolecular assembly. Three CB6 molecules are assembled around a tetranuclear uranyl complex in [(UO 2) 4(HL3) 2(L3)O 2(OH) 2(H 2O) 4]•2CB6•0.5CB8•HL3•NO 3•20H 2O (4), with two of them being bridging and giving rise to a one-dimensional, linear supramolecular architecture. Finally, the 3-amino substituted ligand HL4 gives the highly symmetric complex [UO 2(HL4)(L4) 2]•3CB6•16H 2O (5), in which the uranyl ion is chelated by three carboxylate groups. Three CB6 molecules are assembled around the planar complex to give a triangular, discrete species. In compounds 3-5, the usual packing of CB6 molecules into columns or layers is not retained as it is frequently in the presence of uranyl complexes. This is due to the CB6-assembling role of the heterodifunctional ligands, which hold the CB6 molecules at the periphery of mono-, di-, or tetranuclear uranyl complexes of quite usual, planar geometry. © 2011 American Chemical Society.

Sculfort S.,CNRS Coordination Chemistry | Braunstein P.,CNRS Coordination Chemistry
Chemical Society Reviews | Year: 2011

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-d10 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 d10-d10 interactions. Although the focus of this review is on d10-d10 interactions involving metals from the group 11, we shall also briefly examine for comparison some complexes displaying intramolecular d10-d 10 interactions involving metals from other groups (188 references). © 2011 The Royal Society of Chemistry.

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