Viser treff 391-410 av 525

    • Radical Group Transfer of Vinyl and Alkynyl Silanes Driven by Photoredox Catalysis 

      Baussiere, Floriane; Haugland, Marius Myreng (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-15)
      Radical group transfer is a powerful tool for the formation of C−C bonds. These processes typically involve radical addition to C−C π bonds, followed by fragmentation of the resulting cyclic intermediate. Despite the advantageous lability of organosilanes in this context, silicon-tethered radical acceptor groups have remained underexplored in radical group transfer reactions. We report a general ...
    • Raman spectroscopy online monitoring of biomass production, intracellular metabolites and carbon substrates during submerged fermentation of oleaginous and carotenogenic microorganisms 

      Dzurendová, Simona; Olsen, Pernille Margrethe; Byrtusova, Dana; Tafintseva, Valeria; Shapaval, Volha; Horn, Svein Jarle; Kohler, Achim; Szotkowski, Martin; Marova, Ivana; Zimmermann, Boris (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-18)
      Background - Monitoring and control of both growth media and microbial biomass is extremely important for the development of economical bioprocesses. Unfortunately, process monitoring is still dependent on a limited number of standard parameters (pH, temperature, gasses etc.), while the critical process parameters, such as biomass, product and substrate concentrations, are rarely assessable in-line. ...
    • Rare and Nonexistent Nitrosyls: Periodic Trends and Relativistic Effects in Ruthenium and Osmium Porphyrin-Based {MNO}7 Complexes 

      Demissie, Taye Beyene; Conradie, Jeanet; Vazquez-Lima, Hugo; Ruud, Kenneth; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-14)
      Relativistic and nonrelativistic density functional theory calculations were used to investigate rare or nonexistent ruthenium and osmium analogues of nitrosylhemes. Strong ligand field effects and, to a lesser degree, relativistic effects were found to destabilize {RuNO}<sup>7</sup> porphyrins relative to their {FeNO}<sup>7</sup> analogues. Substantially stronger relativistic effects account for ...
    • Rational selection of co-catalysts for the deaminative hydrogenation of amides 

      Artús Suàrez, Lluís; Jayarathne, Upul; Balcells, David; Bernskoetter, Wesley H.; Hazari, Nilay; Jaraiz, Martin; Nova, Ainara (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-20)
      The catalytic hydrogenation of amides is an atom economical method to synthesize amines. Previously, it was serendipitously discovered that the combination of a secondary amide co-catalyst with (<sup>iPr</sup>PNP)Fe(H)(CO) (<sup>iPr</sup>PNP = N[CH<sub>2</sub>CH<sub>2</sub>(P<sup>i</sup>Pr<sub>2</sub>)]<sub>2</sub>−), results in a highly active base metal system for deaminative amide hydrogenation. ...
    • Real-space numerical grid methods in quantum chemistry 

      Frediani, Luca; Sundholm, Dage (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-11-03)
    • A really close look at molecules 

      Svenson, Johan (Journal article; Tidsskriftartikkel, 2013)
      With a “magnifying glass”, a highly sophisticated atomic force microscope (AFM) scientists have recently developed a technique that allows single molecule visualization with atomic resolution.
    • Recolonization and recovery of an Arctic benthic community subject to mine-tailings deposits 

      Trannum, Hilde C; Pedersen, Kristine B.; Renaud, Paul E; Christensen, Guttorm N.; Evenset, Anita (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-22)
      Deposition of large volumes of mine tailings takes place in several Norwegian fjords, but the impacts on marine ecosystems have received relatively little scientific attention. At a 40 + − year old tailing deposition area for a copper mine in the Arctic fjord Repparfjorden, we investigated both short-term colonization of mine tailingscontaminated sediments through a field experiment, and the present ...
    • Recombinant expression and purification of an ATP-dependent DNA ligase from Aliivibrio salmonicida 

      Williamson, Adele Kim; Pedersen, Hege (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-05)
      The genome of the psychrophilic fish-pathogen Aliivibrio salmonicida encodes a putative ATP-dependent DNA ligase in addition to a housekeeping NAD-dependent enzyme. In order to study the structure and activity of the ATP dependent ligase in vitro we have undertaken its recombinant production and purification from an Escherichia coli based expression system. Expression and purification of this ...
    • Redetermination and H-atom refinement of (S)-(+)-ibuprofen. Corrigendum 

      Hansen, Lars Kr; Perlovich, German; Bauer-Brandl, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2006)
      [Erratum to document cited in CA140:010932]
    • Redetermination of 3-hydroxybenzamide 

      Hansen, Lars Kr; Perlovich, German; Bauer-Brandl, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2007)
    • Redetermination of p-ethoxyacetanilide (phenacetin) 

