Download or read book SUR LES APPLICATIONS DE LA RESONANCE MAGNETIQUE NUCLEAIRE DANS LES CRISTAUX LIQUIDES written by J.. COURTIEU and published by . This book was released on 1974 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: ANALYSE DE CETTE METHODE SOUS DEUX ASPECTS PARTICULIERS: AVANTAGES PAR RAPPORT AUX AUTRES TYPES DE MESURES TELS QUE MICROONDES, IR, OU DIFFRACTION ELECTRONIQUE; ET LIMITES APPELEES "A TERME" DONT ON ENTREVOIT LA DISPARITION. LE PRINCIPAL AVANTAGE EST LA POSSIBILITE D'UNE MESURE DIRECTE DE LA FORME DES SYSTEMES DE SPIN. ON A PU, DANS LE CAS DES MOLECULES NON RIGIDES, DETERMINER LA STRUCTURE FINE DES BARRIERES DE POTENTIEL S'OPPOSANT A LA LIBRE ROTATION DES GROUPES MOBILES. PAR CONTRE ON NE PEUT ETUDIER DES SYSTEMES DE PLUS DE 7 OU 8 NOYAUX COMPTE TENU DES ORDINATEURS UTILISES POUR LE CALCUL. ON MONTRE DANS CE CAS L'INTERET DES SUBSTITUTIONS ISOTOPIQUES QUI PERMETTRAIENT L'ELARGISSEMENT DU CHAMP D'ACTION DE LA RMN EN PHASE NEMATIQUE

Download or read book Nuclear Magnetic Resonance of Liquid Crystals written by J.W. Emsley and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: The liquid crystalline state has been known for about a century and has been studied by many techniques. Nuclear magnetic resonance has been used to study mesophases for thirty years, but it has been in very recent years that advances in this form of spectroscopy have led to a rapid growth in its applications to the study both of liquid crystals and of solutes dissolved in them. It has become apparent that no other method of studying liquid crystals can yield such a wealth of data and it is unrivalled as a means of probing the behaviour of the molecules in mesophases. There has also been a steady increase in the study of the shape of small molecules dissolved in liquid crystals via the analysis of their NMR spectrum. In fact, the study of solutes was until recently regarded as a separate activity to the study of liquid crystals themselves, but this artificial division arose only from the gap between the large amount of information that could be derived from the spectrum of a small molecule and the rather meagre data set obtainable from the spectra of liquid crystals. This gap has, however, narrowed and it is now possible to derive a very detailed picture of the structure and orientational ordering of the large molecules typical of those which form liquid crystals. There has also been a rapid growth of interest in the liquid crystalline state.

Download or read book Applications de la r sonance magn tique nucl aire de l tat solide double rotation et tudes dynamiques de cristaux mol culaires written by Eric Cochon and published by . This book was released on 1993 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Magnetic Resonance of Liquid Crystals written by Ronald Y. Dong and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Intended for researchers and students in physics, chemistry and materials science, this book provides the necessary background information and sufficient mathematical and physical detail to study the current research literature. The book begins with a survey of liquid crystal phases and field effects, together with an introduction to the basic physics of nuclear magnetic resonance. It then discusses orientational ordering and molecular field theories for various liquid crystal molecules and nmr studies of uniaxial and biaxial phases. Subsequent chapters consider spin relaxation processes and rotational, translational, and internal molecular dynamics of liquid crystals. The final chapter discusses two-dimensional and multiple- quantum nmr spectroscopies and their application in elucidating liquid crystal properties. This second edition, updated throughout, incorporates many new references and includes new mathematical appendices.

