Nos tutelles

CNRS

Nos partenaires

Rechercher




Accueil

Productions scientifiques

gastaldi.

ACL - Articles dans des revues à comité de lecture

24 références.
2019

  • Besson, E.; Gastaldi, S.; Bloch, E.; Zielonka, J.; Zielonka, M.; Kalyanaraman, B.; Aslan, S.; Karoui, H.; Rockenbauer, A.; Ouari, O.; Hardy, M. Analyst 2019, 144 (14), 4194-4203.
    Résumé : The generation of superoxide radical anion in biological systems is one of the major initiating events in the redox biology of NADPH oxidases and mitochondrial redox signalling. However, the pallette of chemical tools for superoxide detection is very limited, hampering progress in understanding the chemical biology of superoxide. Although EPR spin trapping is regarded as the most rigorous technique for superoxide detection, rapid reduction of the EPR-active superoxide spin adducts to EPR-silent hydroxylamines, or to hydroxyl radical adducts by bioreductants, significantly limits the applicability of this technique in biological systems. To overcome these limitations, in this work, we report the synthesis and characterization of a new mesoporous silica functionalized with a phosphorylated cyclic spin trap (DIPPMPO nitrone). The DIPPMPO-grafted silica is a versatile spin-trap agent enabling the identification of a wide range of carbon or oxygen-centered transient radicals in organic and in aqueous media. Moreover, superoxide was efficiently trapped under in vitro conditions in both cell-free and cellular systems. The generated superoxide adduct exhibited an exceptional half-life of 3.5 h and a resistance toward bioreductant agents such as glutathione for several hours.

  • Dol, C.; Gerbaud, G.; Guigliarelli, B.; Bloch, E.; Gastaldi, S.; Besson, E. Physical Chemistry Chemical Physics 2019, 21 (29), 16337-16344.
    Résumé : The development of new open shell systems is essential for advances in spin science. In this work, we report the synthesis and characterization of three nanostructured materials, namely SBA-15 silicas, periodic mesoporous organosilicas (PMOs) and lamellar polysilsesquioxanes, all functionalized with the same diazene-based phenoxyl radical precursor. The impact of the nature of the material, i.e. loading of radical precursor and structure, on half-lifetimes (t(1/2)) and relaxation times of phenoxyl radicals was investigated. Although phenoxyl radicals are transient in solution, their t(1/2) range from hours to years at room temperature (RT) when they are embedded in nanostructured materials. The above mentioned functionalized materials were used to generate the corresponding phenoxyl radicals and their relaxation times were measured (T-1e and T-m) from 50 K to RT. The results were rationalized in terms of limited mobility of the radical as a result of supramolecular interactions and structure rigidity. All these data show that it is possible to design functionalized nanostructured material with radicals possessing specific electronic relaxation properties which can be of interest in fields like DNP, organic magnetism or spin qubit.
2018

  • Vibert, F.; Bloch, E.; Bertrand, M. P.; Gastaldi, S.; Besson, E. Journal of Physical Chemistry C 2018, 122 (1), 681-686.
    Résumé : Diazenes, precursors of sulfinyl radicals, were used to functionalize nanostructured SBA-15 silicas either in the framework or on the pore by formation of covalent links, or by simple adsorption on the surface. Depending on their design and on the experimental conditions, these materials proved to be effective tools to study the behavior and the reactivity of arylsulfinyl radicals made persistent because of confinement effects. When the covalently linked precursors were irradiated at room temperature, a spectacular increase of the lifetime of the expected sulfinyl radicals was registered (up to 17 h). At higher temperature, upon thermal initiation at 473 K, the decomposition of the adsorbed precursor enabled visualization of the rearrangement of the corresponding arylsulfinyl radicals into sulfonyl radicals via O-S coupling.
2017

