Kei Matsuzaki

Constitution of konjac glucomannan: chemical analysis and 13C NMR spectroscopy

The constitution of konjac glucomannan was determined by methylation analysis and 13C NMR spectroscopy. The results of methylation analysis showed that the branching point is C-6 carbon of glucosyl units. 13C NMR spectroscopy (1D and DEPT) of konjac glucomannan supported the presence of β-C-1-linked C-6 carbon of glucosyl units as the branching units. This result differs from previous investigations. The 13C NMR spectra indicated that the ratio of terminal glucosyl units to terminal mannosyl units is ca. 2 and branching frequency is ca. 8%, supporting the results by Smith et al. From the splitting of main chain signals the sequences of glucosyl and mannosyl units in konjac glucomannan are estimated and a model structure for the glucomannan is proposed.

Discotic Liquid Crystals of Transition Metal Complexes, 3: the First-Established Discotic Lamellar Phase in Bis[1,3- di(p-n-alkoxyphenyl)propane-1,3-dionato]copper(II)

Abstract A new series of disk-like complexes, bis[1,3-di(p-n-alkoxyphenyl)propane-1,3-dionato]copper(II) (abbreviated as CnO-Cu, n = 1-12), has been synthesized. It was found that each of the complexes from C3O-Cu to C12O-Cu is a discogen, and that each of them has only one discotic mesophase. C3O-Cu is the first compound substituted by the shortest side chains in the discogen, so far as we know. The mesomorphic textures could be observed as mosaic textures for C3O-Cu ~ C5O-Cu and as big broken fan-like textures for C6O-Cu ~ C12O-Cu. The cutectic point calculated from Le Chatelier-Schroder relations agrees well with the found eutectic point in the binary phase diagram between C8O-Cu and C8-Cu. This is the first example of such agreement in the discogens of the organic transition metal complexes. It has been established for the first time from X-ray diffraction measurements that each of the discotic mesophases in the complexes from C6O-Cu to C12O-Cu is a discotic lamellar phase. It becomes clear that this ...

Discotic Liquid Crystals of Transition Metal Complexes, 5: Double Melting Behavior and Double Clearing Behavior of Discogens

Abstract Two new octa-substituted disk-like bis(β-diketonato) copper(II) complexes, 8C8-Cu and 8C8O-Cu, have been synthesized. The same type of octa-substituted copper complexes, SC9O-Cu, which was synthesized for the first time by A. M. Giroud-Godquin et al., has also been prepared. The thermal behavior of these three complexes was investigated by means of microscopic observations and DSC measurements. It was found that the 8C8-Cu exhibits not a discotic mesomorphism but a usual double melting behavior via the isotropic liquid, and that the 8C8O-Cu exhibits an unusual double melting behavior via the discophase which had not been reported by A. M. Giroud-Godquin et al. Furthermore, it was found that the 8C8O-Cu exhibits a new thermal phenomenon of “double clearing behavior” which is originated from a superheating of the transition from the crystalline phase to the discotic phase. Such double clearing behavior of the 8C8O-Cu is the first example in the mesomorphic compounds, so far as we know.

Synthesis, structure and antiviral activity of sulfates of cellulose and its branched derivatives

Abstract Cellulose and branched cellulose having d -glucopyranose or d -galacto-pyranose as side chains were sulfated with piperidine N-sulfonic acid or SO3-dimethylformamide complex. The structures of the sulfated polysaccharides were analysed by elemental analysis and 13[C]-NMR spectroscopy. The 13[C]-NMR spectra of cellulose sulfate were assigned and degree of substitution values of each hydroxyl group were obtained. The reactivity was in the order C-6 ⪢ C-2> C-3. Sulfated polysaccharides with high degree of substitution values showed high anti-human-immuno-deficiency-virus activity.

Double Melting Behavior of Disk-like Complexes Substituted by Long Chains, 1: the Substituent Effect

Abstract The bis (β-diketonato) copper (II) complexes, 2c and 2d. exhibit double melting behavior; 2c (m.p. of K1:122.4 - 122.8[ddot]C, m.p. of K2:135.2 - 135.6[ddot]C), 2d (m.p. of K1:168.8 - 169.2[ddot]C. m.p. of K2:208.3 - 208.6[ddot]C). The corresponding β-diketone ligands, 1c and 1d, also exhibit double melting behavior; 1c (m.p. of K1:83.4 - 83.9[ddot]C. m.p. of K1:84.9 - 85.4[ddot]C). 1d (m.p. of K1:103.5 - 103.6[ddot]C, m.p. of K2:108.1 - 108.2[ddot]C). 2c and 2d are the first examples exhibiting double melting behavior in the disk-like transition metal complexes substituted by long chains. Because the previously reported complexes (2a and 2b) exhibit discotic mesomorphism, the double melting behavior of 2c and 2d is thought of as thermal behavior close to mesomorphism. The chief determining factors which lead to either mesomorphism or double melting behavior are the substituent effect and the effect of central metal.

