Nos tutelles



Accueil > Publications


publié le , mis à jour le


  • S. P. Babailov, E. V. Peresypkina, Y. Journaux, et K. E. Vostrikova, « Nickel(II) complex of a biradical: Structure, magnetic properties, high NMR temperature sensitivity and moderately fast molecular dynamics », Sensors and Actuators B: Chemical, vol. 239, p. 405-412.

  • P. Barbier Saint Hilaire, A. Warnet, Y. Gimbert, U. M. Hohenester, G. Giorgi, M. - F. Olivier, F. Fenaille, B. Colsch, C. Junot, et J. - C. Tabet, « Mechanistic study of competitive releases of H2O, NH3 and CO2 from deprotonated aspartic and glutamic acids: Role of conformation », Journal of Chromatography B, vol. 1047, p. 64-74.
    Résumé : The aims of this study were to highlight the impact of minor structural differences (e.g. an aminoacid side chain enlargement by one methylene group), on ion dissociation under collision-induced dissociation conditions, and to determine the underlying chemical mechanisms. Therefore, we compared fragmentations of deprotonated aspartic and glutamic acids generated in negative electrospray ionization. Energy-resolved mass spectrometry breakdown curves were recorded and MS3 experiments performed on an Orbitrap Fusion for high-resolution and high-mass accuracy measurements. Activated fragmentations were performed using both the resonant and non-resonant excitation modes (i.e., CID and HCD, respectively) in order to get complementary information on the competitive and consecutive dissociative pathways. These experiments showed a specific loss of ammonia from the activated aspartate but not from the activated glutamate. We mainly focused on this specific observed loss from aspartate. Two different mechanisms based on intramolecular reactions (similar to those occurring in organic chemistry) were proposed, such as intramolecular elimination (i.e. Ei-like) and nucleophilic substitution (i.e. SNi-like) reactions, respectively, yielding anions as fumarate and α lactone from a particular conformation with the lowest steric hindrance (i.e. with antiperiplanar carboxyl groups). The detected deaminated aspartate anion can then release CO2 as observed in the MS3 experimental spectra. However, quantum calculations did not indicate the formation of such a deaminated aspartate product ion without loss of carbon dioxide. Actually, calculations displayed the double neutral (NH3+CO2) loss as a concomitant pathway (from a particular conformation) with relative high activation energy instead of a consecutive process. This disagreement is apparent since the concomitant pathway may be changed into consecutive dissociations according to the collision energy i.e., at higher collision energy and at lower excitation conditions, respectively. The latter takes place by stabilization of the deaminated aspartate solvated with two residual molecules of water (present in the collision cell). This desolvated anion formed is an α lactone substituted by a methylene carboxylate group. The vibrational excitation acquired by [(D−H)−NH3]−during its isolation is enough to allow its prompt decarboxylation with a barrier lower than 8.4 kJ/mol. In addition, study of glutamic acid-like diastereomers constituted by a cyclopropane, hindering any side chain rotation, confirms the impact of the three-dimensional geometry on fragmentation pathways. A significant specific loss of water is only observed for one of these diastereomers. Other experiments, such as stable isotope labeling, need to be performed to elucidate all the observed losses from activated aspartate and glutamate anions. These first mechanistic interpretations enhance understanding of this dissociative pathway and underline the necessity of studying fragmentation of a large number of various compounds to implement properly new algorithms for de novo elucidation of unknown metabolites.
    Mots-clés : CSOB, Electrospray high-resolution mass spectrometry, POLE 3, Regioselective dissociation, Unexpected cleavage of aspartate anion.

  • M. Beaupérin, D. Polat, F. Roudesly, S. Top, A. Vessières, J. Oble, G. Jaouen, et G. Poli, « Approach to ferrocenyl-podophyllotoxin analogs and their evaluation as anti-tumor agents », Journal of Organometallic Chemistry.
    Résumé : Podophyllotoxin is a natural product endowed of a high antimitotic activity and a high affinity for tubulin. Its action results in the cessation of cell division, inducing cell death. However, its high toxicity restrains its use as drug. To overcome this drawback, several chemical modifications of the native podophyllotoxin have been made. However, to date, no reports have so far been directed toward incorporation of a metallocene moiety. The search for new organometallic drugs is a central field in drug discovery, including the domain of cancer therapy. In particular, metallocenyl moieties are known to increase or decrease, depending on the degree of conjugation in the organometallic motif, the selectivity of drugs toward cancer cells. The conjugate organometallic compound reduces the damage of healthy tissues, yet permitting the selective desired antimitotic and cytotoxic effects of the active principle. We report here the synthesis of ferrocene-containing podophyllotoxin analogs and preliminary antiproliferative tests.
    Mots-clés : Antitumor agent, Bioorganometallic chemistry, CHEMBIO, Ferrocene, Multi-step synthesis, Palladium, Podophyllotoxin, POLE 1, POLE 3, ROCS.

  • V. N. Bochatay, L. Debien, F. Chemla, F. Ferreira, O. Jackowski, et A. Perez-Luna, « Synthesis of allenylzinc reagents by 1,2-rearrangement of alkynyl(disilyl)zincates derived from acetylenic epoxides and acetylenic aziridines », Comptes Rendus Chimie.
    Résumé : Lithium alkynyl(disilyl)zincates obtained from metalated ethynyloxiranes, as well as from N-tert-butanesulfinyl(ethynyl)aziridines or N-tert-butanesulfonyl(ethynyl)aziridines, undergo 1,2-migration of the organosilyl group with ring opening of the oxirane or aziridine ring by SNi displacement. A developed protocol that involves nBuLi for the metalation step offers a straightforward approach to the corresponding δ-oxy- and δ-amino α-silyl allenylzinc intermediates. The reagents derived from the epoxides are amenable to subsequent in situ condensation with aldehydes or ketones to provide 1,3-diols but not those derived from aziridines that only react sluggishly in similar condensations.
    Mots-clés : alkynes, carbenoids, POLE 1, rearrangement, ROCS, silicon, Zinc.

  • T. Borelli, S. Brenna, G. Broggini, J. Oble, et G. Poli, « (Diacyloxyiodo)benzenes-Driven Palladium-Catalyzed Cyclizations of Unsaturated N-Sulfonylamides: Opportunities of Path Selection », Advanced Synthesis & Catalysis, vol. 359, nᵒ 4, p. 623-628.
    Résumé : A study of the palladium(II)-catalyzed cyclization of unsaturated N-sulfonylamides was undertaken, using (diacyloxyiodo)benzenes as terminal oxidizing agents. Different reactivities were observed as a function of the nature of the unsaturation (terminal vs. internal), or of the hypervalent iodine compound used (diacetoxyiodobenzene vs. bistrifluoroacetoxyiodobenzene). Proper parameter selection allows the direction of the cyclization to be chosen towards either a global aminoacetoxylation, an allylic amination via aminopalladation, or an allylic amination via allylic C–H activation.
    Mots-clés : allylic compounds, amination, C–H activation, homogeneous catalysis, Palladium, POLE 1, ROCS.

  • E. Darii, S. Alves, Y. Gimbert, A. Perret, et J. - C. Tabet, « Meaning and consequence of the coexistence of competitive hydrogen bond/salt forms on the dissociation orientation of non-covalent complexes », Journal of Chromatography B, vol. 1047, p. 45-58.
    Résumé : Non-covalent complexes (NCC) between hexose monophosphates (HexP) and arginine (R) were analyzed using ESI MS and MS/MS in negative mode under different (hard, HC and soft, SC) desolvation conditions. High resolution mass spectrometry (HRMS) revealed the presence of different ionic species, namely, homo- and heteromultimers of R and HexP. Deprotonated heterodimers and corresponding sodiated species were enhanced under HC likely due to a decrease in available charge number associated with the reduction of H+/Na+ exchange. The quantum calculations showed that the formation of covalent systems is very little exothermic, therefore, such systems are disfavored. Desolvation dependent CID spectra of deprotonated [(HexP+R)‒H]− complexes demonstrated that they can exist within the hydrogen bond (HB) and salt bridge (SB) forms, yielding either NCC separation or covalent bond cleavages, respectively. Although HB forms are the main species, they cannot survive under HC; therefore, the minor SB forms became detectable. Energy-resolved mass spectrometry (ERMS) experiments revealed diagnostic fragment ions from both SB and HB forms, providing evidence that these isomeric forms are inconvertible. SB formation should result from the ionic interactions of highly acidic group of HexP with strongly basic guanidine group of arginine and thus requires an arginine zwitterion (ZW) form. This was confirmed by quantum calculations. Ion-ion interactions are significantly affected by the presence of sodium cation as demonstrated by the fragmentation patterns of sodiated complex species. Regarding CID data, only SB between protonated amino group of R and deprotonated phosphate group of HexP could be suggested, but the primary amine is not enough basic then, the SB must be fleeting. Nevertheless, the observation of the covalent bond cleavages suggests the presence of structures with a free negative charge able to induce fragmentations. Indeed, according to quantum calculations, solvated salt (SS) systems involving Na+/COO− salt solvated by neutral phosphate and negative charge on sugar ring are preferentially formed.
    Mots-clés : CSOB, POLE 3.

