A new and improved synthesis of a potential antitumour 7h-pyrido[4,3-c ]carbazole analog.

The 6-ethyl-10-methoxy-7H-pyrido[4,3-c ]carbazole is synthesized via a novel and convenient method involving the condensation of the 2-lithio-5-methoxyindole with the appropriate alkyl pyridyl ketone. Quaternarization of this compound by means of a rigid bis(ethyl-piperidyl) linking chain leads to a new potential antitumour dimer.     

Development of a definitive method for iodine speciation in aquatic systems

Summary A definitive method of isotope dilution mass spectrometry (IDMS) was developed to determine four different iodine species in aquatic systems (iodide, iodate and two organoiodine compounds: one of the organic species is chromatographically elutable from a column filled with an anion exchanger resin, the other one is not). The iodine species were analysed after the isotope dilution step with an enriched ¹²⁹I spike and after their chromatographic separation. The total iodine concentration was measured after decomposition of organic compounds in the aquatic system by UV irradiation. Different types of natural water samples (river water, water of a pond, moorland lake water) were analysed and important water parameters like pH-value, redox potential, oxygen content and dissolved organic carbon were measured for each of these samples. The total iodine concentration in the different samples differed only slightly in the range of 2–7 g/l. In most of the moorland lake water samples only the two organoiodine species could be detected. In these samples the concentration of iodide and iodate was less than the detection limit of 0.5 g/l and 0.1 g/l, respectively. On the other hand, all four iodine species could be determined in most of the river water samples. Positive correlations were found for the oxygen content of the water samples and the iodate concentration as well as for the redox potential and the anionic organoiodine compound.In memoriam of Dr. I. Linus Barnes who died in January, 1990. Dr. Barnes was senior scientist at the National Institute of Standard and Technology in Gaithersburg, USA. He made numerous outstanding contributions to the field of mass spectrometry and IDMS     

Quantitative formation of [2]catenanes using copper(I) and palladium(II) as templating and assembling centers: the entwining route and the threading approach

Transition metal-mediated templating and self-assembly have shown powerful potentials for the synthesis of interlocked molecules. These two strategies were combined in designing and preparing a new type of coordination catenanes incorporating Cu(I) and Pd(II) metal centers. The ligand designed here contains a phenanthroline core and pyridine sidearms (compound 1). Using this phenanthroline-pyridine conjugated ligand, two approaches were examined, which were shown to be surprisingly efficient for the catenane synthesis: the entwining route (entwining of two ligands around Cu(I) followed by Pd(II) clipping) and the threading approach (Cu(I)-templated threading of a cyclic ligand on an acyclic ligand followed by the Pd(II) clipping of the second ring). In the former method, stepwise treatment of 1 with Cu(CH(3)CN)(4)PF(6) (templating center) and enPd(NO(3))(2) (assembling center) gives rise to the quantitative formation of CuPd(2) catenane 18. In the latter method, Cu(I) templates the threading of phenanthroline-containing macrocycle 2 on ligand 1, which is followed by Pd(II) clipping to give hetero catenane 20. In both approaches, the formation of catenanes is convincing thanks to the strong templating effect of Cu(I), while the ring closure steps are efficiently furnished by Pd(II)-directed self-assembly.     

Processus des misanthropes

Summary We consider a system of identical interacting particles moving on the lattice ^d . The rate at which a particle at the site x jumps to the site y is p(y–x)b((x), (y)) where p is an irreducible probability on ^d and b((x), (y)) is an increasing (resp. decreasing) function of the number (x) (resp. (y)) of particles at site x (resp. y). We study the convergence of the system to equilibrium and describe the invariant measures.     

A simple molecule with a complex crystal structure: interplay of 31P solid-state NMR spectroscopy and single-crystal x-ray diffraction in the structure determination of a ruthenium diphosphine diamine complex

A comprehensive 31P solid-state NMR study of Ru(eta1-Ph2PCH2CH2OCH3)2(eta2-en)Cl2 (en = ethylenediamine) (1), by 1D (contact time variation, inversion-recovery, SPARTAN) and 2D techniques (homonuclear J-resolved, SECSY) indicated that the crystal structure of 1 should be complex. The single-crystal x-ray structure determination confirmed the presence of eight independent molecules in the asymmetric unit, with 31P isotropic chemical shifts in the range 27.3-40.1 ppm, while the spans of the phosphorus chemical shift tensors are of the order of 170 ppm. Based on unique structural features and NMR data, one molecule has been tentatively assigned.     

Towards artificial muscles at the nanometric level

The authors describe their study of molecular systems suited to the fabrication of machines and (rotory or linear) motors at the molecular level. They indicate that a future application of these molecular'muscles'could be in the area of information storage and processing.     

Relationship between vitamin D status and skin phototype in general adult population

A link between bone mineral density and skin color has been reported recently, and pigmentation has been shown to affect cutaneous vitamin D production. In the present study, we investigated the relationship between phototype, global self-assessed sun exposure, geographical location and vitamin D serum levels in 1191 French adults. When the factors were analyzed separately, individuals with lower phototypes as well as those with lower sun exposure showed significantly lower levels of vitamin D than those with darker phototypes or those with higher sun exposure. However, when factors were analyzed as a whole, the vitamin D status was no longer linked with the phototype, but with sun exposure and geographical location. Since phototypes and global self-assessments of sun exposure were positively linked, our data suggest that lower vitamin D levels in fair-skinned individuals are due to their sun exposure behavior.