Total synthesis of an oxepine natural product, (±)-janoxepin

The total synthesis of (±)-janoxepin, a novel antiplasmodial d-leucine derived oxepine-pyrimidinone-ketopiperazine isolated from the fungus Aspergillus janus, is described. The cornerstones of the synthetic route are pyrimidinone preparation, ring-closing metathesis, aldol introduction of the enamide, and dihydro-oxepine elaboration. This synthetic route proved very efficient for the formation of a number of janoxepin analogues, including dihydro-janoxepin and tetrahydro-janoxepin.     

Magnetodielectric CuCr0.5V0.5O2: an example of a magnetic and dielectric multiglass

The complex dielectric susceptibility and spin glass properties of polycrystalline CuCr(0.5)V(0.5)O(2) delafossite have been investigated. Electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy show that the Cr(3+) and V (3+) magnetic cations are randomly distributed on the triangular network of CdI(2)-type layers. In contrast to CuCrO(2), CuCr(0.5)V(0.5)O(2) exhibits two distinctive (magnetic and electric) glassy states evidenced by memory effects in electric and magnetic susceptibilities. A large magnetodielectric coupling is observed at low temperature.     

Asymptotic linearity and Hadamard differentiability

For a mapping between Banach spaces, two weaker variants of the usual notion of asymptotic linearity are defined and explored. It is shown that, under inversion through the unit sphere, they correspond to Hadamard and weak Hadamard differentiability at the origin of the inversion. Nemytskii operators from Sobolev spaces to Lebesgue spaces over R^N${\mathbb{R}}^N$ share these weaker properties but they are not asymptotically linear in the usual sense.     

Weak–Strong Uniqueness of Dissipative Measure-Valued Solutions for Polyconvex Elastodynamics

For the equations of elastodynamics with polyconvex stored energy, and some related simpler systems, we define a notion of a dissipative measure-valued solution and show that such a solution agrees with a classical solution with the same initial data, when such a classical solution exists. As an application of the method we give a short proof of strong convergence in the continuum limit of a lattice approximation of one dimensional elastodynamics in the presence of a classical solution. Also, for a system of conservation laws endowed with a positive and convex entropy, we show that dissipative measure-valued solutions attain their initial data in a strong sense after time averaging.     

I18 – the microfocus spectroscopy beamline at the Diamond Light Source

The design and performance of the microfocus spectroscopy beamline at the Diamond Light Source are described. The beamline is based on a 27 mm‐period undulator to give an operable energy range between 2 and 20.7 keV, enabling it to cover the K‐edges of the elements from P to Mo and the L₃‐edges from Sr to Pu. Micro‐X‐ray fluorescence, micro‐EXAFS and micro‐X‐ray diffraction have all been achieved on the beamline with a spot size of ～3 µm. The principal optical elements of the beamline consist of a toroid mirror, a liquid‐nitrogen‐cooled double‐crystal monochromator and a pair of bimorph Kirkpatrick–Baez mirrors. The performance of the optics is compared with theoretical values and a few of the early experimental results are summarized.     

1,4-Aryl migration under copper(I) atom transfer conditions

Reaction of N-alkyl-N-(trichloroacetyl)arylsulfonamides with CuCl/amines leads to N-alkyl-N-(dichloroacetyl)-arylsulfonamides via reduction or N-alkyl-aryldichloroacetamides via 1,4-aryl migration with loss of SO₂. The ratio of reduction to aryl migration is dependent upon the temperature and the ligand utilised. Along with amide bond hydrolysis these reactions may compete when carrying out slow atom transfer radical cyclisation reactions using sulfonamides.     

The Production and Characterisation of Novel Conducting Redox‐Active Oligomeric Thin Films From Electrooxidised Indolo[3,2,1‐jk]carbazole

Novel thin‐film materials have been produced from indolo[3,2,1‐jk]carbazole (see picture). These are conducting and redox‐active and, unusually, consist of three distinct covalently coupled luminescent dimer species, consistent with a specific radical‐cation coupling mechanism.

     

The free solution electrophoretic mobility of peptides by a bead modeling methodology

A bead modeling methodology, BMM, discussed previously to compute the free solution electrophoretic mobility of peptides [H. Pei, Y. Xin, S.A. Allison, J. Sep. Sci. 31 (2008) 554-564], is generalized to avoid the approximation of orientationally preaveraging hydrodynamic interaction. In general, peptide mobilities computed without preaveraging are lower by about 2%. The BMM is then used to study the free solution electrophoretic mobility of several insect oostatic peptides reported previously in a variety of different buffer systems ranging in pH from 2.25 to 8.1 [V. Solinova, V. Kasicka, D. Koval, J. Hlavacek, Electrophoresis, 25 (2004) 2299-2308]. With minor adjustment of the intrinsic pK(a0) of the N-terminal peptide, good agreement between modeling and experiment is achieved for peptide models with random secondary structures in the entire pH range. Model mobilities of these peptides appear to be relatively insensitive to the assumed secondary structure.     

Synthesis and coordination chemistry of fluorinated phosphonic acids

Phosphonic acids [(HO)₂P(O)C₂H₄C_nF_2n+1] (n = 4, 6) and [(HO)₂P(O)C₆H₄-4-C_nF_2n+1] (n = 0, 1, 6) have been prepared in good yields. Deprotonation and reaction with cis-[PtCl₂(PPh₃)₂] affords fluorinated platinum complexes which have been characterised by elemental analysis, mass spectrometry, IR and NMR spectroscopies. The structures of [Pt{O₂P(O)C₆H₄-4-F}(PPh₃)₂], [Pt{O₂P(O)C₆H₄-4-CF₃}(PPh₃)₂] and [Pt{O₂P(O)C₂H₄C₆F₁₃}(PPh₃)₂] have been determined by single crystal X-ray diffraction.     

Lanthaballs: Chiral,Structurally Layered Polycarbonate Tridecanuclear Lanthanoid Clusters

New balls please! The viability of using carbonate as the primary anion in cluster formation is demonstrated in the synthesis of ‘lanthaballs’, spherical tridecanuclear lanthanoid complexes with a novel [Ln(CO₃)₆] moiety in a [Ln₁₃(CO₃)₁₄] core (see picture). The chirality of the lanthaballs is evidenced in the configuration of extended columns of π‐stacked phenanthroline ligands. The structural and magnetic properties of lanthaballs are investigated.