The mesomorphic behavior of octa (dodecyloxymethyl) phthalocyanine was studied with DSC, optical ... more The mesomorphic behavior of octa (dodecyloxymethyl) phthalocyanine was studied with DSC, optical microscopy, and X-ray diffraction. Two discotic mesophases were observed as a function of temperature. Their structure corresponds to the piling up of the flat molecules in columns which are laterally assembled according to a two-dimensional hexagonal lattice (D = 31.2 Å). The repeat distance of the molecules along
... Self-organization of nanostructured functional dendrimers. Joaquín Barberá, Bertrand Donnio, ... more ... Self-organization of nanostructured functional dendrimers. Joaquín Barberá, Bertrand Donnio, Lionel Gehringer, Daniel Guillon, Mercedes Marcos, Ana Omenat and José Luis Serrano J. Mater. Chem., 2005, 15, 4093-4105. DOI ...
ABSTRACT The synthesis, thermal properties and organisation of side-chain liquid-crystalline (SCL... more ABSTRACT The synthesis, thermal properties and organisation of side-chain liquid-crystalline (SCLC) polysalts and of their analogous low molecular weight (LMW) pyridinium salts are described. They contain three distinct parts: a phenyl benzoate aromatic core, a flexible aliphatic chain (6 or 12 methylene units) and a pyridinium group associated with bromine counterions. The polysalts are obtained upon spontaneous anionic polymerisation of 4-vinylpyridine in the presence of 4-methoxyphenyl 4′-(ω-bromoalkoxy)benzoate. Fully quaternised polymers of high molecular weights are obtained. Their thermotropic polymorphism was studied by means of differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. Despite the presence of the spacer and of a mesogenic group known for its nematogenic character, only smectic A mesophases were observed for the LMW pyridinium salt with the longer spacer (C12) and for the polysalts with the two spacer lengths (C6, C12). These compounds were shown to form in a large range of temperature a single layered structure. An organisation model is proposed in which the pyridinium cations and the aromatic cores are perpendicular to the layer, while the spacers adopt a disorganised conformation.
In this manuscript, a complete and comprehensive study on main-chain liquid crystalline dendrimer... more In this manuscript, a complete and comprehensive study on main-chain liquid crystalline dendrimers is reported. In order to be able to finely tune, and thus control, the mesomorphism of such multicomponent supermolecules, various structural parameters were systematically modified, such as the core nature and connectivity, the degree and topology of branching, the molecular architecture, the generation, and the chain substitution pattern of the peripherally grafted pro-mesogenic groups. The increase of the molecular complexity and the effects of the structural manipulations proved to be very interesting for the design of multifunctional molecular materials, and provided new types of mesophases, enlarging as such the diversity of liquid crystalline supramolecular organizations.
ABSTRACT We report the synthesis of a new homologous series of symmetric bent-shaped liquid cryst... more ABSTRACT We report the synthesis of a new homologous series of symmetric bent-shaped liquid crystal dimers bearing oxybiphenylcarboxylate mesogens linked by a pentamethylene spacer. The dimers were characterised by optical, thermal, X-ray diffraction and computational techniques. Shorter dimers showed an I-N-SmA-SmC phase sequence with strong first-order phase transitions. For the longer dimers, the unconventional uniaxial SmA phase present in shorter members collapsed. A 9:1 binary mixture of a bent dimer with a non-mesogenic dimer exhibited upon the SmA-SmC phase transition a maximum layer contraction of 1%.
EXAFS was used to investigate the local structure of the polar spines of rhodium (II) soaps in th... more EXAFS was used to investigate the local structure of the polar spines of rhodium (II) soaps in the columnar liquid crystalline state. It was also used to ascertain the degree of blending of the cores in binary mixtures of rhodium (II) and copper (II) soaps. For the pure rhodium soaps, the columns are shown to result from the stacking of binuclear metal-metal bonded dirhodium tetracarboxylate units bonded to one another by apical ligation of the metal atom of each complex with one of the oxygen atoms of the adjacent molecule. Mixtures of rhodium (II) and copper (II) soaps give a hexagonal columnar mesophase in which pure rhodium and pure copper columns are randomly distributed.
