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  • 1501.
    Wikmark, Ylva
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Humble, Maria Svedendahl
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Combinatorial Library Based Engineering of Candida antarctica Lipase A for Enantioselective Transacylation of sec-Alcohols in Organic Solvent2015Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 14, s. 4284-4288Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A method for determining lipase enantioselectivity in the transacylation of sec-alcohols in organic solvent was developed. The method was applied to a model library of Candida antarctica lipase A (CalA) variants for improved enantioselectivity (E values) in the kinetic resolution of 1-phenylethanol in isooctane. A focused combinatorial gene library simultaneously targeting seven positions in the enzyme active site was designed. Enzyme variants were immobilized on nickel-coated 96-well microtiter plates through a histidine tag (His6 -tag), screened for transacylation of 1-phenylethanol in isooctane, and analyzed by GC. The highest enantioselectivity was shown by the double mutant Y93L/L367I. This enzyme variant gave an E value of 100 (R), which is a dramatic improvement on the wild-type CalA (E=3). This variant also showed high to excellent enantioselectivity for other secondary alcohols tested.

  • 1502.
    Willy, Benjamin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of pincer complex-catalyzed oxidative C-H activation borylation reactions: Synthetic applications and mechanistic studies2010Inngår i: Abstracts of Papers, 239th ACS National Meeting, San Francisco, CA, United States, March 21-25, 2010, Washington D C: American Chemical Society , 2010Konferansepaper (Annet vitenskapelig)
  • 1503.
    Winqvist, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies towards a method for incorporation of 3'-deoxy-3'-C-methylenephosphonate linkages into oligonucleotides2002Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Synthetic strategies towards 3’-deoxy-3’-C-methylenephosphinate building blocks were explored. The key transformations involved stereoselective hydroboration of 1-[2-O-(tert-butyldimethylsilyl-5-O-(4-methoxytrityl)-3-deoxy-3-C-methylene- ß -D-erythro-pentofuranosyl]uracil to give the corresponding 3’-deoxy-3’-C- hydroxymethyl derivative with ribo-configuration, as well as the further conversion into a precursor with a suitable leaving group, e. g., triflate, for subsequent substitution with the phosphinic acid synthon bis(trimethylsilyl)hypophosphite. Improvements of these steps enabled synthesis of 2’-O-(tert-butyldimethylsilyl-5’-O-( 4-methoxytrityl)-3’-deoxy-3’-C-methylenephosphinate uridine in a respectable overall yield of 40% over 6 steps, from the corresponding 2’-O-(tert-butyldimethylsilyl- 5’-O-(4-methoxytrityl)uridine.

    For the introduction of internucleosidic 3’-deoxy-3’-C-methylenephosphonate linkages into oligonucleotides, a preparatory study of the elongation steps, i. e., coupling of the phosphinate building block to the 5’-hydroxyl function of a nucleoside derivative and subsequent oxidation, was performed. Of several coupling reagents studied for the activation of the phosphinate building block prior to coupling, the most promising proved to be N,N-bis(2-oxo-3-oxazolidin-1-yl)phosphinic chloride. The oxidation of the resulting 3’-deoxy-3’-C-methylenephosphinate ester to the corresponding 3’-deoxy-3’-C-methylenephosphonate linkage was achieved using iodine in pyridine-water, in the presence of a catalyst, i. e., either a base (triethylamine) or an acid (pyridinium salt).

  • 1504. Wojcik, Anna
    et al.
    Broclawik, Ewa
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lundberg, Marcus
    Moran, Graham
    Borowski, Tomasz
    Role of Substrate Positioning in the Catalytic Reaction of 4-Hydroxyphenylpyruvate Dioxygenase-A QM/MM Study2014Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, nr 41, s. 14472-14485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ring hydroxylation and coupled rearrangement reactions catalyzed by 4-hydroxyphenylpyruvate dioxygenase were studied with the QM/MM method ONIOM(B3LYP:AMBER). For electrophilic attack of the ferryl species on the aromatic ring, five channels were considered: attacks on the three ring atoms closest to the oxo ligand (C1, C2, C6) and insertion of oxygen across two bonds formed by them (C1-C2, C1-C6). For the subsequent migration of the carboxymethyl substituent, two possible directions were tested (C1-C2, C1-C6), and two different mechanisms were sought (stepwise radical, single-step heterolytic). In addition, formation of an epoxide (side)product and benzylic hydroxylation, as catalyzed by the closely related hydroxymandelate synthase, were investigated. From the computed reaction free energy profiles it follows that the most likely mechanism of 4-hydroxyphenylpyruvate dioxygenase involves electrophilic attack on the C1 carbon of the ring and subsequent single-step heterolytic migration of the substituent. Computed values of the kinetic isotope effect for this step are inverse, consistent with available experimental data. Electronic structure arguments for the preferred mechanism of attack on the ring are also presented.

  • 1505.
    Wolpher, Henriette
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ruthenium(II) Polypyridyl Complexes in Supramolecular Systems relevant to Artificial Photosynthesis2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the synthesis and properties of ruthenium complexes relevant to artificial photosynthesis. The work includes preparation of RuIIpolypyridine complexes as well as multi component systems where RuII(bpy)3 or RuII(tpy)2 type complexes are used as photosesnsitizers.

    In the first part, the synthesis and characterisation of bipyridyl(pyridyl)methane type ligands and the corresponding ruthenium(II) bistridentate polypyridyl complexes is described. The bipyridyl-pyridyl methane type ligands were designed to increase the excited state lifetime of ruthenium(II) bisterpyridine-type complexes by altering the ligand field as compared to normal terpyridine ligands.

    In the second part photoinduced electron transfer and formation of charge separated states in donor-photosensitizer dyads or donor-photosensitizer-acceptor triads is studied. The first covalently linked donor-photosensitizer-acceptor triad with tyrosine as electron donor was prepared, and long lived light induced charge separation was observed. RuIIterpyridine complexes linked to carotenoid or tyrosine were also prepared, for studies of light induced charge separation on a TiO2 surface. Tryptofan was covalently linked to Ru(bpy)3 and proton coupled electron transfer from tryptophan to photogenerated ruthenium(III) was demonstrated. A pH-dependent study of the electron transfer rate gave insight into the mechanism of proton coupled electron transfer in amino acids.