  • T. Driant, F. Nachon, C. Ollivier, P. - Y. Renard, et E. Derat, « On the Influence of the Protonation States of Active Site Residues on AChE Reactivation: A QM/MM Approach », ChemBioChem, vol. 18, nᵒ 7, p. 666-675.
    Résumé : Acetylcholinesterase (AChE), an enzyme of the serine hydrolase superfamily, is a mediator of signal transmission at cholinergic synapses by catalyzing acetylcholine cleavage into acetate and choline. This enzyme is vulnerable to covalent inhibition by organophosphate compounds (like VX). Covalent inhibition of AChE does not revert spontaneously. Known reactivator compounds have limited action in restoring catalytic activity. QM/MM simulations of VX-inhibited AChE reactivation by pralidoxime (2-PAM), a classical reactivator, were performed. These afforded a broad view of the effect of protonation states of active-site residues, and provide evidence for the role of Glu202, which needs to be protonated for reactivation to occur. In situ deprotonation of 2-PAM for both protonation states of Glu202 showed that His447 is able to deprotonate 2-PAM with the assistance of Glu202. Because the active site of serine hydrolases is highly conserved, this work provides new insights on the interplay between the catalytic triad residues and this glutamate, newly identified as protonatable.
    Mots-clés : acetylcholinesterase, Computational chemistry, MACO, organophosphate, POLE 1, protonation, QM/MM, reactivation.

  • L. Ferrand, Y. Lyu, A. Rivera-Hernández, B. J. Fallon, M. Amatore, C. Aubert, et M. Petit, « Hydroboration and Diboration of Internal Alkynes Catalyzed by a Well-Defined Low-Valent Cobalt Catalyst », Synthesis.
    Résumé : Thieme E-Books & E-Journals
    Mots-clés : MACO, POLE 1.

  • L. Ferrand, Y. Tang, C. Aubert, L. Fensterbank, V. Mouriès-Mansuy, M. Petit, et M. Amatore, « Niobium-Catalyzed Intramolecular Addition of O–H and N–H Bonds to Alkenes: A Tool for Hydrofunctionalization », Organic Letters, vol. 19, nᵒ 8, p. 2062-2065.
    Résumé : A convenient, versatile, and easy to handle intramolecular hydrofunctionalization of alkenes (C–O and C–N bonds formation) is reported using a novel niobium-based catalytic system. This atom economic and eco-friendly methodology provides an additional synthetic tool for the straightforward formation of valuable building blocks enabling molecular complexity. Various pyran, furan, pyrrolidine, piperidine, lactone, and lactam derivatives as well as spirocyclic compounds are produced in high yields and selectivities.
    Mots-clés : MACO, POLE 1.

  • C. Fopp, K. Isaac, E. Romain, F. Chemla, F. Ferreira, O. Jackowski, M. Oestreich, et A. Perez-Luna, « Stereodivergent Synthesis of β-Heteroatom-Substituted Vinyl­silanes by Sequential Silylzincation–Copper(I)-Mediated Electrophilic­ Substitution », Synthesis, vol. 49, nᵒ 04, p. 724-735.
    Résumé : Thieme E-Books & E-Journals
    Mots-clés : POLE 1, ROCS.

  • G. A. Garcia, H. Dossmann, L. Nahon, S. Daly, et I. Powis, « Identifying and Understanding Strong Vibronic Interaction Effects Observed in the Asymmetry of Chiral Molecule Photoelectron Angular Distributions », ChemPhysChem, vol. 18, nᵒ 5, p. 500-512.
    Résumé : Electron–ion coincidence imaging is used to study chiral asymmetry in the angular distribution of electrons emitted from randomly-oriented enantiomers of two molecules, methyloxirane and trifluoromethyloxirane, upon ionization by circularly polarized VUV synchrotron radiation. Vibrationally-resolved photoelectron circular dichroism (PECD) measurements of the outermost orbital ionization reveal unanticipated large fluctuations in the magnitude of the forward–backward electron scattering asymmetry, including even a complete reversal of direction. Identification and assignment of the vibrational excitations is supported by Franck–Condon simulations of the photoelectron spectra. A previously proposed quasi-diatomic model for PECD is developed and extended to treat polyatomic systems. The parametric dependence of the electronic dipole matrix elements on nuclear geometry is evaluated in the adiabatic approximation. It provokes vibrational level dependent shifts in amplitude and phase, to which the chiral photoelectron angular distributions are especially sensitive. It is shown that single quantum excitation of those vibrational modes, which experience only a relatively small displacement of the ion equilibrium geometry along the normal coordinate and which are then only weakly excited in the Franck–Condon limit, can be accompanied by big shifts in scattering phase; hence the observed big fluctuations in PECD asymmetry for such modes.
    Mots-clés : circular dichroism, CSOB, photoelectron circular dichroism, photoelectron spectroscopy, photoionization, Photophysics, POLE 3.

  • M. Gormen, P. Pigeon, Y. Wang, A. Vessières, S. Top, F. Martial, C. Gros, M. J. McGlinchey, et G. Jaouen, « Side-Chain Effects on the 1-(Bis-aryl-methylidene)-[3]ferrocenophane Skeleton: Antiproliferative Activity against TNBC Cancer Cells and Comparison with the Acyclic Ferrocifen Series », European Journal of Inorganic Chemistry, vol. 2017, nᵒ 2, p. 454-465.
    Résumé : As part of our ongoing study of the toxicity of compounds derived from 1,1-bis(4-hydroxyphenyl)-2-ferrocenylbut-1-ene, we have recently shown that closely analogous [3]ferrocenophane complexes have an in vitro toxicity level substantially higher than that of their ferrocene counterparts, particularly in the case of mono- and diphenol complexes. In this study we have examined whether the presence of a dimethylamino chain, analogous to the chain in hydroxytamoxifen, is capable of producing in the ferrocenophane series the same antiestrogenic effect observed for OH-Tam and Fc-OH-Tam. To this end, we have synthesized and characterized new complexes bearing various side-chains [O(CH2)3NMe2, O(CH2)3piperidine, O(CH2)3pyrrolidine, NHCO(CH2)2NMe2] and studied the biochemical properties of those complexes possessing appropriate solubility. The results revealed that the new complexes of [3]ferrocenophane have very strong antiproliferative effects; one of the compounds bearing an NHCO(CH2)2NMe2 chain has an IC50 value of 0.05 ± 0.02 µm for MDA-MB-231 breast cancer cells. All the complexes showed affinity for the estradiol receptor. At the low (nanomolar range) concentrations at which the estrogenic/antiestrogenic effect is expressed in these molecules, the presence of an amino-substituted side-chain does not induce in the [3]ferrocenophane series the antiestrogenic effect observed with OH-Tam and Fc-OH-Tam. However, this effect has been found for the complex with a slightly longer chain [O(CH2)4NMe2].
    Mots-clés : Antitumor agents, Bioorganometallic chemistry, CHEMBIO, Ferrocene, POLE 3, substituent effects, Toxicity.

