Katsumi Suda

Synthesis, crystal structure and spectroscopic study of Para substituted 2-hydroxy-3-methoxybenzalideneanilines

Abstract Eight Schiff bases derived from 2-hydroxy-3-methoxybenzaldehyde and different para substituted anilines have been synthesized and their structures were elucidated by physical measurements and FT-IR. NMR assignments were made using 1H, 13C NMR and aided by 2D COSY homonuclear, HMQC and HMBC heteronuclear correlation techniques. IR spectral analysis of the model compounds was found useful in understanding the degree of stabilization upon this series of enol-imino tautomers, which possess different substituents in the aniline fragment. In order to rationalize the stabilization of tautomer in solid state, the crystallography data of 1-{(4-methylphenylimino)methyl}- and 1-{(4-chlorophenylimino)methyl}-2-hydroxy-3-methoxyphenol were adopted wherein the 4-chloro (4-Cl) and 4-methyl (4-CH3) containing compounds crystallized into orthorhombic lattice with a non-centrosymmetric space group P212121. The relationship between the stabilization of bonding involved in heteronuclear six-membered ring of the tautomer and the conformation of the molecules in crystal phase was reported.

Monoclinic superstructure of SrMgF4 with perovskite-type slabs

Crystals of Ce-doped SrMgF4, strontium magnesium tetrafluoride, have been found to have a monoclinic P21 structure with doubled a and tripled c cell lengths compared with the orthorhombic Cmcm structure previously reported in the literature. The perovskite-type slabs, composed of corner-sharing MgF6 octahedra and Sr atoms, are stacked along the b axis. The six crystallographically independent MgF6 octahedra are rotated so as to provide long periodicities along a and c. The coordination numbers and bond distances around the six crystallographically independent Sr atoms are slightly different in each case. In the superstructure, the Sr atoms lie on local mirror planes which are thought to originate at the high-temperature phase transition.

Oxide ion motion in bismuth sesquioxide (σ-Bi2O3)

The δ-form of Bi 2 O 3 and the melt were studied by EXAFS near the Bi-L 3 edge and Bi-L 3 edge and by X-ray diffraction. EXAFS data analyses were made on the basis of a two-shell model. A non-linear least-squares fitting was carried out by the cumulant expansion up to fourth-order term. The Bi-O distances of the first and second shells slightly decrease with increasing temperature in spite of increase of the lattice constant. The cumulants of higher order are almost constant with temperature. Comparison using primary differential of XANES by energy shows a slight change between the δ-form and the melt indicating a change in symmetry of coordianting atoms

Reinvestigation of β‐Li3TaO4

The structure of β-Li3TaO4 has been reinvestigated with an image plate diffractometer. It crystallizes with a cation-ordered, distorted rock-salt-type lattice structure, composed of distorted TaO6 and LiO6 octahedra. Some evidence of a superlattice was observed, but it had no impact on the established structural model.

Monoclinic superstructure of SrMgF4with perovskite-type slabs

Crystals of Ce-doped SrMgF4, strontium magnesium tetrafluoride, have been found to have a monoclinic P2(1) structure with doubled a and tripled c cell lengths compared with the orthorhombic Cmcm structure previously reported in the literature. The perovskite-type slabs, composed of corner-sharing MgF6 octahedra and Sr atoms, are stacked along the b axis. The six crystallographically independent MgF6 octahedra are rotated so as to provide long periodicities along a and c. The coordination numbers and bond distances around the six crystallographically independent Sr atoms are slightly different in each case. In the superstructure, the Sr atoms lie on local mirror planes which are thought to originate at the high-temperature phase transition.