    Finally, the last part of the thesis presents the preparation and properties of the first complex containing a photosensitizer covalently linked to a Fe-hydrogenase active site model.

  • 1506.
    Wolpher, Henriette
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Abrahamsson, Maria
    Eriksson, Lars
    Norrby, Per-Ola
    Johansson, Olof
    Bergquist, Jonas
    Hammarström, Leif
    Åkermark, Björn
    Ruthenium complexes of a bipyridyl(pyridyl)methane ligand: Effect of substituents at the methylene group on structure and photophysicsManuskript (Annet vitenskapelig)
  • 1507.
    Wolpher, Henriette
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Borgström, Magnus
    Hammarström, Leif
    Bergquist, Jonas
    Sundström, Villy
    Styring, Stenbjörn
    Sun, Licheng
    Åkermark, Björn
    Synthesis and Properties of an Iron Hydrogenase Active Site Model Linked to Ruthenium tris-Bipyridine Photosensitizer2003Inngår i: Inorganic Chemical Communications, Vol. 6, s. 989-991Artikkel i tidsskrift (Fagfellevurdert)
  • 1508. Wolpher, Henriette
    et al.
    Johansson, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Abrahamsson, Maria
    Kritikos, Mikael
    Sun, Licheng
    Åkermark, Björn
    A tridentate ligand for preparation of bisterpyridine-like ruthenium(II) complexes with an increased excited state lifetime2004Inngår i: Inorganic Chemistry Communications, ISSN 1387-7003, Vol. 7, nr 3, s. 337-340Artikkel i tidsskrift (Fagfellevurdert)
  • 1509.
    Wolpher, Henriette
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johansson, Olof
    Abrahamsson, Maria
    Kritikos, Mikael
    Sun, Licheng
    Åkermark, Björn
    A tridentate ligand for preparation of bisterpyridine-like ruthenium(II) complexes with an increased excited state lifetime2004Inngår i: Inorganic Chemistry Communications, ISSN 1387-7003, Vol. 7, nr 3, s. 337-340Artikkel i tidsskrift (Fagfellevurdert)
  • 1510.
    Wolpher, Henriette
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pan, Jingxi
    Johansson, Anh
    Lundqvist, Maria
    Persson, Petter
    Bergquist, Jonas
    Polivka, Tomas
    Sun, Licheng
    Åkermark, Björn
    Electron transfer studies of terpyridine based ruthenium(II)-donor dyads attached to nanostructured TiO2Manuskript (Annet vitenskapelig)
  • 1511.
    Wolpher, Henriette
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sinha, Subrata
    Pan, Jingxi
    Johansson, Anh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lundqvist, Maria J.
    Persson, Petter
    Lomoth, Reiner
    Bergquist, Jonas
    Sun, Licheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundström, Villy
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polívka, Tomás
    Synthesis and electron transfer studies of ruthenium-terpyridine-based dyads attached to nanostructured TiO22007Inngår i: Inorganic Chemistry, ISSN 0020-1669, Vol. 46, nr 3, s. 638-651Artikkel i tidsskrift (Fagfellevurdert)
  • 1512. Wu, Emilia L.
    et al.
    Engström, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jo, Sunhwan
    Stuhlsatz, Danielle
    Yeom, Min Sun
    Klauda, Jeffery B.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Im, Wonpil
    Molecular Dynamics and NMR Spectroscopy Studies of E. coli Lipopolysaccharide Structure and Dynamics2013Inngår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 105, nr 6, s. 1444-1455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lipopolysaccharide (LPS), a component of Gram-negative bacterial outer membranes, comprises three regions: lipid A, core oligosaccharide, and O-antigen polysaccharide. Using the CHARMM36 lipid and carbohydrate force fields, we have constructed a model of an Escherichia coil R1 (core) 06 (antigen) LPS molecule. Several all-atom bilayers are built and simulated with lipid A only (LIPA) and varying lengths of 0 (LPS0), 5 (LPS5), and 10 (LPS10) O6 antigen repeating units; a single unit of 06 antigen contains five sugar residues. From H-1,H-1-NOESY experiments, cross-relaxation rates are obtained from an O-antigen polysaccharide sample. Although some experimental deviations are due to spin-diffusion, the remaining effective proton-proton distances show generally very good agreement between NMR experiments and molecular dynamics simulations. The simulation results show that increasing the LPS molecular length has an impact on LPS structure and dynamics and also on LPS bilayer properties. Terminal residues in a LPS bilayer are more flexible and extended along the membrane normal. As the core and O-antigen are added, per-lipid area increases and lipid bilayer order decreases. In addition, results from mixed LPS0/5 and LPS0/10 bilayer simulation's show that the LPS O-antigen conformations at a higher concentration of LPS5 and LPS10 are more orthogonal to the membrane and less flexible. The O-antigen concentration of mixed LPS bilayers does not have a significant effect on per-lipid area and hydrophobic thickness. Analysis of ion and water penetration shows that water molecules can penetrate inside the inner core region, and hydration is critical to maintain the integrity of the bilayer structure.

  • 1513. Wu, Emilia L.
    et al.
    Fleming, Patrick J.
    Yeom, Min Sun
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Klauda, Jeffery B.
    Fleming, Karen G.
    Im, Wonpil
    E. coil Outer Membrane and Interactions with OmpLA2014Inngår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 106, nr 11, s. 2493-2502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The outer membrane of Gram-negative bacteria is a unique asymmetric lipid bilayer composed of phospholipids (PLs) in the inner leaflet and lipopolysaccharides (LPSs) in the outer leaflet. Its function as a selective barrier is crucial for the survival of bacteria in many distinct environments, and it also renders Gram-negative bacteria more resistant to antibiotics than their Gram-positive counterparts. Here, we report the structural properties of a model of the Escherichia coli outer membrane and its interaction with outer membrane phospholipase A (OmpLA) utilizing molecular dynamics simulations. Our results reveal that given the lipid composition used here, the hydrophobic thickness of the outer membrane is similar to 3 angstrom thinner than the corresponding PL bilayer, mainly because of the thinner LPS leaflet. Further thinning in the vicinity of OmpLA is observed due to hydrophobic matching. The particular shape of the OmpLA barrel induces various interactions between LPS and PL leaflets, resulting in asymmetric thinning around the protein. The interaction between OmpLA extracellular loops and LPS (headgroups and core oligosaccharides) stabilizes the loop conformation with reduced dynamics, which leads to secondary structure variation and loop displacement compared to that in a DLPC bilayer. In addition, we demonstrate that the LPS/PL ratios in asymmetric bilayers can be reliably estimated by the per-lipid surface area of each lipid type, and there is no statistical difference in the overall membrane structure for the outer membranes with one more or less LPS in the outer leaflet, although individual lipid properties vary slightly.

  • 1514. Wångsell, Fredrik
    et al.
    Russo, Francesco
    Sävmarker, Jonas
    Åsa, Rosenquist
    Samuelsson, Bertil
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Larhed, Mats
    Design and synthesis of BACE-1 inhibitors utilizing a tertiary hydroxyl motif as the transition state mimic2009Inngår i: Bioorganic & Medicinal Chemistry Letters, ISSN 0960-894X, Vol. 19, nr 16, s. 4711-4714Artikkel i tidsskrift (Fagfellevurdert)
  • 1515. Xia, Ming
    et al.
    Liu, Jianhui
    Gao, Yan
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Synthesis and photophysical and electrochemical study of tyrosine covalently linked to high-valent copper(III) and manganese(IV) complexes2007Inngår i: Helvetica Chimica Acta, ISSN 0018-019X, Vol. 90, nr 3, s. 553-561Artikkel i tidsskrift (Fagfellevurdert)
  • 1516.
    Xu, Chao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Afewerki, Samson
    Incerti-Pradillos, Celia
    Córdova, Oscar
    Guo, Peng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid-Sweden University, Sweden.
    Hedin, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    The Use of Porous Palladium(II)-polyimine in Cooperatively-catalyzed Highly Enantioselective Cascade Transformations2015Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 357, nr 9, s. 2150-2156Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Porous organic polymers have prospects as functional substrates for catalysis, with quite different molecular properties from inorganic substrates. Here we disclose for the first time that porous palladium(II)-polyimines are excellent catalysts for cooperatively catalyzed and enantioselective cascade reactions. In synergy with a chiral amine co-catalyst, polysubstituted cyclopentenes and spirocyclic oxindoles, including the all-carbon quaternary stereocenter, were synthesized in high yields. High diastereo- and enantioselectivities were achieved for these dynamic kinetic asymmetric transformations (DYKAT) of enals with propargylic nucleophiles.

  • 1517.
    Xu, Quan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    C-C Coupling of Ketones with Methanol Catalyzed by a N-Heterocyclic Carbene-Phosphine Iridium Complex2015Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, s. 3576-3579Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An N-heterocyclic carbene–phosphine iridium complex system was found to be a very efficient catalyst for the methylation of ketone via a hydrogen transfer reaction. Mild conditions together with low catalyst loading (1 mol %) were used for a tandem process which involves the dehydrogenation of methanol, CC bond formation with a ketone, and hydrogenation of the new generated double bond by iridium hydride to give the alkylated product. Using this iridium catalyst system, a number of branched ketones were synthesized with good to excellent conversions and yields.

  • 1518.
    Xu, Quan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rujirawanich, Janjira
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Active Cationic NHC, Phosphine Iridium Catalysts for Base Free Asymmetric Hydrogenation of KetonesManuskript (preprint) (Annet vitenskapelig)
  • 1519.
    Xu, Yunhua
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Artificial systems involving water oxidation and solar cells are promising ways for the conversion of solar energy into fuels and electricity. These systems usually consist of a photosensitizer, an electron donor and / or an electron acceptor. This thesis deals with the synthesis and photoinduced electron transfer of several donor-sensitizer-acceptor supramolecular systems.

    The first part of this thesis describes the synthesis and properties of two novel dinuclear ruthenium complexes as electron donors to mimic the donor side reaction of Photosystem II. These two Ru2 complexes were then covalently linked to ruthenium trisbipyridine and the properties of the resulting trinuclear complexes were studied by cyclic voltammetry and transient absorption spectroscopy.

    The second part presents the synthesis and photoinduced electron transfer of covalently linked donor-sensitizer supramolecular systems in the presence of TiO2 as electron acceptors. Electron donors are tyrosine, phenol and their derivatives, and dinuclear ruthenium complexes. Intramolecular electron transfer from the donor to the oxidized sensitizer was observed by transient absorption spectroscopy after light excitation of the Ru(bpy)32+ moiety. The potential applications of Ru2-based electron donors in artificial systems for water oxidation and solar cells are discussed.

    In the final part, the photoinduced interfacial electron transfer in the systems based on carotenoids and TiO2 is studied. Carotenoids are shown to act as both sensitizers and electron donors, which could be used in artificial systems to mimic the electron transfer chain in natural photosynthesis.

  • 1520. Xu, Yunhua
    et al.
    Duan, Lele
    Tong, Lianpeng
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Visible light-driven water oxidation catalyzed by a highly efficient dinuclear ruthenium complex2010Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, nr 35, s. 6506-6508Artikkel i tidsskrift (Fagfellevurdert)
  • 1521.
    Xu, Yunhua
    et al.
    Royal Institute of Technology (KTH).
    Duan, Lele
    Royal Institute of Technology (KTH).
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tong, Lianpeng
    Royal Institute of Technology (KTH).
    Lee, Bao-Lin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhang, Rong
    Dalian University of Technology (DUT), (P.R. China).
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Royal Institute of Technology (KTH), Department of Organic Chemistry.
    Synthesis and catalytic water oxidation activities of ruthenium complexes containing neutral ligands2011Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 34, s. 9520-9528Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two dinuclear and one mononuclear ruthenium complexes containing neutral polypyridyl ligands have been synthesised as pre-water oxidation catalysts and characterised by 1H and 13C NMR spectroscopy and ESI-MS. Their catalytic water oxidation properties in the presence of [Ce-(NH4)2(NO3)6] (CeIV) as oxidant at pH 1.0 have been investigated. At low concentrations of CeIV (5 mM), high turnover numbers of up to 4500 have been achieved. An 18O-labelling experiment established that both O atoms in the evolved O2 originate from water. Combined electrochemical study and electrospray ionisation mass spectrometric analysis suggest that ligand exchange between coordinated 4-picoline and free water produces Ru aquo species as the real water oxidation catalysts.

