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Henrion M.,CNRS Molecular Chemistry Laboratory | Ritleng V.,CNRS Molecular Chemistry Laboratory | Ritleng V.,Luniversite Of Strasbourg Usias | Chetcuti M.J.,CNRS Molecular Chemistry Laboratory
ACS Catalysis | Year: 2015

The chemistry of nickel N-heterocyclic carbene complexes is a research area that has blossomed over the last 10 years, and a large number of new complexes with a variety of architectural motifs are now known. The evolution of this chemistry has led to increasing applications of these complexes in catalytic bond formation. The rapid expansion of this field now calls for a review of the kinds of reactions that are catalyzed and a summary of the state of the art at this time. As the breadth of reactions catalyzed by such complexes is vast, this review specifically targets catalytic C-C bond formation, in particular C-C cross-couplings and C-C couplings via C-H bond activation, mediated by nickel-N-heterocyclic carbene complexes. A special emphasis is placed on mechanistic data, because this allows possible new insights into catalyst improvement. © 2015 American Chemical Society.


Compain P.,CNRS Molecular Chemistry Laboratory | Compain P.,Institut Universitaire de France | Bodlenner A.,CNRS Molecular Chemistry Laboratory
ChemBioChem | Year: 2014

A bunch of keys, one lock: The multivalent effect in glycosidase inhibition is a new, rapidly emerging area with exciting potential and scope. This review presents a description of the different types of neoglycoclusters and their evaluation as glycosidase inhibitors. The first promising therapeutic applications are discussed, as well as the mechanisms underlying the observed inhibitory multivalent effect. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Iehl J.,CNRS Molecular Chemistry Laboratory | Nierengarten J.-F.,CNRS Molecular Chemistry Laboratory | Harriman A.,Northumbria University | Bura T.,CNRS The Institute of Chemistry and Processes for Energy, Environment and Health | Ziessel R.,CNRS The Institute of Chemistry and Processes for Energy, Environment and Health
Journal of the American Chemical Society | Year: 2012

A sophisticated model of the natural light-harvesting antenna has been devised by decorating a C 60 hexa-adduct with ten yellow and two blue boron dipyrromethene (Bodipy) dyes in such a way that the dyes retain their individuality and assist solubility of the fullerene. Unusually, the fullerene core is a poor electron acceptor and does not enter into light-induced electron-transfer reactions with the appended dyes, but ineffective electronic energy transfer from the excited-state dye to the C 60 residue competes with fluorescence from the yellow dye. Intraparticle electronic energy transfer from yellow to blue dyes can be followed by steady-state and time-resolved fluorescence spectroscopy and by excitation spectra for isolated C 60 nanoparticles dissolved in dioxane at 293 K and at 77 K. The decorated particles can be loaded into polymer films by spin coating from solution. In the dried film, efficient energy transfer occurs such that photons absorbed by the yellow dye are emitted by the blue dye. Films can also be prepared to contain C 60 nanoparticles loaded with the yellow Bodipy dye but lacking the blue dye and, under these circumstances, electronic energy migration occurs between yellow dyes appended to the same nanoparticle and, at higher loading, to dye molecules on nearby particles. Doping these latter polymer films with the mixed-dye nanoparticle coalesces these multifarious processes in a single system. Thus, long-range energy migration occurs among yellow dyes attached to different particles before trapping at a blue dye. In this respect, the film resembles the natural photosynthetic light-harvesting complexes, albeit at much reduced efficacy. The decorated nanoparticles sensitize amorphous silicon photocells. © 2011 American Chemical Society.


