Etude RMN de l'Acetone en Solution dans une Phase Nematique

Abstract

Abstract-The NMR spectrum of acetone oriented in the nematic phase of butyl-p-@'-ethoxyphenyloxycarbonyl) phenyl carbonate has been studied in the 48" to 58°C temperature range. The determination of direct coupling constants allows the computation of orientation parameters; these values lead us to emphasize the intervention of polarizability in orientatior. phenomena. (Fig. 1). (Fig. 2); ya est le rapport gyromagnitique du proton; le symbole ( ) indique qu'il s'agit d'une valeur moyenne, la moltcule n'ttant pas rigide. 533

Oxygen-17 NMR spectroscopy: Basic principles and applications (part II)

“…The order parameters S xx and S zz were derived from the 1 H NMR spectrum according to the procedure described by Courtieu and Gounelle [908] using the 1 H, 1 H direct coupling constant within the same CH 3 -group, D AA , and from one CH 3 -group to the other, D AA 0 (Fig. 188, Table 185).…”

Nuclear magnetic resonance spectrometry

“…Investigations of variable frequency pulsed NMR (604), nitrogen-15 labeled formamide (605), p-dithin (606), ethylene carbonate and monothiocarbonate (607), D20 (608), paraffinic chain motions (609), furan and thiophene (610), methyl halides (611), amphiphiles (612), and sodium-23 ions (613) have been reported for lyotropic liquid crystal systems. Relaxation in nematic phase liquid crystals (614-616) has been described as have studies of the following molecules oriented in the nematic phase: ethylene sulfite (617), ethylene oxide and sulfide (618) ethylene carbonates and thiocarbonates (619-621), substituted benzenes (622-631), cyclopropane (632), cyclobutane (633), 1,3-butadiene (634), trimethylene oxide (635), deuterated methanes and 2,2dimethylpropane (636), norbornadiene (637), quinoxaline (638), 1,1-difluoroethane (639), 1,2-difluoroethane (640), 3,5-dichloropyridine (641), 7-picoline (642), anisylidene p-aminophenyl acetate (643), dimethylformamide (644), 1.4-naphthoquinone (645), butadiene sulfone (646), thiophene (647) 1,4-dioxin and 1,4-dithiin (648), thieno[2,3ojthiophene (649), 2,1,3-benzothiadiazole (650), 2-furaldehyde (651), phthalazine (652), furanand thiophene-2.5dialdehydes (653), acetonitrile (654), acetone (655), tropone (656), 3,3'-biisoxazole (657), ß-propiolactone (658) , l,l,2,2-tetrachloro-3,3,4,4-tetrafluorocyclobutane (659) , methylmercuric halides (660), -cyclopentadienylmanganese tricarbonyl (661), and the hydride cluster, H3Ru3,CO)6C(CH3) (662).…”

Determination of the Quadrupolar Coupling Constant and the Asymmetry Parameter of Oxygen‐17 in Acetone by 17O‐ and 1H‐NMR in Nematic Phases

“…In thermotropic phases, a very large spectral width is necessary due to the stronger orientation, as shown in ) and with the interatomic distances used to calculate the order parameters [25] mation to derive the two order parameters necessary to fully describe the orientation of the acetone molecule, using the interatomic distances cited in the literature.…”

“…The order parameters S, and S, are derived from the 'H-NMR spectrum according to the procedure described by Courtieu & Gounelle [25] using the 'H,'H direct coupling constants D,, (within the same CH,-group) and DAN (from one CH,-group to the other). The values of D,, and DAN were determined by an iterative simulation of the experimental spectra, using the programme PANIC [28] and are summarized, together with the indirect coupling constant JAA' in Table I .…”