  • 1522.
    Xu, Yunhua
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eilers, Gerriet
    Borgström, Magnus
    Pan, Jingxi
    Abrahamsson, Maria
    Magnuson, Ann
    Lomoth, Reiner
    Bergquist, Jonas
    Polivka, Tomas
    Sun, Licheng
    Sundström, Villy
    Styring, Stenbjörn
    Hammarström, Leif
    Åkermark, Björn
    Synthesis and Characterization of Novel Dinuclear Ruthenium Complexes Covalently Linked to Ru(II) Trisbipyridine: an Approach to Mimics of the Donor Side of PS IIManuskript (Annet vitenskapelig)
  • 1523. Xu, Yunhua
    et al.
    Fischer, Andreas
    Duan, Lele
    Tong, Lianpeng
    Gabrielsson, Erik
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Chemical and light-driven oxidation of water catalyzed by an efficient dinuclear ruthenium complex2010Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, nr 47, s. 8934-8937Artikkel i tidsskrift (Fagfellevurdert)
  • 1524.
    Xu, Yunhua
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pan, Jie
    Huang, Ping
    Feyziyev, Yashar
    Lomoth, Reiner
    Hammarström, Leif
    Styring, Stenbjörn
    Polivka, Tomas
    Sundström, Villy
    Åkermark, Björn
    Sun, Licheng
    Synthesis and Photoinduced Electron Transfer Study of a Substituted Phenol Covalently Linked to Ruthenium Trisbipyridine with or without Four Ester GroupsManuskript (Annet vitenskapelig)
  • 1525.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Stereoselective Formation of C–O, C–C and C–B Bonds: A Voyage from Asymmetric Reactions Enabled by Lipases to Stereoselective Palladium-Catalyzed Oxidative Transformations of Enallenes2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis has been focused on enzymatic kinetic resolutions and stereoselective oxidative transformations of enallenes catalyzed by PdII.

    In the first part of the thesis, a detailed discussion on Candida antarctica lipase B (CALB)-catalyzed kinetic resolution (KR) of δ-functionalized alkan-2-acetates is shown. We gained a deeper insight into the mechanism of enzyme-substrate recognition. Changing from an anhydrous solvent to water or a water-containing organic solvent enhanced the enantioselectivity. The effect of –OH was also confirmed by a lipase mutant suggesting that the water molecule mentioned above can be partly mimicked.

    In the second part of the thesis, we developed an efficient KR for allenic alcohols. On this basis, a novel synthesis of optically pure 2-substituted 2,3-dihydrofurans from allenic alcohols via a Ru-catalyzed cycloisomerization was reported. The developed protocol enabled us to assemble an optically pure precursor for total synthesis with three chiral centers from readily available allenol in 2 days.

    In the third part, we reported a class of reactions involving C–H cleavage under mild conditions: PdII-catalyzed oxidative transformations of enallenes. These reactions are particularly attractive since a number of meticulous structures have been achieved from readily accessible starting materials. The directing effect of an unsaturated hydrocarbon was found to be key for these transformations.

    In the final part, we developed the carbonylative insertion reaction discussed in the third part of the thesis into an asymmetric version. By using this methodology, a number of cyclopentenone compounds were obtained in good to excellent enantioselectivity.

  • 1526.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development and Application ofEnzymatic Asymmetric Synthesis ofFunctionalized Alcohols2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The main focus of this thesis lies on enzymatic asymmetric organic reactions. In the first part ofthis work, we looked into the lipase-catalyzed transesterification and hydrolysis at the molecularlevel. It was shown that the low enantioselectivity of CALB-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity ofthe CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation isunusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation betweenthe enantioselectivity of transesterification of the alcohol and hydrolysis of the correspondingacetate with a high enantioseletivity in both cases. The results confirm previous predictions frommolecular modeling. The water effect was mimicked by CALB variant Ala281Ser, whichshowed an enhanced enantioselectivity in transesterification of δ-functionalized alkan-2-olscompared to wild type CALB.

    In the second part of the thesis, enzymatic kinetic resolution to resolve 1-substituted buta-2,3-dien-1-ol was studied. The initial goal was to use Shvo catalyst as racemization catalyst for anenvisioned dynamic kinetic resolution of this substrate. To our surprise, 2,3-dihydrofurans wasformed when α-allenic alcohols was treated with Shvo catalyst and the chiral center that endedup in the product was unchanged. Based on the KR and cycloisomerization, we furthermoredeveloped a one-pot procedure combining kinetic resolution and cyclization to optically pureoxygen-containing heterocycles. The mechanism of the Ru-catalyzed cycloisomerization wasstudied and a Ru-carbenoid was suggested as a crucial intermediate for forming the 2,3-dihydrofurans.

  • 1527.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lihammar, Richard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Investigation of the Impact of Water on the Enantioselectivity Displayed by CALB in the Kinetic Resolution of δ-Functionalized Alkan-2-ol Derivatives2014Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 42, s. 13517-13521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is shown that the low enantioselectivity of Candida antarctica lipase B (CALB)-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity of the CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation is unusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation between the enantioselectivity of transesterification of the alcohol and hydrolysis of the corresponding acetate (E>200 in both cases). The results confirm previous predictions from molecular modeling. The water effect was mimicked by CALB variant Ala281Ser, which showed an enhanced enantioselectivity in transesterification of δ-functionalized alkan-2-ols compared to wild-type CALB.