Nierengarten I.,CNRS Molecular Chemistry Laboratory | Nierengarten J.-F.,CNRS Molecular Chemistry Laboratory
Chemistry - An Asian Journal | Year: 2014

Among the large variety of bioactive C60 derivatives, fullerene derivatives substituted with sugar residues, that is, glycofullerenes, are of particular interest. The sugar residues are not only solubilizing groups; their intrinsic biological properties also provide additional appealing features to the conjugates. The most recent advances in the synthesis and the biological applications of glycofullerenes are summarized in the present review article with special emphasis on globular glycofullerenes, that is, fullerene sugar balls, constructed on a hexa-substituted fullerene scaffold. The high local concentration of carbohydrates around the C60 core in fullerene sugar balls is perfectly suited to the binding of lectins through the "glycoside cluster effect", and these compounds are potential anti-adhesive agents against bacterial infection. Moreover, mannosylated fullerene sugar balls have shown antiviral activity in an Ebola pseudotyped infection model. Finally, when substituted with peripheral iminosugars, dramatic multivalent effects have been observed for glycosidase inhibition. These unexpected observations have been rationalized by the interplay of interactions involving the catalytic site of the enzyme and non-glycone binding sites with lectin-like abilities. Sweet 60s: The most recent advances in the synthesis and biological applications of glycofullerenes are summarized in the present review article, with special emphasis on globular glycofullerenes, that is, fullerene sugar balls, constructed on a hexa-substituted fullerene scaffold. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Oertel A.M.,CNRS Molecular Chemistry Laboratory | Ritleng V.,CNRS Molecular Chemistry Laboratory | Chetcuti M.J.,CNRS Molecular Chemistry Laboratory
Organometallics | Year: 2012

Cyclopentadienyl N-heterocyclic carbene (NHC) nickel complexes of general formula [Ni(R-NHC-nBu)XCp] [R-NHC-nBu = 1-butyl-3-methyl-, 1-isopropyl-3-butyl-, 1-phenyl-3-butyl-, 1-(2,4,6-trimethylphenyl)-3-butyl-, 1-(2,6- diisopropylphenyl)-3-butyl-imidazol-2-ylidene; X = Cl or I; Cp = η 5-C 5H 5], which bear an n-butyl side-chain attached to one of the nitrogen atoms of the NHC ring, were synthesized as models for trialkoxysilylpropyl-substituted complexes. They were prepared by the direct reactions of nickelocene with the corresponding imidazolium salts (R-NHC-nBu̇HX). The new complexes [Ni(Me-NHC-nBu)ClCp] (1a), [Ni(iPr-NHC-nBu)ClCp] (1b), [Ni(Ph-NHC-nBu)ICp] (1c), [Ni(Mes-NHC-nBu)ICp] (1d), and [Ni(iPr 2Ph-NHC-nBu)ICp] (1e) were obtained in moderate to good yields and were fully characterized by standard spectroscopic techniques, and in the cases of 1a,b,d,e by single-crystal X-ray crystallography. The bulky electron-rich pentamethylcyclopentadienyl derivatives, [Ni(Mes-NHC-nBu) ICp*] (2d) and [Ni(iPr 2Ph-NHC-nBu)ICp*] (2e) (Cp* = η 5-C 5Me 5), were prepared from reactions of in situ prepared [Ni(acac)Cp*] with the corresponding carbene precursors. Both Cp* complexes were also fully characterized spectroscopically, and their structures were established by single-crystal X-ray crystallography. All new complexes catalyzed the Suzuki-Miyaura cross-coupling of phenylboronic acid with aryl halides in the absence of cocatalysts or reductants. However, the small dialkyl-substituted species 1a and 1b proved to be the least efficient. In addition, in contrast to our previous results with the closely related diaryl-substituted species [Ni(Ar 2NHC)LCp †] (L = Cl -, NCMe (PF 6 -); Cp † = Cp, Cp*), in which complexes that bear the electron-rich Cp* ligand were much more active than those bearing the Cp ligand, no substantial catalytic behavior differences were observed between the Cp complexes 1d,e and their Cp* counterparts 2d,e. A TOF of up to 352 h -1, a so far unprecedented rate for nickel(II) complexes under similar conditions, was even observed with the Cp complex 1d. In view of these encouraging results, the triethoxysilylpropyl-substituted analogue of 1d, [Ni(Mes-NHC-TES)ClCp] (1d-TES) (Mes-NHC-TES = 1-(2,4,6-trimethylphenyl)-3-[3-(triethoxysilyl)propyl]imidazol-2- ylidene), was prepared, fully characterized, and tested catalytically. As it showed similar catalytic activity to 1d, it was heterogenized on alumina to give 1d-Al. The latter species, however, exhibited a greatly reduced catalytic activity compared to 1d and 1d-TES. Possible reasons for both the excellent activities of 1d and 1d-TES and the disappointing activity of 1d-Al are discussed. © 2012 American Chemical Society.


