Viser treff 161-180 av 611

    • NMR absolute shielding scale and nuclear magnetic dipole moment of 207 Pb 

      Adrjan, Bożena; Makulski, Włodzimierz; Jackowski, Karol; Demissie, Taye Beyene; Ruud, Kenneth; Antušek, Andrej; Jaszuński, Michał (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-24)
      An absolute shielding scale is proposed for <sup>207</sup>Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH<sub>3</sub>)<sub>4</sub> molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH<sub>3</sub>)<sub>4</sub>, extrapolated to zero density of the buffer gas to ...
    • Synthetic analogs of stryphnusin isolated from the marine sponge Stryphnus fortis inhibit acetylcholinesterase with no effect on muscle function or neuromuscular transmission 

      Moodie, Lindon; Zuzek, Monika; Frangez, Robert; Andersen, Jeanette hammer; Hansen, Espen; Olsen, Elisabeth Klungerbo; Cergolj, Marija; Sepcic, Kristina; Hanssen, Kine Østnes; Svenson, Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11-09)
      The marine secondary metabolite stryphnusin (1) was isolated from the boreal sponge Stryphnus fortis, collected off the Norwegian coast. Given its resemblance to other natural acetylcholinesterase antagonists, it was evaluated against electric eel acetylcholinesterase and displayed inhibitory activity. A library of twelve synthetic phenethylamine analogs, 2a–7a and 2b–7b, containing tertiary and ...
    • Relativistic DFT Calculations of Hyperfine Coupling Constants in 5d Hexafluorido Complexes: [ReF6]2- and [IrF6]2- 

      Haase, Pi A. B.; Repisky, Michal; Komorovsky, Stanislav; Bendix, Jesper; Sauer, Stephan P. A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-12)
      The performance of relativistic density functional theory (DFT) methods has been investigated for the calculation of the recently measured hyperfine coupling constants of hexafluorido complexes [ReF<sub>6</sub> ] <sup>2-</sup> and [IrF<sub>6</sub> ] <sup>2-</sup> . Three relativistic methods were employed at the DFT level of theory: the 2-component zeroth-order regular approximation ...
    • Osmium-nitrido corroles as NIR indicators for oxygen sensors and triplet sensitizers for organic upconversion and singlet oxygen generation 

      Borisov, Sergey M.; Alemayehu, Abraham; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-26)
      The photophysical properties of nitridoosmium(VI) corroles have been investigated. The complexes exhibit room temperature NIR phosphorescence (l<sub>max</sub> 779–795 nm). Long decay times (110–150 ms in solution and 136–183 ms in polystyrene) are responsible for efficient quenching of the emission by oxygen. All the complexes act as efficient sensitizers of singlet oxygen (quantum yields of ...
    • Synergy between Experimental and Computational Approaches to Homogeneous Photoredox Catalysis 

      Demissie, Taye Beyene; Hansen, Jørn H (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-06-03)
      In this Frontiers article, we highlight how state-of-the-art density functional theory calculations can contribute to the field of homogeneous photoredox catalysis. We discuss challenges in the fields and potential solutions to be found at the interface between theory and experiment. The exciting opportunities and insights that can arise through such an interdisciplinary approach are highlighted.
    • Solvatofluorochromic, non-centrosymmetric π-expanded diketopyrrolopyrrole 

      Grzybowski, Marek; Jeżewski, Artur; Deperasinska, Irena; Friese, Daniel Henrik; Banasiewicz, Marzena; Hugues, Vincent; Kozankiewicz, Bolesław; Blanchard-Desce, Mireille; Gryko, Daniel (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-01-05)
      A novel non-centrosymmetric π-expanded diketopyrrolopyrrole was designed and synthesized. Strategic placement of tert-butyl groups at the periphery of a diketopyrrolopyrrole allowed us to selectively fuse one moiety via tandem Friedel–Crafts-dehydration reactions, resulting in a non-centrosymmetric dye. The structure of the dye was confirmed by X-ray crystallography, revealing that it contains a ...
    • Theoretical Analysis of NMR Shieldings in XSe and XTe (X= Si, Ge, Sn and Pb): The Spin–Rotation Constant Saga 