  • 1528.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Control of Selectivity in Palladium(II)-Catalyzed Oxidative Transformations of Allenes2018Inngår i: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 51, nr 6, s. 1520-1531Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Oxidation reactions play a central role in organic synthesis, and it is highly desirable that these reactions are mild and occur under catalytic conditions. In Nature, oxidation reactions occur under mild conditions via cascade processes, and furthermore, they often occur in an enantioselective manner with many of them involving molecular oxygen or hydrogen peroxide as the terminal oxidant. Inspired by the reactions in Nature, we have developed a number of Pd(II)-catalyzed cascade reactions under mild oxidative conditions. These reactions have an intrinsic advantage of step economy and rely on selectivity control in each step. In this Account, we will discuss the control of chemo-, regio-, and diastereoselectivity in Pd(II)-catalyzed dehydrogenative cascade coupling reactions. The enantioselective version of this methodology has also been addressed, and new chiral centers have been introduced using a catalytic amount of a chiral phosphoric acid (CPA). Research on this topic has provided access to important compounds attractive for synthetic and pharmaceutical chemists. These compounds include carbocyclic, heterocyclic, and polycyclic systems, as well as polyunsaturated open-chain structures. Reactions leading to these compounds are initiated by coordination of an allene and an unsaturated pi-bond moiety, such as olefin, alkyne, or another allene, to the Pd(II) center, followed by allene attack involving a C(sp(3))-H cleavage under mild reaction conditions. Recent progress within our research group has shown that weakly coordinating groups (e.g., hydroxyl, alkoxide, or ketone) could also initiate the allene attack on Pd(II), which is essential for the oxidative carbocyclization. Furthermore, a highly selective palladium-catalyzed allenic C(sp(3))-H bond oxidation of allenes in the absence of an assisting group was developed, which provides a novel and straightforward synthesis of [3]dendralene derivatives. For the oxidative systems, benzoquinone (BQ) and its derivatives are commonly used as oxidants or catalytic co-oxidants (electron transfer mediators, ETMs) together with molecular oxygen. A variety of transformations including carbocyclization, acetoxylation, arylation, carbonylation, borylation, beta-hydride elimination, alkynylation, alkoxylation, and olefination have been demonstrated to be compatible with this Pd(II)-based catalytic oxidative system. Recently, several challenging synthetic targets, such as cyclobutenes, seven-membered ring carbocycles, spirocyclic derivatives, functional cyclohexenes, and chiral cyclopentenone derivatives were obtained with high selectivity using these methods. The mechanisms of the reactions were mainly studied by kinetic isotope effects (KIEs) or DFT computations, which showed that in most cases the C(sp(3))-H cleavage is the rate-determining step (RDS) or partially RDS. This Account will describe our efforts toward the development of highly selective and atom-economic palladium(II)-catalyzed oxidative transformation of allenes (including enallenes, dienallenes, bisallenes, allenynes, simple allenes, and allenols) with a focus on overcoming the selectivity problem during the reactions.

  • 1529.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wulff, William D.
    Yin, Xiaopeng
    Zhu, Can
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective Palladium-Catalyzed Carbonylative Carbocyclization of Enallenes via Cross-Dehydrogenative Coupling with Terminal Alkyne: Efficient Construction of a-Chirality of Ketones2017Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, nr 16, s. 4535-4539Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An enantioselective PdII/Brønsted acid-catalyzed carbonylative carbocyclization of enallenes ending with a cross-dehydrogenative coupling (CDC) with a terminal alkyne was developed. VAPOL phosphoric acid was found as the best co-catalyst among the examined 28 chiral acids, for inducing the enantioselectivity of α-chiral ketones. As a result, a number of chiral cyclopentenones were easily synthesized in good to excellent enantiomeric ratio with good yields.

  • 1530.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhu, Can
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enzyme- and Ruthenium-Catalyzed Enantioselective Transformation of alpha-Allenic Alcohols into 2,3-Dihydrofurans2016Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 18, s. 5568-5572Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient one-pot method for the enzyme- and ruthenium-catalyzed enantioselective transformation of alpha-allenic alcohols into 2,3-dihydrofurans has been developed. The method involves an enzymatic kinetic resolution and a subsequent ruthenium-catalyzed cycloisomerization, which provides 2,3-dihydrofurans with excellent enantioselectivity (up to >99%ee). A ruthenium carbene species was proposed as a key intermediate in the cycloisomerization.

  • 1531.
    Yang, Hai-Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pathipati, Stalin R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Nickel-Catalyzed 1,2-Aminoarylation of Oxime Ester-Tethered Alkenes with Boronic Acids2017Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 12, s. 8441-8445Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A nickel-catalyzed 1,2-aminoarylation of oximeester-tethered alkenes with boronic acids was developed. A variety of pyrroline derivatives were synthesized in good yields via the successive formation of C(sp(3))-N and C(sp(3))-C(sp(2)) bonds. For cyclobutanone-derived oxime esters, the reaction provided aliphatic nitriles incorporating an aromatic group in the gamma-position. A mechanism involving iminyl radical and carbon-centered radical intermediates was proposed.

  • 1532.
    Yang, Hai-Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A redox-economical synthesis of trifluoromethylated enamides with the Langlois reagent2017Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 15, nr 8, s. 1771-1775Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A redox-economical strategy for the synthesis of trifluoromethylated enamides using copper catalysis is reported. The reaction employs the inexpensive Langlois reagent (CF3SO2Na) and takes place without the need of an external oxidant. The trifluoromethylated enamide products can easily be converted into the corresponding ketone, saturated amide or oxazole.

  • 1533.
    Yang, Hai-Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Divergent Iron-Catalyzed Coupling of O-Acyloximes with Silyl Enol Ethers2017Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 8, s. 1779-1783Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An iron-catalyzed coupling reaction of O-acyloximes and O-benzoyl amidoximes with silyl enol ethers is reported. The protocol provides access to functionalized pyrroles, 1,6-ketonitriles, pyrrolines and imidazolines via carbon-centered radicals generated from an initially formed iminyl radical. The intramolecular cyclization and ring-opening processes of the iminyl radical take place preferentially over reactions that proceed through a 1,3-hydrogen transfer, providing insights into iron-catalyzed reactions with oxime derivatives. The cheap and environmentally friendly iron catalyst, the broad substrate scope and the functional group compatibility make this protocol useful for synthesis of valuable nitrogen-containing products.

