Yoshio Takai

The crystal structure of cycloinulohexaose produced from inulin by cycloinulo-oligosaccharide fructanotransferase

Abstract The crystal of cycloinulohexaose trihydrate, C 36 H 60 O 30 ·3H 2 O, is trigonal, space group R 3, with unit-cell dimensions a = 24.688 (17), c = 6.477 (3) A for a hexagonal cell, Z = 3. The molecule, which consists of six (2 → 1)-linked β- d -fructofuranose residues, has C 3 symmetry. The conformations of two d -fructofuranosyl moieties in an asymmetric unit are 4 T 3 with P = 348.1° and τ m = 38.9° for Fl, and 4 T 3 with P = 350.5° and τ m = 41.2° for F2. The conformations of OCH 2 CO in the 18-crown-6-ring are gauche - for O-1−C-1−C-2−O-1′ (+ 52.3°) and trans for O-1−C-1′−C-2′−O-1 (+ 163.4°).

Liquid crystals formed by transition metal–poly(yne) polymers: a relation between magnetic anisotropy and polymer structure

High resolution 31P n.m.r. studies of lyotropic liquid crystals formed by transition metal–poly(yne) polymers indicates that the magnetic anisotropy of the polymers may be systematically controlled by including different transition metal atoms in the polymer structure.

Direct N.H.R. Observation of Lyotropic Liquid Crystals Formed by Transition Metal-Poly-Yne Polymers

Abstract The lyotropic liquid crystals formed by metal-poly-yne polymers I and II have been directly detected by high resolution P-n.m.r. method which has revealed that the main chain of the polymers aligns itself in the direction perpendicular to an applied magnetic field.

Enantioselective complexation of chiral linear hosts containing monosaccharide moieties with chiral organic amines

Abstract New chiral linear hosts ( 1–3 , a : peracetylated derivatives, b : permethylated derivatives) containing monosaccharide end groups were designed on the basis of the structural features of permethylated 1F-fructonystose (MeFruNys), which shows a remarkable chiral discrimination ability, and then synthesized. The chiral discrimination ability of their hosts toward chiral organic ammonium guests were evaluated using FAB mass spectrometry and 1H NMR. Their hosts showed chiral discrimination for some guests. As the contrasting compounds ( 4 and 5 ) hardly showed any chiral discrimination, it was clarified that the structural features extracted from MeFruNys are very significant factors for chiral recognition. The 1H NMR shift induced by adding a potassium ion (counter anion: SCN−) in (CD3)2CO suggested that the cation moiety of the chiral guests was located at the binding site consisting of the –O–C–C–O– units and the ring-oxygens of the saccharide moieties. The structure of the complex of host 1b with 1-(1-naphthyl)ethylammonium ion (NEA+) was estimated by the 1H NMR induced shifts and the molecular dynamics simulation.

Facile ee-determination from a single measurement by fast atom bombardment mass spectrometry: a double labeling method

Abstract From a single fast atom bombardment mass spectrum, the optical purity (enantiomeric excess: ee ) of chiral organic primary and secondary amine salts (guests) such as tryptophan 2-propyl ester hydrochloride and proline 2-propyl ester hydrochloride was easily determined with a high accuracy using both the deuterium-labeled/unlabeled enantiomeric host pair (DD-Gal2deg and LL-Gal2deg-d 24 ) and the corresponding deuterium-labeled internal standard guest (for example, the S -amino acid ester-d m salt).

Combinatorial evaluation of the chiral discrimination of permethylated carbohydrates using fast-atom bombardment mass spectrometry

The chiral discrimination abilities of several variously permethylated carbohydrates toward various amino acid 2-propyl esters were combinatorially evaluated from the relative peak intensity of the 1:1 diastereomeric complex ions with the deuterium-labeled L-amino acid 2-propyl ester protonated ion and with the unlabeled D-amino acid 2-propyl ester protonated ions in FAB mass spectrometry. The chiral discrimination abilities evaluated using FAB mass spectrometry approximately corresponded to the ratio of the association constants (K(R)/K(S)) toward each enantiomer in the solution. Therefore, this evaluation method is very useful for the screening of the chiral discrimination abilities of carbohydrates and their derivatives.

Lyotropic Liquid-Crystalline Materials Containing Palladium and Nickel

Abstract Polymers having backbones composed of conjugated acetylenes and palladium- or nickel-atoms have been found to form lyotropic liquid crystals in trichloroethylene of tetrahydrofuran.

Chiral recognition in molecular complexation for the crown ether–amino ester system. A facile FAB mass spectrometric approach

Various degrees of chiral recognition properties of chiral crown ether hosts toward amino acid ester guests are directly, easily and reliably evaluated by the enantiomer deuterium-labelled racemic guest method using conventional FAB mass spectrometry.

Caffeoyltryptophan from green robusta coffee beans

Abstract A new compound, caffeoyltryptophan, was isolated from the coffee beans Coffea canephora and its structure was determined by FD mass, IR and 1 H NMR spectroscopy.

Chiral discrimination of permethylated gluco-oligosaccharide toward amino acid ester salts

The chiral discrimination ability of permethylated glucopyrano-oligosaccharides toward amino acid 2-propyl ester hydrochlorides was evaluated using FAB mass spectrometry. In the given permethylated homo-oligosaccharides, permethylated β-cello-oligosaccharide series (II) showed remarkably higher S-selectivity toward tryptophan ester salts (Trp-O-iPr+) independent of the numbers (n) of the glucopyranose unit (n=2–5). The hexamer and heptamer of the permethylated β-malto-oligosaccharide series (I) showed the very similar enantioselectivity to permethylated α- and β-cyclodextrin.