Relativistic Navier-Stokes equations in the Meixner-Prigogine scheme

Viscous effects are included in the relativistic Meixner-Prigogine scheme (see: A. Sandoval-Villalbazo, L.S. García-Colín, Physica A 234 (1996) 358). A relativistic generalization of the Navier-Stokes equations is obtained within this framework. The system obtained is analyzed and compared with related work.     

Structure of salvigenolide,a novel diterpenoid with a rearranged neo-clerodane skeleton from salviafulgens

From the aerial parts of Salvia fulgens Cav. (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This novel compound named salvigenolide, showed a six-seven A/B ring system with a trans fussion. A probable biogenetic route is proposed. Its structure and relative stereochemistry as in $\text{1}$, were established by spectroscopic means and X-ray diffraction analysis.     

Fast atom bombardment mass spectrometry of carbobenzyloxy-protected amino acids and peptides

The positive fast atom bombardment (FAB) mass spectra of 15 N-carbobenzyloxy derivatives of α-amino acids are presented together with those of some synthetic peptides containing other widely employed protecting groups. The data obtained allow a fragmentation pattern to be established for the N-carbobenzyloxy moiety and to obtain detailed structural information on the main fragment ions. A study of the ion current ratio vs. time pattern shows that important fragments derive from the parent protonated molecule through FAB-induced condensed-phase reactions.     

Partial molal volumes for iron(II)-diimine complexes in water and in aqueous methanol

Summary Partial molal volumes of the perchlorate or chloride salts of several tris-diimine-iron(II) cations have been determined in aqueous and methanol-water solutions by vibrating-tube densimetry. Partial molal volumes of the cations at infinite dilution have been estimated for aqueous solution, and compared with values for related cations. Trends of limiting partial molal volumes for perchlorate salts in methanol-water media are compared with trends in transfer chemical potentials for the respective cations; both are discussed in terms of ligand-dependent preferential solvation behaviour.     

New derivatives of 3-methylisoxazolo[5,4-b]pyridine

The synthesis and properties of 4,6-dichloro- (IV), 4-chloro- (XII) and 6-chloro-3-methyl-isoxazolo[5,4-b]pyridine (XI) are described. Depending on the reaction conditions compound IV with hydrazine or methoxide gave mono- or bi-substituted products. The halogen atom at the 4-position was shown to be the more mobile.     

Purine N-oxides: XXXVII. Derivatives from 6-chloropurine 3-oxide

Interaction of 6-chloropurine 3-oxide with several amines led to 6-substituted purine 3-oxides. 6-Chloropurine 3-oxide and selenourea gave 6-selenopurine 3-oxide. 6-Mereaptopurine 3-oxide, prepared from the 6-chloro derivative and ammonium dithioearbonate, was transformed with chlorine and hydrogen fluoride into 6-purinesulfonyl fluoride 3-oxide which upon ammonolysis afforded purine-6-sulfonamide 3-oxide. Methanelhiol and 6-ehloropurint: 3-oxide yielded the known 6-methylthiopurine 3-oxide, which by treatment with chlorine was oxidized to 6-methyl-sulfonylpurine 3-oxide. Reaction of the latter with hydroxylamine led to an improved synthesis of 6-hydroxylaminopurine 3-oxide, which by interaction with manganese dioxide was transformed into 6-nitrosopurine 3-oxide.     

Photocytotoxicity of a new Rh2(II,II) complex: increase in cytotoxicity upon irradiation similar to that of PDT agent hematoporphyrin

A new type of heteroleptic dirhodium complex cis-[Rh(2)(mu-O2CCH3)2-(bpy)(dppz)]2+ (3) was synthesized and its potential as a photodynamic therapy (PDT) agent was investigated. Although 27% hypochromicity of the absorption of 3 in the near-UV and visible regions is observed in the presence of duplex DNA, relative viscosity measurements reveal that the complex does not intercalate between the DNA bases. The DNA photocleavage with visible light by 3 proceeds via both oxygen dependent and independent mechanisms, and it is more efficient than that of related complexes. The increase in the cytotoxicity of 3 towards human skin cells is similar to that of hematoporphyrin, a key ingredient in a PDT drug currently in use. This feature makes this complex a useful candidate for further PDT studies.