Discotic Liquid Crystals of Transition Metal Complexes, 4:1 Novel Discotic Liquid Crystals Obtained from Substituted Bis(dithiolene)nickel Complexes by a New Method

Abstract Two new disc-like complexes, bis [1, 2-di (p-nonyloxyphenyl) ethane-1, 2-dithiolene] nickel (6a) and bis[1, 2-di-(p-undecyloxyphenyl) ethane-l, 2-dithiolene] nickel (6b), have been synthesized by a new method. It was found that the complexes exhibit discotic mesomorphism. The half-wave potentials for the reduction of the nickel complexes (6a, b) determined by cyclic voltammetry, are -0.06V (6a) and -0.07V for (6b) vs. SCE in CH2Cl2. The nickel complexes (6a, b) are only a few examples of π-acceptor discotic liquid crystals.

Discotic Liquid Crystals of Transition Metal Complexes, 1: Bis[1,3-di(p-n-octylphenyl)propane-1,3-dionato]copper(II) and Bis[1,3-di(p-n-octyloxyphenyl)propane-1,3-dionato]copper(II)

Abstract It was found that the bis β-diketonato copper (II) complexes IIa, IIb have discotic mesophases; IIa(D1:76.1 - 117.2°C, D2:117.2 - 141.6°C), IIb(D: 82.5 - 173.3°C), and that the corresponding β-diketone ligands Ia, Ib have classical mesophases; Ia (Smectic: 28.5 - 60.7°C), Ib(Smectic:72.3 - 83.6°C). Ila has two discotic mesophases, which is the first example exhibiting discotic mesogen polymorphism. The temperature range of mesophase for β-diketone ligand with octyloxy chains lb is narrower than that of the ligand with octyl chains la, and on the contrary the range of the Cu(II) complex with octyloxy chains IIb is wider than that of the Cu(II) complex with octyl chains IIa. It is the first example of such substituent effect in mesomorphism.

First Examples Exhibiting both Double Melting Behavior and Mesomorphism in a Series of Long Chain Substituted Compounds: 1,3-Di(p-n-alkoxyphenyl)propane-1,3-dione

Abstract A new series of β-diketones substituted by the same kind of chains, (alkoxy groups) having different lengths (CnO-Diketone, n = 1-12), has been synthesized. It was found that CnO-Diketone shows triple melting behavior for n = 1, double melting behavior for n = 2-7, and smectic mesomorphism for n = 8-12. It is the first example exhibiting both double (triple) melting behavior and mesomorphism in a series of long chain substituted compounds, so far as we know. Furthermore, it is noteworthy that the critical change from double melting behavior to mesomorphism occurs between n = 7 and n = 8, which is also the first example in the long chain substituted compounds, so far as we know.

Synthesis of water-soluble, branched polysaccharides having d-mannopyranose, d-arabinofuranose, or oligo-d-arabinofuranose side-chains and their antitumor activity☆

Branched polysaccharides having D-mannopyranose, D-arabinofuranose, or oligo-D-arabinofuranose side-chains were synthesized by the reaction of 3,4,6-tri-O-acetyl-(1,2-O-ethylorthoacetyl)-beta-D-mannopyranose, 3,5-di-O-benzoyl-(1,2-O-ethylorthobenzoyl)-beta-D-arabinofuranose, or 3-O-benzoyl-(1,2,5-O-orthobenzoyl)-beta-D-arabinofuranose with cellulose acetate or curdlan acetate, followed by desterification. The structure and antitumor activity of the water-soluble portion of the polysaccharides thus obtained were investigated. Polysaccharides synthesized from (1----3)-beta-D-glucan as the main chain with oligo-D-arabinofuranose side-chains exhibited high antitumor activity.

Discotic Liquid Crystals of Transition Metal Complexes VI. Monotropic Lamella Mesomorphism of Tetrakis(N-Alkyldithiolato)Dinickel(II) and Bis(N-Alkylxanthato)Nickel(II) Complexes

Abstract It was found that each of the tetrakis(n-alkyldithiolato)dinickel(II), (Cn-DTA)4-Ni2, complexes where n-alkyl is n-pentyl through n-dodecyl, exhibits a broken-fan texture on cooling from an isotropic liquid, and that the phase gave a characteristic lamella structure X-ray diffraction powder pattern. Furthermore, the infrared spectrum of this phase is more similar to that of the isotropic liquid than that of the crystal. Therefore, the phase can be described as a monotropic lamella mesophase. Interestingly, each of the complexes of bis(n-alkylxanthato)nickel(II), (Cn-Xan)2Ni, (n = 5, 7, 9, 11) exhibits double (triple) melting behavior via the isotropic liquid, whereas each of the complexes of (Cn-Xan)2Ni (n = 4, 6, 8, 10, 12) shows ordinary single melting behavior. Such unique double melting accompanied by an even-odd effect appears to be the first example of this in the long chain substituted compounds. Each of the complexes of (Cn-Xan)2 Ni (n = 9, 11, 12) has a monotropic lamella mesophase exhib...