Now showing items 8-27 of 247

    • Ab initio and relativistic DFT study of spin–rotation and NMR shielding constants in XF6 molecules, X = S, Se, Te, Mo, and W 

      Ruud, Kenneth; Demissie, Taye Beyene; Jaszunski, Michal (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Ab initio studies of two pyrimidine derivatives as possible photo-switch systems 

      Csehi, András; Woywod, Clemens Joachim; Halász, Gábor J.; Vibok, Agnes (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      The six lowest lying electronic singlet states of 8-(pyrimidine-2-yl)quinolin-ol and 2-(4-nitropyrimidine-2- yl)ethenol have been studied theoretically using the complete active space self-consistent-field (CASSCF) and Møller-Plesset second-order perturbation theory (MP2) methods. Both molecules can be viewed as consisting of a frame and a crane component. As a possible mechanism for the excited-state ...
    • Ab initio wavefunctions in bioinorganic chemistry : more than a succes d'estime? 

      Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      Dedicated to the memory of Björn Roos (1937–2010), one of the fathers of modern multiconfigurational quantum chemistry, who also cared deeply about chemical applications, and a fun and inspiring friend to countless theoretically oriented chemists.
    • Absolute NMR shielding scales and nuclear spin–rotation constants in 175LuX and 197AuX (X= 19F, 35Cl, 79Br and 127I) 

      Demissie, Taye Beyene; Jaszuński, Michal; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-28)
      We present nuclear spin–rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in 175LuX and 197AuX (X = 19F, 35Cl, 79Br, 127I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. ...
    • Accurate prediction of emission energies with TD-DFT methods for platinum and iridium OLED materials 

      Morello, Glenn Robert (Journal article; Tidsskriftartikkel, 2017-05-02)
      Accurate prediction of triplet excitation energies for transition metal complexes has proven to be a difficult task when confronted with a variety of metal centers and ligand types. Specifically, phosphorescent transition metal light emitters, typically based on iridium or platinum, often give calculated results of varying accuracy when compared to experimentally determined T1 emission values. ...
    • An Acylation-Finkelstein Approach to Radioiodination of Bioactives: The Role of Amide Group Anchimeric Assistance 

      Fjellaksel, Richard; Dugalic, Damir; Demissie, Taye Beyene; Riss, Patrick; Hjelstuen, Ole Kristian; Sundset, Rune; Hansen, Jørn H (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-28)
      Herein, we report a straightforward sequential acylation‐Finkelstein approach to achieve iodination of amine containing bioactives. The utility was demonstrated by successful radiolabelling with <sup>123</sup>I in high radiochemical yield. Moreover, microwave‐assisted Finkelstein reaction can be employed to enhance conversion and reaction rates to obtain the desired iodides. The method is of interest ...
    • Adaptive order polynomial algorithm in a multi-wavelet representation scheme 

      Durdek, Antoine Pacifique Romain; Jensen, Stig Rune; Juselius, Jonas; Wind, Peter; Flå, Tor; Frediani, Luca (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Aldol condensations on a 3-alkylidene-2,5-diketopiperazine - synthesis of two marine natural products 

      Fairhurst, Magnus John E.; Muhammad, Zeeshan; Haug, Bengt Erik; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-06)
      The synthesis of two marine natural products containing a 3-alkylidene-6-arylidene-2,5-diketopiperazine scaffold by employing two consecutive aldol condensations starting with 1,4-diacetyl-2,5-diketopiperazine is reported. The target compounds contain a phenol or an imidazole group as aryl substituents, respectively, and suitable conditions for the aldol condensation of 1-acyl-3-alkylidene-2,5-dik ...
    • All-electron fully relativistic Kohn-Sham theory for solids based on the Dirac-Coulomb Hamiltonian and Gaussian-type functions 

      Kadek, Marius; Repisky, Michal; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-03)
      We present the first full-potential method that solves the fully relativistic four-component Dirac-Kohn-Sham equation for materials in the solid state within the framework of atom-centered Gaussian-type orbitals (GTOs). Our GTO-based method treats one-, two-, and three-dimensional periodic systems on an equal footing, and allows for a seamless transition to the methodology commonly used in studies ...
    • The alternative sigma factor RpoQ regulates colony morphology, biofilm formation and motility in the fish pathogen Aliivibrio salmonicida 

      Khider, Miriam; Willassen, Nils Peder; Hansen, Hilde (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-12)
      <i>Background</i>: Quorum sensing (QS) is a cell-to cell communication system that bacteria use to synchronize activities as a group. LitR, the master regulator of QS in <i>Aliivibrio salmonicida</i>, was recently shown to regulate activities such as motility, rugosity and biofilm formation in a temperature dependent manner. LitR was also found to be a positive regulator of <i>rpoQ</i>. RpoQ ...
    • Analytic calculations of anharmonic infrared and Raman vibrational spectra 