  • 1534. Yang, Mingjun
    et al.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Säwén, Elin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jana, Madhurima
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    MacKerell, Jr., Alexander D.
    Delineating the conformational flexibility of trisaccharides from NMR spectroscopy experiments and computer simulations2016Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 28, s. 18776-18794Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The conformation of saccharides in solution is challenging to characterize in the context of a single well-defined three-dimensional structure. Instead, they are better represented by an ensemble of conformations associated with their structural diversity and flexibility. In this study, we delineate the conformational heterogeneity of five trisaccharides via a combination of experimental and computational techniques. Experimental NMR measurements target conformationally sensitive parameters, including J couplings and effective distances around the glycosidic linkages, while the computational simulations apply the well-calibrated additive CHARMM carbohydrate force field in combination with efficient enhanced sampling molecular dynamics simulation methods. Analysis of conformational heterogeneity is performed based on sampling of discreet states as defined by dihedral angles, on root-mean-square differences of Cartesian coordinates and on the extent of volume sampled. Conformational clustering, based on the glycosidic linkage dihedral angles, shows that accounting for the full range of sampled conformations is required to reproduce the experimental data, emphasizing the utility of the molecular simulations in obtaining an atomic detailed description of the conformational properties of the saccharides. Results show the presence of differential conformational preferences as a function of primary sequence and glycosidic linkage types. Significant differences in conformational ensembles associated with the anomeric configuration of a single glycosidic linkage reinforce the impact of such changes on the conformational properties of carbohydrates. The present structural insights of the studied trisaccharides represent a foundation for understanding the range of conformations adopted in larger oligosaccharides and how these molecules encode their conformational heterogeneity into the monosaccharide sequence.

  • 1535. Yang, Tao
    et al.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ju, Jing
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liu, Zheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wang, Yingxia
    Li, Guobao
    Liao, Fuhui
    Martin-Matute, Belen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Jianhua
    Microporous Aluminoborates with Large Channels: Structural and Catalytic Properties2011Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, nr 52, s. 12555-12558Artikkel i tidsskrift (Fagfellevurdert)
  • 1536.
    Yang, Yuzhu
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Allenes by Catalytic Coupling of Propargyl Carbonates with Aryl Iodides in the Presence of Diboron Species2016Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, nr 1, s. 250-255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bimetallic copper-/palladium-catalyzed multicomponent reaction of propargyl carbonates, aryl iodides, and diboron species was studied. This procedure can be used for synthesis of di-, tri-, and tetra-substituted allenes. Using diboronic acid, the reaction is supposed to proceed via allenylboronic acid intermediate.

  • 1537.
    Yao, Qingxia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bermejo Gómez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yun, Yifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liu, Leifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Abdelhamid, Hani Nasser
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Martin-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Series of Highly Stable Isoreticular Lanthanide Metal-Organic Frameworks with Expanding Pore Size and Tunable Luminescent Properties2015Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, nr 15, s. 5332-5339Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of highly porous isoreticular lanthanide-based metal organic frameworks (LnMOFs) denoted as SUMOE-7I to SUMOE-7IV (SU = Stockholm University; Ln = La, Ce, Pr, Nd, Sm, Eu, and Gd) have been synthesized using tritopic carboxylates as the organic linkers. The SUMOF-7 materials display one-dimensional pseudohexagonal channels with the pore diameter gradually enlarged from 8.4 to 23.9 angstrom, as a result of increasing sizes of the organic linkers. The structures have been solved by single crystal X-ray diffraction or rotation electron diffraction (RED) combined with powder X-ray diffraction (PXRD). The SUMOF-7 materials exhibit robust architectures with permanent porosity. More importantly, they exhibit exceptionally high thermal and chemical stability. We show that, by inclusion of organic dye molecules, the luminescence properties of the MOFs can be elaborated and modulated, leading to promising applications in sensing and optics.

  • 1538.
    Yao, Qingxia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Bermejo Gómez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yun, Yifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Liu, Leifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Highly porous isoreticular lanthanide metal-organic frameworksManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    As an emerging type of porous materials, metal–organic frameworks (MOFs) have the advantages over conventional inorganic porous materials in that their structures and functions are systematically and predictably designable. Isoreticular expansion is an efficient way for systematic design and control of pore size and shape for MOFs. By using our proposed strategy, a series of highly porous isoreticular lanthanide-based metal-organic frameworks with systematic pore apertures has been obtained, which afford an isoreticular series of MIL-103 structures (termed SUMOF-7I to IV) with pore apertures ranging from 7.2 Å to 23 Å. These materials demonstrated exhibit robust architectures with permanent porosity, and exceptional thermal stability and chemical stability in various solvents. The combination of luminescence property and significant porosity of these MOFs enable them as a potential platform for multifunctional purpose.

  • 1539. Yotapan, Nattawut
    et al.
    Paptchikhine, Alexander
    Bera, Milan
    Avula, Satya Kumar
    Vilaivan, Tirayut
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of Kwazulu Natal, South Africa.
    Simple Proline-Derived Phosphine-Thiazole Iridium Complexes for Asymmetric Hydrogenation of Trisubstituted Olefins2013Inngår i: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, nr 8, s. 674-680Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Proline-based phosphine-thiazole/imidazole ligands have been synthesized and successfully applied in the homogeneous, iridium-catalyzed, asymmetric hydrogenation of trisubstituted functionalized and unfunctionalized olefins. Five different sets of ligands were prepared then evaluated for their catalytic activity and enantioselectivity in asymmetric hydrogenation.

  • 1540.
    Yu, Zheng-Bao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Han, Yu
    Zhao, Lan
    Huang, Shiliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Qi-Yu
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Intergrown New Zeolite Beta Polymorphs with Interconnected 12-Ring Channels Solved by Combining Electron Crystallography and Single-Crystal X-ray Diffraction2012Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 24, nr 19, s. 3701-3706Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new polymorphs of zeolite beta, denoted as SU-78A and SU-78B, were synthesized by employing dicyclohexylammonium hydroxides as organic structuredirecting agents. The structure was solved by combining transmission electron microscopy and single-crystal X-ray diffraction. SU-78 is an intergrowth of SU-78A and SU-78B and contains interconnected 12-ring channels in three directions. The two polymorphs are built from the same building layer, similar to that for the zeolite beta family. The layer stacking in SU-78, however, is different from those in zeolite beta polymorph A, B, and C, showing new zeolite framework topologies. SU-78 is thermally stable up to 600°C.