ABSTRACT We report on the growth control of zinc oxide nanorods to point out the effect of the Zn... more ABSTRACT We report on the growth control of zinc oxide nanorods to point out the effect of the ZnO nanorods quality on the power conversion efficiency (PCE) of transparent conductive oxide (TCO)/ZnO nanorods/dye/spiro-OMeTAD/metal electrode photovoltaic devices. A promising PCE of 0.61% was measured for the best nanorods growth conditions. A careful control of all the growth parameters during the seeds layer deposition and the hydrothermal synthesis was necessary to reach such a high PCE for this kind of device. A regular nanorod layer with a flat upper surface was obtained for ethylenediamine to zinc acetate dihydrate molar ratio equal to 1.74 and a pH of 8.2. The growth was performed at 65 °C for 2 h to avoid zinc oxide brushes deposition on the surface, arising from zinc hydroxyacetate decomposition during the hydrothermal treatment. The effect of ZnO nanorods length (ranging from 1 to 3 μm) on solar cell efficiency was tested. Although the UV–vis absorption increases when the nanorods length increases, the best photovoltaic parameters were measured for the shortest nanorods length studied (1 μm).
... Rev. Lett. 46, 1289 (1981). 5J. C. LeGuillon and J. Zinn-Justin, Phys. Rev. ... Rev. A 33, 26... more ... Rev. Lett. 46, 1289 (1981). 5J. C. LeGuillon and J. Zinn-Justin, Phys. Rev. ... Rev. A 33, 2602 (1986). G. Nounesis, R. Geer, H. Liu, CC Huang, and JW Good-by (unpublished). 2J. M. Viner, D. Lamey, CC Huang, R. Pindak, and JW Goodby, Phys. Rev. A 28, 2433 (1983). 13J. ...
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ABSTRACT The role of several molecular factors is analyzed with respect to the value of the spont... more ABSTRACT The role of several molecular factors is analyzed with respect to the value of the spontaneous polarization measured in ferroelectric liquid crystal compounds containing a sulfinate group as unique chiral center. First, it is shown that different molecular contributions are involved in the distribution of the transverse dipole moments (orientational fluctuations, dilution effect with increasing of the aliphatic chain length of the molecules, tilt angle). Second, it is observed that the presence of a siloxane group in the molecular architecture strongly contributes to the stabilization of the ferroelectric phases with an increase of the spontaneous polarization. Finally, it is shown that the thermotropic behaviour, the polar order and, consequently, all the related electro-optical properties of ferroelectric liquid crystals may depend significantly on the optical purity of the materials.
The mesomorphic behavior of octa (dodecyloxymethyl) phthalocyanine was studied with DSC, optical ... more The mesomorphic behavior of octa (dodecyloxymethyl) phthalocyanine was studied with DSC, optical microscopy, and X-ray diffraction. Two discotic mesophases were observed as a function of temperature. Their structure corresponds to the piling up of the flat molecules in columns which are laterally assembled according to a two-dimensional hexagonal lattice (D = 31.2 Å). The repeat distance of the molecules along
... Self-organization of nanostructured functional dendrimers. Joaquín Barberá, Bertrand Donnio, ... more ... Self-organization of nanostructured functional dendrimers. Joaquín Barberá, Bertrand Donnio, Lionel Gehringer, Daniel Guillon, Mercedes Marcos, Ana Omenat and José Luis Serrano J. Mater. Chem., 2005, 15, 4093-4105. DOI ...
ABSTRACT The synthesis, thermal properties and organisation of side-chain liquid-crystalline (SCL... more ABSTRACT The synthesis, thermal properties and organisation of side-chain liquid-crystalline (SCLC) polysalts and of their analogous low molecular weight (LMW) pyridinium salts are described. They contain three distinct parts: a phenyl benzoate aromatic core, a flexible aliphatic chain (6 or 12 methylene units) and a pyridinium group associated with bromine counterions. The polysalts are obtained upon spontaneous anionic polymerisation of 4-vinylpyridine in the presence of 4-methoxyphenyl 4′-(ω-bromoalkoxy)benzoate. Fully quaternised polymers of high molecular weights are obtained. Their thermotropic polymorphism was studied by means of differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. Despite the presence of the spacer and of a mesogenic group known for its nematogenic character, only smectic A mesophases were observed for the LMW pyridinium salt with the longer spacer (C12) and for the polysalts with the two spacer lengths (C6, C12). These compounds were shown to form in a large range of temperature a single layered structure. An organisation model is proposed in which the pyridinium cations and the aromatic cores are perpendicular to the layer, while the spacers adopt a disorganised conformation.
