Synthesis,structural characterization and in vitro antitumour properties of triorganoantimony(V) disalicylates: Crystal and molecular structures of [5-Y-2-(ho)-C6H3COO]2SbMe3 (YH,Me, MeO)

Triorganoantimony(V) salicylates, [5-Y-2-(HO)-C₆H₃COO]₂SbR₃ (R=Me, Ph; Y=H, Me, MeO), were obtained by reacting R₃SbCl₂ with the appropriate sodium salt. The compounds have been characterized by IR, MS, ¹H and ¹³C NMR spectroscopy. The molecular structure of the three substituted trimethylantimony(V) disalicylates has been determined by X-ray diffraction. The salicylate ligands are mono-coordinated to antimony through an oxygen atom of each carboxylate, leading to a trigonal bipyramidal geometry, with the antimony-methyl groups in equatorial positions and the oxygen atoms in axial positions. The trimethylantimony compounds tested in vitro against a series of human tumour cell lines were found to be inactive.     

Blitzvakuumthermolyse von 1-Chlor-4-methylen-spiro[2.m]alkanen

Flash Vacuum Thermolysis of 1-Chloro-4-methylenespiro[2.m]alkanes The title compounds 5 were prepared by addition of bromochlorocarbene to 1,2-bis(methylene)cycloheptane ( 3a ) and -cyclohexane ( 3b ), respectively, to give 4 , followed by reduction with triphenyltin hydride. Flash vacuum thermolysis of 5 gave instead of the expected vinylcyclopropane rearrangement to the chlorocyclopentenes 8 the halogen-free trienes 7 (80 – 90% yield), which were characterized by their spectra and by Diels-Alder reaction with tetracyanoethene to the adducts 6 . The mechanism of formation of 7 is discussed.     

Capillary gas-chromatographic method for determining non-derivatized sterols – some results for duplicate 24 h diet samples collected in 1994

A gas-chromatographic method for the determination of non-derivatized sterols in duplicate 24 h diet was developed and validated. In the spring and autumn of 1994, 123 people participated in a duplicate 24 h diet study. Each participant collected one duplicate of the food and drink consumed in a continuous 24 h period. The first analytical step involved hydrolysis of the test portion, to which an internal standard solution was added. The sterols were extracted with cyclohexane and determined by capillary gas chromatography with flame ionization detection. Samples were analyzed for cholesterol, coprosterol, brassicasterol, campesterol, stigmasterol and β-sitosterol. The quality control checks showed that the sterol contents of 26 lyophilized subsamples were unstable. In these cases, non-lyophilized subsamples were taken for analysis. The mean intake for all participants was: for cholesterol 202 mg/day per person, for campesterol 27 mg/day per person, for stigmasterol 15 mg/day per person and for β-sitosterol 102 mg/day per person. The mean intake for brassicasterol could not be calculated because too many values were below the limit of detection. Coprosterol could not be detected in the samples.     

Spectroscopy and photophysics of self-organized zinc porphyrin nanolayers. 2. Transport properties of singlet excitation

Exciton diffusion has been studied in 5-25-nm-thick films of zinc tetra-(p-octylphenyl)-porphyrin (ZnTOPP) spin-coated onto quartz slides by intentional doping with quenchers using steady-state as well as time-resolved fluorescence spectroscopy. The fluorescence spectra of the films are very similar to those of solutions, indicating emission from localized exciton states. From the dependence of the fluorescence quenching on the quencher concentration and fluorescence lifetime measurements, the exciton diffusion can be concluded to be quasi-one-dimensional with an exciton diffusion length of 9 +/- 3 nm and an intrastack energy-transfer rate constant of 10(11)-10(12) s(-1). From fluorescence anisotropy decay measurements, we conclude that neighboring stacks aggregate in a herringbone structure, forming ordered domains that are randomly oriented in the substrate plane. These measurements indicate an interstack energy-transfer rate constant of (7 +/- 2) x 10(10) s(-1).     

Rational Unfoldings of ± X k and their relation with geometric equilibrium theory

In this paper, two theorems determine the locus B (buoyancy locus) of the centre of gravity of the displaced water of a ship with any number of 2n sides, as a function of the arbitrary continuous curves that make up those sides, and that generalize the classical wall-sided case (n=1). Although the theorems may have interest from the pure geometrical point of view, they have been obtained with a view to simulate processes in biology that, in analogy to the self-righting of ships, are self-regulating, such as the neural control of body heat and the servo-control of the heart rate.