  • Bloch, E.; Besson, E.; Queyroy, S.; Llewellyn, R.; Gastaldi, S.; Llewellyn, P. L. Acs Applied Materials & Interfaces 2017, 9 (16), 14490–14496.
    Résumé : As the search for functionalized materials for CO2 capture continues, the role of theoretical chemistry is becoming more and more central. In this work, a strategy is proposed where ab initio calculations are compared and validated by adsorption microcalorimetry experiments for a series of, so far unexplored, functionalized SBA-15 silicas with different spacers (aryl, alkyl) and terminal functions (N-3, NO2). This validation then permitted to propose the use of a nitro-indole surface functionality. After synthesis of such a material the predictions were confirmed by experiment. This confirms that it is possible to fine-tune CO2-functional interactions at energies much lower than those observed with amine species.
    Mots-clés : adsorbent, carbon dioxide, co2 capture, design, frameworks, functionalized mesoporous silica, gas-adsorption, in silico design, microcalorimetry, sba-15, separation, sorbents, sorption, zeolites.

  • Dol, C.; Vibert, F.; Bertrand, M. P.; Lalevee, J.; Gastaldi, S.; Besson, E. Acs Macro Letters 2017, 6 (2), 117–120.
    Résumé : New polysilsesquioxane-based lamellar materials, functionalized with radical precursors, were synthesized. They play a double role in the preparation of composite materials: first, as filler homogeneously dispersed in the monomer after delamination, second as radical initiator in photopolymerization. These polysilsesquioxanes enable fast and efficient photopolymerization upon UV light for thick samples. High conversions in monomers as well as the formation of hybrid polymers covalently linked to the filler are observed. This strategy, based on a double bottom-up approach, avoids the solubility/dispersion problem encountered in the classical preparation of composite polymers from preformed organic polymers.
    Mots-clés : nanocomposites, resonance, silica, spin, sulfur.

  • Vibert, F.; Bloch, E.; Bertrand, M. P.; Queyroy, S.; Gastaldi, S.; Besson, E. New Journal of Chemistry 2017, 41 (14), 6678–6684.
    Résumé : Nanostructured functionalized silicas were used as a platform to compare the behaviour of anchored arylsulfanyl radicals depending on the nature of the precursor (diazene/thiol). The radicals generated from thiols exhibit higher half-lifetimes than the radicals generated from diazenes. The ability of thiols to maintain the sulfanyl radical density via degenerate hydrogen atom transfer is likely to account for this sharp difference.
    Mots-clés : chemistry, confinement, magic-angle, mesoporous silica, molecules, nmr, polarization, proton conductivity, pyrolysis, resonance.
2016

  • Besson, E.; Ziarelli, F.; Bloch, E.; Gerbaud, G.; Queyroy, S.; Viel, S.; Gastaldi, S. Chemical Communications 2016, 52 (32), 5531-5533.
    Résumé : Hybrid mesoporous silica materials with wall-embedded nitroxides are shown to efficiently polarize impregnated substrates in high-field dynamic nuclear polarization magic-angle spinning solid-state NMR experiments.
    Mots-clés : solids, spectroscopy.

  • Dol, C.; Bertrand, M. P.; Gastaldi, S.; Besson, E. Tetrahedron 2016, 72 (48), 7744-7748.
    Résumé : Upon irradiation at room temperature, symmetrical diazene precursors enabled the formation of phenoxyl radicals through beta-fragmentation reaction in the solid state. This traceless generation of phenoxyl radicals was investigated by ESR. This study showed that although the fragmentation of beta-phenoxy radicals is a slow process in solution, it could be useful in solid state thanks to the absence of faster competitive pathways. (C) 2016 Elsevier Ltd. All rights reserved.
    Mots-clés : aryloxy-radicals, batteries, beta-fragmentation reaction, chemistry, electron-spin-resonance, esr, hindered phenols, mechanism, oxidation, Phenoxyl radical, rate constants, solvent, spectra.
2015