      Hansen, Lars Kr; Perlovich, German; Bauer-Brandl, Annette D (Journal article; Tidsskriftartikkel; Peer reviewed, 2006)
    • Regiodivergent Synthesis of 11H-Indolo[3,2-c]quinolines and Neocryptolepine from a Common Starting Material 

      Håheim, Katja Stangeland; Lund, Bjarte Aarmo; Sydnes, Magne Olav (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-23)
      A large number of diversely functionalized analogs of the bioactive natural products neocryptolepine and isocryptolepine have been prepared from a series of 3-bromoquinoline derivatives. The neocryptolepines were obtained by a Pd<sup>0</sup>-catalyzed C−C bond coupling followed by C−N bond formation in yields up to 80 %, whereas the indoloquinolines were prepared by a Suzuki-Miyaura cross-coupling ...
    • Regioselective formylation of rhenium-oxo and gold corroles: Substituent effects on optical spectra and redox potentials 

      Einrem, Rune F.; Jonsson, Einar Torfi; Teat, Simon J.; Settineri, Nicholas S.; Alemayehu, Abraham B.; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-28)
      Vilsmeier–Haack formylation of ReO and Au meso-triarylcorroles over 16–18 hours affords moderate to good yields (47–65%) of the ReO-3-formyl and Au-3,17-diformyl derivatives in a highly regioselective manner. Formylation was found to effect substantial upshifts for redox potentials (especially the reduction potentials) as well as significant to dramatic redshifts for both the Soret and Q bands.
    • 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 ...
    • Relativistic Effects on a Metal-Metal Bond: Osmium Corrole Dimers 

      Alemayehu, Abraham; McCormick, Laura J; Vazquez Lima, Hugo; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-07)
      A series of metal–metal bonded osmium corrole dimers, {Os[TpXPC]}2, were synthesized in reasonably good yields (35–46%) via the interaction of the corresponding free-base meso-tris(p-X-phenyl)corroles (H3[TpXPC], X = CF3, H, CH3, and OCH3), Os3(CO)12, and potassium carbonate in 1,2,4-trichlorobenzene under an inert atmosphere at 180 °C over several hours. The complexes are only the second class of ...
    • Relativistic effects on the NMR parameters of Si, Ge, Sn, and Pb alkynyl compounds: Scalar versus spin-orbit effects 

      Demissie, Taye Beyene (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-11-01)
      The NMR chemical shifts and indirect spin-spin coupling constants of 12 molecules containing <sup>29</sup>Si, <sup>73</sup>Ge, <sup>119</sup>Sn, and <sup>207</sup>Pb [X(CCMe)<sub>4</sub>, Me<sub>2</sub>X(CCMe)<sub>2</sub>, and Me<sub>3</sub>XCCH] are presented. The results are obtained from non-relativistic as well as two- and four-component relativistic density functional theory (DFT) calculations. ...
    • Relativistic four-component calculations of Buckingham birefringence using London atomic orbitals 

      Bast, Radovan; Ruud, Kenneth; Rizzo, Antonio; Helgaker, Trygve (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      We present the first relativistic study of the electric-field-gradient induced birefringence (Buckingham birefringence), with application to the series of molecules CX2 (X = O, S, Se, Te). A recently developed atomic-orbital-driven scheme for the calculation of time-dependent molecular properties using one-, two- and four-component relativistic wave functions (Bast et al. in Chem Phys 356:177, 2009) ...
    • Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel 

      Kristkova, Anezka; Komorovsky, Stanislav; Repisky, Michal; Malkin, Vladimir G.; Malkina, Olga L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-16)
      In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density ...
    • Relativistic Four-Component DFT Calculations of Vibrational Frequencies 

      Jakubowska, Katarzyna; Pecul-Kudelska, Magdalena; Ruud, Kenneth (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-29)
      We investigate the effect of relativity on harmonic vibrational frequencies. Density functional theory (DFT) calculations using the four-component Dirac–Coulomb Hamiltonian have been performed for 15 hydrides (H<sub>2</sub>X, X = O, S, Se, Te, Po; XH<sub>3</sub>, X = N, P, As, Sb, Bi; and XH<sub>4</sub>, X = C, Si, Ge, Sn, Pb) as well as for HC≡CPbH<sub>3</sub>. The vibrational frequencies have been ...
    • Relativistic four-component linear damped response TDDFT for electronic absorption and circular dichroism calculations 

      Konecny, Lukas; Repisky, Michal; Ruud, Kenneth; Komorovsky, Stanislav (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-21)
      We present a detailed theory, implementation, and a benchmark study of a linear damped response time-dependent density functional theory (TDDFT) based on the relativistic four-component (4c) Dirac–Kohn–Sham formalism using the restricted kinetic balance condition for the small-component basis and a noncollinear exchange–correlation kernel. The damped response equations are solved by means of a ...