Artikler, rapporter og annet (kjemi): Nye registreringer
Viser treff 301-320 av 565
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Strong Duschinsky Mixing Induced Breakdown of Kasha's Rule in an Organic Phosphor
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-08)We present the novel observation that Duschinsky mixings can lead to the breakdown of Kasha’s rule in a white light phosphor molecule, dibenzo[<i>b,d</i>]thiophen-2-yl (4-chlorophenyl)methanone. Our theoretical analyses show the energy gap between the T<sub>1</sub> and T<sub>2</sub> states (0.48 eV) is too large to allow for any significant population of the T<sub>2</sub> state at room temperature ... -
Electron-Spin Structure and Metal-Ligand Bonding in Open-Shell Systems from Relativistic EPR and NMR: A Case Study of Square-Planar Iridium Catalysts
(Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-28)Electron and nuclear magnetic resonance spectroscopies are indispensable and powerful methods for investigating the molecular and electronic structures of open-shell systems. We demonstrate that the NMR and EPR parameters are extremely sensitive quantitative probes for the electronic spin density around heavy-metal atoms and the metal–ligand bonding. Using relativistic density-functional theory, we ... -
Photo-transformation trajectories of Nitro-Spiropyran in Hybrid Compounds with [60]Fullerene
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-12)Photo- and thermo- isomerization trajectories of various conversion pathways between nitro-spiropyran and its <i>trans–trans–cis</i> merocyanine form were produced and the role of nπ* states was investigated along the corresponding potential energy surface calculated using the ωB97XD functional and the cc-pVDZ basis set. The nondissociative nπ* states on the photoisomerization trajectories can switch ... -
Synthesis and biological evaluation of new dipicolylamine zinc chelators as metallo-β-lactamase inhibitors
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-02)Antibiotics are key drugs in modern healthcare, especially in hospitals, where multiresistant bacteria resides and is a potential threat to human health. In the present work, a new series of adjuvants working synergistically with the carbapenem meropenem, in which a selective zinc-chelating agent was covalently linked to the small bacterial peptide D-Ala-D-Ala, was synthesized and tested against ... -
Four-component relativistic 31P NMR calculations for: Trans -platinum(ii) complexes: Importance of the solvent and dynamics in spectral simulations
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-18)We report a combined experimental-theoretical study on the 31P NMR chemical shift for a number of trans-platinum(II) complexes. Validity and reliability of the 31P NMR chemical shift calculations are examined by comparing with the experimental data. A successful computational protocol for the accurate prediction of the 31P NMR chemical shifts was established for trans-[PtCl2(dma)PPh3] (dma = ... -
Azulicorrole
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-04-12)Acid-catalyzed condensation of pyrrole, 4-trifluoromethylbenzaldehyde, and azulene, followed by DDQ oxidation, has resulted in the isolation of the novel macrocycle azulicorrole, arguably the first example of a carbacorrole aside from N-confused corrole. Despite poor yields (<1%), the free ligand could be structurally characterized and converted to the formal Cu(III) and Au(III) derivatives, of which ... -
Unexpected Molecular Structure of a Putative Rhenium-Dioxo-Benzocarbaporphyrin Complex. Implications for the Highest Transition Metal Valence in a Porphyrin-Type Ligand Environment
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-18)A combination of quantum chemical calculations and synthetic studies was used to address the possibility of very high (>6) valence states of transition metals in porphyrin‐type complexes. With corrole as a supporting ligand, DFT calculations ruled out Re(VII) and Ir(VII) dioxo complexes as stable species. Attempted rhenium insertion into benzocarbaporphyrin (BCP) ligands on the other hand led to two ... -
Towards Rational Computational Engineering of Psychrophilic Enzymes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-12-16)Cold-adapted enzymes from psychrophilic species achieve their high catalytic efficiency at low temperature by a different partitioning of the activation free energy into its enthalpic and entropic components, compared to orthologous mesophilic enzymes. Their lower activation enthalpy, partly compensated by an increased entropic penalty, has been suggested to originate from changes in flexibility of ... -
Characterization and engineering of a DNA polymerase reveals a single amino-acid substitution in the fingers subdomain to increase strand-displacement activity of A-family prokaryotic DNA polymerases
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-09)<i>Background</i> - The discovery of thermostable DNA polymerases such as Taq DNA polymerase revolutionized amplification of DNA by polymerase chain reaction methods that rely on thermal cycling for strand separation. These methods are widely used in the laboratory for medical research, clinical diagnostics, criminal forensics and general molecular biology research. Today there is a growing demand ... -
På vei mot en kollegial tilnærming til undervisning – seminarundervisning og pedagogisk opplæring av stipendiater
