Jacques Le Moigne
Centre national de la recherche scientifique
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Featured researches published by Jacques Le Moigne.
Chemistry: A European Journal | 2001
Laure Catala; Jacques Le Moigne; Nathalie Kyritsakas; Paul Rey; Juan J. Novoa; Philippe Turek
An extensive investigation of the magnetic properties of three series of biradicals (bis-nitronyl nitroxides diNN-R, bis-imino nitroxides diIN-R and mixed INNN-R, where R is either hydrogen, a triple bond or trimethylsilylacetylenic group) has been carried out to give clear values of the intramolecular interactions through the m-phenylene coupling unit with alpha-nitronyl nitroxides (NN) or alpha-imino nitroxides (IN). An EPR study of the molecules in the isolated state is validated by ab initio calculations, which show the respective influence of spin polarisation and molecular conformation on the singlet-triplet gaps. All these results indicate that the triplet state is the ground state for such biradicals, except when the imidazolyl cycles are orthogonal to the phenyl ring. The magnetic properties of the biradicals in the solid state can be rationalised by examination of the short contacts produced between the ONCNO and ONCN groups. EPR studies on single crystals of the H-substituted series have confirmed the presence of a structural distortion for diNN-H whereas diIN-H and INNN-H do not exhibit such a peculiarity. The magnetic behaviour of diIN-H is described well by a four-spins model, with a strong intermolecular antiferromagnetic interaction of -90 K, whereas in the case of the two other compounds, a supplementary contact involves more complex interactions between the dimers. The compound diNN-tmsa exhibits a ferromagnetic intermolecular interaction of +11 K within the dimers, and this could be attributed to the relative disposition of the imidazolyl rings. Compound diNN-tr reveals a chain-like behaviour, whereas diIN-tr shows a predominant antiferromagnetic interaction within the dimers. The values for the intramolecular interactions in the solid state are in good agreement with those found for the isolated molecules.
Tetrahedron Letters | 2000
Laure Catala; Philippe Turek; Jacques Le Moigne; André De Cian; Nathalie Kyritsakas
Abstract The design and synthesis, as well as solid state and ESR characterisation of three new triradicals based on phenyl ethynyl backbone bearing nitronyl-nitroxide and imino-nitroxide groups, are reported. The synthesis of these compounds was based on palladium-coupling reactions between alkynyl and bromo derivatives. An ESR study showed magnetic interactions between the radicals through the phenyl ethynyl-coupling unit in solution.
Liquid Crystals | 1989
Jacques Le Moigne; Armand Soldera; Daniel Guillon; Antoine Skoulios
Abstract Acetylenic and diacetylenic mesomorphic monomers have been prepared in order to obtain long conjugated polymers able to give high non-linear optical hyperpolarizabilities. Here we report the synthesis of such monomers incorporating cholesteryl and methoxybiphenyl groups; their structural and thermal behaviour are described. The occurrence of mesophases in the acetylenic and diacetylenic derivatives is discussed as a function of the spacer length and of the size of the mesogen moiety. The diacetylenic derivatives containing the methoxybiphenyl groups do not exhibit any liquid-crystalline behaviour but are able to polymerize under U.V. radiation.
Molecular Crystals and Liquid Crystals | 1997
Pascale Wautelet; André Bieber; Philippe Turek; Jacques Le Moigne; Jean-Jacques André
Abstract The properties of a series of stable diradicals based either on iminonitroxide (IN) or nitronylnitroxide (NN) are described. Both radical fragments are coupled by various phenylene and phenylethynylene (triple bond) bridges. They are characterized by EPR studies both in solution and in glassy state. Magnetic coupling is evidenced at a very large distance between both radical fragments (up to 36 A). The intramolecular coupling is found to be antiferromagnetic in all cases and in particular for meta- or ortho- substituted phenylene. Semiempirical calculations using configuration interaction show that the linkers with triple bonds induce a stronger conjugated character than the corresponding ones involving a double bond, in agreement with the experimental optical spectra, and that the relevant geometrical parameters are the twist angles; the corresponding barriers of rotation are then evaluated. Calculations show that, for some values of the twist angle, an antiferromagnetic state may be stabilized.
Molecular Crystals and Liquid Crystals | 1995
Philippe Turek; Pascale Wautelet; Jacques Le Moigne; Jean-Louis Stanger; Jean-Jacques André; André Bieber; Paul Rey; André De Cian; Jean Fischer
Abstract A phenyl diethynyl bridge is used as a magnetic coupling unit (MCU) between two iminonitroxide π-radicals. The ethynyl moiety is attached to the central phenyl ring either in the para or in the meta position. The magnetic properties of the resulting bis-imino nitroxide diradicals (p-BIN and m-BIN) are investigated both at the molecular scale and in the condensed phases. An intramolecular through bond spin coupling is observed at an unusual long distance (about 20 AS) in both derivatives. However, the ground state is found to be a singlet spin state in both compounds. The results suggest an interplay between the spin polarization and the spin delocalization (π-conjugation). An intermolecular weak antiferromagnetic spin coupling is occuring in both compounds.
Organic photonic materials and devices. Conference | 2000
Vincent Dumarcher; Licinio Rocha; Christine Denis; Céline Fiorini-Debuisschert; Jean-Michel Nunzi; Frank Sobel; B. Sahraoui; Denis Gindre; Kevin P. Kretsch; Werner J. Blau; S. Pfeiffer; Hartwig Tillmann; Hans-Heinrich Hoerhold; T. Maillou; Jacques Le Moigne
We present a study of Distributed Feedback laser emission in various polymer materials. This laser scheme permits efficient control of the stimulated emission in dye doped polymer materials. Optical feedback is provided by distributed Bragg gratings formed in the film by interference patterns from the pump beam. We demonstrate broad tunability of laser emission in polymeric waveguides doped with stilbenoid, phenylene vinylene and oligomers of phenyl ethynylene used for OLEDs. Laser action was also obtained with Rhodamine 6G in PMMA deposited on surface relief grating and excited in a transverse single beam pumping geometry.
Journal of Organic Chemistry | 2003
Pascale Wautelet; Jacques Le Moigne; Vladimira Videva,†,‖ and; Philippe Turek
Archive | 1987
A. Thierry; Jacques Le Moigne
Chemistry: A European Journal | 2005
Laure Catala; Jacques Le Moigne; Nathalie Gruber; Juan J. Novoa; Pierre Rabu; Elie Belorizky; Philippe Turek
Synthesis | 2002
Pascale Wautelet; Philippe Turek; Jacques Le Moigne