Kleinschmidt J.H.,The Interdisciplinary Center | Popot J.-L.,CNRS Molecular Chemistry Laboratory
Archives of Biochemistry and Biophysics | Year: 2014

Amphipols (APols) are a family of amphipathic polymers designed to keep transmembrane proteins (TMPs) soluble in aqueous solutions in the absence of detergent. APols have proven remarkably efficient at (i) stabilizing TMPs, as compared to detergent solutions, and (ii) folding them from a denatured state to a native, functional one. The underlying physical-chemical mechanisms are discussed. © 2014 Elsevier Inc. All rights reserved.


Nierengarten I.,CNRS Molecular Chemistry Laboratory | Nierengarten J.-F.,CNRS Molecular Chemistry Laboratory
Chemical Record | Year: 2015

Click reactions largely cross the borders of organic synthetic chemistry and are now at the forefront of many interdisciplinary studies at the interfaces between chemistry, physics, and biology. As part of this research, our group is involved in a program on the development of clickable fullerene building blocks and their application in the preparation of a large variety of new advanced materials and bioactive compounds. Importantly, the introduction of the click chemistry concept in fullerene chemistry allowed us to produce compounds that would barely be accessible by using the classical tools of fullerene chemistry. This is particularly the case for the conjugation of fullerenes with other carbon nanoforms, such as carbon nanohorns and graphene. It is also the case for most of the sophisticated molecular ensembles constructed from clickable fullerene hexa-adduct building blocks. In this paper, we have summarized our ongoing progress in this particular field. © 2014 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Iehl J.,CNRS Molecular Chemistry Laboratory | Nierengarten J.-F.,CNRS Molecular Chemistry Laboratory
Chemical Communications | Year: 2010

A fullerene hexakis-adduct incorporating complementary reactive centres with very different and selective reactivity has been prepared and functionalized with three different peripheral groups by successive alkyne-azide and thiol-ene click reactions. © 2010 The Royal Society of Chemistry.


Choppin S.,CNRS Molecular Chemistry Laboratory | Ferreiro-Medeiros L.,CNRS Molecular Chemistry Laboratory | Barbarotto M.,CNRS Molecular Chemistry Laboratory | Colobert F.,CNRS Molecular Chemistry Laboratory
Chemical Society Reviews | Year: 2013

The classical Reformatsky reaction introduced for the first time in 1887 has been recognized as one among the most useful methods for C-C bond formation. Diastereoselective versions based on the use of chiral auxiliaries as well as enantioselective protocols using chiral ligands have been successfully developed during the last few years. This tutorial review highlights the main recent achievements (since 2004) in the diastereoselective Reformatsky reaction; diastereochemical control has been efficiently achieved using a large variety of chiral auxiliaries to perform the synthesis of specific cyclic and acyclic chiral moieties. The diastereoselective Reformatsky reactions employed in the total synthesis of natural products are also described. © 2013 The Royal Society of Chemistry.


Wencel-Delord J.,CNRS Molecular Chemistry Laboratory | Colobert F.,CNRS Molecular Chemistry Laboratory
Chemistry - A European Journal | Year: 2013

A "niche" topic in the past decade, the asymmetric C-H bond activation has been attracting growing interest over the last few years. Particularly significant advances have been achieved in the field of direct, stereoselective transformations of C(sp2)-H bonds. This Concept article intends to showcase different types of asymmetric C(sp2)-H bond activation reactions, emphasising both the nature of the stereo-discriminating step and the variability of valuable scaffolds that could be rapidly constructed by means of such strategies. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA.

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