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Now showing items 514-527 of 527
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Vibrational Corrections to NMR Spin-Spin Coupling Constants from Relativistic Four-Component DFT Calculations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2022-09-22)Zero-point vibrational (ZPV) corrections to the nuclear spin–spin coupling constants have been calculated using four-component Dirac–Kohn–Sham DFT for H<sub>2</sub>X (where X = O, S, Se, Te, Po), XH<sub>3</sub> (where X = N, P, As, Sb, Bi), and XH<sub>4</sub> (where X = C, Si, Ge, Sn, and Pb) molecules and for HC≡CPbH<sub>3</sub>. The main goal was to study the influence of relativistic effects on ... -
Vibrionaceae core, shell and cloud genes are non-randomly distributed on Chr 1: An hypothesis that links the genomic location of genes with their intracellular placement
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-06)<i>Background</i> - The genome of <i>Vibrionaceae</i> bacteria, which consists of two circular chromosomes, is replicated in a highly ordered fashion. In fast-growing bacteria, multifork replication results in higher gene copy numbers and increased expression of genes located close to the origin of replication of Chr 1 (<i>ori1</i>). This is believed to be a growth optimization strategy to satisfy ... -
Vinyl Sulfoxonium Ylide: A New Vinyl Carbenoid Transfer Reagent for the Synthesis of Heterocycles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-10)Sulfoxonium ylides have recently gained prominence as safe carbenoid precursors in metal-catalyzed reactions. The stability and reactivity of sulfoxonium ylides depend on the substitution of the ylide carbon. The reactivity of vinyl-substituted sulfoxonium ylides is different and offers several advantages over known stabilized sulfoxonium ylides in the case of carbenoid transfer reactions. Herein, ... -
Visible light-exposed lignin facilitates cellulose solubilization by lytic polysaccharide monooxygenases
(Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-24)Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccharides such as cellulose and are crucial for the conversion of plant biomass in Nature and in industrial applications. Sunlight promotes microbial conversion of plant litter; this effect has been attributed to photochemical degradation of lignin, a major redox-active component of secondary plant cell walls ... -
Visible-light photocatalytic double C–H Functionalization of indoles: a synergistic experimental and computational study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-02-21)Herein is disclosed a novel visible-light photocatalytic double C–H functionalization of indoles. The reaction affords 2,3-difunctional- ized indoles in up to 84% yield, but the reaction rate depends strongly on electronic substituent effects. Mechanistic DFT studies and control experiments suggest that the secondary functionalization occurs through an independent photocatalytic oxidation ... -
Wavelet formulation of the polarizable continuum model. II. Use of piecewise bilinear boundary elements
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-07-27)The simplicity of dielectric continuum models has made them a standard tool in almost any Quantum Chemistry (QC) package. Despite being intuitive from a physical point of view, the actual electrostatic problem at the cavity boundary is challenging: the underlying boundary integral equations depend on singular, long-range operators. The parametrization of the cavity boundary should be molecular- ... -
A weighted minimum distance using hybridization of particle swarm optimization and Bacterial Foraging
(Journal article; Tidsskriftartikkel; Peer reviewed, 2014) -
When Optimization Is Just an Illusion
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013)Bio-inspired optimization algorithms have been successfully applied to solve many problems in engineering, science, and economics. In computer science bio-inspired optimization has different applications in different domains such as software engineering, networks, data mining, and many others. However, some applications may not be appropriate or even correct. In this paper we study this phenomenon ... -
X-ray absorption resonances near L2,3-edges from real-time propagation of the Dirac–Kohn–Sham density matrix
(Journal article; Tidsskriftartikkel; Peer reviewed, 2015-08-07)The solution of the Liouville–von Neumann equation in the relativistic Dirac–Kohn–Sham density matrix formalism is presented and used to calculate X-ray absorption cross sections. Both dynamical relaxation effects and spin–orbit corrections are included, as demonstrated by calculations of the X-ray absorption of SF6 near the sulfur L2,3-edges. We also propose an analysis facilitating the interpretation ... -
X-ray Absorption Spectroscopy as a Probe of Ligand Noninnocence in Metallocorroles: The Case of Copper Corroles
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-02)The question of ligand noninnocence in Cu corroles has long been a topic of discussion. Presented herein is a Cu K-edge X-ray absorption spectroscopy (XAS) study, which provides a direct probe of the metal oxidation state, of three Cu corroles, Cu[TPC], Cu[Br8TPC], and Cu[(CF3)8TPC] (TPC = meso-triphenylcorrole), and the analogous Cu(II) porphyrins, Cu[TPP], Cu[Br8TPP], and Cu[(CF3)8TPP] (TPP = ... -
X-ray absorption spectroscopy of archetypal chromium porphyrin and corrole derivatives
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-29)A combination of Cr K-edge XAS and DFT calculations have been performed on archetypal chromium porphyrinoid complexes Cr<sup>IV</sup>[TMP]O (<b>2</b>) and Cr<sup>V</sup>[TPC]O (<b>3</b>), and the results have been compared to the reference compound Cr<sup>III</sup>[TPP]Cl (<b>1</b>), where TPP<sup>2−</sup>, TMP<sup>2−</sup>, and TPC<sup>3−</sup> are the anions of <i>meso</i>-tetraphenylporphyrin, ... -
X-ray absorption spectroscopy of exemplary platinum porphyrin and corrole derivatives: metal- versus ligand-centered oxidation
(Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-30)A combination of Pt L<sub>3</sub>-edge X-ray absorption spectroscopy (EXAFS and XANES) and DFT (TPSS) calculations have been performed on powder samples of the archetypal platinum porphyrinoid complexes Pt<sup>II</sup>[TpCF<sub>3</sub>PP], Pt<sup>IV</sup>[TpCF<sub>3</sub>PP]Cl<sub>2</sub>, and Pt<sup>IV</sup>[TpCF<sub>3</sub>PC](Ar)(py), where TpCF<sub>3</sub>PP<sup>2-</sup> = meso-tetrakis(p-tr ... -
X-ray crystal structure of Vibrio alkaline phosphatase with the non-competitive inhibitor cyclohexylamine
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-15)<i>Background</i> - <i>Para</i>-nitrophenyl phosphate, the common substrate for alkaline phosphatase (AP), is available as a cyclohexylamine salt. Here, we report that cyclohexylamine is a non-competitive inhibitor of APs.<br><br> <i>Methods</i> - Cyclohexylamine inhibited four different APs. Co-crystallization with the cold-active <i>Vibrio</i> AP (VAP) was performed and the structure solved.<br><br> ... -
β-Octabromo- and β-Octakis(trifluoromethyl)isocorroles: New Sterically Constrained Macrocyclic Ligands
(Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-26)Presented herein is a study of the acid-induced demetalation of two sterically hindered copper corroles, Cu b-octabromomeso-triphenylcorrole (Cu[Br8TPC]) and b-octakis(trifluoromethyl)-meso-tris(p-methoxyphenyl)corrole (Cu[(CF3 )8TpOMePC]). Unlike reductive demetalation, which affords the free-base boctabromocorrole, demetalation of Cu[Br8TPC] under nonreductive conditions (CHCl3 /H2SO4 ) ...