  • B. Habchi, S. Alves, D. J. - R. Bouveresse, B. Moslah, A. Paris, Y. Lécluse, P. Gauduchon, P. Lebailly, D. N. Rutledge, et E. Rathahao-Paris, « An innovative chemometric method for processing direct introduction high resolution mass spectrometry metabolomic data: independent component–discriminant analysis (IC–DA) », Metabolomics, vol. 13, nᵒ 4, p. 45.
    Résumé : IntroductionTo perform large scale metabolomic analyses, high throughput approaches are required. The direct introduction mass spectrometry (DIMS) approach appears to be very attractive to achieve this goal. However, processing DIMS data is still very challenging due to the large number of samples and the intrinsic complexity of the mass spectra.ObjectivesThe objective of this study is to develop a computational procedure, based on an innovative chemometric method, i.e. Independent component–discriminant analysis (IC–DA), for processing DIMS data.MethodMetabolomic fingerprints were obtained by direct introduction high resolution mass spectrometry (DI-HRMS) analysis of urine samples of subjects that had been professionally exposed to pesticides. Spectral data were processed using the developed IC–DA procedure. Results obtained from this method were compared to those obtained by the conventional Partial least squares–discriminant analysis (PLS–DA). For both the IC–DA and PLS–DA methods, a validation was performed based on a permutation test.ResultIC–DA results enabled a good detection of discriminant variables and a clear discrimination of control samples and exposure classes whereas a less striking discrimination was obtained with PLS–DA. Putative annotation of these variables was performed using metabolomic databases. Targeted correlation analysis was used for the detection of ions associated with the most discriminant variables, consolidating their identity assignment.ConclusionThis study demonstrated the efficiency of IC–DA to discriminate the different exposure groups. As well the improvement of high throughput metabolomic studies was provided by combining DI–HRMS with this new chemometric tool.
    Mots-clés : CSOB, POLE 3.

  • G. Izzet, F. Volatron, et A. Proust, « Tailor–made Covalent Organic-Inorganic Polyoxometalate Hybrids: Versatile Platforms for the Elaboration of Functional Molecular Architectures », The Chemical Record, vol. 17, nᵒ 2, p. 250-266.
    Résumé : Post-functionalization of organically modified polyoxometalates (POMs) is a powerful synthetic tool to devise functional building blocks for the rational elaboration of POM-based molecular materials. In this personal account we focus on iodoaryl-terminated POM platforms, describe reliable routes to the synthesis of covalent organic-inorganic POM-based hybrids and their integration into advanced molecular architectures or multi-scale assemblies as well as their immobilization onto surfaces. Valorisation of the remarkable redox properties of POMs in the fields of artificial synthesis and molecular electronic is especially considered.
    Mots-clés : artificial photosynthesis, E-POM, modified electrodes, organic-inorganic hybrids, palladium cross-coupling, POLE 2, Polyoxometalates.

  • C. Lévêque, V. Corcé, L. Chenneberg, C. Ollivier, et L. Fensterbank, « Photoredox/Nickel Dual Catalysis for the C(sp3)–C(sp3) Cross-Coupling of Alkylsilicates with Alkyl Halides », European Journal of Organic Chemistry, vol. 2017, nᵒ 15, p. 2118-2121.
    Résumé : Alkylsilicates were engaged under photoredox/nickel dual catalysis conditions with alkyl halides for the first time. The C(sp3)–C(sp3) cross-coupling products were obtained in moderate yields and were accompanied by the homocoupling products of the alkyl halide derivatives. These promising findings are strongly suggestive of the high synthetic potential of the dual catalytic approach for the forging of alkyl carbon–carbon bonds.
    Mots-clés : cross-coupling, C–C coupling, MACO, Nickel, photoredox catalysis, POLE 1, radical reactions.

  • A. Parrot, A. Bernard, A. Jacquart, S. A. Serapian, C. Bo, E. Derat, O. Oms, A. Dolbecq, A. Proust, R. Métivier, P. Mialane, et G. Izzet, « Photochromism and Dual-Color Fluorescence in a Polyoxometalate–Benzospiropyran Molecular Switch », Angewandte Chemie International Edition, vol. 56, nᵒ 17, p. 4872-4876.
    Résumé : The photophysical properties of a Keggin-type polyoxometalate (POM) covalently bounded to a benzospiropyran (BSPR) unit have been investigated. These studies reveal that both closed and open forms are emissive with distinct spectral features (λem (closed form)=530 nm, λem (open form)=670 nm) and that the fluorescence of the BSPR unit of the hybrid is considerably enhanced compared to BSPR parent compounds. While the fluorescence excitation energy of the BSPR reference compounds (370 nm) is close to the intense absorption responsible of the photochromic character (350 nm), the fluorescence excitation of the hybrid is shifted to lower energy (400 nm), improving the population of the emissive state. Combined NOESY NMR and theoretical calculations of the closed form of the hybrid give an intimate understanding of the conformation adopted by the hybrid and show that the nitroaryl moieties of the BSPR is folded toward the POM, which should affect the electronic properties of the BSPR.
    Mots-clés : density functional calculations, E-POM, fluorescence, MACO, molecular photoswitches, photochromism, POLE 1, POLE 2, Polyoxometalates.

  • A. Pontes da Costa, D. Rosa Nunes, M. Tharaud, J. Oble, G. Poli, et J. Rieger, « Pd(0)-Nanoparticles Embedded in Core-Shell Nanogels as Recoverable Catalysts for the Mizoroki-Heck Reaction », ChemCatChem, p. n/a-n/a.
    Résumé : Core-shell nanogels are attractive stabilizers and supports for catalytically active metallic nanoparticles. Herein, we present the synthesis and the characterization of a nanostructured well-defined core-shell nanogel with the ability to stabilize palladium(0) nanoparticles in its core. This hybrid nanogel displays a remarkable stability in both solid state and in solution. This feature allowed its successful application as catalyst for the Mizoroki-Heck reaction between n-butyl acrylate and a series of bromo- and iodo-arenes. The yields spanned from good to excellent, and catalyst recycling could be achieved up to three times without significant activity loss. Three-phase tests indicated that the hybrid nanogel acts as a Pd(0) nano-reservoir. The catalysis proceeds in a quasi-homogenous fashion, with part of the catalytic activity occurring outside the nanogel explaining the observed limited recyclability.
    Mots-clés : Core-Shell Nanogels by PISA, Mizoroki-Heck Reaction, Palladium, POLE 1, RAFT Dispersion Polymerization, Recycling, ROCS.

  • E. Rathahao-Paris, S. Alves, L. Debrauwer, J. - P. Cravedi, et A. Paris, « An efficient data-filtering strategy for easy metabolite detection from the direct analysis of a biological fluid using Fourier transform mass spectrometry », Rapid Communications in Mass Spectrometry, vol. 31, nᵒ 6, p. 485-494.
    Résumé : Rationale High-throughput analyses require an overall analytical workflow including not only a robust and high-speed technical platform, but also dedicated data-processing tools able to extract the relevant information. This work aimed at evaluating post-acquisition data-mining tools for selective extraction of metabolite species from direct introduction high-resolution mass spectrometry data. Methods Investigations were performed on spectral data in which seven metabolites of vinclozolin, a dicarboximide fungicide containing two chloride atoms, were previously manually identified. The spectral data obtained from direct introduction (DI) and high-resolution mass spectrometry (HRMS) detection were post-processed by plotting the mass defect profiles and applying various data-filtering methods based on accurate mass values. Results Exploration of mass defect profiles highlighted, in a specific plotting region, the presence of compounds containing common chemical elements and pairs of conjugated and non-conjugated metabolites resulting from classical metabolic pathways. Additionally, the judicious application of mass defect and/or isotope pattern filters removed many interfering ions from DI-HRMS data, greatly facilitating the detection of vinclozolin metabolites. Compared with previous results obtained by manual data treatment, three additional metabolites of vinclozolin were detected and putatively annotated. Conclusions Tracking simultaneously several specific species could be efficiently performed using data-mining tools based on accurate mass values. The selectivity of the data extraction was improved when the isotope filter was used for halogenated compounds, facilitating metabolite ion detection even for low-abundance species. Copyright © 2016 John Wiley & Sons, Ltd.
    Mots-clés : CSOB, POLE 3.