  • Vibert, F.; Marque, S. R. A.; Bloch, E.; Queyroy, S.; Bertrand, M. P.; Gastaldi, S.; Besson, E. Journal of Physical Chemistry C 2015, 119 (10), 5434-5439.
    Résumé : Bis-silylated diazenes were designed to prepare wall-functionalized hybrid silieas Via the sol-gel process. These precursors enabled the Straightforward generation of arylsulfanyl radicals by either photolysis or thertnolysis. Theif locatioir in the framework Of the megipotots materials was evidenced by spin trapping experiments: The incidence of confinement on the radical lifetime was investigated by electron pararnagnetic resonance (EPR). An amazing persistence (t(1/2) = 27 min) was recorded at 473 K.
2014

  • Vibert, F.; Marque, S. R. A.; Bloch, E.; Queyroy, S.; Bertrand, M. P.; Gastaldi, S.; Besson, E. Chemical Science 2014, 5 (12), 4716-4723.
    Résumé : Nanostructured hybrid silicas, in which covalently anchored aromatic thiols are regularly distributed over the pores, enable a dramatic increase in the half-lives of the corresponding arylsulfanyl radicals. This enhancement is not only due to limited diffusion but also to the structure of the organic monolayer on the surface of the pores. Molecular dynamics modeling shows that at high loadings, in spite of their spatial vicinity, supramolecular interactions disfavor the coupling of arylsulfanyl radicals. As compared to phenylsulfanyl radical in solution, the half-life measured at 293 K can be increased by 9 orders of magnitude to reach 65 h.
2013

  • Campolo, D.; Gastaldi, S.; Roussel, C.; Bertrand, M. P.; Nechab, M. Chemical Society Reviews 2013, 42 (21), 8434-8466.
    Résumé : Substrates, bearing axial chirality, can cyclize intra-or inter-molecularly with concomitant transfer of axial-to-central chirality to produce at least one stereocenter. In order to satisfy a strict definition of axial-to-central chirality transfer, the initial axial chirality must be lost during the cyclization process. Highly functionalized enantiopure carbocycles and heterocycles were prepared using this strategy. The transformations of configurationally stable substrates take place with high regio- and stereo-selectivity. Selected examples involving allenes, biaryls, arylamides and transient axially chiral short-lived species are discussed. Special attention is focused on the mechanistic rationale of the chirality transfer.

  • Poulhes, F.; Mouysset, D.; Gil, G.; Bertrand, M. P.; Gastaldi, S. Polymer 2013, 54 (14), 3467-3471.
    Résumé : The design of omega-amino-alpha-alkoxy-acetate as monomer enables to dramatically speed up the formation of polyamides catalyzed by the supported lipase B of Candida antarctica. Only 30 min are needed to reach 93% conversion whereas 240 h are necessary to observe the same level of conversion with a monomer devoided of an oxygen atom in position beta relative to the electrophilic carbonyl group. Yields, Mn, Mw, DPn and PDI reach very good values for an enzymatic synthesis of polyamides. (C) 2013 Elsevier Ltd. All rights reserved.
2012

  • Chatgilialoglu, C.; Mozziconacci, O.; Tamba, M.; Bobrowski, K.; Kciuk, G.; Bertrand, M. P.; Gastaldi, S.; Timokhin, V. I. Journal of Physical Chemistry A 2012, 116 (29), 7623-7628.
    Résumé : The reactions of alpha-hydroxyl and alpha-alkoxyl alkyl radicals with methanesulfonyl chloride (MeSO2Cl) have been studied by pulse radiolysis at room temperature. The alkyl radicals were produced by ionizing radiation of N2O-saturated aqueous solution containing methanol, ethanol, isopropanol, or tetrahydrofuran. The transient optical absorption spectrum consisted of a broad band in the region 280-380 nm with a maximum at 320 nm typical of the MeSO2 center dot radical. The rate constants in the interval of 1.7 X 10(7)-2.2 x 10(8) M-1 s(-1) were assigned to an electron transfer process that leads to MeSO2Cl center dot-, subsequently decaying into MeSO2 center dot radical and Cl-. The rate constants for the addition of CH3SO2 center dot to acrolein and propiolic acid were found to be 4.9 x 10(9) M-1 s(-1) and 5.9 x 10(7) M(-1)s(-1), respectively, in aqueous solutions and reversible. The reactivity of tosyl radical (p-CH3C6H4SO2 center dot) toward a series of alkenes bearing various functional groups was also determined by competition kinetics in benzene. The rate constants for the addition of tosyl radical to alkenes vary in A much narrower range than the rate constants for the reverse reaction. The stabilization of the adduct radical substantially contributes to the increase of the rate constant for the addition of tosyl radical to alkenes and, conversely, retards the beta-elimination of tosyl radical.

