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Eric Besson

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Papers by Eric Besson

One-pot synthesis of organic polymer functionalized mesoporous silicas

Microporous and Mesoporous Materials, 2021

Polymer functionalization of ordered mesoporous silicas (OMS) offer wide applications owing to th... more Polymer functionalization of ordered mesoporous silicas (OMS) offer wide applications owing to their synergy properties. In this study, a new approach for polymer functionalization of OMS is demonstrated by the co-condensation of silica precursor and a functional polymer bearing triethoxysilane end-group in the presence of a tailored poly(ethylene oxide)-b-polystyrene (PEO-b-PS) amphiphilic copolymer used as pore template. The novelty of this strategy resides in the co-micellization of PEO-b-PS and functional polymer that enables the incorporation of the latter into the mesoporous silica. By changing the nature of the functional polymer, as well as their loading concentration and process conditions, different ordered polymermesoporous silicas containing aryl, nitro or amide groups and high polymer content, up to 38 wt% were synthesized. These materials exhibit high specific surface area (488 m 2 g-1) and large pores (8 nm) with acceptable CO2 adsorption capacity and selectivity towards CH4 and N2.

Coniferyl Alcohol Radical Detection by the Dirigent Protein At DIR6 Monitored by EPR

ChemBioChem, 2020

Supporting information for this article is given via a link at the end of the document.

Probing the efficiency of thermal and photochemical bond homolysis in functionalized nanostructured SBA-15 silicas

Microporous and Mesoporous Materials, 2021

implementation of these activation modes between the solution and the mesoporous silicas. Moreove... more implementation of these activation modes between the solution and the mesoporous silicas. Moreover, the thermal experiments enabled to measure the CO bond dissociation constants of alkoxyamines covalently anchored to a nanostructured silica, their values were in the same order of magnitude than those determined in solution.

Monitoring Crystallization Processes in Confined Porous Materials by Dynamic Nuclear Polarization Solid-State Nuclear Magnetic Resonance

Establishing mechanistic understanding of crystallization processes at the molecular level is cha... more Establishing mechanistic understanding of crystallization processes at the molecular level is challenging, as it requires both the detection of transient solid phases and monitoring the evolution of both liquid and solid phases as a function of time. Here, we demonstrate the application of dynamic nuclear polarization (DNP) enhanced NMR spectroscopy to study crystallization under nanoscopic confinement, revealing a viable approach to interrogate different stages of crystallization processes. We focus on crystallization of glycine within the nanometric pores (7−8 nm) of a tailored mesoporous SBA-15 silica material with wall-embedded TEMPO radicals. The results show that the early stages of crystallization, characterized by the transition from the solution phase to the first crystalline phase, are straightforwardly observed using this experimental strategy. Importantly, the NMR sensitivity enhancement provided by DNP allows the detection of intermediate phases that would not be observable using standard solid-state NMR experiments. Our results also show that the metastable β polymorph of glycine, which has only transient existence under bulk crystallization conditions, remains trapped within the pores of the mesoporous SBA-15 silica material for more than 200 days.

Modulating lifetimes and relaxation times of phenoxyl radicals through their incorporation into different hybrid nanostructures

Physical Chemistry Chemical Physics, 2019

Playing with the structural features of various hybrid materials enables to adjust physical prope... more

Diazene-Functionalized Lamellar Materials as Nanobuilding Blocks: Application as Light-Sensitive Fillers to Initiate Radical Photopolymerizations

ACS Macro Letters, 2017

New polysilsesquioxane-based lamellar materials, functionalized with radical precursors, were syn... more 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 homogenously 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 pre-formed organic polymers.

Erbium-doped polymer-based materials and waveguides for amplification at 1,55 μm

Integrated Optics: Devices, Materials, and Technologies X, 2006

A key parameter for the choice of an erbium-doped material suitable for efficient amplification a... more

Evidence for the contribution of degenerate hydrogen atom transport to the persistence of sulfanyl radicals anchored to nanostructured hybrid materials

New Journal of Chemistry, 2017

Nanostructured functionalized silicas were used as a platform to compare the behaviour of anchore... more

Investigating Unusual Organic Functional Groups to Engineer the Surface Chemistry of Mesoporous Silica to Tune CO2-Surface Interactions

ACS applied materials & interfaces, Jan 26, 2017

As the search for functionalized materials for CO2 capture continues, the role of theoretical che... more 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 (N3, 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.