  • F. Roudesly, J. Oble, et G. Poli, « Metal-catalyzed CH activation/functionalization: The fundamentals », Journal of Molecular Catalysis A: Chemical, vol. 426, Part B, p. 275-296.
    Résumé : An isolated CH bond in a molecule has a very low reactivity owing to the large kinetic barrier associated to the CH bond cleavage and the apolar nature of this bond. For this reason, the selective reactivity of such a non-functional group is under active study since several decades and is still regarded as the Holy Grail in chemistry. Metal-catalyzed CH activation/functionalization chemistry allows the step-economical and original construction of CC as well as CO and CN bonds starting from hydrocarbons (or hydrocarbon fragments) without the need of prior non catalytic oxidation steps. Furthermore, it can be of utmost importance in the domain of multistep syntheses, and also in transformations of societal significance such as the conversion of methane into methanol. This tutorial review addresses to students and researchers who would like to become acquainted with this fascinating topic. After a brief historical introduction, the main mechanistic fundaments of metal-catalyzed CH activation are exposed. Then, a selection of seminal advances and conceptual breakthroughs are presented.
    Mots-clés : C-heteroatom bond formation, CC bond formation, CH activation, CH functionalization, Mechanistic study, POLE 1, ROCS.

  • S. Roy, B. Sharma, J. Pécaut, P. Simon, M. Fontecave, P. D. Tran, E. Derat, et V. Artero, « Molecular Cobalt Complexes with Pendant Amines for Selective Electrocatalytic Reduction of Carbon Dioxide to Formic Acid », Journal of the American Chemical Society, vol. 139, nᵒ 10, p. 3685-3696.
    Résumé : We report here on a new series of CO2-reducing molecular catalysts based on Earth-abundant elements that are very selective for the production of formic acid in dimethylformamide (DMF)/water mixtures (Faradaic efficiency of 90 ± 10%) at moderate overpotentials (500–700 mV in DMF measured at the middle of the catalytic wave). The [CpCo(PR2NR′2)I]+ compounds contain diphosphine ligands, PR2NR′2, with two pendant amine residues that act as proton relays during CO2-reduction catalysis and tune their activity. Four different PR2NR′2 ligands with cyclohexyl or phenyl substituents on phosphorus and benzyl or phenyl substituents on nitrogen were employed, and the compound with the most electron-donating phosphine ligand and the most basic amine functions performs best among the series, with turnover frequency >1000 s–1. State-of-the-art benchmarking of catalytic performances ranks this new class of cobalt-based complexes among the most promising CO2-to-formic acid reducing catalysts developed to date; addressing the stability issues would allow further improvement. Mechanistic studies and density functional theory simulations confirmed the role of amine groups for stabilizing key intermediates through hydrogen bonding with water molecules during hydride transfer from the Co center to the CO2 molecule.
    Mots-clés : MACO, POLE 1.

  • Y. Wang, P. Pigeon, M. J. McGlinchey, S. Top, et G. Jaouen, « Synthesis and antiproliferative evaluation of novel hydroxypropyl-ferrociphenol derivatives, resulting from the modification of hydroxyl groups », Journal of Organometallic Chemistry.
    Résumé : As previously reported, the ferrocenyl derivative HO(CH2)3C(Fc) = C(C6H4OH)2 (2) shows an excellent cytotoxic effect against MDA-MB-231 (TNBC) cancer cell lines. Building on an analysis of this molecular framework, a series of novel hydroxypropyl-ferrociphenol derivatives with modified terminal hydroxyl groups were synthesized, and their antiproliferative activities against MDA-MB-231 cell lines were evaluated. Biological results showed that compound 8, whose terminal hydroxyl was protected by acetylation, exhibited the greatest cytotoxic effect among this series of hydroxypropyl derivatives. Furthermore, the impact of acetyl as a protecting group on the cytotoxicity of hydroxypropyl-ferrociphenol compounds by incorporating it at alkyl or phenyl hydroxyl positions of the core structure has been studied. Several of the compounds presented in this study revealed lipophilicity more suitable for formulation in lipid nanocapsules (LNCs) for subsequent in vivo studies. They also inhibit the cancer cell growth of MDA-MB-231 at a submicromolar IC50 value, providing an interesting potential for further development as innovative anticancer agents.
    Mots-clés : anticancer agents, CHEMBIO, ferrocifen, mda-mb-231, organometallics, POLE 3, quinone methides.

  • I. Zelocualtecatl-Montiel, F. García-Álvarez, J. R. Juárez, L. Orea, D. Gnecco, A. Mendoza, F. Chemla, F. Ferreira, O. Jackowski, D. M. Aparicio, A. Perez-Luna, et J. L. Terán, « Asymmetric Tandem Conjugate Addition–Aldol Condensation with N-Acryloyloxazolidines Derived from 2-Phenylglycinol », Asian Journal of Organic Chemistry, vol. 6, nᵒ 1, p. 67-70.
    Résumé : The tandem 1,4-addition–aldol condensation reaction of diethylzinc, α,β-unsaturated chiral enantiopure oxazolidines derived from 2-phenylglycinol, and carbonyl compounds is disclosed. The reaction proceeds through a radical-polar crossover mechanism involving the aldol condensation of a trisubstituted zinc enolate through a Zimmerman–Traxler transition state. Installation of a 2-pyridine moiety at the hemiaminal position of the chiral auxiliary allows obtaining both excellent asymmetric induction and diastereoselectivity (up to >90 % de). The developed protocol is suitable for aromatic and aliphatic aldehydes, as well as ketones.
    Mots-clés : aldol reaction, chiral oxazolidines, Diastereoselectivity, domino reactions, POLE 1, radical-polar mechanism, ROCS.


  • A. Ali Mohamed, S. Salhi, S. Abid, R. El Gharbi, et A. Fradet, « Quasi-alternating polyesteramides from ε-caprolactone and α-amino acids », Journal of Applied Polymer Science, vol. 133, nᵒ 46, p. n/a-n/a.
    Résumé : Glycine-ɛ-caprolactone-based and α-alanine-ɛ-caprolactone-based polyesteramides with a strong tendency to form alternating sequences (degree of randomness = 1.64 and 1.31) were synthesized by melt polycondensation of intermediate hydroxy- and ethyl ester-terminated amides. These intermediates were synthesized by the reaction of equimolar amounts of ɛ-caprolactone and glycine or L-α-alanine ethyl esters in mild conditions. The structure and microstructure of these polyesteramides are discussed on the basis of an in-depth nuclear magnetic resonance study. Both polyesteramides are semi-crystalline, but the glycine-based one presents the highest melting enthalpy. This polyesteramide also exhibits higher Young's modulus and stress at break than its α- and β-alanine counterparts. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44220.
    Mots-clés : biopolymers and renewable polymers, POLE 4, Polyesteramides, polyesters, POLYMERES, α-amino acids.

  • M. E. Arbi, K. Jalléli, F. Trigui, P. Pigeon, M. Görmen, S. Top, S. Aifa, I. Fliss, G. Jaouen, et R. Hammami, « Efficacy of a novel ferrocenyl diaryl butene citrate compound as a biocide for preventing healthcare-associated infections », vol. 7, nᵒ 5, p. 948-954.
    Résumé : The antiseptic and disinfectant potential of a formulation containing the tamoxifen analogue 1,1-bis[4-(3-dimethylaminopropoxy)phenyl]-2-ferrocenyl-but-1-ene citrate was assessed according to European standards and pharmacopeia in comparison with a commercial antiseptic product containing hexamidine diisethionate, chlorhexidine digluconate and chlorocresol as active ingredients. The formulation met the phase 1 requirement of reducing by 5 cycles the counts of microorganisms frequently involved in healthcare-associated infections, namely Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538, Enterococcus hirae ATCC 10541 and Candida albicans ATCC 10231. It also killed a clinical isolate of Acinetobacter baumannii which is highly resistant to antibiotics and antiseptics. In phase 2/step 2 tests, it reduced the counts of E. coli ATCC 10536 by 4 log cycles within 60 seconds on hands (standard EN 1499). The novel formula is a potent biocide, and this demonstration could lead to the development of a new commercial antiseptic.
    Mots-clés : CHEMBIO, POLE 3.

