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Featured researches published by Sandra Pinet.


Journal of the American Chemical Society | 2013

Enhanced electrogenerated chemiluminescence in thermoresponsive microgels.

Florent Pinaud; Lorenzo Russo; Sandra Pinet; Isabelle Gosse; Valérie Ravaine; Neso Sojic

The electrochemistry, photoluminescence and electrogenerated chemiluminescence of thermoresponsive redox microgels were investigated. For the first time, reversible ECL enhancement is demonstrated in stimuli-responsive 100-nm microgel particles. Such an unexpected amplification reached 2 orders of magnitude, and it is intrinsically correlated with the collapse of the microgel particles. The swell-collapse transition decreases the average distance between adjacent redox sites and favors the electron-transfer processes in the microgels resulting in the enhanced ECL emission.


Journal of Nutrition | 2012

The Fraction of α-Linolenic Acid Present in the sn-2 Position of Structured Triacylglycerols Decreases in Lymph Chylomicrons and Plasma Triacylglycerols during the Course of Lipid Absorption in Rats

Leslie Couëdelo; Carole Vaysse; Emilie Vaique; Alexandre Guy; Isabelle Gosse; Thierry Durand; Sandra Pinet; Maud Cansell; Nicole Combe

Little is known about the ability of α-linolenic acid (Ln) to remain in the sn-2 position of TG during the absorption process. The goal of this study was to determine the Ln distribution in the lymph (Study 1) and plasma (Study 2) TG of rats fed a single i.g. load of structured TG [300 mg/rat of either oleic acid (O)/Ln/O TG (OLnO) or Ln/O/O TG (LnOO), n = 7 rats]. In an early fraction (3-4 h) of lymph (OLnO group; 100% Ln in the sn-2 position), 46 ± 2% Ln was maintained in this position in lymph TG. There was even less (29 ± 6%) in the last fraction (7-24 h) (P < 0.05). Ln was also found (9 ± 3%) in the sn-2 position of lymph TG in the LnOO group. The Ln content in lymph phospholipids was twice as high in rats when they were fed LnOO (4.2 ± 0.1%) than OLnO (2.3 ± 0.2%) (P < 0.005). Six hours postprandially (Study 2), 21 ± 3% of the Ln incorporated into plasma TG was located in the sn-2 position in the OLnO group compared to 13 ± 2% in the LnOO group (P < 0.001). Overall, these results indicate that the amount of Ln that moved from the sn-2 position of structured TG to the sn-1(3) position of lymph TG increased during absorption. This may account for a substantial hydrolysis of the 2-monolinolenylglycerols in enterocytes, leading to the intramolecular redistribution of Ln in lymph TG and, consequently, in plasma TG.


Journal of Physical Chemistry B | 2015

Differential Photoluminescent and Electrochemiluminescent Behavior for Resonance Energy Transfer Processes in Thermoresponsive Microgels.

Florent Pinaud; Romain Millereux; Pierre Vialar-Trarieux; Bogdan Catargi; Sandra Pinet; Isabelle Gosse; Neso Sojic; Valérie Ravaine

Stimuli-responsive microgels with redox and luminescent resonance energy transfer (LRET) properties are reported. Poly(N-isopropylacrylamide) microgels are functionalized simultaneously with two models dyes: a derivative of tris(bipyridine) ruthenium complex and cyanine 5. Both moieties are chosen as a pair of luminophores with a spectral overlap for resonance energy transfer, where the ruthenium complex acts as a donor and the cyanine an acceptor. The effect of the temperature on the efficiency of the LRET of the microgels has been investigated and compared using either photoluminescence (PL) or electrochemiluminescence (ECL) as the excitation process. In PL, the synthesized microgels exhibit resonance energy transfer regardless of the swelling degree of the microgels. The transfer efficiency is a function of the donor-acceptor distance and can be tuned either by the swell-collapse phase transition or by the dye content in the microgel network. In ECL, the microgels emit light only at the wavelength of the ruthenium complex because the resonance energy transfer does not occur. Indeed, even within the microgel matrix, the cyanine dye is oxidized at the potential required for ECL generation, which impairs its emitting properties. Thus, both excitation channels (i.e., PL and ECL) show differential behavior for the resonance energy transfer processes.


