Biomimetic oxidation of alcohols by coenzyme PQQ-trimethyl ester

Oxidation of alcohols to corresponding carbonyl compounds by coenzyme PQQ-trimethyl ester was performed in the presence of aluminum t-butoxide or aluminum chloride under anaerobic conditions. Reduced PQQTME (PQQTMEH₂) was obtained by acidification of an aluminum complex of reduced PQQTME which was isolated in the reaction.     

Synthesis of crown ether-terminated poly(methyl methacrylate) by radical chain transfer polymerization

Mercapto-16-crown-5 was prepared starting from tetraethyleneglycol and 3-chloro-2-chloromethyl-1-propene. Radical polymerization of methyl methacrylate was carried out in the presence of mercapto-16-crown-5 as a chain transfer agent to give crown ether-terminated poly(methyl methacrylate). The end crown group was characterized by IR and ¹H-NMR spectra. Sodium cation was selectively extracted by this crown-containing polymer. The molecular weight of the obtained polymer had influence upon the ability of extraction of sodium cation.     

Polymerization of vinyl acetate in fatty acids and properties of poly (vinyl alcohols) derived from the poly (vinyl acetates)

Polymerization of vinyl acetate (VAc) in various fatty acids (carbon numbers 4–18) was carried out. Chain transfer constants to the acids were determined to be 20–35×10^–4, from which the constant to a methylene group was obtained to be 0.73×10^–4. Viscometry in aqueous solution of derived poly (vinyl alcohol) (PVA) showed the usual behavior in terms of Huggins constant obtained by the Schulz–Blaschkes equation for PVAs derived from fatty acid systems lower than hexadecanoic acid. PVA derived from octadecanoic acid system showed abnormality, indicating association of alkyl groups. Contact angles on surfaces of PVAs cast from aqueous solutions were measured. While those of PVA derived from lower acid systems were 62°, those of PVAs derived from higher aids were higher and increased to 92° with increase in carbon number to octadecanoic acid. Alkyl groups in the PVAs were estimated to appear on the surfaces. Surface tension of aqueous solution of the PVA derived from octadecanoic acid showed high surface activity, and depended on pH of the solution, indicating the presence and cleavage of lactone ring at the combined portion between PVA and the acid.     

Photolysis of triphenyl phosphate in aqueous methanol

Upon UV irradiation in methanol, triphenyl phosphate ( 1a ) gave biphenylyl phenyl phosphate ( 2a ) as the main product, whereas the addition of water to the solution caused an increase of the yield of biphenyl ( 3a ). These products were formed through a singlet excited state and an intramolecular excimer, respectively. © 1996 John Wiley & Sons, Inc.     

New Types of Planar Chiral [2.2]Paracyclophanes and Construction of One‐Handed Double Helices

New types of planar chiral (R_p)‐ and (S_p)‐4,7,12,15‐tetrasubstituted [2.2]paracyclophanes were synthesized from racemic 4,12‐dihydroxy[2.2]paracyclophane as the starting compound. Regioselective dibromination and transformation afforded a series of planar chiral (R_p)‐ and (S_p)‐4,7,12,15‐tetrasubstituted [2.2]paracyclophanes, which can be used as chiral building blocks. In this study, left‐ and right‐handed double helical structures were constructed via chemoselective Sonogashira–Hagihara coupling. The double helical compounds were excellent circularly polarized luminescence (CPL) emitters with large molar extinction coefficients, good photoluminescence quantum efficiencies, and large CPL dissymmetry factors.     

Spin-lattice relaxation times of bound water—Its determination and implications for tissue discrimination

Measurements were made of T1 of bound water (T1b) and bound water fraction () for gelatin solutions and human tissues (sera, brain tumor, cerebral white matter). Bound water fraction in each sample was measured by means of thermal analysis (differential scanning calorimetry: DSC). T1 values were measured by FONAR QED 80-. T1b values were calculated by an equation derived from the fast-exchange two-state model. In the study of gelatin solutions, the relationship between T1 and water content differed depending on the sort of solutions. This was considered to be due to differences in T1b values. In each biological tissue the values of T1b and had different distributions. These results indicate that values of T1b and for biological tissues may be altered in correspondence to the changes in pathophysiological states in those tissues.