      Cornaton, Yann; Ringholm, Magnus; Louant, Orian; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-07)
      Using a recently developed recursive scheme for the calculation of high-order geometric derivatives of frequency-dependent molecular properties [Ringholm et al., J. Comp. Chem., 2014, 35, 622], we present the first analytic calculations of anharmonic infrared (IR) and Raman spectra including anharmonicity both in the vibrational frequencies and in the IR and Raman intensities. In the case of anharmonic ...
    • Analytic calculations of hyper-Raman spectra from density functional theory hyperpolarizability gradients 

      Ringholm, Magnus; Bast, Radovan; Oggioni, Luca; Ekström, Ulf Egil; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Analytic cubic and quartic force fields using density-functional theory 

      Ringholm, Magnus; Jonsson, Dan Johan; Bast, Radovan; Gao, Bin; Thorvaldsen, Andreas johan; Ekstrøm, Ulf; Helgaker, Trygve; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Analytic density functional theory calculations of pure vibrational hyperpolarizabilities: The first dipole hyperpolarizability of retinal and related molecules 

      Gao, Bin; Ringholm, Magnus; Bast, Radovan; Ruud, Kenneth; Thorvaldsen, Andreas johan; Jaszuński, Michał (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-01-09)
      We present a general approach for the analytic calculation of pure vibrational contributions to the molecular (hyper)polarizabilities at the density-functional level of theory. The analytic approach allows us to study large molecules, and we apply the new code to the study of the first dipole hyperpolarizabilities of retinal and related molecules. We investigate the importance of electron ...
    • Analytic evaluation of the dipole Hessian matrix in coupled-cluster theory 

      Jagau, TC; Gauss, J; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      The general theory required for the calculation of analytic third energy derivatives at the coupled-cluster level of theory is presented and connected to preceding special formulations for hyperpolarizabilities and polarizability gradients. Based on our theory, we have implemented a scheme for calculating the dipole Hessian matrix in a fully analytical manner within the coupled-cluster singles and ...
    • Anomalous dispersion analysis of inhibitor flexibility : a case study of the kinase inhibitor H-89 

      Pflug, Alexander; Johnson, Kenneth; Engh, Richard Alan (Journal article; Tidsskriftartikkel; Peer reviewed, 2012)
      With its ability to show the interactions between drug-target proteins and small-molecule ligands, X-ray crystallography is an essential tool in drug-discovery programmes. However, its usefulness can be limited by crystallization artifacts or by the data resolution, and in particular when assumptions of unimodal binding (and isotropic motion) do not apply. Discrepancies between the modelled crystal ...
    • Anomalous phosphorescence from an organometallic white-light phosphor 

      Paul, Lopa; Chakrabarti, Swapan; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-25)
      We report theoretical results on the possible violation of Kasha’s rule in the phosphorescence process of (acetylacetonato)bis(1-methyl-2-phenylimidazole)iridium(III), and show that the anomalous emission from both the T1 and T2 states is key to its white-light phosphorescence. This analysis is supported by the calculated Boltzmann-averaged phosphorescence lifetime of 2.21 μs, estimated including ...
    • Antibiotikaresistent - hva nå? 

      Leiros, Hanna-Kirsti S. (Conference object; Konferansebidrag, 2010-09-02)
    • Antimicrobial activity of amphipathic α,α-disubstituted β-amino amide derivatives against ESBL–CARBA producing multi-resistant bacteria; effect of halogenation, lipophilicity and cationic character 

      Paulsen, Marianne Hagensen; Ausbacher, Dominik; Bayer, Annette; Engqvist, Magnus; Hansen, Terkel; Haug, Tor; Anderssen, Trude; Andersen, Jeanette Hammer; Sollid, Johanna U. Ericson; Strøm, Morten B. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-06)
      The rapid emergence and spread of multi-resistant bacteria have created an urgent need for new antimicrobial agents. We report here a series of amphipathic α,α-disubstituted β-amino amide derivatives with activity against 30 multi-resistant clinical isolates of Gram-positive and Gram-negative bacteria, including isolates with extended spectrum β-lactamase – carbapenemase (ESBL-CARBA) production. A ...
    • Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates 

      Gevorgyan, Ashot; Mkrtchyan, Satenik; Grigoryan, Tatevik; Iaroshenko, Viktor O (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-04-06)
      The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N‐oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation ...