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.     

Practical Use of Corrected Fluorescence Excitation and Emission Spectra of Fluorescent Proteins in Förster Resonance Energy Transfer (FRET) Studies

Corrected fluorescence excitation and emission spectra have been obtained from several enhanced variants of the green fluorescent protein (EGFP) isolated from the jellyfish Aequorea victoria, blue fluorescence protein (EBFP), cyan fluorescent protein (ECFP), EGFP and yellow fluorescent protein (EYFP–citrine) and from the red fluorescent protein (DsRed) isolated from the coral species Discosoma. The spectra are stored in a database. This report describes how the spectra can be used as templates to derive the critical transfer distance for any pair of fluorescent proteins.     

Cation control on the synthesis of p-t-butylthiacalix[4](bis)crown ethers

Bridging of p-t-butylthiacalix[4]arene with ethylene glycol ditosylates gave diametrically bridged thiacalix[4]monocrowns-4 and -5, 1,2-alternate thiacalix[4]biscrowns-4 and -5 and 1,3-alternate thiacalix[4]biscrown-5, dependent on the metal carbonate used. They show excellent extraction ability towards Ag⁺ cations.     

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.     

Flash vacuum thermolysis of spirocyclohexadienones

In an attempt to prepare short-bridged hydroxymetacyclophanes $\text{1b-d}$, the spirocyclohexadienones $\text{2b-d}$ were pyrolyzed by flash vacuum thermolysis (FVT). Instead of $\text{1b-d}$, variable amounts of 4-(5-hexenyl)phenol ($\text{4b}$), β-hydroxybenzocycloalkenes ($\text{5b-d}$) and 4-(trans-1-alkenyl) phenols ($\text{6c-d}$) were obtained. The formation of these products is explained by invoking cleavage of a spiro bond in $\text{2}$ under formation of the intermediate diradical $\text{3}$ which, depending on the length of the aliphatic chain and on the temperature, has several pathways open for isomerization to spin-paired products.     

WAVELENGTH DEPENDENCE OF HEMATOPORPHYRIN DERIVATIVE PHOTODYNAMIC TREATMENT EFFECTS ON RAT EARS

The in vivo wavelength dependence of hematoporphyrin derivative (HpD) photodynamic treatment (PDT) has been studied. Ears of 136 rats were treated at six red and four blue-green laser wavelengths (615-635, 488-514.5 nm). Hematoporphyrin derivative was administered intraperitoneally (15 mg/kg) and 24 h later both ears were irradiated, at different wavelengths, for t = 6.5, 10 or 15 min at 60 mW/cm2. Four parameters (thickness, average erythema, eschar and loss of tissue) were quantified and a combined score (CS) of effects was established statistically. The maximum combined score during follow-up was taken as a measure for the biological effect. The light distribution in rat ears during irradiation with red and blue-green light was estimated from in vivo measurements and the transport theory. Statistical analysis of the combined score data yielded values for the relative biological effectiveness (RBE). Relative biological effectiveness maxima occurred at 501.7 and 625 nm. Analyzing erythema and loss of tissue separately yielded maxima at the same wavelengths. Quantitative agreement between the latter two sets of relative biological effectiveness values was obtained only when they were referred to the actual light energy fluence in tissue, rather than to the incident fluence. These relative biological effectiveness values are about 2.3 at 501.7 nm and 1.35 at 625 nm, taking relative biological effectiveness = 1 at 630 nm.