  • Cissokho, I.; Farnet, A. - M.; Ferre, E.; Bertrand, M. P.; Gil, G.; Gastaldi, S. Chimia 2012, 66 (6), 435-438.
    Résumé : The system laccase/mediator/dioxygen is able to trigger radical reactions with radical precursors which are not natural substrates of this enzyme. The radical generation has been accomplished by single electron transfer oxidation of a 1,3-dicarbonyl precursor. The process is exemplified with a radical cascade.

  • Poulhes, F.; Mouysset, D.; Gil, G.; Bertrand, M. P.; Gastaldi, S. Polymer 2012, 53 (6), 1172-1179.
    Résumé : The optimization of CAL-B-promoted (Novozym 435) A/B and AA/BB type polymerizations leading to polyetheramides, from amino ethylesters or diethyl esters and diamines based on ethylene- or diethylene-glycol moieties, is disclosed herein. From these preliminary experiments it became obvious that it is of prime importance: to avoid the presence of water by carefully drying the enzyme prior to use; to eliminate ethanol from the reaction medium, by working under reduced pressure in order to drive the amidation reaction forward; to select an appropriate high boiling solvent, the best choice being diphenyl ether. Under such experimental conditions, polyetheramides were obtained in 70-80% yield with an average degree of polymerization (DPn) up to 17. (C) 2012 Elsevier Ltd. All rights reserved.

  • Poulhes, F.; Mouysset, D.; Gil, G.; Bertrand, M. P.; Gastaldi, S. Tetrahedron-Asymmetry 2012, 23 (11-12), 867-875.
    Résumé : and AABB enzymatic polymerizations have been carried out under reduced pressure; they give rise to optically active polymers in good yield, with a good degree of polymerization, and a narrow polydispersity index. This approach demonstrates that the presence of a methyl group at the stereogenic center at the alpha-position relative to the nitrogen atom does not slow down the polymerization as compared with the polycondensation of a related achiral monomer. (c) 2012 Elsevier Ltd. All rights reserved.

  • Queyroy, S.; Vanthuyne, N.; Gastaldi, S.; Bertrand, M. P.; Gil, G. Advanced Synthesis & Catalysis 2012, 354 (9), 1759-1764.
    Résumé : The use of N-octanoyldimethylglycine trifluoroethyl ester as acyl donor in the kinetic resolution of aliphatic amines catalysed by proteases led to enantiomeric ratios >200 in most cases. The resolutions mediated by Protex 6L were shown to be much faster than the resolutions achieved with the most efficient commercially available serine proteases, i.e., alkaline protease, Properase 1600L, and Subtilisin
2011

  • Farnet, A. M.; Chevremont, A. C.; Gil, G.; Gastaldi, S.; Ferre, E. Chemosphere 2011, 82 (2), 284-289.
    Résumé : We investigated the potential of the laccase from the white-rot fungus Marasmius quercophilus to transform certain alkylphenols (p-nonylphenol, p-octylphenol and p-t-octylphenol). We tested the reactivity of this enzyme under different conditions: in liquid cultures and using the partially purified laccase with and without 2,2'-azino-bis-3-ehtylbenzothiazoline-6-sulfonicacid (ABTS) as a mediator. The percentage of p-t-octylphenol disappearance in liquid cultures was 69.0 +/- 1.5% and 81 +/- 5% after a 8-d or 15-d incubation, respectively, with p-nonylphenol, these percentages were 62 +/- 4% and