Silica materials with wall-embedded nitroxides provide efficient polarization matrices for dynamic nuclear polarization NMR

Chemical Communications, 2016

Hybrid silica materials with wall-embedded nitroxides efficiently polarize impregnated substrates... more

Theoretical investigation of the reaction of dialkylzincs with α-alkoxycarbonyl radicals. Evaluation of α-bromoacrylates as radical acceptors in radical-polar crossover processes

Tetrahedron, 2015

The evaluation of ethyl α-bromoacrylate as radical acceptor in dialkylzinc radical-polar cascades... more The evaluation of ethyl α-bromoacrylate as radical acceptor in dialkylzinc radical-polar cascades addresses the question of the parameters controlling homolytic substitution at zinc by αalcoxycarbonyl radicals. Under non-degassed medium ethyl α-bromoacrylate reacts with diethylzinc to give a bromocyclopropane. The reaction involves successively radical addition, SH2 at zinc, conjugate addition of the resulting enolate to the electrophilic substrate and ring closure. Theoretical calculations were performed to get a better insight into the detailed mechanism. They highlight the impact of zinc(II) chelation on the formal SH2 step. Additional experiments performed in the presence of other electrophiles-aldehydes and acylsilanes-are discussed.

Design of Wall-Functionalized Hybrid Silicas Containing Diazene Radical Precursors. EPR Investigation of Their Photolysis and Thermolysis

The Journal of Physical Chemistry C, 2015

Bis-silylated diazenes were designed to prepare wall-functionalized hybrid silicas via the sol−ge... more Bis-silylated diazenes were designed to prepare wall-functionalized hybrid silicas via the sol−gel process. These precursors enabled the straightforward generation of arylsulfanyl radicals by either photolysis or thermolysis. Their location in the framework of the mesoporous materials was evidenced by spin trapping experiments. The incidence of confinement on the radical lifetime was investigated by electron paramagnetic resonance (EPR). An amazing persistence (t 1/2 = 27 min) was recorded at 473 K.

Arylsulfanyl radical lifetime in nanostructured silica: dramatic effect of the organic monolayer structure

Chem. Sci., 2014

Half-lives of up to 80 h at 293 K are recorded for arylsulfanyl radicals in nanostructured silica... more

Polymer-based materials for amplification in the telecommunication window: Influence of erbium complex concentration on relevant parameters for the elaboration of waveguide amplifiers around 1550nm

Optical Materials, 2007

Erbium-doped polymer-based optical waveguides offer an attractive alternative for inorganic ampli... more Erbium-doped polymer-based optical waveguides offer an attractive alternative for inorganic amplifiers in the eye-safe telecommunication window at 1550 nm. We are succeeded in doping a standard polymethyl-methacrylate (PMMA) matrix with an octupolar erbium complex designed to display quadratic nonlinear optical response and IR luminescence in the same time. We have investigated the influence of erbium complex concentration on various parameters such as spun coated thickness, reactive ionic etching rate, refractive index and near infrared luminescence. The optimal erbium concentration for emission at 1550 nm reaches 1 wt.%. These carefully optimized processing and optical parameters are of great relevance for a further design and elaboration of polymer-based single mode waveguide amplifiers.

A Novel and Simplified Procedure for Patterning Hydrophobic and Hydrophilic SAMs for Microfluidic Devices by Using UV Photolithography