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-19)Seminarundervisning har en viktig rolle i realfagsundervisning i høyere utdanning. Læringsaktivitetene i seminarene samsvarer ofte godt med eksamensformen og dermed bidrar seminarundervisning betydelig til <i>constructive alignment</i> (Biggs, 1999) i et emne. Den viktige rollen seminarundervisning har står i sterk kontrast med den begrensede eller fraværende opplæring ... -
A thermally stable {FeNO}(8) complex: properties and biological reactivity of reduced MNO systems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2012-10-06)Reduced nitrogen oxide ligands such as NO<sup>−</sup>/HNO or nitroxyl participate in chemistry distinct from nitric oxide (NO). Nitroxyl has been proposed to form at heme centers to generate the Enemark–Feltham designated {FeNO}<sup>8</sup> system. The synthesis of a thermally stable {FeNO}<sup>8</sup> species namely, [Co(Cp<sup>*</sup>)<sub>2</sub>][Fe(LN<sub>4</sub>)(NO)] (3), housed in a heme-like ... -
Gold dipyrrin-bisphenolates: A combined experimental and DFT study of metal-ligand interactions
(Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-02)Given that noninnocent and metalloradical-type electronic structures are ubiquitous among dipyrrin-bisphenolate (DPP) complexes, we synthesized the gold(III) derivatives as potentially innocent paradigms against which the properties of other metallo-DPP derivatives can be evaluated. Electronic absorption spectra, electrochemical studies, a single-crystal X-ray structure, and DFT calculations all ... -
The crystal structure of haemoglobin from Atlantic cod
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-16)The crystal structure of haemoglobin from Atlantic cod has been solved to 2.54 A˚ resolution. The structure consists of two tetramers in the crystallographic asymmetric unit. The structure of haemoglobin obtained from one individual cod suggests polymorphism in the tetrameric assembly. -
On derivatives of smooth functions represented in multiwavelet bases
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-24)We construct high-order derivative operators for smooth functions represented via discontinuous multiwavelet bases. The need for such operators arises in order to avoid artifacts when computing functionals involving high-order derivatives of solutions of integral equations. Previously high-order derivatives had to be formed by repeated application of a first-derivative operator that, while uniquely ... -
Four-component relativistic time-dependent density-functional theory using a stable noncollinear DFT ansatz applicable to both closed- and open-shell systems
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-11-14)We present a formulation of relativistic linear response time-dependent density functional theory for the calculation of electronic excitation energies in the framework of the four-component Dirac-Coulomb Hamiltonian. This approach is based on the noncollinear <i>ansatz</i> originally developed by Scalmani and Frisch [J. Chem. Theory Comput. 8, 2193 (2012)] and improves upon the past treatment of ... -
Relativistic four-component linear damped response TDDFT for electronic absorption and circular dichroism calculations
(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 ... -
The quantitative level of T315I mutated BCR-ABL predicts for major molecular response to second-line nilotinib or dasatinib treatment in patients with chronic myeloid leukemia
(Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05)The BCR-ABL T315I mutation causes resistance to imatinib, nilotinib and dasatinib in chronic myeloid leukemia. Forty BCR-ABL positive patients with imatinib resistance were analyzed for T315I mutated clones after six months on nilotinib or dasatinib treatment by quantitative allele-specific ligation polymerase chain reaction with a sensitivity of 0.05%. Ligation polymerase chain reaction revealed ... -
Engineering low-temperature expression systems for heterologous production of cold-adapted enzymes
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016-02-26)Production of psychrophilic enzymes in the commonly used mesophilic expression systems is hampered by low intrinsic stability of the recombinant enzymes at the optimal host growth temperatures. Unless strategies for low-temperature expression are advanced, research on psychrophilic enzymes may end up being biased toward those that can be stably produced in commonly used mesophilic host systems. Two ... -
Caesium Fluoride-Mediated Hydrocarboxylation of Alkenes and Allenes: Scope and Mechanistic Insights
(Journal article; Tidsskriftartikkel; Peer reviewed, 2019-09-11)A caesium fluoride-mediated hydrocarboxylation of olefins is disclosed that does not rely on precious transition metal catalysts and ligands. The reaction occurs at atmospheric pressures of CO<sub>2</sub> in the presence of 9-BBN as a stoichiometric reductant. Stilbenes, β-substituted styrenes and allenes could be carboxylated in good yields. The developed methodology can be used for preparation of ... -
Catalytic Intermolecular Functionalization of Benzimidazoles
(Peer reviewed; Chapter; Bokkapittel, 2019-06-25)This chapter describes contemporary strategies for selective catalytic intermolecular functionalization of the benzimidazole scaffold. Functionalization at nitrogen and position C-2 is well developed employing copper, palladium, rhodium, nickel, and cobalt catalysis. Direct CH activation is the predominant approach to C-2 functionalization. Nickel-based catalysts can activate C—O bonds in conjunction ...