Download or read book Nuclear Magnetic Resonance Spectroscopy of Liquid Crystals written by Ronald Y. Dong and published by World Scientific. This book was released on 2010 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: This edited volume provides an extensive overview of how nuclear magnetic resonance can be an indispensable tool to investigate molecular ordering, phase structure, and dynamics in complex anisotropic phases formed by liquid crystalline materials. The chapters, written by prominent scientists in their field of expertise, provide a state-of-the-art scene of developments in liquid crystal research. The fantastic assortment of shape anisotropy in organic molecules leads to the discoveries of interesting new soft materials made at a rapid rate which not only inject impetus to address the fundamental physical and chemical phenomena, but also the potential applications in memory, sensor and display devices. The review volume also covers topics ranging from solute studies of molecules in nematics and biologically ordered fluids to theoretical approaches in treating elastic and viscous properties of liquid crystals. This volume is aimed at graduate students, novices and experts alike, and provides an excellent reference material for readers interested in the liquid crystal research. It is, indeed, a reference book for every science library to have. Sample Chapter(s). Chapter 1: Novel Strategies for Solving Highly Complex NMR Spectra of Solutes in Liquid Crystals (1,464 KB). Contents: Novel Strategies for Solving Highly Complex NMR Spectra of Solutes in Liquid Crystals (E E Burnell et al.); Analytical Potentials of Natural Abundance Deuterium NMR Spectroscopy in Achiral Thermotropics and Polypeptide Chiral Oriented Solvents (P Lesot & C Aroulande); Noble Gas Probes in NMR Studies of Liquid Crystals (J Jokisaari); Bicelles OCo A Much Needed Magic Wand to Study Membrane Proteins by NMR Spectroscopy (R Soong et al.); Advances in Proton NMR Relaxometry in Thermotropic Liquid Crystals (P J Sebastiuo et al.); Deuterium NMR Study of Magnetic Field Distortions in Ferroelectric Mesogens (R Y Dong); Deuteron NMR Study of the Effects of Random Quenched Disorder in 12CB Silica Dispersions (D Finotello & V Pandya); Dynamics of Liquid Crystals by Means of Deuterium NMR Relaxation (C A Veracini & V Domenici); Translational Self-Diffusion Measurements in Thermotropics by Means of Statistic Field Gradients NMR Diffusometry (M Cifelli); Deuterium NMR Studies of Static and Dynamic Director Alignment for Low Molar Mass Nematics (A Sugimura & G R Luckhurst); Viscoelastic Properties of Liquid Crystals: Statistical-Mechanical Approaches and Molecular Dynamics Simulations (A V Zakharov); Carbon-13 NMR Studies of Thermotropic Liquid Crystals (R Y Dong); A Combined DFT and Carbon-13 NMR Study of a Biaxial Bent-Core Mesogen (A Marini et al.). Readership: Chemists, physicists and material scientists. In particular, NMR spectroscopists.

Download or read book SIMULATION OF NUCLEAR MAGNETIC RESONANCE SPECTRA OF LIQUID CRYSTALS POLYMER LIQUID CRYSTALS AND CONVENTIONNAL POLYMERS written by Hervé Gérard and published by . This book was released on 1993 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: LE BUT DE CETTE ETUDE EST LA SIMULATION ET L'EXPLOITATION DE SPECTRES DE RMN DE CRISTAUX LIQUIDES NEMATIQUES ET DE POLYMERES. LES FORMES DE RAIE RMN SONT ANALYSEES GRACE A DEUX MODELES COMPLEMENTAIRES, LE PREMIER (MODELE A CONFORMATION UNIQUE) DECRIVANT LA CONTRIBUTION PUREMENT MOLECULAIRE (GEOMETRIE ET MOUVEMENTS INTERNES A LA MOLECULE), LE SECOND LA CONTRIBUTION DES MOUVEMENTS COLLECTIFS (MODES VISCO-ELASTIQUES). DES RAPPELS SUR LA METHODE RMN ET LA NOTION D'ORDRE ORIENTATIONNEL AU SEIN DE LA PHASE NEMATIQUE SONT FOURNIS DANS LA PREMIERE PARTIE OU SONT EGALEMENT DECRITS CES DEUX MODELES. DANS UNE DEUXIEME PARTIE, CES MODELES SONT APPLIQUES AUX DONNEES RELATIVES A DES MOLECULES NEMATIQUES DE FAIBLE MASSE MOLECULAIRE AINSI QU'A DES POLYMERES NEMATIQUES. CETTE APPLICATION PERMET D'OBTENIR DES INFORMATIONS SUR LA STRUCTURE ET LES MOUVEMENTS INTERNES A LA MOLECULE, L'ORDRE ORIENTATIONNEL REGNANT AU SEIN DE LA PHASE ET LES PROPRIETES VISCO-ELASTIQUES DU MATERIAU ETUDIE. ENFIN, ON MONTRE QUE L'EXTENSION DE CES MODELES AUX DONNEES RMN DE POLYMERES NE PRESENTANT PAS DE PHASE NEMATIQUE EN PHASE PURE PERMET D'OBTENIR DES INFORMATIONS SIMILAIRES EN CONSIDERANT QUE LEUR PHASE AMORPHE PRESENTE LOCALEMENT UN ORDRE NEMATIQUE