  • 1541.
    Yuan, Ning
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Swedish University of Agricultural Sciences, Sweden.
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Huang, Zhehao
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Heidenreich, Niclas
    Leubner, Sebastian
    Inge, A. Ken
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Gaar, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stock, Norbert
    Persson, Ingmar
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Probing the active catalytic species generated from Pd(II)@MIL-101-NH2 in Heck coupling reactions: An operando X-ray absorption spectroscopy studyArtikkel i tidsskrift (Fagfellevurdert)
  • 1542.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-Catalyzed Geminal Oxyfluorination and Oxytrifluoro-Methylation of Diazocarbonyl Compounds2016Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 29, s. 8410-8415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new reaction for the rhodium-catalyzed geminal-difunctionalization-based fluorination is presented. The substrates are aromatic and aliphatic diazocarbonyl compounds. As the fluorine source a stable and easily accessible benziodoxole reagent was used. A variety of alcohol, phenol, and carboxylic acid reagents were employed to introduce the second functionality. The reaction was extended to trifluoromethylation using a benziodoxolon reagent. The fluorination and trifluoromethylation reactions probably proceed by a rhodium-containing onium ylide type intermediate, which is trapped by either the F or CF3 electrophiles.

  • 1543.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Intramolecular Aminofluorination, Oxyfluorination, and Carbofluorination with a Stable and Versatile Hypervalent Fluoroiodine Reagent2015Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 29, s. 8533-8537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Application of a fluoroiodine analogue of the Togni reagent was studied in fluorocyclization reactions. In the presence of a transition-metal catalyst the applied fluoroiodine reagent can be used for aminofluorination, oxyfluorination, and carbofluorination reactions. The described procedure has a very broad synthetic scope for preparation of functionalized hetero- and isocyclic compounds having a tertiary fluorine substituent.

  • 1544.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-Catalyzed Oxy-Aminofluorination of Diazoketones with Tetrahydrofurans and N-Fluorobenzenesulfonimide2016Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, nr 10, s. 6687-6691Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed a rhodium-catalyzed oxy-aminofluorination method for transformation of diazoketones. The reaction is based on addition of tetrahydrofuran derivatives and N-fluorobenzenesulfonimide (NFSI) to the diazoketone substrate. The reaction can be performed under mild conditions with high regioselectivity. The synthetic scope involves a wide variety of diazoketones and tetrahydrofuran derivatives. The reaction is supposed to proceed via a tetrahydrofuran based onium ylide intermediate, which is formed from rhodium-carbenoid.

  • 1545.
    Zaccheus, Mona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural and Conformational Studies of Oligo- and Polysaccharides2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The focus of this thesis is to examine the structural properties of polysaccharides produced by bacteria, as well as the dynamic and conformational behavior of a synthetically derived oligosaccharide.

    The primary structures of the O-polysaccharide repeating units of four different Escherichia coli (E. coli) strains, namely O175, O177, O103 and TD2158, as well as the first report of a capsular polysaccharide produced by lactic acid bacteria Leuconostoc mesenteroides ssp. cremoris PIA2 are reported in paper I–V. Structural analyses have been performed using a combination of nuclear magnetic resonance spectroscopy and chemical component analysis.

    The elucidated structures in paper I–III, as well as paper V, are composed of linear repeating units of varying composition and length. In paper IV, the structure of the O-polysaccharide repeating unit of E. coli TD2158 is determined to be a branched hexasaccharide structure with a heterogeneous substitution pattern, with either a β-GlcpNAc or β-Glcp residue branching to the backbone chain. Incubation with bacteriophage HK620 tailspike protein shows that the polysaccharide is selectively cleaved at the α-GlcpNAc-(1→2)-α-Rhap-linkage of the backbone chain, yielding a 9:1 ratio of β-GlcpNAc/β-Glcp containing hexasaccharides after digestion.

    In paper VI the conformational properties of a trisaccharide, which constitutes an internal epitope of the LeaLex hexasaccharide over-expressed on the surface of squamous lung cancer cells, have been analyzed using NMR spectroscopy and molecular dynamics simulations. The β-(1→3)-linkage of the trisaccharide was shown to be highly flexible.

  • 1546.
    Zaccheus, Mona
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jackson, Trudy A.
    Wang, An
    Auzanneau, France-Isabelle
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conformational Dynamics of a Central Trisaccharide Fragment of the LeaLex Tumor Associated Antigen Studied by NMR Spectroscopy and Molecular Dynamics Simulations2012Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 25, s. 4705-4715Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Certain carbohydrate structures are recognized as cancer antigens, and identification of these and relevant epitopes are essential in fighting the disease. The trisaccharide beta-D-GlcpNAc-(1?3)-beta-D-Galp-(1?4)-beta-D-GlcpNAc-OMe represents a model for the central region of the LeaLex hexasaccharide and it has herein been investigated by 1D 1H,1H-NOESY experiments to obtain effective interresidue protonproton distances as well as by 2D J-HMBC experiments to determine transglycosidic 3JCH coupling constants. Molecular dynamics (MD) simulations using explicit water as solvent and three different carbohydrate force fields, namely, GLYCAM06, PARM22/SU01, and CHARMM2011, were employed for the interpretation of experimental data. Overall, the force field based MD simulations are able to reproduce the experimental data and the ? torsion angle at the beta-(1?3)-linkage is concluded to be flexible. In addition, different minor states were present for the three force fields with either anti-? or non-exo-anomeric conformations. Transitions between the exo-anomeric and the non-exo-anomeric conformations for the f torsion angle at the beta-(1?4)-linkage in one of the MD simulations were analyzed in detail. It was found that hydrogen-bonding water molecules, interresidue hydrogen bonds and the transitions between antiperiplanar and synperiplanar conformations for the tH torsion angle of an N-acetyl group were all essential in the description of the glycosidic transition process. In particular, the transition of tH may be a general way of regulating other transitions into less populated but biologically important conformational regions.

