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.

Alkali-metal-graphite intercalation compounds (alkali-metal-GIC's) absorb hydrogen in two ways: physisorption and chemisorption. Hydrogen uptake through the physisorption process occurs at low temperatures below about 200 K in higher stage alkali-metal-GIC's, where hydrogen molecules are stabilized to form a two-dimensional condensed phase in the galleries of the graphite sheets. The concentration of absorbed hydrogen molecules is saturated at a rate of H2/alkali metal atom ∼2. The hydrogen physisorption shows a strong isotope effect and a swelling effect on c-axis lattice expansion. In the case of hydrogen uptake through the chemisorption process, dissociated hydrogen species are stabilized in the intercalate spaces. The activity of the chemisorption increases in the order Cs < Rb < K. The introduction of hydrogen generates a charge transfer from the host alkali metal GIC's to the hydrogen since hydrogen has strong electron affinity. The hydrogenated potassium-GIC's have intercalates consisting of K+-H−-K+ triple atomic layer sandwiches which are inserted between metallic graphite sheets. The inserted two-dimensional hydrogen layer is suggested to consist of H ions with a weakly metallic nature. The superconductivity of the hydrogenated potassium-GIC is also discussed in terms of the change in the electronic and lattice dynamical properties by hydrogen uptake. The hydrogen-absorption in alkali-metal-GIC's is an interesting phenomenon in comparison with that in transition metal hydrides from the point of hydrogen storage. The hydrogen-alkali-metal-ternary GIC's obtained from hydrogen absorption have novel electronic properties and lattice structures which provide attractive problems for GIC research. The studies of hydrogen-alkali-metal ternary GIC's are reviewed in this article.

A high-resolution 13 C NMR study is reported on the antiferroelectric liquid crystal MHPOBC, 4-[(1-methylheptyloxy)carbonyl]phenyl 4-[4-(octyloxy)biphenyl]carboxylate. The structures of the two alkyl chains, the chiral and achiral chains, are analyzed using isotropic shielding constants, cross polarization efficiency, and the field alignment-induced shifts. A comprehensive theoretical treatment for the alignment-induced shift is given. It is shown that the average direction of the chiral chain deviates from the molecular long axis by as much as 43°(bent chain structure), while that of the achiral chain extends along the molecular long axis. The relationships of this particular shape of the molecule with the emergence of the molecular biaxiality and with the onset of antiferroelectricity are discussed.