Biomimetic Explorations Towards the Bisorbicillinoids: Total Synthesis of Bisorbicillinol, Bisorbibutenolide, and Trichodimerol

Strikingly simple cascade dimerization sequences can be used to assemble the complex frameworks of bisorbicillinoids such as bisorbicillinol (1), bisorbibutenolide (2), and trichodimerol (3). The mechanistic facets of the biomimetic total syntheses of these bioactive natural products were also explored. Inspection of the unique molecular architecture of these compounds reveals that they are likely to be assembled in nature by a dimerization of two oxidized forms of sorbicillin.     

Darstellung und Eigenschaften einiger neuer Arsenat- und Vanadat-Halogen-Apatite

Preparation and Properties of Some New Arsenate and Vanadate Halogen Apatites The preparation of new apatite-like compounds of the composition Na₂Nd₂Pb₆(RO₄)₆X₂ (with R = As, V and X = Cl, Br and also R = P and X = Br) is reported. Crystallographic data for these as well as for the already known Na₂Nd₂Pb₆(PO₄)₆Cl₂ are determined from the corresponding X-ray powder diagrams. Also the infrared and Raman spectra were recorded and briefly discussed.     

Abschätzung mittlerer Schwingungsamplituden der Metall—Sauerstoff-Bindungen einiger Hexaoxometallate

Mean amplitudes of vibration of a series of hexaoxometalates have been estimated using an approximation method and recently reported spectroscopic data arising from the study of the respective lithium salts.     

$\delta$-pairing forces and collective pairing vibrations

The collective pairing Hamiltonian is obtained in the framework of the generator coordinate method in the Gaussian overlap approximation with a slightly modified BCS function used as a generator function. The collective variable , measuring the monopole moment of the pairing field, and the gauge transformation angle are chosen as generator coordinates. The vibrational ground states are calculated by diagonalisation of the collective pairing Hamiltonian in the harmonic-oscillator basis.Received: 28 April 2003, Revised: 1 October 2003, Published online: 18 June 2004PACS: 21.30.-x Nuclear forces - 21.60.Ev Collective models     

Isolation and characterization of kallosin A,a novel rearranged pseudopterane diterpenoid from the Caribbean sea plume Pseudopterogorgia kallos (Bielschowsky)

The Caribbean alcyonacean Pseudopterogorgia kallos is shown to contain a novel rearranged pseudopterane diterpene, kallosin A (1), possessing several unusual structural features. In addition to having two distinct 2(3H)- and 2(5H)-furanone moieties, kallosin A is based on a new carbon skeleton. The structural assignment of 1 was based mainly on 1D and 2D NMR spectral data and was further supported by accurate mass measurement and single-crystal X-ray diffraction analysis.     

Pre-equilibrium dipole strength in charge asymmetric peripheral heavy-ion reactions

We report on the results obtained from the study of the ³²S + ⁶⁴Ni and ³²S + ⁵⁸Ni peripheral reactions at incident energies E _lab = 288 MeV and E _lab = 320 MeV, respectively. High-energy γ-rays were detected in an array of 8 seven-pack BaF₂ clusters. Coincidence with complex fragments detected in 12 three-stage telescopes ensured the selection of peripheral reaction events. All of the relevant reaction parameters were kept constant with the exception of the different initial dipole moment caused by the different entrance channel charge asymmetry. While for quasi-elastic events no N/Z effect was observed in the differential γ-ray multiplicities of the two reactions, for deep-inelastic events a larger dipole γ-ray emission occurs during the more N/Z asymmetric reaction. A theoretical interpretation based on a collective Bremsstrahlung analysis of the reaction dynamics is presented. Received: 26 September 2002 / Accepted: 13 November 2002 / Published online: 6 March 2003 RID="a" ID="a"e-mail: pierroutsakou@na.infn.it RID="b" ID="b"Present address: INFN, Laboratori Nazionali di Legnaro, Padova, Italy. Communicated by C. Signorini     

Neutron diffraction structure of Y2V10O28·24H2O at 297 and 60 K

The structure of yttrium-decavanadate-24-hydrate, [Y₂V₁₀O₂₈·24H₂O], was determined by neutron diffraction at temperatures of 297 and 60 K. Space group P-1, triclinic, Z = 2; at 297 K : a = 9.36(1), b = 9.86(1), c = 23.53(3) Å, = 98.79(2), = 98.15(2), = 89.30(2), V = 2123(5); at 60 K : a = 9.19(3), b = 9.85(3), c = 23.31(12) Å, = 99.03(3), = 98.99(6), = 89.39(6)°, V = 2058(13). Final R factors of 10 and 9.4% were obtained using 1955 and 1100 observed structure factors at both temperatures, respectively. The position of the 24 water molecules was determined and the characteristics of the hydrogen bonds were analyzed at both temperatures.     

Magnetic properties of aerugite Co<Subscript>10</Subscript>Ge<Subscript>3</Subscript>O<Subscript>16</Subscript>

This paper reports on the first study of the temperature and field dependences of the magnetization, heat capacity, and electrical properties of synthesized polycrystalline samples of aerugite Co₁₀Ge₃O₁₆, as well as on x-ray diffraction analysis of this compound. It is shown that the cobalt ions in this compound occupy three nonequivalent positions. The results of the experimental and theoretical studies suggest that aerugite is a ferrimagnet with two uncompensated magnetic moments of the cobalt atom per formula unit.