Download or read book La r sonance magn tique nucl aire dans les solvants cristaux liquides chiraux written by Christie Aroulanda and published by . This book was released on 2002 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les cristaux liquides (CL) sont des milieux anisotropes et fluides, particulièrement intéressants comme solvants pour la résonance magnétique nucléaire (RMN). Ils permettent notamment de déterminer la structure de solutés et d'étudier leur comportement orientationnel. En particulier, dans un CL chiral (CLC), les interactions énantiosélectives soluté/solvant imposent deux énantiomères ou deux éléments énantiotopes à s'orienter différemment l'un de l'autre, contrairement au comportement observé dans un CL achiral. Ainsi, sur la base d'arguments de la Théorie des Groupes, il est récemment apparu que l'orientation des solutés non plans de symétrie Cs, C2v, D2d ou S4 dans un CL nématique achiral et dans un CLC nématique est différente, ce qui mène dans leur cas à des spectres de RMN distincts. L'objectif principal de cette Thèse est de valider expérimentalement ce concept, tout en illustrant le potentiel analytique de la RMN en milieu CLC dans le domaine de la stéréochimie organique. Pour cela, diverses structures rigides ou flexibles, polaires ou apolaires, de symétrie Cs, C2v, et D2d sont étudiées par RMN du 13C et du 2H notamment, dans un CLC nématique polypeptidique faiblement orienté pour solvant. Dans chaque exemple, les différences d'orientation des groupements, directions ou faces énantiotopes sont mises en évidence puis analysées en terme de paramètres d'ordre orientationnel. En particulier, l'inéquivalence dans un environnement chiral des directions énantiotopes de molécules C2v prochirales sans atome tétraédrique prostéréogène est présentée. En marge de ces résultats, nous montrons l'intérêt analytique de la RMN du 2H en abondance naturelle pour mesurer la pureté énantiomérique de molécules chirales ou analyser les rapports isotopiques 1H/2H de solutés prochiraux. L'ensemble des travaux démontre que la RMN en milieu orienté chiral et/ou achiral est un outil d'analyse performant, capable de fournir des informations de stéréochimie indispensables aux chimistes.

Download or read book NMR of Liquid Crystal Dendrimers written by Carlos Rodrigues da Cruz and published by CRC Press. This book was released on 2016-12-08 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dendrimers are hyperbranched molecules with well-defined nanometer-scale dimensions. Important technological applications of these systems, both in biomedicine and materials science, have been recently proposed. Liquid crystal dendrimers are fascinating materials that combine the characteristics of dendrimers with the anisotropic physical behaviour and molecular self-organization typical of liquid crystals. This unique association of physical and chemical properties, together with the possibility of multi-selective functionalization put forward by dendrimers, opens new perspectives for applications. Nuclear magnetic resonance (NMR) is a powerful experimental technique applied in materials science and an important tool to the study of molecular organization and dynamics. This book presents an introduction to dendrimers properties with special insight into liquid crystal dendrimers and a detailed description of the NMR theory and experimental techniques used in the investigation of these materials. It also discusses recent NMR research results on liquid crystal dendrimers, with emphasis on molecular order and dynamics studies. This book introduces the properties of dendrimers, with special insight into liquid crystal dendrimers, and a detailed description of NMR theory and experimental techniques used in the investigation of these materials. It also discusses results of recent NMR research on liquid crystal dendrimers, with an emphasis on molecular order and dynamics studies. Advanced undergraduate and graduate students of physics, chemistry, and materials science and researchers in the fields of dendrimers, liquid crystals, and NMR will find the book extremely useful.

Download or read book Introduction la R sonance Magn tique Nucl aire written by Serge Akoka and published by Editions Ellipses. This book was released on 2022-10-04 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cet ouvrage propose une approche phénoménologique des principes et de quelques applications de la RMN. Les explications s’appuient sur de nombreuses illustrations. Chaque chapitre se termine par une liste de lectures pour aller plus loin dans le domaine traité. Il s'adresse aux étudiants de licences et masters scientifiques, aux étudiants de médecine et de pharmacie et aux chercheurs non spécialistes mais qui doivent avoir recours à cette technique.

