Cu-Chelex as a selective adsorbent for o-nitroso derivatives of phenolic substances

Summary Chelex resins in several metal forms were tested for selective uptake of o-nitrosonaphthols and o-nitrosophenols from aqueous solution. Cu-Chelex was the most efficient resin over a wide pH range, and the taken-up nitroso compounds were effectively eluted with concentrated ammonia: acetonitrile (4:1, v/v) after washing the resin with acetonitrile to eliminate non-specific binding. The upper and lower limits of uptake capacity of the resin for 1-nitroso-2-naphthol were 0.5 mol/100 mg and 1.25 mol/100 mg, respectively. A preliminary recovery experiment using urine and cucumber juice showed that Cu-Chelex would be useful for screening of o-nitroso derivatives of phenolic substances in complicated samples such as biological fluids and foods.     

A new method for the synthesis of some 9-β-D-arabinofuranosylpurines by a combination of chemical and enzymatic reactions

An enzymatic transarabinosylation between 2-chlorohypoxanthine and 1-β-$\text{D}$-arabinofuranosyluracil gave 9-β-$\text{D}$-arabinofuranosyl-2-chlorohypoxanthine which was chemically converted to 9-β-$\text{D}$-arabinofuranosylguanine and its derivatives.     

PHOTOCHEMISTRY OF ALL-TRANS- AND 13-CIS-14,15-DIDEUTERIORETINAL

Abstract— All- trans - and 13- cis -14,15-dideuterioretinal were synthesized and their solution photochemistry examined. Quantum yields of trans → cis or cis → trans photoisomerization and the number and ratio of primary photoproducts, determined by high pressure liquid chromatographic analysis, are essentially identical to that of their corresponding retinal isomer. The C-14, C-15 carbon-hydrogen modes play no particularly important role in the deactivation of electronically excited linear polyenes related to retinal.     

Synthesis of inorganic-organic hybrids by incorporation of inorganic components into organic polymer using metal alkoxides

Inorganic-organic hybrids have been synthesized by incorporation of the inorganic component of Ti(OC₂H₅)₄ into the organic polymer of ethyl cellulose. The inorganic-organic hybrids did not dissolve in toluene used as a solvent for the starting materials. The ethanol was formed as a by-product of the alcoholysis condensation reaction between Ti(OC₂H₅)₄ and ethyl cellulose. These results suggest that ethoxy groups of Ti(OC₂H₅)₄ react with hydroxy groups of ethyl cellulose to form cross-linking bonds of –O–Ti–O–. The reaction of Ti(OC₂H₅)₄ with ethyl cellulose was further investigated by Fourier transform infrared (FT-IR) spectroscopy. The FT-IR spectroscopic experiments revealed that the Ti–O bond state of Ti(OC₂H₅)₄ was changed by refluxing a toluene solution of Ti(OC₂H₅)₄ with ethyl cellulose. The inorganic-organic hybrids have an interesting dielectric property; their dielectric constant is higher than that of ethyl cellulose and that of a simple mixture of TiO₂ and ethyl cellulose.     

Effect of urea addition on chiral separation of dansylamino acids by capillary zone electrophoresis with cyclodextrins

The chiral separation ability of unmodified and di- and trimethylated -, β- and γ-cyclodextrins (CDs) as chiral selectors in capillary zone electrophoresis was investigated in the presence of urea derivatives using twelve dansylamino acids as model solutes. The addition of these urea derivatives (unsubstituted, methyl-, ethyl- and 1,3-dimethylureas) produced dramatic enhancement in the enantioselectivity of unmodified β-CD but also reduced the enantioselectivities of the other CDs.     

Collision-energy-resolved Penning ionization electron spectroscopy of p-benzoquinone: study of electronic structure and anisotropic interaction with He(*)(2 (3)S) metastable atoms

Collision energy dependence of partial ionization cross sections (CEDPICS) of p-benzoquinone with He(*)(2 (3)S) metastable atoms indicates that interaction potentials between p-benzoquinone and He(*)(2 (3)S) are highly anisotropic in the studied collision energy range (100-250 meV). Attractive interactions were found around the C==O groups for in-plane and out-of-plane directions, while repulsive interactions were found around CH bonds and the benzenoid ring. Assignment of the first four ionic states of p-benzoquinone and an analogous methyl-substituted compound was examined with CEDPICS and anisotropic distributions of the corresponding two nonbonding oxygen orbitals (n(O) (+),n(O) (-)) and two pi(CC) orbitals (pi(CC) (+),pi(CC) (-)). An extra band that shows negative CEDPICS was observed at ca. 7.2 eV in Penning ionization electron spectrum.     