  • J. J. Baldoví, Y. Duan, C. Bustos, S. Cardona-Serra, P. Gouzerh, R. Villanneau, G. Gontard, J. M. Clemente-Juan, A. Gaita-Ariño, C. Giménez-Saiz, A. Proust, et E. Coronado, « Single ion magnets based on lanthanoid polyoxomolybdate complexes », Dalton Transactions, vol. 45, nᵒ 42, p. 16653 - 16660.
    Résumé : Polyoxometalate (POM) chemistry has recently offered excellent examples of single ion magnets (SIMs) and molecular spin qubits. Compared with conventional coordination compounds, POMs provide rigid and highly symmetric coordination sites. However, all POM-based SIMs reported to date exhibit a very limited range of possibilities for chemical processability. We present herein two new families of POM-based SIMs which are soluble in organic solvents: [Ln(β-Mo8O26)2]5− {LnIII = Tb, Dy, Ho, Er, Tm and Yb} and the functionalised POMs [Ln{Mo5O13(OMe)4NNC6H4-p-NO2}2]3− {LnIII = Tb, Dy, Ho, Er, Yb and Nd}. In addition, these two families represent the first SIMs based on polyoxomolybdates. A magneto-structural analysis of these families is presented, which is based on an effective crystal field model, and compared with the results reported in analogous lanthanoid SIMs based on polyoxotungstates.
    Mots-clés : E-POM, EPOM, POLE 2.

  • M. Barbazanges, E. Caytan, D. Lesage, C. Aubert, L. Fensterbank, V. Gandon, et C. Ollivier, « Chiral Phosphate in Rhodium-Catalyzed Asymmetric [2+2+2] Cycloaddition: Ligand, Counterion, or Both? », Chemistry – A European Journal, vol. 22, nᵒ 25, p. 8553-8558.
    Résumé : Investigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium-catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4-diphenylphosphinobutane (dppb), and Ag(S)-TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X-type ligand.
    Mots-clés : chirality, CSOB, cycloaddition, homogeneous catalysis, ligand effects, MACO, POLE 1, POLE 3, Rhodium.

  • M. Beauperin, S. Top, M. - A. Richard, D. Plażuk, P. Pigeon, S. Toma, V. Poláčková, et G. Jaouen, « The length of the bridging chain in ansa-metallocenes influences their antiproliferative activity against triple negative breast cancer cells (TNBC) », vol. 45, nᵒ 33, p. 13126-13134.
    Résumé : In order to examine whether the length of the bridging chain in ansa-ferrocenes affects their antiproliferative activity against MDA-MB-231 triple negative breast cancer cell lines (TNBC), we synthesized derivatives of the type 1-[bis-(4-hydroxyphenyl)]methylidene-[n]ferrocenophane and 1-[(4-hydroxyphenyl)-phenyl]methylidene-[n]ferrocenophane with n = 3, 4, 5. We found that the derivatives of [3]ferrocenophane, the compounds with the shortest bridging chains, are the most active. IC50 values were 0.09 ± 0.01, 2.41 ± 0.10, and 1.85 ± 0.25 μM for the dihydroxyphenyl derivatives, with n = 3, 4, 5, respectively. These differences can be explained in terms of modification of the key metabolites (radical versus quinone methides) within the ansa series depending on the length of the bridging chain. The derivative of [5]ferrocenophane, possessing two –[bis-(4-hydroxyphenyl)]methylidene groups, was also prepared. Surprisingly, this relatively large molecule is also active (IC50 = 2.7 ± 0.3 μM). Two ruthenocenophane analogs were also synthesized. These ruthenium compounds are practically inactive against MDA-MB-231 cells. The unusual chemistry of these different compounds is discussed in terms of elucidating the mechanism underlying their diverse antiproliferative activity, and their specific advantages are evaluated.
    Mots-clés : CHEMBIO, POLE 3.

  • K. Belal, S. Poitras-Jolicoeur, J. Lyskawa, G. Pembouong, G. Cooke, P. Woisel, et F. Stoffelbach, « A triple carboxylic acid-functionalized RAFT agent platform for the elaboration of well-defined telechelic 3-arm star PDMAc », vol. 52, nᵒ 9, p. 1847-1850.
    Résumé : This communication describes the synthesis of a triple acid-functionalized RAFT agent and its use to prepare well-defined 3-arm star polymers of N,N-dimethylacrylamide (DMAc). A simple esterification reaction allowed the convenient integration of three electron-rich naphthalene recognition units on the RAFT agent platform and subsequently the elaboration of a naphthalene end-decorated telechelic 3-arm star PDMAc. This functionalized star polymer was further exploited to build a hydrogel with a complementary homoditopic host unit featuring tetracationic macrocycle cyclobis(paraquat-p-phenylene) units.
    Mots-clés : POLE 4, POLYMERES.

  • K. Belal, F. Stoffelbach, J. Lyskawa, M. Fumagalli, D. Hourdet, A. Marcellan, L. De Smet, V. R. de la Rosa, G. Cooke, R. Hoogenboom, et P. Woisel, « Recognition-mediated hydrogel swelling controlled by interaction with a negative thermoresponsive LCST polymer », Angewandte Chemie (International Edition), vol. 55, nᵒ 45, p. 13974-13978.
    Résumé : Most polymeric thermoresponsive hydrogels contract upon heating beyond the lower critical solution temperature (LCST) of the polymers used. Herein, we report a supramolecular hydrogel system that shows the opposite temperature dependence. When the non-thermosesponsive hydrogel NaphtGel, containing dialkoxynaphthalene guest molecules, becomes complexed with the tetra cationic macrocyclic host CBPQT4+, swelling occurred as a result of host–guest complex formation leading to charge repulsion between the host units, as well as an osmotic contribution of chloride counter-ions embedded in the network. The immersion of NaphtGel in a solution of poly(N-isopropylacrylamide) with tetrathiafulvalene (TTF) end groups complexed with CBPQT4+ induced positive thermoresponsive behaviour. The LCST-induced dethreading of the polymer-based pseudorotaxane upon heating led to transfer of the CBPQT4+ host and a concomitant swelling of NaphtGel. Subsequent cooling led to reformation of the TTF-based host–guest complexes in solution and contraction of the hydrogel.
    Mots-clés : POLE 4, POLYMERES.

  • V. Besse, N. Illy, G. David, S. Caillol, et B. Boutevin, « A Chitosan Derivative Containing Both Carboxylic Acid and Quaternary Ammonium Moieties for the Synthesis of Cyclic Carbonates », ChemSusChem, vol. 9, nᵒ 16, p. 2167-2173.
    Résumé : Chitosan, a renewable feedstock, is modified and used as a catalytic support in the presence of potassium iodide. The system is highly efficient towards the incorporation of carbon dioxide (CO2) into epoxides. It demonstrates very good thermal stability and is recyclable more than five times without loss of activity. The optimal reaction conditions were determined using allylglycidyl ether as a model and extended to a wide range of other epoxides. Cyclic carbonates were obtained with very high yield in a few hours under mild conditions (2–7 bar≈0.2–0.7 MPa, 80 °C) and no solvent.
    Mots-clés : chitosan, cyclic carbonates, epoxides, heterogeneous catalysis, POLE 4, POLYMERES, supported catalyst.

  • V. N. Bochatay, Z. Neouchy, F. Chemla, F. Ferreira, O. Jackowski, et A. Pérez-Luna, « 4-Amino-1-allenylsilanes from 4-Aminopropargylic Acetates through a Silylzincation/Elimination Sequence », Synthesis, vol. 48, nᵒ 19, p. 3287-3300.
    Résumé : Thieme E-Books & E-Journals
    Mots-clés : POLE 1, ROCS.

  • T. T. Boukerche, S. Alves, P. Le Faouder, A. Warnet, J. Bertrand-Michel, M. Bouchekara, M. Belbachir, et J. - C. Tabet, « Atypical cleavage of protonated N-fatty acyl amino acids derived from aspartic acid evidenced by sequential MS(3) experiments », Amino Acids, vol. 48, nᵒ 12, p. 2717-2729.
    Résumé : Lipidomics calls for information on detected lipids and conjugates whose structural elucidation by mass spectrometry requires to rationalization of their gas phase dissociations toward collision-induced dissociation (CID) processes. This study focused on activated dissociations of two lipoamino acid (LAA) systems composed of N-palmitoyl acyl coupled with aspartic and glutamic acid mono ethyl esters (as LAA(*D) and LAA(*E)). Although in MS/MS, their CID spectra show similar trends, e.g., release of water and ethanol, the [(LAA(*D/*E)+H)-C2H5OH](+) product ions dissociate via distinct pathways in sequential MS(3) experiments. The formation of all the product ions is rationalized by charge-promoted cleavages often involving stepwise processes with ion isomerization into ion-dipole prior to dissociation. The latter explains the maleic anhydride or ketene neutral losses from N-palmitoyl acyl aspartate and glutamate anhydride fragment ions, respectively. Consequently, protonated palmitoyl acid amide is generated from LAA(*D), whereas LAA(*E) leads to the [*E+H-H2O](+) anhydride. The former releases ammonia to provide acylium, which gives the C n H(2n-1) and C n H(2n-3) carbenium series. This should offer structural information, e.g., to locate either unsaturation(s) or alkyl group branching present on the various fatty acyl moieties of lipo-aspartic acid in further studies based on MS (n) experiments.
    Mots-clés : CSOB, ESI/MS n, Ion–dipole, N-fatty-acyl amino-acid, POLE 3, Regioselectivity.