  • 1547.
    Zaccheus, Mona V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ali, Tara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cloeckaert, Axel
    Zygmunt, Michel S.
    Weintraub, Andrej
    Iriarte, Maite
    Moriyon, Ignacio
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The Epitopic and Structural Characterization of Brucella suis Biovar 2 O-Polysaccharide Demonstrates the Existence of a New M-Negative C-Negative Smooth Brucella Serovar2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 1, s. e53941-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The brucellae are Gram-negative bacteria that cause an important zoonosis. Studies with the main Brucella species have shown that the O-antigens of the Brucella smooth lipopolysaccharide are alpha-(1 -> 2) and alpha-(1 -> 3)-linked N-formyl-perosamine polysaccharides that carry M, A and C (A = M, A>M and A<M) epitopes relevant in serodiagnosis and typing. We report that, in contrast to the B. suis biovar 1 O-antigen used as a reference or to all described Brucella O-antigens, B. suis biovar 2 O-antigen failed to bind monoclonal antibodies of C (A = M), C (M>A) and M specificities. However, the biovar 2 O-antigen bound monoclonal antibodies to the Brucella A epitope, and to the C/Y epitope shared by brucellae and Yersinia enterocolitica O:9, a bacterium that carries an N-formyl-perosamine O-antigen in exclusively alpha-(1 -> 2)-linkages. By C-13 NMR spectroscopy, B. suis biovar 1 but not B. suis biovar 2 or Y.enterocolitica O:9 polysaccharide showed the signal characteristic of alpha-(1 -> 3)-linked N-formyl-perosamine, indicating that biovar 2 may altogether lack this linkage. Taken together, the NMR spectroscopy and monoclonal antibody analyses strongly suggest a role for alpha-(1 -> 3)-linked N-formyl-perosamine in the C (A = M) and C (M>A) epitopes. Moreover, they indicate that B. suis biovar 2 O-antigen lacks some lipopolysaccharide epitopes previously thought to be present in all smooth brucellae, thus representing a new brucella serovar that is M-negative, C-negative. Serologically and structurally this new serovar is more similar to Y. enterocolitica O:9 than to other brucellae.

  • 1548.
    Zaccheus, Mona V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Broeker, Nina K.
    Lundborg, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Uetrecht, Charlotte
    Barbirz, Stefanie
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies of the O‐antigen polysaccharide from Escherichia coli TD2158 having O18 serogroup specificity and aspects of its interaction with the tailspike endoglycosidase of the infecting bacteriophage HK6202012Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 357, s. 118-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have analyzed the O-antigen polysaccharide of the previously uncharacterized Escherichia coli strain TD2158 which is a host of bacteriophage HK620. This bacteriophage recognizes and cleaves the polysaccharide with its tailspike protein (TSP). The polysaccharide preparation as well as oligosaccharides obtained from HK620TSP endoglycosidase digests were analyzed with NMR spectroscopy. Additionally, sugar analysis was performed on the O-antigen polysaccharide and MALDI-TOF MS was used in oligosaccharide analysis. The present study revealed a heterogeneous polysaccharide with a hexasaccharide repeating unit of the following structure: α-D-Glcp-(1→6|) →2)-α-L-Rhap-91→6)-α-D-Glcp-(1→4)-α-D-Ga|lp-(1→3)-α-D-GlcpNAc-(1→ β-D-Glcp/β-D-GlcpNAc-(1→3) A repeating unit with a D-GlcNAc substitution of D-Gal has been described earlier as characteristic for serogroup O18A1. Accordingly, we termed repeating units with D-Glc substitution at D-Gal as O18A2. NMR analyses of the polysaccharide confirmed that O18A1- and O18A2-type repeats were present in a 1:1 ratio. However, HK620TSP preferentially bound the D-GlcNAc-substituted O18A1-type repeating units in its high affinity binding pocket with a dissociation constant of 140 μM and disfavored the O18A2-type having a β-D-Glcp-(1→3)-linked group. As a result, in hexasaccharide preparations, O18A1 and O18A2 repeats were present in a 9:1 ratio stressing the clear preference of O18A1-type repeats to be cleaved by HK620TSP.

  • 1549.
    Zani, Lorenzo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of novel amino-acid-derived sulfinamides and their evaluation as ligands for the enantioselective transfer hydrogenation of ketones2008Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, nr 27, s. 4655-4664Artikkel i tidsskrift (Fagfellevurdert)
  • 1550. Zerbetto, Mirco
    et al.
    d'Ortoli, Thibault Angles
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polimeno, Antonino
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Differential Dynamics at Glycosidic Linkages of an Oligosaccharide as Revealed by C-13 NMR Spin Relaxation and Stochastic Modeling2018Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 122, nr 8, s. 2287-2294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Among biomolecules, carbohydrates are unique in that not only can linkages be formed through different positions, but the structures may also be branched. The trisaccharide beta-D-Glcp-(1 -> 3)[beta-D-Glcp-(1 -> 2)]-alpha-D-Manp-OMe represents a model of a branched vicinally disubstituted structure. A C-13 site -specific isotopologue, with labeling in each of the two terminal glucosyl residues, enabled the acquisition of high-quality C-13 NMR relaxation parameters, T-1 and T-2, and heteronuclear NOE, with standard deviations of <= 0.5%. For interpretation of the experimental NMR data, a diffusive chain model was used, in which the dynamics of the glycosidic linkages is coupled to the global reorientation motion of the trisaccharide. Brownian dynamics simulations relying on the potential of mean force at the glycosidic linkages were employed to evaluate spectral densities of the spin probes. Calculated NMR relaxation parameters showed a very good agreement with experimental data, deviating <3%. The resulting dynamics are described by correlation times of 196 and 174 ps for the beta-(1 -> 2)- and beta-(1 -> 3)-linked glucosyl residues, respectively, i.e., different and linkage dependent. Notably, the devised computational protocol was performed without any fitting of parameters.

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