Viser treff 161-180 av 581

    • Understanding Hyperporphyrin Spectra: TDDFT Calculations on Diprotonated Tetrakis(p-aminophenyl)porphyrin 

      Conradie, Jeanet; Wamser, Carl C.; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-29)
      A detailed TDDFT study (with all-electron STO-TZ2P basis sets and the COSMO solvation model) has been carried out on the effect of diprotonation on the UV−vis−NIR spectra of free-base tetraphenylporphyrin and tetrakis(p-aminophenyl)porphyrin. The diprotonated forms have been modeled as their bis-formate complexes, i.e., as so-called porphyrin diacids. The dramatic redshift of the Q-band of ...
    • Phylogenetic Revision of the Genus Aliivibrio: Intra- and Inter-Species Variance Among Clusters Suggest a Wider Diversity of Species 

      Klemetsen, Terje; Karlsen, Christian René; Willassen, Nils Peder (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-18)
      Genus Aliivibrio is known to harbor species exhibiting bioluminescence as well as pathogenic behavior affecting the fish farming industry. Current phylogenetic understanding of Aliivibrio has largely remained dormant after reclassification disentangled it from the Vibrio genus in 2007. There is growing evidence of wider diversity, but until now the lack of genomes and selective use of type strains ...
    • 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.
    • Mechanistic Insights into Copper-Catalyzed Carboxylations 

      Obst, Marc; Gevorgyan, Ashot; Bayer, Annette; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-02)
      The copper-NHC-catalyzed carboxylation of organoboranes with CO<sub>2</sub> was investigated using computational and experimental methods. The DFT and DLPNO-CCSD(T) results indicate that nonbenzylic substrates are converted via an inner-sphere carboxylation of an organocopper intermediate, whereas benzylic substrates may simultaneously proceed along both inner- and outer-sphere CO<sub>2</sub> insertion ...
    • Phidianidine A and Synthetic Analogues as Naturally Inspired Marine Antifoulants 

      Labriere, Christophe; Elumalai, Vijayaragavan; Staffansson, Jannie; Cervin, Gunnar; Le Norcy, Tiffany; Denardou, Hugo; Réhel, Karine; Moodie, Lindon W. K.; Hellio, Claire; Pavia, Henrik; Hansen, Jørn H; Svenson, Johan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-10-15)
      Stationary and slow-moving marine organisms regularly employ a natural product chemical defense to prevent being colonized by marine micro- and macroorganisms. While these natural antifoulants can be structurally diverse, they often display highly conserved chemistries and physicochemical properties, suggesting a natural marine antifouling pharmacophore. In our current report, we investigate the ...
    • Anti-proliferative activity of a novel tricyclic triterpenoid acid from Commiphora africana resin against four human cancer cell lines 

      Isaksson, Johan; Rylandsholm, Fredrik G.; Bouř, Petr; Svendsen, John Sigurd Mjøen; Brichtová, Eva; Choi, Sng Un; Lee, Sang‑Ho; Jung, Young-Sik; No, Zae Sung; Aasen, Arne Jørgen; Dekebo, Aman; Dinku, Worku (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-17)
      Myrrh, a resin derived from the damaged bark of Commiphora genus, has traditionally been used for treatment of various human diseases, such as amenorrhea, ache, tumors, fever, and stomach pains. In spite of this widespread use of the myrrh in Ethiopia, the pharmacological activity and chemical composition have not been studied in detail. A new tricyclic triterpene acid (3S,4S,14S,7E,17E,21Z)-3, ...
    • Multiwavelets applied to metal–ligand interactions: Energies free from basis set errors 

      Brakestad, Anders; Wind, Peter; Jensen, Stig Rune; Frediani, Luca; Hopmann, Kathrin Helen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-02)
      Transition metal-catalyzed reactions invariably include steps where ligands associate or dissociate. In order to obtain reliable energies for such reactions, sufficiently large basis sets need to be employed. In this paper, we have used high-precision multiwavelet calculations to compute the metal–ligand association energies for 27 transition metal complexes with common ligands, such as H2, CO, ...
    • Simple, Axial Ligand-Mediated Route to Water-Soluble Iridium Corroles 

      Thomassen, Ivar K.; Rasmussen, Daniel; Einrem, Rune F.; Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-15)
      The synthesis and purification of water-soluble porphyrin-type compounds for photodynamic therapy and other medical applications is often a tedious exercise. Here, we have investigated the simple stratagem of adding a water-soluble axial ligand to the standard protocol for iridium insertion into simple meso-triarylcorroles. Early results showed that six-coordinate Ir[TpXPC](dna)2 derivatives, in ...
    • Synthesis of Potential Metallo-β-Lactamase Inhibitors 

      Paulsen, Marianne Hagensen (Master thesis; Mastergradsoppgave, 2012-06-04)
      Oppgaven omhandler syntesen av mulige metallo-beta-lactamaser inhibitorer.
    • Novel DYRK1A Inhibitor Rescues Learning and Memory Deficits in a Mouse Model of Down Syndrome 

      Stensen, Wenche; Rothweiler, Ulli; Engh, Richard Alan; Stasko, Melissa R.; Bederman, Ilya; Costa, Alberto C. S.; Fugelli, Anders; Svendsen, John Sigurd Mjøen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-17)
      Down syndrome (DS) is a complex genetic disorder associated with substantial physical, cognitive, and behavioral challenges. Due to better treatment options for the physical co-morbidities of DS, the life expectancy of individuals with DS is beginning to approach that of the general population. However, the cognitive deficits seen in individuals with DS still cannot be addressed pharmacologically. ...
    • ThermoSlope: A Software for Determining Thermodynamic Parameters from Single Steady-State Experiments 