Journal of Organic Chemistry | 2012

Development of functionalized cyclotriveratrylene analogues: introduction of withdrawing and π-conjugated groups.

Lisa Peyrard; Marie-Laurence Dumartin; Sabine Chierici; Sandra Pinet; Gediminas Jonusauskas; Pierre Meyrand; Isabelle Gosse

Cyclotriveratrylene analogues (CTVs) are supramolecular bowl-shaped molecules known for their ability to complex organic and organometallic guests, to form liquid crystals, polymers, or nanostructures. In this Article, we report the synthesis of new cyclotriveratrylene analogues with fluorescence properties in which various electron-withdrawing or π-extended conjugated groups are appended to the wide rim ortho to the methoxy-donating groups. Synthetically, these functionalized CTVs cannot be obtained as CTVs with electron-rich functions by the typical method (i.e., the trimerization of the corresponding benzyl alcohol) but are prepared from a common key intermediate, the C(3)-triiodocyclotriveratrylene (CTV-I(3)), in good yields. Despite the synthetic difficulties encountered due to the presence of three reactive centers, we have demonstrated the possibility of performing Sonogashira coupling and Huisgen cycloaddition reactions directly to the CTV core for the first time. CTVs with π-extended conjugated groups reveal interesting fluorescence profiles. More broadly, this study utilizes CTV-I(3) to introduce novel functionalities into CTVs to keep exploring their potential applications.


Phosphorus Sulfur and Silicon and The Related Elements | 1997

[4π + 2π] Cycloadditions of N-Acyl-Thioformamides

Yannick Vallée; Pierre-Yves Chavant; Sandra Pinet; Nadia Pelloux-Leon; Roger Arnaud; Vincenzo Barone

Abstract Thiocarbonyl compounds, such as thioaldehydes and thioketones, are good dienophiles in the Diels-Alder reaction. Here we show that suitably substituted thioformamides can also be used in this reaction. A theoretical study of the [4π + 2π] cycloaddition of thiocarbonyls with butadiene has been performed and was used to determine the needed substituents.


Journal of Chemical Research-s | 2001

Total synthesis of bernumicine and bernumidine, two alkaloids from Berberis nummularia †

Sandra Pinet; Pierre Y. Chavant; M. T. Averbuch‐Pouchot; Yannick Vallée

Bernumicine and bernumidine are two alkaloids extracted from Berberis nummularia. Their total synthesis has been completed and it has been shown that the configuration of the stereogenic carbon of both is (R).


Organic Letters | 2002

Dialkylzinc-assisted alkynylation of nitrones.

Sandra Pinet; Shashi U. Pandya; Pierre Y. Chavant; and Alexander Ayling; Yannick Vallée


Journal of the American Chemical Society | 2002

Chemosensors for the marine toxin saxitoxin.

Robert E. Gawley; Sandra Pinet; Claudia M. Cardona; Probal K. Datta; Tong Ren; Wayne C. Guida; Jason Nydick; Roger M. Leblanc


Chemistry: A European Journal | 2009

Differential Photoluminescent and Electrochemiluminescent Detection of Anions with a Modified Ruthenium(II)-Bipyridyl Complex

Emanuela Berni; Isabelle Gosse; Denis Badocco; Paolo Pastore; Neso Sojic; Sandra Pinet


European Journal of Organic Chemistry | 2005

Tandem Addition/Cyclization of Alkynylzinc Reagents to Enantiopure 2-tert-Butyl-3,5-dimethyl-2,3-dihydroimidazol-4-one N-Oxide: Potential Precursors of Quaternary α-Amino Acids

Frédéric Cantagrel; Sandra Pinet; Yves Gimbert; Pierre Y. Chavant

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Isabelle Gosse

Centre national de la recherche scientifique

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Yannick Vallée

Centre national de la recherche scientifique

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Alexandre Guy

University of Montpellier

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Neso Sojic

University of Bordeaux

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Sabine Chierici

Joseph Fourier University

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Thierry Durand

University of Montpellier

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