      Demissie, Taye Beyene (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-21)
      The nuclear spin-rotation (NSR) and absolute nuclear magnetic resonance (NMR) shielding tensors of the nuclei in the series of X<sup>77</sup>Se and X<sup>125</sup>Te (X = <sup>29</sup>Si, <sup>73</sup>Ge, <sup>119</sup>Sn and <sup>207</sup>Pb) are calculated using fourcomponent relativistic density functional theory (DFT) and coupled-cluster singles-doubles with a perturbative triples correction ...
    • Cyclic Voltammetric Study of 2-Hydroxybenzophenone (HBP) Derivatives and the Correspondent Change in the Orbital Energy Levels in Different Solvents 

      Adeniyi, Adebayo A.; Ngake, Tankiso L.; Conradie, Jeanet (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-14)
      The experimental UV and CV of five substituted 2-hydroxybenzophenones in solvents acetonitrile, n-dimethylformamide and dimethylsulfoxide are presented. Results obtained were used to determine their experimental highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and the results were compared to their theoretical model. The derivatives with an electron withdrawing ...
    • Infrared Spectroelectrochemistry of Iron-Nitrosyl Triarylcorroles. Implications for Ligand Noninnocence 

      Rahman, Md. Hafizur; Ryan, Michael D.; Vazquez-Lima, Hugo; Alemayehu, Abraham; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-13)
      Recent DFT calculations have suggested that iron nitrosyl triarylcorrole complexes have substantial {FeNO}<sup>7</sup> −corrole<sup>•2−</sup> character. With this formulation, reduction of Fe(C)(NO) complexes, where C = triarylcorrole, should be centered on the corrole macrocycle rather than on the {FeNO}<sup>7</sup> moiety. To verify this proposition, visible and infrared spectroelectrochemical ...
    • Phase transfer catalyzed conjugate addition-initiated ring-closure (CAIRC) reactions with 2-bromo-2-cyclopentenones 

      Yirsaw, Alemayehu Mekonnen; carlson, Rolf (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-07)
      When 2-bromo-2-cyclopentenone is treated with various carbon nucleophiles containing active methylenes, it undergoes a conjugate addition initiated-ring closure (CAIRC) reaction. This leads to the formation of carboand heterocyclic compounds in a regioselective fashion with good to high yield. Several bases and phase transfer catalysts were investigated. CsF-Si(OEt)4 as base together with ...
    • An averaged polarizable potential for multiscale modeling in phospholipid membranes 

      Witzke, Sarah; List, Nanna Holmgaard; Olsen, Jógvan Magnus Haugaard; Steinmann, Casper; Petersen, Michael; Beerepoot, Maarten; Kongsted, Jacob (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-03)
      A set of average atom-centered charges and polarizabilities has been developed for three types of phospholipids for use in polarizable embedding calculations. The lipids investigated are 1,2-dimyristoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, and 1-palmitoyl-2-oleoyl-sn-glycerol-3-phospho-L-serine given their common use both in experimental and computational ...
    • Electronic circular dichroism of fluorescent proteins: A computational study 

      Pikulska, Anna; Steindal, Arnfinn Hykkerud; Beerepoot, Maarten; Pecul, Magdalena (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-02-03)
      The electronic circular dichroism (ECD) properties of the green fluorescent protein and other fluorescent proteins have been calculated with density functional theory. The influence of different embedding models on the ECD signal of the chromophore has been investigated by modeling the protein environment by the polarizable continuum model (QM/PCM), by the polarizable embedding model (PE-QM/MM), by ...
    • Convergence of environment polarization effects in multiscale modeling of excitation energies 

      Beerepoot, Maarten; Steindal, Arnfinn Hykkerud; Ruud, Kenneth; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-03-26)
      We present a systematic investigation of the influence of polarization effects from a surrounding medium on the excitation energies of a chromophore. We use a combined molecular dynamics and polarizable embedding time-dependent density functional theory (PE-TD-DFT) approach for chromophores in pro- teins and in homogeneous solvents. The mutual polarization between the chromophore and its ...
    • Ligand and solvent effects on CO2 insertion into group 10 metal alkyl bonds 

