Browsing by Author "Howard, JK"

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    6.02 - 1,3-Oxa/Thia-2-Azoles
    (Elsevier, 2023) Howard, JK
    This article describes developments concerning 1,3,2-dithiazole, 1,3,2-dioxazole and 1,3,2-oxathiazole containing molecules throughout 2006–19. Research effort has not been equally distributed among these molecular classes with a significant focus on 1,3,2-dithiazoles and their derivatives and less on the 1,3,2-dioxazoles and 1,3,2-oxathiazoles. New methods for the synthesis of 1,3,2-dithiazolium cations have been described, expanding the substrate scope of these molecules. New neutral 1,3,2-dithiazolyl radical analogs have been produced and extensively studied on reduction of 1,3,2-dithiazolium cations. Special attention has been given to the magnetic properties of 1,3,2-benzodithiazolyl radical derivatives primarily using X-ray diffraction to study the intermolecular molecular parameters of these molecules. Synthetic applications of 1,3,2-benzodithiazole S-oxides (particularly o-benzenedisulfonimide) as Brønsted-Lowry acid catalysts has also witnessed a significant acceleration over the last decade. © 2023 Elsevier B.V.
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    New contrast options - diversity and specifity of deuteration
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Holden, PJ; Cagnes, MP; Davydova, N; Duff, AP; Howard, JK; Krause-Heuer, AM; Yepuri, NR; Darwish, TA
    The Australian National Deuteration Facility (NDF) continues to develop new capabilities in molecular deuteration. The tailoring of deuteration approach to solve specific contrast problems has greatly increased the range of systems that can be investigated and recent capability development and new applications will be described. The common problem of how to obtain good contrast during SANS of membrane proteins solubilised in detergent micelles has been solved by specific deuteration of detergent head groups and hydrophobic tails to different levels to contrast match at 100% D20 buffer. Likewise, in investigating the lo cation of a purely hydrophobic transmembrane peptide in bicontinuous cubic phase liquid crystals Page 25 ANBUG-AINSE Neutron Scattering Symposium, AANSS 2018 / Book of Abstracts suitable for drug delivery, a mixture of deuterated and hydrogenated phytanoyl monoethanolamide was used to perfectly contrast match out either gyroid or diamond phase lipids to pinpoint the peptides location. In Soft Matter, investigation of structure of the ligands in the shell layer of self-assembled monolayerprotected nanoparticles has been made possible by use of various combinations of immiscible deuterated or hydrogenated Phenylethanethiol (PET) and Dodecanethiol (DDT) and MONSA modelling of SANS data showed the janus and belt like distribution of the ligands on the surface and the effects of nanoparticle core size and ligand ratio on the patterning. Other case studies will include use of deuterated ionic liquids and new previously unavailable deuterated molecules will be highlighted. This work was supported by the National Collaborative Research Infrastructure Strategy © The Authors.
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    Rhenium(i) complexation–dissociation strategy for synthesising fluorine-18 labelled pyridine bidentate radiotracers
    (Royal Society of Chemistry, 2020-02-28) Klenner, MA; Zhang, B; Ciancaleoni, G; Howard, JK; Maynard-Casely, HE; Clegg, JK; Massi, M; Fraser, BH; Pascali, G
    A novel fluorine-18 method employing rhenium(I) mediation is described herein. The method was found to afford moderate to high radiochemical yields of labelled rhenium(I) complexes. Subsequent thermal dissociation of the complexes enabled the radiosynthesis of fluorine-18 labelled pyridine bidentate structures which could not be radiofluorinated hitherto. This rhenium(I) complexation–dissociation strategy was further applied to the radiosynthesis of [18F]CABS13, an Alzheimer's disease imaging agent, alongside other 2,2′-bipyridine, 1,10-phenanthroline and 8-hydroxyquinoline labelled radiotracers. Computational modelling of the reaction mechanism suggests that the efficiency of rhenium(I) activation may be attributed to both an electron withdrawal effect by the metal center and the formation of an acyl fluoride intermediate which anchors the fluoride subsequent to nucleophilic addition. © The Royal Society of Chemistry 2020 - Open Access