Béatrice Dubessy

French National Centre for Scientific Research, Lutetia Parisorum, Île-de-France, France

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Publications (5)22.52 Total impact

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    ABSTRACT: ABii diphosphonatocavitands self-assemble in chloroform solution to form dimeric molecular capsules. The molecular capsules can incarcerate an N-methylpyridinium or N-methylpicolinium guest. We have demonstrated that the supramolecular assembly acts as a molecular rotor as a result of the restricted motion of the guest inside the molecular cavity. In the solid state, X-ray diffraction analysis of the free host showed that two cavitands interact through strong hydrogen bonds to give the supramolecular self-assembled capsule. The solid-state structure of the N-methylpicolinium complex is comparable to that of the free host and indicates that the guest is not a prerequisite for the formation of the capsule. DOSY NMR studies provided a definitive argument for the formation of the free and complexed supramolecular capsule in CDCl(3) solution. In solution, the tumbling of the N-methylpyridinium and N-methylpicolinium guests about the equatorial axes of the host can be frozen and differs by the respective energy barriers, with the larger picolinium substrate having a larger value (ΔG(++) = 69.7 kJ mol(-1)) than the shorter pyridinium guest (ΔG(++) = 44.8 kJ mol(-1)). This behavior corresponds to the restricted rotation of a rotator in a supramolecular rotor.
    Journal of the American Chemical Society 10/2010; 132(44):15637-43. · 10.68 Impact Factor
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    ABSTRACT: An inherently chiral ABii diphosphonato cavitand (±)-4 bearing a single quinoxaline bridging moiety was synthesized and resolved by chiral HPLC. Its chiroptical properties were investigated and VCD experiments allowed the determination of its absolute configuration. Distinguishable diastereomeric complexes in solution with l-adrenaline were observed by 1H and 31P NMR together with a noticeable enantio-discrimination at 253K (dr ∼2:1) in favor of the dextrorotatory cavitand (+)-4.
    Tetrahedron Asymmetry 01/2010; 21(11):1534-1541. · 2.12 Impact Factor
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    ABSTRACT: iii-Phosphorylated cavitands incorporating an N-methylpyridinium guest moiety as the fourth bridging unit form supramolecular associations by inclusion of the charged CH(3)N(+)-pyridinium head into a neighboring host cavity. The dimeric association is favored in solution and was characterized by NMR, mass spectrometry, DOSY experiments, and single crystal X-ray analysis.
    The Journal of Organic Chemistry 06/2009; 74(10):3923-6. · 4.56 Impact Factor
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    ABSTRACT: Four tetraphosphorylated TiiiiPO cavitands 1 encapsulate the pyridinium heads of a tetrakis(N-methylpyridinium)porphyrin iodide to form a 4:1:4 (host)4/guest4+/4I- complex. The single-crystal X-ray diffraction analysis shows the arrangement of the four cavities bound to the CH3N+ groups of the porphyrin moiety and the four iodide anions nested between the phenethyl substituents of the hosts. 1H NMR investigations show that the structure is preserved in chloroform solution and underscore the effect of the counteranions.
    The Journal of Organic Chemistry 07/2007; 72(12):4528-31. · 4.56 Impact Factor
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    ABSTRACT: The recent results in the chemistry of cavitands have proved that they are very efficient molecular receptors and potential precursors of molecular devices. In this context, we have investigated the synthesis and binding properties of phosphorylated cavitands. The stereoselective synthesis and the structural studies of the new compounds showed that these bowl-shaped molecules possess a well defined aromatic cavity surrounded by four phosphoryl groups (P=O or P=S). They are very efficient ligands for metal and organic cations. They are able to encapsulate cationic species by cooperative effect of the preorganized aromatic cavity and the four phosphorylated groups. Moreover, the upper and lower rim functionalitics can lead to the formation of molecular capsules and supramolecular assemblies whose properties and structures have been investigated by X-ray diffraction and NMR studies in solution.
    Phosphorus Sulfur and Silicon and the Related Elements 06/2002; Sulfur(and Silicon and the Related Elements):1485-1488. · 0.60 Impact Factor