  • J. E. Boulicault, S. Alves, et R. B. Cole, « Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation », Journal of The American Society for Mass Spectrometry, vol. 27, nᵒ 8, p. 1301-1313.
    Résumé : MALDI-MS has been developed for the negative ion mode analysis of polyoxometalates (POMs). Matrix optimization was performed using a variety of matrix compounds. A first group of matrixes offers MALDI mass spectra containing abundant intact singly charged anionic adduct ions, as well as abundant in-source fragmentations at elevated laser powers. A relative ranking of the ability to induce POM fragmentation is found to be: DAN > CHCA > CNA > DIT> HABA > DCTB > IAA. Matrixes of a second group provide poorer quality MALDI mass spectra without observable fragments. Sample preparation, including the testing of salt additives, was performed to optimize signals for a model POM, POMc12, the core structure of which bears four negative charges. The matrix 9-cyanoanthracene (CNA) provided the best signals corresponding to singly charged intact POMc12 anions. Decompositions of these intact anionic species were examined in detail, and it was concluded that hydrogen radical-induced mechanisms were not prevalent, but rather that the observed prompt fragments originate from transferred energy derived from initial electronic excitation of the CNA matrix. Moreover, in obtained MALDI mass spectra, clear evidence of electron transfer to analyte POM species was found: a manifestation of the POMs ability to readily capture electrons. The affinity of polyanionic POMc12 toward a variety of cations was evaluated and the following affinity ranking was established: Fe3+ > Al3+ > Li+ > Ga3+ > Co2+ > Cr3+ > Cu2+ > [Mn2+, Mg2+] > [Na+, K+]. Thus, from the available cationic species, specific adducts are preferentially formed, and evidence is given that these higher affinity POM complexes are formed in the gas phase during the early stages of plume expansion.Graphical Abstractᅟ
    Mots-clés : CSOB, POLE 3.

  • R. Breitwieser, T. Auvray, F. Volatron, C. Salzemann, A. - T. Ngo, P. - A. Albouy, A. Proust, et C. Petit, « Binary Superlattices from {Mo132} Polyoxometalates and Maghemite Nanocrystals: Long-Range Ordering and Fine-Tuning of Dipole Interactions », Small, vol. 12, nᵒ 2, p. 220-228.
    Résumé : In the present article, the successful coassembly of spherical 6.2 nm maghemite (γ-Fe2O3) nanocrystals and giant polyoxometalates (POMs) such as 2.9 nm {Mo132} is demonstrated. To do so, colloidal solutions of oleic acid-capped γ-Fe2O3 and long-chain alkylammonium-encapsulated {Mo132} dispersed in chloroform are mixed together and supported self-organized binary superlattices are obtained upon the solvent evaporation on immersed substrates. Both electronic microscopy and small angles X-ray scattering data reveal an AB-type structure and an enhanced structuration of the magnetic nanocrystals (MNCs) assembly with POMs in octahedral interstices. Therefore, {Mo132} acts as an efficient binder constituent for improving the nanocrystals ordering in 3D films. Interestingly, in the case of didodecyldimethylammonium (C12)-encapsulated POMs, the long-range ordered binary assemblies are obtained while preserving the nanocrystals magnetic properties due to weak POMs–MNCs interactions. On the other hand, POMs of larger effective diameter can be employed as spacer blocks for MNCs as shown by using {Mo132} capped with dioctadecyldimethylammonium (C18) displaying longer chains. In that case, it is shown that POMs can also be used for fine-tuning the dipolar interactions in γ-Fe2O3 nanocrystal assemblies.
    Mots-clés : binary superlattices, E-POM, EPOM, maghemites, magnetic dipolar interactions, POLE 2, Polyoxometalates, {mo132}.

  • N. Bridonneau, L. - M. Chamoreau, G. Gontard, J. - L. Cantin, J. von Bardeleben, et V. Marvaud, « A high-nuclearity metal-cyanide cluster [Mo6Cu14] with photomagnetic properties », vol. 45, nᵒ 23, p. 9412-9418.
    Résumé : A high-nuclearity metal-cyanide cluster [Mo6Cu14] has been prepared and its photomagnetic properties investigated. The photoswitchable magnetic phenomenon observed is thermally reversible (T ≈ 230 K). In the field of photomagnetism, [Mo6Cu14] represents a unique example of a nanocage and the highest nuclearity observed so far.
    Mots-clés : E-POM, EPOM, POLE 2.

  • M. C. Bridoux, A. Schwarzenberg, S. Schramm, et R. B. Cole, « Combined use of direct analysis in real-time/Orbitrap mass spectrometry and micro-Raman spectroscopy for the comprehensive characterization of real explosive samples », Analytical and Bioanalytical Chemistry, vol. 408, nᵒ 21, p. 5677-5687.
    Résumé : Direct Analysis in Real Time (DART™) high-resolution Orbitrap™ mass spectrometry (HRMS) in combination with Raman microscopy was used for the detailed molecular level characterization of explosives including not only the charge but also the complex matrix of binders, plasticizers, polymers, and other possible organic additives. A total of 15 defused military weapons including grenades, mines, rockets, submunitions, and mortars were examined. Swabs and wipes were used to collect trace (residual) amounts of explosives and their organic constituents from the defused military weapons and micrometer-size explosive particles were transferred using a vacuum suction-impact collection device (vacuum impactor) from wipe and swap samples to an impaction plate made of carbon. The particles deposited on the carbon plate were then characterized using micro-Raman spectroscopy followed by DART-HRMS providing fingerprint signatures of orthogonal nature. The optical microscope of the micro-Raman spectrometer was first used to localize and characterize the explosive charge on the impaction plate which was then targeted for identification by DART-HRMS analysis in both the negative and positive modes. Raman spectra of the explosives TNT, RDX and PETN were acquired from micrometer size particles and characterized by the presence of their characteristic Raman bands obtained directly at the surface of the impaction plate nondestructively without further sample preparation. Negative mode DART-HRMS confirmed the types of charges contained in the weapons (mainly TNT, RDX, HMX, and PETN; either as individual components or as mixtures). These energetic compounds were mainly detected as deprotonated species [M–H]−, or as adduct [M + 35Cl]−, [M + 37Cl]−, or [M + NO3]− anions. Chloride adducts were promoted in the heated DART reagent gas by adding chloroform vapors to the helium stream using an “in-house” delivery method. When the polarity was switched to positive mode, DART-HRMS revealed a very complex distribution of polymeric binders (mainly polyethylene glycols and polypropylene glycols), plasticizers (e.g., dioctyl sebacate, tributyl phosphate), as well as wax-like compounds whose structural features could not be precisely assigned. In positive mode, compounds were identified either as protonated molecules or ammonium adduct species. These results clearly demonstrate the complementarity of micro-Raman microscopy combined with DART-MS. The former technique provides structural information on the type of explosives present at the surface of the sample, whereas the latter provides not only a confirmation of the nature of the explosive charge but also useful additional information regarding the nature of the complex organic matrix of binders, plasticizers, polymers, oils, and potentially other organic additives and contaminants present in the sample. Combining these two techniques provides a powerful tool for the screening, comprehensive characterization, and differentiation of particulate explosive samples for forensic sciences and homeland security applications.Graphical AbstractComprehensive characterization of explosive particles collected from swipe samples by micro-Raman and DART™-HRMS
    Mots-clés : CSOB, POLE 3.

