Radical reactions in malonic acid single crystal between 4 K and 300 K

For three out of the four different radicals which are produced by γ-irradiation in malonic acid single crystals, two stereo-isomers have been observed. The structures and orientations of these radicals were determined. ?H₂COOH proceeds from the cation and is already formed at 4 K; as to H?(COOH)₂, it proceeds from the molecular form of the protonated anion COOHCH₂?(OH)₂.     

Isolation, Purification and Characterization of Large-Ring Cyclodextrins (CD36∼ ∼CD39)

Large-ring cyclodextrins (LR-CDs) composed of more than 9 d-glucose units are not well studied. In this study, LR-CDs composed of 36, 37, 38 and 39 d-glucose units (CD₃₆∼ ∼CD₃₉) were isolated and purified from a LR-CD mixture, and their physicochemical properties including aqueous solubility, surface tension, specific rotation and acid-catalyzed hydrolysis rate were elucidated. The aqueous solubilities of CD₃₆∼ ∼CD₃₉ were greater than those of α-, β-, γ-CD, CD₉, CD₁₀, CD₁₄ and CD₂₆. CD₃₆∼ ∼CD₃₉ did not show any surface activity. The acid-catalyzed hydrolysis of CD₃₆∼ ∼CD₃₉ was a little faster than that of other LR-CDs (CD₉∼ ∼CD₃₅). There was no marked difference in specific rotation or the acid-catalyzed hydrolysis rate among CD₃₆∼ ∼CD₃₉. Furthermore, we compared these findings with the physicochemical properties of α-, β-, γ-CD and other LR-CDs (CD₉∼ ∼CD₃₅).     

Studies on the constituents of Swertia japonica MAKINO I. On the structures of new secoiridoid diglycosides

Eight new secoiridoid diglycosides, 6'-O-alpha-L-arabinopyranosylswertiamarin (1), 3'-O-beta-D-glucopyranosylswertiamarin (2), 4'-O-beta-D-glucopyranosylswertiamarin (3), 3'-O-beta-D-galactopyranosylswertiamarin (4), 6'-O-alpha-D-galactopyranosylswertiamarin (5), 6'-O-alpha-D-mannopyranosylswertiamarin (6), 6'-O-beta-D-fructofuranosylswertiamarin (7) and 5'-O-beta-D-glucopyranosylamaroswerin (12), were isolated, together with five known compounds from the whole plants of Swertia japonica MAKINO. The structures of the new compounds were elucidated on the basis of chemical and spectroscopic evidence. Compounds 6 and 7 are the first naturally occuring iridoid diglycosides having an alpha-D-mannopyranosyl unit and beta-D-fructofuranosyl unit, respectively.     

Structures of new ceramides from the fruit bodies of Grifola frondosa

Four new phytosphingosine-type ceramides, (2S,3S,4R)-2-[(2'R)-2'-hydroxydocosanoylamino]-1,3,4-octadecane triol (1), (2S,3S,4R)-2-[(2'R)-2'-hydroxytricosanoylamino]-1,3,4-octadecan etriol (2), (2S,3S,4R)-2-[(2'R)-2'-hydroxypentacosanoylamino]-1,3,4-octadec anetriol (3) and (2S,3S,4R)-2-[(2'R)-2'-hydroxyhexacosanoylamino]-1,3,4-octadeca netriol (4), have been isolated from the fruit bodies of Grifola frondosa. The structures of the new compounds were elucidated on the basis of their spectral data.     

Distribution of 67Ga-citrate in 3'-methyl-4-dimethylaminoazobenzene-induced hepatoma of rats

The distribution of 67Ga-citrate in the hepatoma of rat induced by 3'-methyl-4-dimethylaminoazobenzene was studied. 67Ga uptake ratio resected specimen, autoradiography and histological specimen were compared each other. 67Ga uptake ratio of the tumor was increased 1.6 to 7.2 times (average 4.4) to control group. Regardless of the size of the tumor, macroautoradiographically observed distribution of 67Ga-citrate in the hepatoma was higher in the peripheral zone than in the central zone. Histologically the degeneration of tumor cell was low or absent in the peripheral zone of tumor, whereas it was intense in the central zone. 67Ga-citrate was highly accumulated in the zone which the degeneration was low or absent. We, however, could not demonstrate the site where 67Ga-citrate was incorporated.     

MNDO MO theoretical study of electronic structure and homolytic dissociation of perfluoroalkanoyl peroxides

The MNDO molecular orbital method was applied to alkanoyl peroxides and the effect of fluorination on the electronic structure and the rate of the homolytic 0-0 cleavage of alkanoyl peroxides were analyzed. The fluorine atom introduced at the carbon atom makes the peroxy 0-0 bond long and the dihedral angle between two COO planes large. The analysis of two-atom energy and its components energies has shown that the rate of the 0-0 cleavage correlates well with the destabilization of the resonance energy of the 0-0 bond and not with the electrostatic energy. The effect of elongation of the perfluoroalkyl group is also well elucidated by the two-atom energy. The perfluoroalkyl group lowers the σ*(0-0) anti-bonding orbital considerably, and this fully explains the observed rate of induced decomposition of perfluoroalkanoyl peroxides with benzene.     