Template-directed DNA photoligation via alpha-5-cyanovinyldeoxyuridine

[reaction: see text] We describe an efficient template-directed photoligation of oligodeoxynucleotides (ODNs) using alpha-5-cyanovinyldeoxyuridine (alpha(C)U). An efficient photoligation was produced by photoirradiation of an ODN containing alpha(C)U at the 3' end with an ODN containing thymine at the 5' end in the presence of a template ODN. This photoligation method is a new and efficient way to synthesize branched ODNs.     

A new route to 2'-O-alkyl-2-thiouridine derivatives via 4-O-protection of the uracil base and hybridization properties of oligonucleotides incorporating these modified nucleoside derivatives

Oligonucleotides containing 2-thiouridine (s2U) in place of uridine form stable RNA duplexes with complementary RNAs. Particularly, this modified nucleoside has proved to recognize highly selectively adenosine, the genuine partner, without formation of a mismatched base pair with the guanosine counterpart. In this paper, we describe new methods for the synthesis of 2-thiouridine and various 2'-O-alkyl-2-thiouridine derivatives. Oligoribonucleotides having these modified nucleoside derivatives were synthesized, and their hybridization and structural properties were studied in detail by the 1H NMR analysis of these modified nucleosides and Tm experiments of RNA duplexes with their complementary RNA strands.     

Quantitative evaluation of stress distribution in bulk polymer samples through the comparison of mechanical behaviors between giant single‐crystal and semicrystalline samples of poly(trans‐1,4‐diethyl muconate)

The Raman shift and crystallite modulus were measured under the application of tensile force for a giant single crystal and a series of uniaxially oriented semicrystalline samples of poly(trans‐1,4‐diethyl muconate) (polyEMU). The apparent Raman shift factor α^app or a vibrational frequency shift per 1 GPa tensile stress was higher for the semicrystalline samples with lower crystallinity or lower bulk modulus. The apparent crystallite modulus E or Young's modulus along the chain axis in the crystalline region was not constant but varied remarkably between the giant single crystal and semicrystalline samples. A systematic change in α^app and E among the polyEMU samples with different preparation history could be interpreted quantitatively on the basis of a mechanical series parallel model consisting of crystalline and amorphous phases. The origin of different E and α^app was speculated to be a stress concentration on the taut‐tie chain contained as a parallel crystalline component in the mechanical model. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 444–453, 2003     

Influence of the Coordination of Donor Solvent Molecules to 1,4,7,10-Tetramethyl-1,4,7,10- tetraazacyclododecanenickel(II) and Analogous Nickel(II) Complexes on Their Steric Factors

Coordination equilibrium constants (K _NiS) of some donor solvent molecules to 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecanenickel(II) ([Ni(Me₄[12]aneN₄)]²⁺) were determined in nitrobenzene (a noncoordinating bulk solvent). The first (K _NiS1) and second stepwise coordination equilibrium constants (K _NiS2) for 1,4,7,10-tetraazacyclododecanenickel(II) ([Ni([12]aneN₄)]²⁺), 1,4,8,11-tetraazac yclotetradecane- nickel(II) ([Ni([14] aneN₄)]²⁺), 1,4,8,11-tetrathiacyclotetra-decanenickel(II) ([Ni([14]aneS₄)]²⁺) were also reinvestigated. The K _NiS values for [Ni(Me₄[12]aneN₄)]²⁺ were compared to those of [Ni([12]aneN₄)]²⁺, (1R,4S, 8R,11S)-1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecanenickel(II) (R,S,R,S-[Ni(Me₄[14]aneN₄)]²⁺), R,R,S,S-[Ni(Me₄[14]aneN₄)]²⁺, [Ni([14]aneN₄)]²⁺, and [Ni([14]aneS₄)]²⁺. Coordination of pyridine (Py), N,N,N′,N′-tetramethylurea (TMU), and N,N-dimethylacetamide (DMA) to [Ni(Me₄[12]aneN₄)]²⁺ was observed, although these donor solvent molecules did not coordinate to R,S,R,S-[Ni(Me₄[14]aneN₄)]²⁺. The K _NiS values for Py, TMU, and DMA are 7.9, 2.8, and 9.0 dm³⋅mol⁻¹, respectively. Some hydrogen-bonding waters were coordinated to R,S,R,S-[Ni(Me₄[14]aneN₄)]²⁺, but such waters did not coordinate to [Ni(Me₄[12] aneN₄)]²⁺. Also, the K _NiS2 values were larger than the corresponding K _NiS1 values for [Ni([14]aneS₄)]²⁺. Furthermore, the K _NiS1 values for [Ni([12]aneN₄)]²⁺ were the largest among these nickel(II) complex cations. The K _NiS, K _NiS1, and K _NiS2 values are discussed in terms of properties of the donor solvents and steric strains of these nickel(II) complex cations.