  • X. Callies, C. Fonteneau, S. Pensec, L. Bouteiller, G. Ducouret, et C. Creton, « Adhesion and non-linear rheology of adhesives with supramolecular crosslinking points », vol. 12, nᵒ 34, p. 7174-7185.
    Résumé : Soft supramolecular materials are promising for the design of innovative and highly tunable adhesives. These materials are composed of polymer chains functionalized by strongly interacting moieties, sometimes called “stickers”. In order to systematically investigate the effect of the presence of associative groups on the debonding properties of a supramolecular adhesive, a series of supramolecular model systems has been characterized by probe-tack tests. These model materials, composed of linear and low dispersity poly(butylacrylate) chains functionalized in the middle by a single tri-urea sticker, are able to self-associate by six hydrogen bonds and range in molecular weight (Mn) between 5 and 85 kg mol−1. The linear rheology and the nanostructure of the same materials (called “PnBA3U”) were the object of a previous study. At room temperature, the association of polymers via hydrogen bonds induces the formation of rod-like aggregates structured into bundles for Mn < 40 kg mol−1 and the behavior of a soft elastic material was observed (G′ ≪ G′′ and G′ ∼ ω0). For higher Mn materials, the filaments were randomly oriented and the polymers displayed a crossover towards viscous behavior although terminal relaxation was not reached in the experimental frequency window. All these materials show, however, similar adhesive properties characterized by a cohesive mode of failure and low debonding energies (Wadh < 40 J m−2 for a debonding speed of 100 μm s−1). The debonding mechanisms observed during the adhesion tests have been investigated in detail with an Image tools analysis developed by our group. The measure of the projected area covered by cavities growing in the adhesive layer during debonding can be used to estimate the true stress in the walls of the cavities and thus to characterize the in situ large strain deformation of the thin layer during the adhesion test itself. This analysis revealed in particular that the PnBA3U materials with Mn < 40 kg mol−1 soften very markedly at large deformation like yield stress fluids, explaining the low adhesion energies measured for these viscoelastic gels.
    Mots-clés : POLE 4, POLYMERES.

  • V. E. Campbell, M. Tonelli, I. Cimatti, J. - B. Moussy, L. Tortech, Y. J. Dappe, E. Rivière, R. Guillot, S. Delprat, R. Mattana, P. Seneor, P. Ohresser, F. Choueikani, E. Otero, F. Koprowiak, V. G. Chilkuri, N. Suaud, N. Guihéry, A. Galtayries, F. Miserque, M. - A. Arrio, P. Sainctavit, et T. Mallah, « Engineering the magnetic coupling and anisotropy at the molecule–magnetic surface interface in molecular spintronic devices », Nature Communications, vol. 7, p. 13646.
    Résumé : Controlling the magnetic response of a molecular device is important for spintronic applications. Here the authors report the self-assembly, magnetic coupling, and anisotropy of two transition metal complexes bound to a ferrimagnetic surface, and probe the role of the nature of the transition metal ion.
    Mots-clés : E-POM, POLE 2.

  • S. Catrouillet, L. Bouteiller, O. Boyron, C. Lorthioir, E. Nicol, S. Pensec, et O. Colombani, « Patchy Supramolecular Bottle-Brushes Formed by Solution Self-Assembly of Bis(urea)s and Tris(urea)s Decorated by Two Incompatible Polymer Arms », Langmuir, vol. 32, nᵒ 35, p. 8900-8908.
    Résumé : In an attempt to design urea-based Janus nanocylinders through a supramolecular approach, nonsymmetrical bis(urea)s and tris(urea)s decorated by two incompatible polymer arms, namely, poly(styrene) (PS) and poly(isobutylene) (PIB), were synthesized using rather straightforward organic and polymer chemistry techniques. Light scattering experiments revealed that these molecules self-assembled in cyclohexane by cooperative hydrogen bonds. The extent of self-assembly was limited for the bis(urea)s. On the contrary, reasonably anisotropic 1D structures (small nanocylinders) could be obtained with the tris(urea)s (Nagg ∼ 50) which developed six cooperative hydrogen bonds per molecule. 1H transverse relaxation measurements and NOESY NMR experiments in cyclohexane revealed that perfect Janus nanocylinders with one face consisting of only PS and the other of PIB were not obtained. Nevertheless, phase segregation between the PS and PIB chains occurred to a large extent, resulting in patchy cylinders containing well separated domains of PIB and PS chains. Reasons for this behavior were proposed, paving the way to improve the proposed strategy toward true urea-based supramolecular Janus nanocylinders.
    Mots-clés : POLE 4, POLYMERES.

  • L. Chenneberg, C. Lévêque, V. Corcé, A. Baralle, J. - P. Goddard, C. Ollivier, et L. Fensterbank, « Single-Electron-Transfer Oxidation of Trifluoroborates and Silicates with Organic Reagents: A Comparative Study », Synlett, vol. 27, nᵒ 05, p. 731-735.

  • L. Chenneberg et C. Ollivier, « Tin-free Alternatives to the Barton-McCombie Deoxygenation of Alcohols to Alkanes Involving Reductive Electron Transfer », CHIMIA International Journal for Chemistry, vol. 70, nᵒ 1, p. 67-76.
    Résumé : Echoing the recent celebration of the fortieth anniversary of the Barton-McCombie reaction, this review aims to explore another facet of radical processes for deoxygenation of alcohols by considering SET (single electron transfer) reduction of carboxylic ester, thiocarbonate and thiocarbamate derivatives. Various protocols have been developed relying on the use of organic and organometallic SET reagents, electrochemical conditions, photoinduced electron transfer processes and visible-light photoredox catalysis. Applications to the synthesis of molecules of interest provide a glimpse into the scope of these different approaches.
    Mots-clés : Alcohols, deoxygenation, electron transfer, MACO, POLE 1, radicals, reduction.

  • M. C. Chong, G. Reecht, H. Bulou, A. Boeglin, F. Scheurer, F. Mathevet, et G. Schull, « Narrow-Line Single-Molecule Transducer between Electronic Circuits and Surface Plasmons », Physical Review Letters, vol. 116, nᵒ 3, p. 036802.
    Résumé : A molecular wire containing an emitting molecular center is controllably suspended between the plasmonic electrodes of a cryogenic scanning tunneling microscope. Passing current through this circuit generates an ultranarrow-line emission at an energy of ≈1.5 eV which is assigned to the fluorescence of the molecular center. Control over the linewidth is obtained by progressively detaching the emitting unit from the surface. The recorded spectra also reveal several vibronic peaks of low intensities that can be viewed as a fingerprint of the emitter. Surface plasmons localized at the tip-sample interface are shown to play a major role in both excitation and emission of the molecular excitons.
    Mots-clés : POLE 4, POLYMERES.

  • M. W. Cooke, M. - P. Santoni, B. Hasenknopf, et G. S. Hanan, « Heteroleptic ruthenium(II) chromophores based on tunable polytopic 4′-(benzamidinato)-2,2′:6′,2′′-terpyridines », vol. 45, nᵒ 44, p. 17850-17858.
    Résumé : A modulable and simple approach towards heteroleptic ruthenium(II) complexes of amidine-based polypyridine ligands is presented. New complexes 1 and 2 ([(terpyridine)Ru(terpyridine-C6H4-C(NR)(NHR))]2+ with R = propyl and R = phenyl derivatives, respectively) were characterized by NMR spectroscopy in solution and by X-ray diffraction, which confirmed the obtention of the (E) stereoisomer alone. Depending on the bulkiness of the R-substituents introduced on the amidine moiety, rotational isomerism around the C–N bond could be observed at r.t. Spectroscopic and electrochemical studies showed that the nature of the R-substituents introduced on the amidine moiety can significantly influence the redox and ground-state acido-basic properties of the complexes, while maintaining their electronic features. This particular tunability of polytopic 4′-(amidinato)-terpyridines offers an interesting perspective for photoactive units in larger multi-functional arrays.
    Mots-clés : GOBS, POLE 3.

  • S. De, J. - R. Jiménez, Y. Li, L. - M. Chamoreau, A. Flambard, Y. Journaux, A. Bousseksou, et R. Lescouëzec, « One synthesis: two redox states. Temperature-oriented crystallization of a charge transfer {Fe <sub>2</sub> Co <sub>2</sub> } square complex in a {FeIILSCoIIILS} <sub>2</sub> diamagnetic or {FeIIILSCoIIHS} <sub>2</sub> paramagnetic state », RSC Advances, vol. 6, nᵒ 21, p. 17456-17459.