Synthesis of 1‐(4‐thiazolyl)azulenes: Reactions of bromoacetyl‐substituted azulenes with thioamides,thioureas, and thiosemicarbazones

1‐(Bromoacetyl)‐3‐methylazulene (1a) and methyl 3‐(bromoacetyl)azulene‐1‐carboxylate (1b) reacted with thioamides 3a,b and thioureas 3c,d in boiling ethanol to give the corresponding (4‐thiazolyl)azulenes 4a‐d and 5a‐d in good yields, respectively. The reactions of dibromoacetyl‐substituted azulene (2) also gave (4‐thiazolyl) azulenes 5a‐d in lower yields and the azulene 2 was recovered. By heating compounds 5a‐d in 100% phosphoric acid, the ester group was eliminated to yield 1‐(4‐thiazolyl)azulenes 6a‐d. Compounds 1a,b reacted with thiosemicarbazones 7a‐f to afford [(2‐alkylidenehydrazino)thiazol‐4‐yl]azulenes 8a‐f and 9a‐f in moderate to high yields via their hydromides.     

Ultrathin poly(N-isopropylacrylamide) grafted layer on polystyrene surfaces for cell adhesion/detachment control

We investigated physicochemical properties of two types of poly(N-isopropylacrylamide) (PIPAAm)-grafted tissue culture polystyrene (TCPS) surfaces, to elucidate the influential factors for thermally regulated cell adhesion and detachment to PIPAAm-grafted surfaces. The two types of PIPAAm-grafted surfaces were prepared by the electron beam polymerization method. Attenuated total reflection Fourier transform infrared spectroscopy revealed that amounts of the grafted polymers were 1.4 +/- 0.1 microg/cm2 for PIPAAm-1.4 and 2.9 +/- 0.1 microg/cm2 for PIPAAm-2.9. Both PIPAAm-grafted surfaces showed hydrophobic/hydrophilic property alterations in response to temperature. However, PIPAAm-1.4 surfaces were more hydrophobic (cos theta = 0.21 at 37 degrees C and cos theta = 0.35 at 20 degrees C) than PIPAAm-2.9 (cos theta = 0.42 at 37 degrees C and cos theta = 0.50 at 20 degrees C) both above and below the PIPAAm's transition temperature. Thicknesses of the grafted PIPAAm layers were estimated to be 15.5 +/- 7.2 nm for PIPAAm-1.4 and 29.5 +/- 8.4 nm for PIPAAm-2.9, by the use of UV excimer laser and atomic force microscope. Bovine carotid artery endothelial cells (ECs) adhere to the surfaces of PIPAAm-1.4 and proliferate to form confluent cell monolayers. The cell monolayers were harvested as single cell sheets by temperature decrease from 37 to 20 degrees C. On the contrary, ECs did not adhere to the surfaces of PIPAAm-2.9. This phenomenon was correlated with an adsorption of cell adhesion protein, fibronectin, onto surfaces ofPIPAAm-1.4 and -2.9. In the case of nano-ordered thin grafted surfaces, the surface chain mobility is strongly influenced by the thickness of PIPAAm grafted layers because dehydration of PIPAAm chains should be enhanced by the hydrophobic TCPS surfaces. PIPAAm graft amounts, that is, thickness of the PIPAAm grafted layers, play a crucial role in temperature-induced hydrophilic/hydrophobic property alterations and cell adhesion/detachment behavior.     

Studies on cytotoxic constituents in pericarps of Mallotus japonicus. IV

Two new phloroglucinol derivatives, isomallotolerin (1) and isomallotochromanol (2), were isolated from the cytotoxic fraction of the pericarps of Mallotus japonicus. The new derivatives were identified as 3-(3-methyl-2-hydroxybut-3-enyl)-5-(3-acetyl-2,4-dihydroxy-5-methy l-6- methoxybenzyl)-phlorisobutyrophenone (1) and 6-acetyl-5,7-dihydroxy-8-(3-acetyl-2,4-dihydroxy-5-methyl-6-methoxybenzy l)-2,2- dimethyl-3-hydroxychroman (2) from chemical and spectral data. Isomallotolerin and its acetate were found to be cytotoxic to KB cell line.     

Synthesis and Electroconductive Properties of Radical Salts Derived from Tetrathiafulvalene Dimers

Palladium(II)- or copper(II)-catalyzed homo-coupling reaction of either trimethylstannyltetrathiafulvalene or tetrathiafulvalenylzinc chloride produces symmetrical bitetrathiafulvalenes (bi-TTFs) in good yields, whereas palladium(0)-catalyzed cross-coupling reaction of tetrathiafulvalenylzinc chloride with 4-iodotetrathiafulvalenes leads to the corresponding unsymmetrically substituted bi-TTFs in moderate-to-high yields. The X-ray analysis of bi-TTF derivatives showed planar structures, and the cyclic voltammetry suggested that bi-TTFs have good donor ability comparable to that of BEDT-TTF. The symmetrical bi-TTFs formed the corresponding CT-complexes and cation radical salts. These CT-complexes and radical salts were found to be metallic or semiconducting, reflecting the effect of stoichiometry control in the dimeric TTF system. The X-ray structures of two cation radical salts revealed a unique stacking, and the precise conducting path in BEDO-bi-TTF·ClO₄ was discussed on the basis of MO calculations.