Oxidation of a dinuclear manganese(II) complex to an oxide‐bridged dimanganese(IV) complex

Bis{μ‐2‐[bis(pyridin‐2‐ylmethyl)amino]acetato}bis[diaquamanganese(II)] bis(trifluoromethanesulfonate) monohydrate, [Mn₂(C₁₄H₁₄N₃O₂)₂(H₂O)₄](CF₃O₃S)₂·H₂O, (I), and bis{μ‐3‐[bis(pyridin‐2‐ylmethyl)amino]propionato}bis[aquamanganese(II)] bis(trifluoromethanesulfonate) dihydrate, [Mn₂(C₁₅H₁₆N₃O₂)₂(H₂O)₂](CF₃O₃S)₂·2H₂O, (II), form binuclear seven‐coordinate complexes. Oxidation of (II) with ammonium hexanitratocerate(IV), (NH₄)₂[Ce(NO₃)₆], gave the oxide‐bridged dimanganese(IV) complex di‐μ‐oxido‐bis(bis{3‐[bis(pyridin‐2‐ylmethyl)amino]propionato}manganese(IV)) bis[triaquatetranitratocerate(IV)], [Mn₂O₂(C₁₅H₁₆N₃O₂)₂][Ce(NO₃)₄(H₂O)₃]₂, (III). The manganese complexes in (II) and (III) sit on a site of symmetry.     

Protein‐free ligand screening: simplification of chiral chromatographic development via novel adaptation of NMR screening methodologies

We demonstrate here a promising NMR method that provides evidence for chiral compound selector interaction as a first‐pass screening method. A novel adaptation of commonly used protein‐based screening technologies, this approach relies upon ligand‐to‐stationary phase interaction wherein the stationary phase is tethered to sepharose beads. At only minutes per experiment, this methodology significantly reduces the time required for chiral separation methodology development and complements currently available chromatographic purity technologies.Copyright © 2009 John Wiley & Sons, Ltd.     

Harmonic entanglement with second-order nonlinearity

We investigate the second-order nonlinear interaction as a means to generate entanglement between fields of differing wavelengths and show that perfect entanglement can, in principle, be produced between the fundamental and second-harmonic fields in these processes. Neither pure second-harmonic generation nor parametric oscillation optimally produce entanglement; such optimal entanglement is rather produced by an intermediate process.     

Anomalous excitation spectra of frustrated quantum antiferromagnets

We use series expansions to study the excitation spectra of spin-1/2 antiferromagnets on anisotropic triangular lattices. For the isotropic triangular lattice model (TLM), the high-energy spectra show several anomalous features that differ strongly from linear spin-wave theory (LSWT). Even in the Néel phase, the deviations from LSWT increase sharply with frustration, leading to rotonlike minima at special wave vectors. We argue that these results can be interpreted naturally in a spinon language and provide an explanation for the previously observed anomalous finite-temperature properties of the TLM. In the coupled-chains limit, quantum renormalizations strongly enhance the one-dimensionality of the spectra, in agreement with experiments on Cs2CuCl4.     

Einstein metrics and quaternionic Kähler manifolds

The research is partially suported by a grant from the Natural Sciences and Engineering Research Council of Canada