      Lund, Bjarte Aarmo; Brandsdal, Bjørn Olav (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-26)
      The determination of the temperature dependence of enzyme catalysis has traditionally been a labourious undertaking. We have developed a new approach to the classical Arrhenius parameter estimation by fitting the change in velocity under a gradual change in temperature. The evaluation with a simulated dataset shows that the approach is valid. The approach is demonstrated as a useful tool by ...
    • Anti-Colonization Effect of Au Surfaces with Self-Assembled Molecular Monolayers Functionalized with Antimicrobial Peptides on S. epidermidis 

      Karlsen, Eskil André; Stensen, Wenche; Juskewitz, Eric; Svenson, Johan; Berglin, Mattias; Svendsen, John Sigurd Mjøen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-10)
      Medical devices with an effective anti-colonization surface are important tools for combatting healthcare-associated infections. Here, we investigated the anti-colonization efficacy of antimicrobial peptides covalently attached to a gold model surface. The gold surface was modified by a self-assembled polyethylene glycol monolayer with an acetylene terminus. The peptides were covalently connected ...
    • Synthesis of 5,7-diarylindoles via Suzuki-Miyaura coupling in water 

      Elumalai, Vijayaragavan; Hansen, Jørn H (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-16)
      The synthesis of novel 5,7-diaryl and diheteroaryl indoles has been explored via efficient double Suzuki–Miyaura coupling. The method notably employs a low catalyst loading of Pd(PPh<sub>3</sub>)<sub>4</sub> (1.5 mol%/coupling) and water as the reaction solvent to obtain 5,7-diarylated indoles without using N-protecting groups in up to 91% yield. The approach is also suitable for N-protected and ...
    • 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 ...
    • The Dog That Didn't Bark: A New Interpretation of Hypsoporphyrin Spectra and the Question of Hypsocorroles 

      Ghosh, Abhik; Conradie, Jeanet (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-11-11)
      Nearly a half-century after Gouterman classified the UV–vis–NIR spectra of porphyrin derivatives as normal, hyper, or hypso, we propose a heretofore unsuspected “mechanism” underlying hypso spectra. Hypsoporphyrins, which exhibit blueshifted optical spectra relative to normal porphyrins (such as Zn porphyrins), typically involve dn transition metal ions, where n > 6. The spectral blueshifts have ...
    • Synthesis, Spectroscopy, Electrochemistry and DFT of Electron-Rich Ferrocenylsubphthalocyanines 

      Conradie, Jeanet; Swarts, Petrus (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-01)
      A series of novel ferrocenylsubphthalocyanine dyads Y-BSubPc(H)<sub>12</sub> with ferrocenylcarboxylic acids Y-H = (FcCH<sub>2</sub>CO<sub>2</sub>-H), (Fc(CH<sub>2</sub>)<sub>3</sub>CO<sub>2</sub>-H) or (FcCO(CH<sub>2</sub>)<sub>2</sub>CO<sub>2</sub>-H) in the axial position were synthesized from the parent Cl-BSubPc(H)<sub>12</sub> via an activated triflate-SubPc intermediate. UV/Vis data revealed ...
    • X-ray absorption spectroscopy of exemplary platinum porphyrin and corrole derivatives: metal- versus ligand-centered oxidation 

      Ghosh, Abhik (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 ...
    • Ligand-Centered Triplet Diradical Supported by a Binuclear Palladium(II) Dipyrrindione 

      Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-04)
      Oligopyrroles form a versatile class of redox-active ligands and electron reservoirs. Although the stabilization of radicals within oligopyrrolic π systems is more common for macrocyclic ligands, bidentate dipyrrindiones are emerging as compact platforms for one-electron redox chemistry in transition-metal complexes. We report the synthesis of a bis(aqua) palladium(II) dipyrrindione complex and its ...
    • Mechanistic Insights into Carbamate Formation from CO2 and Amines: The Role of Guanidine–CO2 Adducts, 

      Mannisto, Jere K.; Pavlovic, Ljiljana; Tiainen, Tony; Nieger, Martin; Sahari, Aleksi; Hopmann, Kathrin Helen; Repo, Timo (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-09-02)
      Capture of CO<sub>2</sub> by amines is an attractive synthetic strategy for the formation of carbamates. Such reactions can be mediated by superbases, such as 1,1,3,3-tetramethylguanidine (TMG), with previous implications that zwitterionic superbase–CO<sub>2</sub> adducts are able to actively transfer the carboxylate group to various substrates. Here we report a detailed investigation of zwitterionic ...
    • Heavy-element–ligand covalence: ligand noninnocence in molybdenum and tungsten Viking-helmet Corroles 

      Ghosh, Abhik (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-07)
      Extensive DFT calculations with several exchange–correlation functionals indicate that molybdenum-dichlorido Viking helmet corroles are noninnocent with significant Mo<sup>IV</sup>-corrole<sup>˙2−</sup> character. The effect is mediated by a Mo(4d)-corrole(π) orbital interaction similar to that postulated for MnCl, FeCl and FeNO corroles. The effect also appears to operate in tungsten-dichlorido ...