      Deziel, Anthony P.; Espinosa, Matthew; Pavlovic, Ljiljana; Charboneau, David J.; Hazari, Nilay; Hopmann, Kathrin Helen; Mercado, Brandon Q. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-09)
      The insertion of carbon dioxide into metal element σ-bonds is an important elementary step in many catalytic reactions for carbon dioxide valorization. Here, the insertion of carbon dioxide into a family of group 10 alkyl complexes of the type (<sup>R</sup>PBP)M(CH<sub>3</sub>) (<sup>R</sup>PBP = B(NCH<sub>2</sub>PR<sub>2</sub>)<sub>2</sub>C<sub>6</sub>H<sub>4</sub><sup>−</sup>; R = Cy or <sup>t</sup>Bu; ...
    • Rhenium Corrole Dimers: Electrochemical Insights into the Nature of the Metal–Metal Quadruple Bond 

      Alemayehu, Abraham; Mccormick-Mcpherson, Laura J; Conradie, Jeanet; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-17)
      The interaction of free-base triarylcorroles with Re<sub>2</sub>(CO)<sub>10</sub> in 1,2- dichlorobenzene in the presence of 2,6-lutidine at 180 °C under strict anerobic conditions afforded approximately 10% yields of rhenium corrole dimers. The compounds exhibited diamagnetic <sup>1</sup> H NMR spectra consistent with a metal−metal quadruple bond with a σ<sup>2</sup> π<sup>4</sup> δ<sup>2</sup> ...
    • Avoiding Electron Spill-Out in QM/MM Calculations on Excited States with Simple Pseudopotentials 

      Marefat Khah, Alireza; Reinholdt, Peter; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob; Hattig, Christof (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-07)
      QM/MM calculations of electronic excitations with diffuse basis sets often have large errors due to spill-out of electrons from the quantum subsystem. The Pauli repulsion of the electrons by the environment has to be included to avoid this. We propose transferable atomic all-electron pseudopotentials that can readily be combined with most MM force fields to avoid electron spill-out. QM/MM excitation ...
    • Metallo-β-Lactamase Inhibitor Phosphonamidate Monoesters 

      Palica, Katarzyna; Vorácová, Manuela; Skagseth, Susann; Andersson Rasmussen, Anna; Allander, Lisa; Hubert, Madlen; Sandegren, Linus; Leiros, Hanna-Kirsti S.; Andersson, Hanna; Erdélyi, Máté (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-25)
      Being the second leading cause of death and the leading cause of disability-adjusted life years worldwide, infectious diseases remain-contrary to earlier predictions-a major consideration for the public health of the 21st century. Resistance development of microbes to antimicrobial drugs constitutes a large part of this devastating problem. The most widely spread mechanism of bacterial resistance ...
    • Electrochemical Potential of the Metal Organic Framework MIL-101(Fe) as Cathode Material in Li-Ion Batteries 

      Keshavarz, Fatemeh; Kadek, Marius; Barbiellini, Bernardo; Bansil, Arun (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-16)
      We discuss the characteristic factors that determine the electrochemical potentials in a metal-organic framework used as cathode for Li-ion batteries via density functional theory-based simulations. Our focus is on MIL-101(Fe) cathode material. Our study gives insight into the role of local atomic environment and structural deformations in generating electrochemical potential.
    • Electrochemical degradation of per- and poly-fluoroalkyl substances using boron-doped diamond electrodes 

      Uwayezu, Jean Noel; Carabante, Ivan; Lejon, Tore; van Hees, Patrick; Karlsson, Patrik; Hollman, Patrik; Kumpiene, Jurate (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-16)
      Electrochemical degradation using boron-doped diamond (BDD) electrodes has been proven to be a promising technique for the treatment of water contaminated with per- and poly-fluoroalkyl substances (PFAS). Various studies have demonstrated that the extent of PFAS degradation is influenced by the composition of samples and electrochemical conditions. This study evaluated the significance of several ...
    • The Story of 5d Metallocorroles: From Metal–Ligand Misfits to New Building Blocks for Cancer Phototherapeutics 

      Alemayehu, Abraham; Thomas, Kolle E.; Einrem, Rune Finsås; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-23)
      CONSPECTUS: Porphyrin chemistry is Shakespearean: over a century of study has not withered the field’s apparently infinite variety. Heme proteins continually astonish us with novel molecular mechanisms, while new porphyrin analogues bowl us over with unprecedented optical, electronic, and metal-binding properties. Within the latter domain, corroles occupy a special place, exhibiting a unique ...