Two conformers of 10,11‐dihydro‐5H‐dibenzo[a,d]cyclo­heptene spiro‐linked with homobenzoquinone epoxide

The crystal structures of the two thermally equilibrated conformational isomers of the epoxide 1′,5′‐dimethyl­spiro[10,11‐dihydro‐5H‐dibenzo[a,d]cyclo­heptene‐5,8′‐4′‐oxatricyclo[5.1.0.0^3,5]octane]‐2′,6′‐dione, C₂₃H₂₀O₃, have been determined by X‐ray diffraction. In the tricyclic dione skeleton, the oxirane and cyclo­propane rings adopt an anti structure with respect to the conjunct quinone frame. The spiro‐linked 10,11‐dihydro‐5H‐dibenzo[a,d]cyclo­heptene ring of the major isomer has a fairly twisted boat form, folding opposite to the adjoining cyclo­propane methyl substituent, whereas the seven‐membered ring of the minor isomer has an almost ideal twist–boat form, inversely folding to the side of the relevant methyl group. The conformational structures of these isomers have been compared with those of the corresponding isomers of the unepoxidized homobenzoquinone.     

Permeation of aromatic compounds in aqueous solutions through thin,dense cellulose acetate membranes

The partition and diffusion coefficients of aqueous solutions of aromatic compounds through a thin, dense cellulose acetate membrane were measured at 20°C. The water content and the thickness of the prepared membranes varied from 0.121 to 0.610 by volume fraction and from 17 to 88 μm, respectively. The aromatic solutes used were phenol, aniline, hydroquinone and p-chlorophenol. The solute concentration ranged between 9.0 x 10^-5 and 1.0 x 10^-3 mol/l. The partition coefficients had the following order: p-chlorophenol, phenol, aniline, hydroquinone; they were experimentally correlated with the water content of the swollen membranes.The dependence of the diffusion coefficients on the water content of the membrane was examined using as basis a pore model and a free volume model, respectively. The diffusion coefficients were adequately correlated with the water content of the membrane according to the relation given by the free volume model.     

A Cell‐Targeted Non‐Cytotoxic Fluorescent Nanogel Thermometer Created with an Imidazolium‐Containing Cationic Radical Initiator

A cationic fluorescent nanogel thermometer based on thermo‐responsive N‐isopropylacrylamide and environment‐sensitive benzothiadiazole was developed with a new azo compound bearing imidazolium rings as the first cationic radical initiator. This cationic fluorescent nanogel thermometer showed an excellent ability to enter live mammalian cells in a short incubation period (10 min), a high sensitivity to temperature variations in live cells (temperature resolution of 0.02–0.84 °C in the range 20–40 °C), and remarkable non‐cytotoxicity, which permitted ordinary cell proliferation and even differentiation of primary cultured cells.     

Synthesis of monoglucosylated high-mannose-type dodecasaccharide,a putative ligand for molecular chaperone,calnexin, and calreticulin

Convergent and stereoselective synthetic routes to Man9GlcNAc2 (1b), alpha-Glc1M9GlcNAc2 (2b), and its stereoisomer beta-Glc1M9GlcNAc2 (3) were established. Interaction analysis of 2b with CRT was measured by 1H NMR spectroscopy, and the first NMR-based evidence for the specific binding of CRT to 2b was obtained.     

Determination of the new morpholino anthracycline MX2.HCl and its metabolites in biological samples by high-performance liquid chromatography.

Methods for determining concentrations of a new morpholino anthracycline MX2.HCl and its metabolites in biological samples using reversed-phase high-performance liquid chromatography and fluorescence detection are described. The limits of detection were less than 1 ng/ml for all compounds after extraction from 0.5 ml of plasma using C18 Sep-Pak cartridges and consecutive solvent extraction. The recoveries from rat plasma ranged from 72.0 to 89.3%. The peak-height ratio of the fluorescence intensities of these compounds versus internal standard showed a linear correlation for concentrations up to at least 500 ng/ml in the plasma (correlation coefficient r greater than 0.999). The within-day and between-day precisions of this assay were in the range 0.8-8.7% (n = 5) and 2.0-3.5% (n = 5), respectively. The concentrations of these compounds in the blood and urine can be also determined by a slight modification of the extraction procedure.     

Surface activity of myristic acid in the poly(methyl methacrylate)/supercritical carbon dioxide system

To confirm the surface activity of myristic acid in the dispersion polymerization of vinyl monomers in scCO2, the interfacial tension (IFT) at the polymer/supercritical carbon dioxide (scCO2) interface has been measured. For the IFT measurements, a high-pressure pendant drop apparatus was constructed. The IFT data was obtained by the axisymmetric drop shape analysis of melt polymer droplets formed at the tip of a capillary. The reliability of the apparatus was confirmed by measuring the IFT of polystyrene (PS)/scCO2 and polypropylene (PP)/CO2 systems. The IFT of the poly(methyl methacrylate) (PMMA)/scCO2 system with and without myristic acid was also measured. The IFT decreased on addition of myristic acid. The magnitude of the IFT depression due to the myristic acid was comparable to that of PS/scCO2 systems with the block copolymer surfactant, PS-b-poly(fluorooctyl acrylate). The surface activity of the myristic acid was confirmed by the decrease of IFT.     

Electronic structure of transition-metal complexes. I. Parametrization for CNDO/2 method

A new parameterization for the first transition metal has been proposed in the framework of CNDO /2 method. We carried out CNDO /2 calculation of hexamine complexes [M(NH₃)₆]²⁺ and hexa-aquo complexes [M(OH₂)₆]²⁺ in the high spin state where M = Mn, Fe, Co, Ni, and Cu, using new parameters. It is shown that the calculated order of binding energy is Mn? L < Fe? L < Co? L < Ni? L ≈ Cu? L (where L means the ligand), and is in good agreement with experiment. We discussed how the orbital nodes affect the nature of bonding between metal and ligand.     

Seed polymerization of tetraethyl ortho-silicate in the presence of rod-like colloidal particles of anionic palygorskite and cationic β-FeO(OH)

Kinetic analyses were made of the seed polymerization of tetraethyl ortho-silicate (TEOS) in the presence of rod-like colloidal particles of palygorskite and cationic -FeO(OH) by turbidity and dynamic light-scattering measurements. Transmission electron microscopic measurements supported the formation of core-shell particles. The seed polymerization of TEOS took place exclusively on the surfaces of palygorskite. The main cause of the observation is due to the fact that the main component of palygorskite is SiO₂ and the affinity between palygorskite and TEOS is high, though the electrostatic repulsion between them is not favorable for shell formation. The shell formation of silica on a -FeO(OH) particle also proceeded. The electrostatic attraction forces between the anionic polar TEOS monomers and cationic -FeO(OH) particles played an important role in shell formation. These results are consistent with a polymerization mechanism consisting of the formation of small preliminary particles followed by their coalescence on the surfaces of the seeds to give the final large particles coated with silica layers.     

Substituent Distribution of Cyanoethyl Cellulose

Estimation of the substitution distribution for cyanoethyl cellulose was carried out by ¹H and ¹³C NMR spectroscopic analyses after the additional acetylation. Based on the complemental function of cyanoethyl and acetyl substituents, the degree of substitution (DS) of cyanoethyl groups could be calculated from the ratios of the ¹H integrated intensities in acetyl methyl ( 1.8–2.1) and cyanoethyl methylene ( 2.6–2.9) protons, and also from the corresponding ratios for acetyl methyl carbon signals ( 19.7–21.3) and cyanoethyl methylene carbon signals ( 17.5–19.0). Good agreement was obtained between the DS values obtained from the NMR spectroscopic analyses and those determined by the conventional nitrogen content method, indicating the validity of the NMR method used. In addition, the NMR method was found to be effective in determining the positional substituent distribution by the quantitative analysis of the three cyan carbon signals ( 118–120).     

Generation of an abasic site in an oligonucleotide by using acid-labile 1-deaza-2'-deoxyguanosine and its application to postsynthetic modification

We developed a new convenient method for generation of an abasic site at the 3'-terminus of an oligonucleotide. This method uses a 1-deaza-2'-deoxyguanosine residue, which easily undergoes depurination under acidic conditions. The abasic site of the oligonucleotide can be further modified with external functional groups. We report herein the chemical stability of 1-deaza-2'-deoxyguanosine in the oligodeoxynucleotide and the application to the postsynthetic modification of an oligonucleotide by utilizing the chemical property of 1-deaza-2'-deoxyguanosine. [Structure: see text]