Complete assignment of the 13 C NMR lines is reported for both isotropic and oriented samples of antiferroelectric liquid-crystalline MHPOBC. Two-dimensional double-quantum coherence spectroscopy (2-D INADEQUATE) in the isotropic phase and field alignment-induced shifts (AIS) were studied. 19 F-13 C dipolar quartets were measured for TFMHPOBC, where a methyl group attached to the chiral center of MHPOBC is replaced by a trifluoromethyl group, to assist the assignment. Shielding tensor principal elements were determined for each carbon by site-separated spinning sideband spectroscopy (2-D TOSS-deTOSS). The orientational order parameter has been evaluated to be 0.73 at 403 K in the S A phase using the experimentally determined AIS and the tensor elements and assuming an intramolecular free rotation model.

Simple cationic sandwich complexes that contained alkyl- or halogen substituents provided ionic liquids (ILs) with the bis(perfluoroalkanesulfonyl)imide anion. Ferrocenium- and cobaltocenium ILs [M(C(5)H(4)R(1))(C(5)H(4)R(2))][Tf(2)N] (M=Fe, Co) and arene-ferrocenium ILs [Fe(C(5)H(4)R(1))(C(6)H(5)R(2))][Tf(2)N] were prepared and their physical properties were investigated. A detailed comparison of their thermal properties revealed the effects of molecular symmetry and substituents on their melting points. Their viscosity increased on increasing the length of the substituent on the cation and the perfluoroalkyl chain length on the anion. Upon cooling, ILs with low viscosities exhibited crystallization, whereas those with higher viscosities tended to exhibit glass transitions. Most of these salts showed phase transitions in the solid state. A magnetic-switching phenomenon was observed for the paramagnetic ferrocenium IL, which was associated with a liquid/solid transformation, based on the magnetic anisotropy of the ferrocenium cation. (57)Fe Mössbauer spectroscopy was applied to [Fe(C(5)H(4)nBu)(2)][Tf(2)N] to investigate the vibrational behavior of the iron atom in the crystal and glassy states of the ferrocenium IL.

Crystal structures and thermal properties of cobaltocenium salts with bis(perfluoroalkylsulfonyl)amide (C(n)F2(n+1)SO2)2N anions [n = 0 (1), 1 (1 a), 2 (1 b), 3 (1 c), and 4 (1 d)] and the 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonylamide anion (2) were investigated. In these solids, the cations are surrounded by four anions around their C5 axis, and stacking of these local structures forms two kinds of assembled structures. In the salts with even n (1, 1 b, and 1 d), the cation and anion are arranged alternately to form mixed-stack columns in the crystal. In contrast, in the salts with odd n (1 a and 1 c), the cations and anions independently form segregated-stack columns. An odd-even effect was also observed in the sum of the phase-change entropies from crystal to melt. All of the salts exhibited phase transitions in the solid state. The phase transitions to the lowest-temperature phase in 1, 1 a, and 2 are accompanied by order-disorder of the anions and symmetry lowering of the space group, which results in the formation of an ion pair. Solid-state (13)C NMR measurements on 1 a and 1 b revealed enhanced molecular motions of the cation in the higher-temperature phases.

The CH dipolar spectra of n-heptane, n-octane, n-nonane, and n-decane in urea inclusion compounds were separately obtained for the α-, β-, and inner-CH2 and CH3 groups using the SASS (switching-angle sample spinning) NMR method. The CH dipolar coupling constant for the CH2 group decreases with the increasing distance from the center of the molecule and with the decreasing chain length. MM2 molecular mechanics calculations suggested that the included molecule can have various conformations, and provided their geometries and populations. The experimental results could be reproduced by using the calculated parameters and assuming the occurrence of dynamical disorder of various conformations in addition to rotation of the included molecule around the long axis. This is the first evidence for the existence of conformations other than all-anti in the included n-alkane molecule; it has long been taken to be in the all-anti conformation. Previous studies which were explained by the all-anti conformation are reinterpreted by dynamical disorder of various conformations.

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a b s t r a c tDecamethylferrocenium salts with perfluoroalkylsulfonate anions (C n F 2nþ1 SO 3 À ; n ¼ 1, 4, and 8) andperfluoroalkylcarboxylate anions (C n F 2nþ1 CO 2 À ; n ¼ 1e4) were prepared to investigate the effects of the anion on the thermal behaviors of the salts. Differential scanning calorimetry (DSC) measurements revealed that all the salts exhibited phase transitions in the solid state. Salts with an octamethylferrocenium cation or decamethylcobaltocenium cation exhibited different phase sequences from those of the corresponding decamethylferrocenium salts. Structural changes associated with the phase transitions were investigated crystallographically for two salts. The phase transition in [Fe(C 5 Me 5 ) 2 ](CF 3 SO 3 ) at À121.6 C was accompanied by ordering of the cation conformations into eclipsed and staggered conformations in different ratios. The unit cell volume became six times larger and the space group changed from Pmn2 1 to P1 in the low-temperature phase. The phase transition in [Fe(C 5 Me 5 ) 2 ](C 3 F 7 CO 2 ) at À115 C was not accompanied by any change in the unit cell or the space group (P2 1 /c). The libration or displacements of the anions that existed in the high-temperature phase was suppressed in the lowtemperature phase, associated with a slight rotational displacement of the molecules. Anions with longer perfluoroalkyl chains exhibited disorder in the solid state even at low temperatures.

To solve a problem of a short lifetime due to a wear of the electrodes, we have been studying a completely electrodeless electric propulsion system. High-density (∼10 13 cm −3 ) helicon plasmas are being used for a dense source of our proposed system. Plasmas are accelerated by the Lorentz force in the axial direction, which is generated by the azimuthal current j θ induced in the plasma and the radial component of the external magnetic field B r . Here, this j θ can be generated by a Rotating Magnetic Field (RMF) scheme proposed. As an initial try of the plasma acceleration, we have measured electron density n e and ion velocity v i using the RMF method, and found that n e (v i ) increased by a maximum of ∼ 15% (16%) compared to those without RMF. These results were the first step that shows experimentally the effectiveness of RMF acceleration scheme in the electrodeless electric propulsion system.

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