Download or read book Nuclear Magnetic Resonance Studies in Lyotropic Liquid Crystals written by CL Khetrapal and published by Springer Science & Business Media. This book was released on 2013-03-13 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: 1. Lyotropic Liquid Crystals The class of compounds known as thermotropic liquid crystals has been widely utilized in basic research and industry during recent years. The properties of these materials are such that on heating from the solid to the isotropic liquid state, phase transitions occur with the formation of one or more intermediate anisotropic liquids. The unique and sometimes startling properties of these liquid crystals are the properties of pure compounds. However, there exists a second class of substances known as lyotropic liquid crystals which obtain their anisotropic properties from the mixing of two or more components. One of the components is amphiphilic, containing a polar head group (generally ionic or zwitterionic) attached to one or more long-chain hydrocarbons; the second component is usually water. Lyotropic liquid crystals occur abundantly in nature, particularly in all living systems. As a consequence, a bright future seems assured for studies on such systems. Even now, many of the properties of these systems are poorly understood. It is the purpose of this review to consolidate the results obtained from nuclear magnetic resonance studies of such systems and to provide a coherent picture of the field. Probably the most familiar example of a lyotropic liquid crystal is soap in water. A common soap is sodium dodecylsulphate where an ionic group (sulphate) is attached to a hydrocarbon chain containing twelve carbons.

Download or read book Applications en chimie structurale de la r sonnance magn tique nucl aire dans les milieux orient s chiraux written by Hussein Khudr and published by . This book was released on 2008 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: La RMN dans les milieux orientés chiraux est actuellement la technique d'analyse des molécules chirales la plus générale. Dans ces phases cristallliquides deux énantiomères s'orientent différemment sous l'effet des interactions entre les molécules chirales et les fibres polypeptidiques. Par conséquent toutes les interactions magnétiques sensibles à l'ordre sont différentes pour deux énantiomères. Dans une première partie, nous avons synthétisé les quatre isomères de chiralité isotopique du [1-2Hl]-glycérol avec d'excellentes puretés énantiomériques. Nous avons mis au point une méthode analytique, rapide et simple pour quantifier ces isomères en mélange par RMN du deutérium en solvant anisotrope chiral. Dans la deuxième partie il est démontré que, dans la mesure où on peut se placer dans des conditions d'échange lent, il est possible d'utiliser des deutériums échangeables pour effectuer une mesure d'excès énantiomérique par RMN du deutérium en solvant cristal liquide polypeptidique. Enfin, dans la troisième partie nous proposons une méthode empirique de détermination des configurations absolues par RMN du deutérium en abondance naturelle en milieu cristal liquide chiral. L'hypothèse de départ est: dans une série de composés homologues, les effets d'orientation différentielle d'énantiomères devraient être comparables. Nous avons réalisé les spectres du deutérium 20 Q-COSY en abondance naturelle sur une série de dioxolanes substitués par divers groupements CH2X ou X est un halogène (F, CI, Br, 1). L'analyse statistique de l'ensemble des résultats montre une cohérence tout à fait remarquable et permettrait l'attribution d'un produit inconnu appartenant à la série.

Download or read book tude par r sonance magn tique nucl aire du deut rium de certains aspects de la dynamique microscopique des cristaux liquides thermotropes written by Bertrand Deloche de Noyelle and published by . This book was released on 1978 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Le D sordre dans les cristaux liquides lyotropes written by Bernard Mely (auteur d'une thèse de sciences.) and published by . This book was released on 1977 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1978 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book tude par r sonance magn tique nucl aire du deut rium written by Bertrand Deloche de Noyelle (auteur d'une thèse de sciences.) and published by . This book was released on 1978 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quelques applications de la r sonance magn tique nucl aire la chimie macromol culaire written by Danièle Reyx and published by . This book was released on 197? with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NMR of Liquid Crystal Dendrimers written by Carlos R. Cruz and published by Jenny Stanford Publishing. This book was released on 2016-12-05 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dendrimers are hyperbranched molecules with well-defined nanometer-scale dimensions. Important technological applications of these systems, both in biomedicine and materials science, have been recently proposed. This book presents an introduction to dendrimers properties with special insight into liquid crystal dendrimers and a detailed description of the NMR theory and experimental techniques used in the investigation of these materials. It also discusses recent NMR research results on liquid crystal dendrimers, with emphasis on molecular order and dynamics studies.