Browsing by Author "Pereira, JEM"

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    Hydrogen bond dynamics, conformational flexibility and polymorphism in antipsychotics
    (Australian Institute of Physics, 2017-02-03) Pereira, JEM; Eckert, J; Yu, DH; Mole, RA; Bordallo, HN
    This work is related to the investigation of three different antipsychotics, one of each generation: aripiprazole (C23H27Cl2N3O2), haloperidol (C21H23ClFNO2) and quetiapine hemifumarate (C23H27N3O4S) using a combination of Inelastic Neutron Scattering (INS) and Density Functional Theory (DFT). These substances were selected because their crystalline structure and the concerns related to their polymorphism are somehow known. We report on data obtained using the direct geometry spectrometer PELICAN, located at the Australian Centre for Neutron Scattering (ACNS, formerly the Bragg Institute) at the Australian Nuclear Research and Technology Organisation (ANSTO). Polymorphic transformations and purity of the samples were determined by calorimetric studies, while their structures were verified by X-rays diffraction. Furthermore, the origin of each of the observed modes is supported by theoretical data provided by Density Functional Theory calculations (DFT).
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    Hydrogen bond dynamics, conformational flexibility and polymorphism in antipsychotics
    (Australian Institute of Nuclear Science and Engineering, 2016-11-29) Pereira, JEM; Eckert, J; Yu, DH; Mole, RA; Bordallo, HN
    This work is related to the investigation of three different antipsychotics, one of each generation: aripiprazole (C23H27Cl2N3O2), haloperidol (C21H23ClFNO2) and quetiapine hemifumarate (C23H27N3O4S) using a combination of Inelastic Neutron Scattering (INS) and Density Functional Theory (DFT). These substances were selected because their crystalline structure and the concerns related to their polymorphism are somehow known [1]. We report on data obtained using the direct geometry spectrometer PELICAN, located at the Australian Centre for Neutron Scattering (ACNS, formerly the Bragg Institute) at the Australian Nuclear Research and Technology Organisation (ANSTO). Polymorphic transformations and purity of the samples were determined by calorimetric studies, while their structures were verified by X-rays diffraction. Furthermore, the origin of each of the observed modes is supported by theoretical data provided by Density Functional Theory calculations (DFT).
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    Spectroscopic studies of glycine/alumina surfaces
    (Australian Institute of Physics, 2017-02-03) Stampfl, APJ; Pereira, JEM
    The basic field of surface adsorption and complexation of amino-acids on various oxide surfaces is an interesting area of investigation that has direct relevance in such diverse fields as chemistry (geochemistry, biochemistry), biotechnology (medical implants, biosensors, tissue engineering, bioelectronics, biomimetics and artificial photosynthesis), radiation technology (radiation damage and detection), colloid chemistry, surface chemistry and physics. The combination of both photoemission and neutron spectroscopy is quite rare and yet extremely powerful as these techniques directly yield the electronic and vibrational structure of a material respectively: two of the most basic properties of materials. Photoemission spectroscopy is clearly surface sensitive and hence is an ideal probe to study surface chemistry. While neutron spectroscopy is the domain of vibrational spectroscopy on bulk materials. There are exceptions to this rule where the surface dominates the scattered signal due to huge surface to volume ratios and large scattering cross-sections from adsorbate molecules. This study aim to exploit such ideas. The deposition of glycine onto alumina from solution is investigated by both inelastic neutron spectroscopy and high resolution photoemission. Studies focused on the extent of adsorption at various pH's, the character of each adsorbate (zwitterionic, basic, acidic), and the number of discrete surface sites of adsorption. Results show strong chemisorption of glycine through an ester type bond with the alumina surface across arrange of pH. Direct sorption of the amine group with alumina is observed only at pH9. Formation of multilayers and/or peptides is postulated to also occur which may have implications in the area of prebiotic chemistry.