  • Gerbaud, G.; Caldarelli, S.; Ziarelli, F.; Gastaldi, S. Journal of Magnetic Resonance 2011, 210 (1), 75-81.
    Résumé : The intensity of the carbon signal in a CPMAS experiment has been measured for two CH and three CH2 moieties in four test molecules under different phase-modulated proton decoupling conditions and as a function of the spinning rate. The proton decoupling schemes investigated were the golden standard TPPM and three of the GTn family. Aim of this analysis was to better describe experimentally the impact and limitations of phase-modulated decoupling. Sizeable differences in the response to decoupling were observed in otherwise chemically identical molecular fragments, such as the CHCH2 found in tyrosine, phenyl-succinic acid or 9-Anthrylmethyl-malonate, probably due to differences in spin-diffusion rates. In keeping with known facts, the efficiency of the decoupling was observed to decrease with the MAS rate, but with somewhat different trends for the tested systems. (C) 2011 Elsevier Inc. All rights reserved.

  • Poulhes, F.; Vanthuyne, N.; Bertrand, M. P.; Gastaldi, S.; Gil, G. Journal of Organic Chemistry 2011, 76 (17), 7281-7286.
    Résumé : The (R)-selective chemoenzymatic dynamic kinetic resolution of primary amines was performed at 38-40 degrees C in MTBE, in good to high yields and with high enantiomeric excesses. These reactions associating CAL-B to octanethiol as radical racemizing agent were carried out in the presence of methyl beta-methoxy propanoate as acyl donor, under photochemical irradiation at 350 nm in glassware.
2010

  • El Blidi, L.; Vanthuyne, N.; Siri, D.; Gastaldi, S.; Bertrand, M. P.; Gil, G. Organic & Biomolecular Chemistry 2010, 8 (18), 4165-4168.
    Résumé : Chemoenzymatic dynamic kinetic resolution (DKR) of amines involving sulfanyl radical-induced racemization happened to be the very first switchable DKR process allowing the synthesis of either (R)- or (S)-amides, in good yield and high enantiomeric excess, depending on the nature of the enzyme; the different steps of the development of (S)-selective DKR are discussed.

  • Farnet, A. M.; Ferre, E.; Gil, G.; Gastaldi, S. Soil Biology & Biochemistry 2010, 42 (6), 1001-1005.
    Résumé : Measuring laccase activities in natural environments requires improvement since this oxidation usually produces radical compounds which can interfere with other molecules from these complex media, leading to misinterpretation of the results. Here the syringaldazine skeleton was used to synthesise a new substrate whose quinone is soluble in water and chemically stable. Hydrophilic moieties were added to syringaldazine at the 3 and 5 positions on both aromatic rings to enhance its solubility in water. Syringaldazine analogue 6c was selected. Laccases from two white-rot fungus strains were first tested and a strong affinity for this substrate was observed. Moreover the laccase activity found using a litter extract was higher with 6c which can be explained by the strong stability of its quinone in water. (C) 2010 Elsevier Ltd. All rights reserved.

  • Olier, C.; Kaafarani, M.; Gastaldi, S.; Bertrand, M. P. Tetrahedron 2010, 66 (2), 413-445.

  • Poulhes, F.; Sylvain, R.; Perfetti, P.; Bertrand, M. P.; Gil, G.; Gastaldi, S. Synthesis-Stuttgart 2010, Nᵒ 8, 1334-1338.
    Résumé : A two-step procedure involving cross-metathesis and reductive amination enables easy access to alpha-methylamines and alpha,alpha'-dimethyldiamines from a wide variety of terminal olefins.