Chuji Katayama

Structure of oxazolomycin, a novel β-lactone antibiotic

Abstract The structure of oxazolomycin exhibiting antitumor activity has been elucidated.

Osladin, a sweet princple of polypodium vulgare. Structure revision

Structure of osladin, a sweet principle of rhizome of Polypodium vulgare, was revised to 26-O-α-L-rhamnopyranosyl-(22R,25S,26R)-22,26-expoxy-6-oxo-5α-cholestan-3β,26-diol-3-o-α-L-rhamnopyrano-syl-(1→2)-β- D-glucopyranoside (1) on the basis of single crystal X-ray diffraction study.

Evalution of X-ray diffraction data from protein crystals by use of an imaging plate

A system has been developed which uses an imaging-plate diffraction apparatus to obtain structure factors for protein crystals. The latter is connected to a graphics workstation through an Ethernet. Pixel data from an imaging plate are transferred via the Ethernet to a workstation and processed to give the structure factors. The quality and precision of the diffraction data were examined from the point of view of spatial uniformity, linearity with exposure, decay with time, and reproducibility. X-rays from an 55Fe source and Debye-Scherrer rings from Si powder were used for calibration purposes. Finally, diffraction data were obtained and evaluated for lysozyme and cytochrome c-553 using this system. The results were satisfactory in terms of sensitivity and precision.

Charge density distribution of a polymethine cyanine dye: (5-dimethylamino-2,4-pentadienylidene)dimethylammonium perchlorate

C9H17N~-. C10~ (orange form), Mr = 252.71, monoclinic, P21/a, a=13.671(3), b=14.899(2), c= 6.186(2)/~, fl =97-27(2) °, V= 1249.9(5) A, 3, Z=4, Dx = 1.343 g cm -3, graphite-monochromated Mo Ka radiation, h = 0.71073 A,, /z = 2.606 cm -1, F(000) = 536, T = 140 K, R = 0.045 for 4331 independent data. A slight alternation is found in the bond lengths of the conjugated system of the polymethine cyanine dye [C-C distances 1.376(2), 1.399(2), 1.378(2) and 1.394(2) A at 140 K]. The charge distribution is estimated by the method of Coppens, Guru Row, Leung, Stevens, Becker & Yang [Acta Cryst. (1979), A35, 63-72] and the result is in good agreement with the ab initio MO calculation. In particular, positive charges are found at the methyl groups [except C(11)] and the odd-numbered C atoms in the chain; negative charges are observed at C(4), C(11) and the N atoms.

The absolute configuration of cycloeudesmol from the red alga Laurencia nipponica Yamada

Abstract The absolute configuration of cycloeudesmol, isolated from the red alga Laurencia nipponica Yamada and Chondria oppositiclada Dawson, is determined by the crystallographic study.

Crystal Structures and Electrical Properties of Hexacyano-Butadiene (HCBD) Charge Transfer Complexes

Abstract We have prepared charge transfer (CT) single crystals comprising TTF derivatives and hexacyanobutadiene (HCBD), which is one of the strongest acceptors. TMTTF gave two crystals in different stoichiometry, one is 2:1 semiconductor and the other is 1:1 insulator. In the 2:1 complex, TMTTF molecules form face-to-face segregated columns with dimerized manner and HCBD lies perpendicular to the donor columns to form side-by-side segregated columns in the cavity produced by donor columns. The ground state of this complex is antiferromagnetic. The 1:1 complex has face-to-face uniform segregated columns and shows some phase transition at around 150K. TTMTTF forms a semi conductive 1:1 complex with uniform face-to-face segregated column.

Structures of two oxidation products obtained from palytoxin

Abstract The structures of two oxidation products of N-(p-bromobenzoyl)palytoxin were unambiguously determined by means of X-ray crystallographic analysis.

Absolute configuration of(–)-1,5-disubstituted 9,10-dihydro-9,10-etheno- or -ethano-anthracenes. Comparison of X-ray and circular dichroism studies

The absolute configuration of (–)-1,5-disubstituted 9,10-dihydro-9,10-etheno-or -ethano-anthracenes as indicated by c.d. spectral analysis are not consistent with those determined by the current X-ray method; this work provides an additional example to the accumulated results that the rigorous exciton theoretical analysis of c.d. spectra does not agree with the Bijvoet method of X-ray crystal analysis.

The Crystal and Electronic Structures of Hexacyano-Butadiene Complexes with Tetrathiafulvalene Derivatives

Abstract The crystal structures and the electronic properties are investigated on the complex crystals made from the acceptor, hexacyanobutadiene (HCBD) and the donors, tetramethyltetrathiafulvalene (TMTTF) and tetra-methylthiotetrathiafulvalene (TTMTTF). The electrical conductivity, the optical spectra and the magnetic properties of these crystals are discussed in connection with the crystalline structures and the phase transitions.

Perylene-hexacyanobutadiene (HCBD) complex

Abstract The solid CT-complex, perylene-HCBD, was found to have 1:1 mixed stacking columns. The degree of CT was evaluated as 0.29 at room temperature from the optical measurements. The structural feature of this complex is discussed comparing with that of the TCNE complexes. Also, the possibility for the occurrence of the neutral-ionic transition is discussed.