In this manuscript, a complete and comprehensive study on main-chain liquid crystalline dendrimer... more In this manuscript, a complete and comprehensive study on main-chain liquid crystalline dendrimers is reported. In order to be able to finely tune, and thus control, the mesomorphism of such multicomponent supermolecules, various structural parameters were systematically modified, such as the core nature and connectivity, the degree and topology of branching, the molecular architecture, the generation, and the chain substitution pattern of the peripherally grafted pro-mesogenic groups. The increase of the molecular complexity and the effects of the structural manipulations proved to be very interesting for the design of multifunctional molecular materials, and provided new types of mesophases, enlarging as such the diversity of liquid crystalline supramolecular organizations.
ABSTRACT We report the synthesis of a new homologous series of symmetric bent-shaped liquid cryst... more ABSTRACT We report the synthesis of a new homologous series of symmetric bent-shaped liquid crystal dimers bearing oxybiphenylcarboxylate mesogens linked by a pentamethylene spacer. The dimers were characterised by optical, thermal, X-ray diffraction and computational techniques. Shorter dimers showed an I-N-SmA-SmC phase sequence with strong first-order phase transitions. For the longer dimers, the unconventional uniaxial SmA phase present in shorter members collapsed. A 9:1 binary mixture of a bent dimer with a non-mesogenic dimer exhibited upon the SmA-SmC phase transition a maximum layer contraction of 1%.
EXAFS was used to investigate the local structure of the polar spines of rhodium (II) soaps in th... more EXAFS was used to investigate the local structure of the polar spines of rhodium (II) soaps in the columnar liquid crystalline state. It was also used to ascertain the degree of blending of the cores in binary mixtures of rhodium (II) and copper (II) soaps. For the pure rhodium soaps, the columns are shown to result from the stacking of binuclear metal-metal bonded dirhodium tetracarboxylate units bonded to one another by apical ligation of the metal atom of each complex with one of the oxygen atoms of the adjacent molecule. Mixtures of rhodium (II) and copper (II) soaps give a hexagonal columnar mesophase in which pure rhodium and pure copper columns are randomly distributed.
ABSTRACT We report on the growth control of zinc oxide nanorods to point out the effect of the Zn... more ABSTRACT We report on the growth control of zinc oxide nanorods to point out the effect of the ZnO nanorods quality on the power conversion efficiency (PCE) of transparent conductive oxide (TCO)/ZnO nanorods/dye/spiro-OMeTAD/metal electrode photovoltaic devices. A promising PCE of 0.61% was measured for the best nanorods growth conditions. A careful control of all the growth parameters during the seeds layer deposition and the hydrothermal synthesis was necessary to reach such a high PCE for this kind of device. A regular nanorod layer with a flat upper surface was obtained for ethylenediamine to zinc acetate dihydrate molar ratio equal to 1.74 and a pH of 8.2. The growth was performed at 65 °C for 2 h to avoid zinc oxide brushes deposition on the surface, arising from zinc hydroxyacetate decomposition during the hydrothermal treatment. The effect of ZnO nanorods length (ranging from 1 to 3 μm) on solar cell efficiency was tested. Although the UV–vis absorption increases when the nanorods length increases, the best photovoltaic parameters were measured for the shortest nanorods length studied (1 μm).
... Rev. Lett. 46, 1289 (1981). 5J. C. LeGuillon and J. Zinn-Justin, Phys. Rev. ... Rev. A 33, 26... more ... Rev. Lett. 46, 1289 (1981). 5J. C. LeGuillon and J. Zinn-Justin, Phys. Rev. ... Rev. A 33, 2602 (1986). G. Nounesis, R. Geer, H. Liu, CC Huang, and JW Good-by (unpublished). 2J. M. Viner, D. Lamey, CC Huang, R. Pindak, and JW Goodby, Phys. Rev. A 28, 2433 (1983). 13J. ...
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ABSTRACT The role of several molecular factors is analyzed with respect to the value of the spont... more ABSTRACT The role of several molecular factors is analyzed with respect to the value of the spontaneous polarization measured in ferroelectric liquid crystal compounds containing a sulfinate group as unique chiral center. First, it is shown that different molecular contributions are involved in the distribution of the transverse dipole moments (orientational fluctuations, dilution effect with increasing of the aliphatic chain length of the molecules, tilt angle). Second, it is observed that the presence of a siloxane group in the molecular architecture strongly contributes to the stabilization of the ferroelectric phases with an increase of the spontaneous polarization. Finally, it is shown that the thermotropic behaviour, the polar order and, consequently, all the related electro-optical properties of ferroelectric liquid crystals may depend significantly on the optical purity of the materials.
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