Products from the reaction of M3(CO)12 (M = Ru or Os) with water

Reaction of the carbonyl Ru₃(CO)₁₂ with water leads to the formation of polynuclear hydrides α-H₄Ru₄(CO)₁₂, α-H₂Ru₄(CO)₁₃; the corresponding reaction with Os₃(CO)₁₂ yields the complexes (H)(OH)Os₃(CO)₁₀, H₂Os₄(CO)₁₃, H₄Os₄(CO)₁₂, H₂Os₅(CO)₁₆, H₂Os₅(CO)₁₅, H₂Os₆(CO)₁₈ and H₂Os₇(CO)₁₉C.     

Differential binding of Mg2+, Zn2+, and Cd2+ at two sites in a hammerhead ribozyme motif, determined by 15N NMR

A decamer duplex model of Domain II of the hammerhead ribozyme was synthesized with [8-13C-1,7,NH2-15N3]-guanosine at the known metal binding site, G10.1 and, for comparison, [2-13C-1,7,NH2-15N3]-guanosine at G16.2. The 15N NMR chemical shifts of the labeled N7s monitored during addition of Mg2+, Cd2+, and Zn2+ showed the same preference for binding at G10.1 over G16.2 for each metal. These results demonstrate that 15N labeling can be used to evaluate the binding of different metals, including Mg2+, to a given nitrogen, as well as to compare the binding potential of different sites.     

60]- and [70]Fullerenes are trifluoromethylated across 5:6-bonds

Trifluoromethylation of [60]- and [70]fullerenes occurs across both 6:6- and 5:6-bonds giving unsymmetrical tetramethyl adducts having four contiguous CF3 groups; both fullerenes give bis adducts which do not involve 6:6-addition, and unsymmetrical hexa-adducts (with contiguous CF3 groups) are also obtained from [60]fullerene.     

Preparation and crystal structure ofexo-2,exo-6-dihydroxy-2,6-dimethyl-9-oxabicyclo[3.3.1]nonane

In a further exploration of the structural factors causing alicyclic diols such asexo-2,exo-6-dihydroxy-2,6-dimethylbicyclo[3.3.1]nonane (1) to adopt the helical tubuland inclusion host structure, the title compound (8) has been synthesized and its crystal structure determined. This 9-oxa analogue of (1) has a totally different structure [C₁₀H₁₈O₃; orthorhombic;P2₁2₁2;a 18.989(4),b 19.064(3),c 14.256(3) Å;Z 20; with finalR 0.065] due to involvement of the ether oxygen atom in the hydrogen bonding network. The structure of the diol (8) approximatesP¯42₁ c symmetry, and 16 of the 20 molecules per cell create a hostlike structure of this symmetry, which consists of tightly bound hydrogen bonded pillars parallel toc. The remaining guestlike molecules occupy inequivalent pseudo ¯4 sites separated byc/2 to form weakly bound columns parallel toc. Hydrogen bonds also occur between the pillars and columns. An ordered structure with sensible intermolecular contacts can be formed inP2₁2₁2₁ with thec axis doubled. A difference betweena andb axial lengths correlates with a difference in occupancies of pseudo-¯4-related sites for the guest-like component of the structure.     

Alkaloids from marine organisms. Part 8: Isolation of bisdemethylaaptamine and bisdemethylaaptamine-9-O-sulfate from an Indonesian Aaptos sp. marine sponge

Bisdemethylaaptamine (6), a proposed biosynthetic precursor of the aaptamines has been isolated from an Aaptos sp. marine sponge harvested off the Indonesian coast, and its identity confirmed by comparison of its spectral data with that of synthetic material. Bisdemethylaaptamine-9-O-sulfate (7) was also isolated from the same source. This is the first report of a sulfated aaptamine.     

Products of the reaction of H2Os3(CO)10 with cyclonona-1,2diene

Treatment of H₂Os₃(CO)₁₀ with cyclonona-l,2-diene produced HOs₃(CO)₉C₉H₁₃ and Os₂(CO)₆(C₉H₄)₂. Single crystal X ray analysis has shown that the latter is not isostructural with Fe₂(CO)₆(C₉H₁₄)₂.     

Synthesis of homoceramides, novel ceramide analogues, and their lack of effect on the growth of hippocampal neurons

The synthesis of a new series of D-erythro-homoceramide analogues is described. Several synthetic approaches were investigated. Homoceramides can be successfully synthesized from L-homoserine as chiral building block and a protected Weinreb-amide as a key intermediate. The synthesis of short-chain analogues with a heptyl side chain, as well as with a phenyl residue in the sphingoid part (instead of the naturally occurring tridecyl side chain), was effected. The homoceramides 15-17 and 24 were investigated for their potential to reverse the inhibitory effect of fumonisin B(1) on axonal growth. Unfortunately, none of the tested compounds showed any biological activity due to their lack of metabolism to glucosylhomoceramide.     

Ionic conductivity of Li2MgSn3O8 ramsdellite

The ionic conductivity of polycrystalline pellets of Li₂MgSn₃O₈ with ramsdellite-type structure was measured by complex impedance technique. The conductivity is 1.2 × 10^?8 (Ω cm)^?1 at 300°C and 2.3 × 10^?4 (Ω cm)^?1 at 450°C. The results are discussed in relation to structural properties.     

Under pressure: predicting pressurized metered dose inhaler interactions using the atomic force microscope

Drug particulate interactions in pressurized metered dose inhalers (pMDI) may lead to a decrease in aerosolization efficiency and subsequent efficacy in patient treatment. The interactions between salbutamol sulfate (commonly used in Ventolin pMDIs) and a series of pMDI canister materials were investigated using the atomic force microscope (AFM) colloid probe technique. Approximately 4000 individual force-distance curves were determined for a drug probe and three surfaces (10 x 10 mum areas) in situ, in a model propellant. The area under each force-distance curve was integrated to obtain separation energy values. Median separation energy values followed the rank order borosilicate glass > aluminum > PTFE, suggesting PTFE to be the most suitable canister coating.     

Capillary zone electrophoresis in the analysis of dyes and other compounds employed in the dye-manufacturing and dye-using industries

High resolution separation of several dyes and related intermediates, as well as other compounds employed in the dye-manufacturing and dye-using industries, has been achieved using capillary zone electrophoresis (CZE).

The analysis of anionic dyes and some non-coloured anionic intermediates has been achieved using 10 mM Na₂B₄O₇−40 mM sodium dodecyl sulphate (SDS) buffer; high-resolution separations of water soluble anionic, neutral and cationic intermediates were also achieved using this micellar buffer. Micellar electrokinetic capillary chromatography (MECC) has also been developed for the analysis of aqueous insoluble, electrically neutral compounds by incorporating a co-solvent, acetonitrile, into a micellar buffer. In addition, MECC has been used successfully for following all the major steps involved in the synthesis of a disperse dye.