  • A. Desmarchelier, B. G. Alvarenga, X. Caumes, L. Dubreucq, C. Troufflard, M. Tessier, N. Vanthuyne, J. Idé, T. Maistriaux, D. Beljonne, P. Brocorens, R. Lazzaroni, M. Raynal, et L. Bouteiller, « Tuning the nature and stability of self-assemblies formed by ester benzene 1,3,5-tricarboxamides: the crucial role played by the substituents », vol. 12, nᵒ 37, p. 7824-7838.
    Résumé : As the benzene 1,3,5-tricarboxamide (BTA) moiety is commonly used as the central assembling unit for the construction of functionalized supramolecular architectures, strategies to tailor the nature and stability of BTA assemblies are needed. The assembly properties of a library of structurally simple BTAs derived from amino dodecyl esters (ester BTAs, 13 members) have been studied, either in the bulk or in cyclohexane solutions, by means of a series of analytical methods (NMR, DSC, POM, FT-IR, UV-Vis, CD, ITC, high-sensitivity DSC, SANS). Two types of hydrogen-bonded species have been identified and characterized: the expected amide-bonded helical rods (or stacks) that are structurally similar to those formed by BTAs with simple alkyl side chains (alkyl BTAs), and ester-bonded dimers in which the BTAs are connected by means of hydrogen bonds linking the amide N–H and the ester CO. MM/MD calculations coupled with simulations of CD spectra allow for the precise determination of the molecular arrangement and of the hydrogen bond pattern of these dimers. Our study points out the crucial influence of the substituent attached on the amino-ester α-carbon on the relative stability of the rod-like versus dimeric assemblies. By varying this substituent, one can precisely tune the nature of the dominant hydrogen-bonded species (stacks or dimers) in the neat compounds and in cyclohexane over a wide range of temperatures and concentrations. In the neat BTAs, stacks are stable up to 213 °C and dimers above 180 °C whilst in cyclohexane stacks form at c* &gt; 3 × 10−5 M at 20 °C and dimers are stable up to 80 °C at 7 × 10−6 M. Ester BTAs that assemble into stacks form a liquid-crystalline phase and yield gels or viscous solutions in cyclohexane, demonstrating the importance of controlling the structure of these assemblies. Our systematic study of these structurally similar ester BTAs also allows for a better understanding of how a single atom or moiety can impact the nature and stability of BTA aggregates, which is of importance for the future development of functionalized BTA supramolecular polymers.
    Mots-clés : POLE 4, POLYMERES.

  • A. Desmarchelier, X. Caumes, M. Raynal, A. Vidal-Ferran, P. W. N. M. van Leeuwen, et L. Bouteiller, « Correlation between the Selectivity and the Structure of an Asymmetric Catalyst Built on a Chirally Amplified Supramolecular Helical Scaffold », Journal of the American Chemical Society, vol. 138, nᵒ 14, p. 4908-4916.
    Résumé : For the first time, supramolecular helical rods composed of an achiral metal complex and a complementary enantiopure monomer provided a good level of enantioinduction in asymmetric catalysis. Mixtures containing an achiral ligand monomer (BTAPPh2, 2 mol %) and an enantiopure ligand-free comonomer (ester BTA, 2.5 mol %), both possessing a complementary benzene-1,3,5-tricarboxamide (BTA) central unit, were investigated in combination with [Rh(cod)2]BArF (1 mol %) in the asymmetric hydrogenation of dimethyl itaconate. Notably, efficient chirality transfer occurs within the hydrogen-bonded coassemblies formed by BTA Ile and the intrinsically achiral catalytic rhodium catalyst, providing the hydrogenation product with up to 85% ee. The effect of the relative content of BTA Ile as compared to the ligand was investigated. The amount of chiral comonomer can be decreased down to one-fourth of that of the ligand without deteriorating the enantioselectivity of the reaction, while the enantioselectivity decreases for mixtures containing high amounts of BTA Ile. The nonlinear relationship between the amount of chiral comonomer and the enantioselectivity indicates that chirality amplification effects are at work in this catalytic system. Also, right-handed helical rods are formed upon co-assembly of the achiral rhodium complex of BTAPPh2 and the enantiopure comonomer BTA Ile as confirmed by various spectroscopic and scattering techniques. Remarkably, the major enantiomer and the selectivity of the catalytic reaction are related to the handedness and the net helicity of the coassemblies, respectively. Further development of this class of catalysts built on chirally amplified helical scaffolds should contribute to the design of asymmetric catalysts operating with low amounts of chiral entities.
    Mots-clés : POLE 4, POLYMERES.

  • D. Diamante, S. Gabrieli, T. Benincori, G. Broggini, J. Oble, et G. Poli, « Dehydrogenative Allylic Aminations of But-3-enoic Acid Derivatives », Synthesis, vol. 48, nᵒ 19, p. 3400-3412.
    Résumé : Thieme E-Books & E-Journals
    Mots-clés : POLE 1, ROCS.

  • M. Dréan, P. Guégan, C. Detrembleur, C. Jérôme, J. Rieger, et A. Debuigne, « Controlled Synthesis of Poly(vinylamine)-Based Copolymers by Organometallic-Mediated Radical Polymerization », Macromolecules, vol. 49, nᵒ 13, p. 4817-4827.
    Résumé : Living/controlled polymerization methods have enabled the synthesis of numerous (co)polymers with defined compositions and architectures. However, the precision design of poly(vinylamine)-based copolymers remains challenging despite their extensive use in various fields of applications and the clear benefits to finely tune their properties. Here, we report on a two-step strategy for the synthesis of tailor-made poly(vinylamine) derivatives through the organometallic-mediated radical (co)polymerization (OMRP) of N-vinylacetamide and/or N-methylvinylacetamide followed by acid hydrolysis of the acetamide groups. A series of well-defined homopolymers as well as statistical and block copolymers with pendant primary and/or secondary amines having controlled molar masses, compositions, and low dispersities were produced accordingly. The reactivity ratios of the comonomers as well as the composition drift along the chain were determined in order to have a precise idea of the polymer structures. These advances represent a significant step toward an efficient platform for synthesis of this important class of amino group-containing (co)polymers.
    Mots-clés : POLE 4, POLYMERES.

  • F. J. S. Duarte, G. Poli, et M. J. Calhorda, « Mechanistic Study of the Direct Intramolecular Allylic Amination Reaction Catalyzed by Palladium(II) », ACS Catalysis, vol. 6, nᵒ 3, p. 1772-1784.
    Résumé : DFT calculations (PBE1PBE/6-31G(d,p), Def2-TZVPPD) were performed to study the intramolecular C–H amination of an unsaturated carbamate catalyzed by [Pd(LL)(OAc)2] (2), where LL is the bis(sulfoxide) ligand PhS(O)(CH2)2S(O)Ph. The coordination takes place by an associative path over a trigonal-bipyramidal transition state. The LL ligand undergoes a coordination shift from κ2S,S to κ1S, leaving an open position for binding of the substrate (C═C). In the next step, the C–H activation, the transition state for the hydrogen abstraction from the substrate to form the σ-allyl complex has an energy of 124.0 kJ mol–1, which is the highest energy in the whole mechanism (TOF-determining transition state). The σ-allyl converts easily in the π-allyl, the acetic acid molecule leaving the coordination sphere. The remaining acetate receives the second hydrogen from the NH group, while the newly formed acetic acid molecule is replaced by the pendant arm of the LL ligand, and the cyclization takes place (nucleophilic attack). During these changes, the metal is reduced to Pd(0) in the form of the Pd(0) complex of the oxazolidinone product, the most stable species in the cycle (TOF-determining intermediate). Either the C–H activation or the Pd(0) oxidation may be the step determining the energy span of the reaction, depending on reaction conditions.
    Mots-clés : POLE 1, ROCS.

  • L. Duarte, S. Nag, M. Castro, E. Zaborova, M. Ménand, M. Sollogoub, V. Bennevault, J. - F. Feller, et P. Guégan, « Chemical Sensors Based on New Polyamides Biobased on (Z) Octadec-9-Enedioic Acid and β-Cyclodextrin », Macromolecular Chemistry and Physics, vol. 217, nᵒ 14, p. 1620-1628.

0 | 50 | 100 | 150 | 200 | 250 | 300 | 350 | 400 | ... | 1000

--- Exporter la sélection au format