Langmuir, 2006

This work describes how selective patterning of hydrophobic and hydrophilic areas inside microcha... more This work describes how selective patterning of hydrophobic and hydrophilic areas inside microchannels of microfluidic devices can be achieved by combining well-known chemical protocols and standard photolithography equipment (365 nm). Two techniques have been performed and compared. The first technique is based on the preparation of selfassembled monolayers of photocleavable organosilane and the second one on photoassisted grafting (365 nm) of self-assembled monolayers (SAMs) on a silicon or glass substrate. In the first case, we begin with monolayers carrying an o-nitrobenzyl function (hydrophobic area) that is photochemically cleaved, revealing a carboxylic acid group (hydrophilic area). The problem is that the energy necessary to cleave this monolayer is too high and the reaction time is more than 1 h with 50 mW/cm 2 irradiation flux. To overcome this practical disadvantage, we propose another approach that is based on the thiol-ene reaction with benzophenone as photoinitiator. In this approach, a monolayer of mercaptopropyltrimethoxysilane (MPTS) is prepared first. Subsequently, a hydrocarbon chain is photografted locally onto the thiol layer, forming a hydrophobic surface while the reminding unmodified thiol surface is oxidized into sulfonic acid (hydrophilic area). We demonstrated the feasibility of this approach and synthesized high-quality self-assembled monolayers by UV grafting with an irradiation time of 30 s at 365 nm (50 mW/cm 2). The modified surfaces have been characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS), AFM, and multiple internal reflection infrared spectroscopy (MIR-FTIR). The difference in the contact angles on the hydrophilic and hydrophobic surfaces reached a remarkable 77°. We have also demonstrated that this method is compatible with selective surface grafting inside microfluidic channels.

Mechanistic Investigation of Enediyne-Connected Amino Ester Rearrangement. Theoretical Rationale for the Exclusive Preference for 1,6- or 1,5-Hydrogen Atom Transfer Depending on the Substrate. A Potential Route to Chiral Naphthoazepines

The Journal of Organic Chemistry, 2012

Memory of chirality (MOC) and deuteriumlabeling studies were used to demonstrate that the cascade... more Memory of chirality (MOC) and deuteriumlabeling studies were used to demonstrate that the cascade rearrangement of enediyne-connected amino esters 1a and 1b evolved through exclusive 1,5-or 1,6-hydrogen atom transfer, subsequent to 1,3-proton shift and Saito−Myers cyclization, depending on the structure of the starting material. These results were independently confirmed by DFT theoretical calculations performed on model monoradicals. These calculations clearly demonstrate that in the alanine series, 1,5-hydrogen shift is kinetically favored over 1,6-hydrogen shift because of its greater exergonicity. In the valine series, the bulk of the substituent at the nitrogen atom has a major influence on the fate of the reaction. N-Tosylation increases the barrier to 1,5-hydrogen shift to the benefit of 1,6-hydrogen shift. The ready availability of 1,6hydrogen atom transfer was explored as a potential route for the enantioselective synthesis of naphthoazepines.

Functionalisation of the framework of mesoporous organosilicas by rare-earth complexes

J. Mater. Chem., 2006

... Eric Besson, Ahmad Mehdi, Catherine Reyé and Robert JP Corriu*. Laboratoire de Chimie Molécul... more

Soft route for monodisperse gold nanoparticles confined within SH-functionalized walls of mesoporous silica

Journal of Materials Chemistry, 2009

In this paper, we report a soft route leading to small gold nanoparticles confined within the fra... more In this paper, we report a soft route leading to small gold nanoparticles confined within the framework of 2D-hexagonal mesoporous SH-functionalised silicas. For that purpose, a hydrophilic bis-silylated precursor containing a disulfide unit was prepared. Framework-functionalised materials were obtained in one step by the ''direct synthesis'' method which consists of a co-hydrolysis and polycondensation of a bridged organosilica precursor with tetraethylorthosilicate (TEOS) in the presence of a non-ionic triblock co-polymer (P123) as structure-directing agent. Reduction of SS groups leads quantitatively to SH functional groups within the framework of 2D hexagonal mesoporous silicas. All these materials have been characterised by TEM, 13 C and 29 Si NMR experiments, nitrogen gas adsorption, powder XRD and elemental analysis. The subsequent growth of monodisperse gold nanoparticles of small size ($2 nm) within the walls of mesoporous materials was studied and is discussed.

Synthesis of a NO-releasing lamellar silsesquioxane by topotactic exchange of CO2 for NO

Journal of Materials Chemistry, 2009

Organic–inorganic hybrid materials constitute a unique class of materials aiming to combine the p... more

Photoresponsive ordered hybrid materials containing a bridged azobenzene group

J. Mater. Chem., 2005