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Shigeru Ohba

Publications and source records attributed to Shigeru Ohba.

12 recordsLinked to original sources
PubMed2004

Swertisin dihydrate.

The title compound, 6-C-glucopyranosyl-7-O-methylapigenin dihydrate, C(22)H(22)O(10).2H(2)O, is a natural C-glucosylflavone. The flavone skeleton is almost planar, the dihedral angle between the pyran moiety and the 4-hydroxyphenyl ring being 9.8 (3) degrees. The basal plane of the pyranosyl ring of the glucose moiety is almost perpendicular to the benzopyran ring system. The flavone skeletons are stacked along the a axis, forming layers parallel to (001). Between these hydrophobic layers, the glucose groups and water molecules of crystallization are connected via O-H...O hydrogen bonds, forming hydrophilic layers.

Flavones↗
PubMed2004

Ammonium 4-methoxycinnamate.

In the title compound, NH(4)(+).C(10)H(9)O(3)(-), bimolecular layers of the anions are formed between layers of the cations. There are N-H.O hydrogen bonds between the ammonium ion and the carboxylate groups of the anions. In the crystal structure, the C=C moiety of the cinnamate ion makes an angle of 117.1 (2) degrees with that of the nearest neighbour, indicating that a pedal rotation is required before beta-type [2+2]-photodimerization can take place, which is the predominant mode of the photochemistry of this compound.

Journal Article↗
PubMed2003

Rac- and meso-3,3'-Bis(3,5-dimethylphenyl)-3H,3'H-2,2'-biindenylidene-1,1'(2H,2'H)-dione.

In the rac isomer of the title compound, C(34)H(28)O(2), the two C-Ph(dimethylphenyl) bond axes make an angle of 58.7 (1) degrees. There is no short contact between the two 3,5-dimethylphenyl rings, although the dihedral angle between them is 4.93 (7) degrees. The meso isomer has a center of symmetry at the middle of the C=C bond, and the two C-Ph(dimethylphenyl) bond axes are antiparallel to one another.

Journal Article↗
PubMed2003

Single-crystal-to-single-crystal photodimerization of 4-chlorocinnamoyl-O,O'-dimethyldopamine.

[2+2]Photodimerization of the title compound, C(19)H(20)ClNO(3), has been observed in situ by single-crystal X-ray diffraction. Pairs of monomers related by centers of symmetry have parallel C=C bonds at a C.C distance of 4.155 (17) A. Irradiation of a single crystal with a mercury lamp achieves 100% conversion to the dimer. Redetermination of the structure during the course of the reaction revealed a linear correlation between the percent conversion to the dimer and the decrease in the cell Volume. The displacement parameters for the pure dimer structure are substantially smaller than those for the pure monomer structure. The dimerization reaction is also induced by irradiation with X-rays, the induction being stronger with Cu Kalpha than with Mo Kalpha radiation.

Journal Article↗
PubMed2000

Four copper(II) complexes with potentially tetradentate tripodal ligands.

The four title Cu(II) compounds are chloro[(2-furylmethyl)bis(2-pyridylmethyl)amine-N,N',N"]copper(II) perchlorate, [CuCl(C(17)H(17)N(3)O)]ClO(4), (I), chloro{2-[bis(2-pyridylmethyl)amino]ethanolato-N,N',N",O}copper(II) hemi[tetrachlorocopper(II)], [CuCl(C(14)H(17)N(3)O)][CuCl(4)](1/2), (II), chloro[(2-morpholinoethyl)bis(2-pyridylmethyl)amine-N,N',N",N"']copper(II) perchlorate, [CuCl(C(18)H(24)N(4)O)]ClO(4), (III), and chloro[(2-piperidinylethyl)bis(2-pyridylmethyl)amine-N,N',N",N"']copper(II) hexafluorophosphate, [CuCl(C(19)H(26)N(4))]PF(6), (IV). They have tripodal potentially tetradentate ligands. In (I), the O atom of the furan moiety weakly coordinates to the Cu atom at a distance of 2.750 (3) A.

Journal Article↗