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  • 1.
    Aili, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Rydberg, Johan
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Nesterenko, Irina
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Björefors, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Baltzer, Lars
    Department of Biochemistry and Organic Chemistry, BMC, Box 599, Uppsala UniVersity, SE-751 24 Uppsala, Sweden.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Folding Induced Assembly of Polypeptide Decorated Gold Nanoparticles2008In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, no 17, p. 5780-5788Article in journal (Refereed)
    Abstract [en]

    Reversible assembly of gold nanoparticles controlled by the homodimerization and folding of an immobilized de novo designed synthetic polypeptide is described. In solution at neutral pH, the polypeptide folds into a helix–loop–helix four-helix bundle in the presence of zinc ions. When immobilized on gold nanoparticles, the addition of zinc ions induces dimerization and folding between peptide monomers located on separate particles, resulting in rapid particle aggregation. The particles can be completely redispersed by removal of the zinc ions from the peptide upon addition of EDTA. Calcium ions, which do not induce folding in solution, have no effect on the stability of the peptide decorated particles. The contribution from folding on particle assembly was further determined utilizing a reference peptide with the same primary sequence but containing both D and L amino acids. Particles functionalized with the reference peptide do not aggregate, as the peptides are unable to fold. The two peptides, linked to the nanoparticle surface via a cysteine residue located in the loop region, form submonolayers on planar gold with comparable properties regarding surface density, orientation, and ability to interact with zinc ions. These results demonstrate that nanoparticle assembly can be induced, controlled, and to some extent tuned, by exploiting specific molecular interactions involved in polypeptide folding.

  • 2.
    Aili, Daniel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Enander, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Rydberg, Johan
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics . Linköping University, The Institute of Technology.
    Aggregation-Induced Folding of a de novo Designed Polypeptide Immobilized on Gold Nanoparticles2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 7, p. 2194 -2195Article in journal (Refereed)
    Abstract [en]

    This communication reports the first steps in the construction of a novel, nanoparticle-based hybrid material for biomimetic and biosensor applications. Gold nanoparticles were modified with synthetic polypeptides to enable control of the particle aggregation state in a switchable manner, and particle aggregation was, in turn, found to induce folding of the immobilized peptides.

  • 3.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Hanke, Felix
    Surface Science Research Centre, University of Liverpool, UK.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Mechanisms of halogen-based covalent self-assembly on metal surfaces2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 15, p. 5768-5775Article in journal (Refereed)
    Abstract [en]

    We computationally study the reaction mechanisms of halogen-based covalent self-assembly, a major route for synthesizing molecular nanostructures and nanographenes on surfaces. Focusing on biphenyl as a small model system, we describe the dehalogenation, recombination, and diffusion processes. The kinetics of the different processes are also investigated, in particular how diffusion and coupling barriers affect recombination rates. Trends across the periodic table are derived from three commonly used close-packed (111) surfaces (Cu, Ag, and Au) and two halogens (Br and I). We show that the halogen atoms can poison the surface, thus hindering long-range ordering of the self-assembled structures. Finally, we present core-level shifts of the relevant carbon and halogen atoms, to provide reference data for reliably detecting self-assembly without the need for atomic-resolution scanning tunneling microscopy.

  • 4.
    Björk, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hanke, Felix
    University of Liverpool.
    Zipping Up: Cooperativity Drives the Synthesis of Graphene Nanoribbons2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 38, p. 14884-14887Article in journal (Refereed)
    Abstract [en]

    We investigate the cooperative effects controlling the synthesis of a graphene nanoribbon on the Au(111) surface starting from an anthracene polymer using density functional calculations including van der Waals interactions. We focus on the high-temperature cyclodehydrogenation step of the reaction and find that the reaction proceeds by simultaneously transferring two H-atoms from the anthracene units to the Au surface, leaving behind a C C bond in the process. This step is significantly more favorable than the three other potential reaction paths. Moreover, we find that successive dehydrogenations proceed from one end of the polyanthracene and propagate step-by-step through the polymer in a domino-like fashion.

  • 5.
    Bubnova, Olga
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Tuning the Thermoelectric Properties of Conducting Polymers in an Electrochemical Transistor2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 40, p. 16456-16459Article in journal (Refereed)
    Abstract [en]

    While organic field-effect transistors allow the investigation of interfacial charge transport at the semiconductor-dielectric interface, an electrochemical transistor truly modifies the oxidation level and conductivity throughout the bulk of an organic semiconductor. In this work, the thermoelectric properties of the bulk of the conducting polymer poly(3,4-ethylenedioxythiophene) -poly(styrene sulfonate) were controlled electrically by varying the gate voltage. In light of the growing interest in conducting polymers as thermoelectric generators, this method provides an easy tool to study the physics behind the thermoelectric properties and to optimize polymer thermoelectrics.

  • 6.
    Bucher, Denis
    et al.
    University of Sydney.
    M Sandala, Gregory
    University of Sydney.
    Durbeej, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Radom, Leo
    University of Sydney.
    Smith, David M
    Rudjer Boskovic Institute.
    The elusive 5'-deoxyadenosyl radical in coenzyme-B12-mediated reactions2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 3, p. 1591-1599Article in journal (Refereed)
    Abstract [en]

    Vitamin B12 and its biologically active counterparts possess the only examples of carbon-cobalt bonds in living systems. The role of such motifs as radical reservoirs has potential application in future catalytic and electronic nanodevices. To fully understand radical generation in coenzyme B12 (dAdoCbl)-dependent enzymes, however, major obstacles still need to be overcome. In this work, we have used Car-Parrinello molecular dynamics (CPMD) simulations, in a mixed quantum mechanics/molecular mechanics (QM/MM) framework, to investigate the initial stages of the methylmalonyl-CoA-mutase-catalyzed reaction. We demonstrate that the 5'-deoxyadenosyl radical (dAdo(center dot)) exists as a distinct entity in this reaction, consistent with the results of extensive experimental and some previous theoretical studies. We report free energy calculations and first-principles trajectories enzymes catalyze coenzyme activation and control highly reactive radical intermediates. that help understand how B12 enzymes catalyze coenzyme activation and control highly reactive radical intermediates.

  • 7.
    Chan, Yang-Hsiang
    et al.
    Department of Chemistry, University of Washington, Seattle, USA.
    Ye, Fangmao
    Department of Chemistry, University of Washington, Seattle, USA.
    Gallina, Maria Elena
    Department of Chemistry, University of Washington, Seattle, USA.
    Zhang, Xuanjun
    Department of Chemistry, University of Washington, Seattle, USA.
    Jin, Yuhui
    Department of Chemistry, University of Washington, Seattle, USA.
    Wu, I-Che
    Department of Chemistry, University of Washington, Seattle, USA.
    Chiu, Daniel T
    Department of Chemistry, University of Washington, Seattle, USA.
    Hybrid Semiconducting Polymer Dot-Quantum Dot with Narrow-Band Emission, Near-Infrared Fluorescence, and High Brightness2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 17, p. 7309-7312Article in journal (Refereed)
  • 8.
    Cirera, Borja
    et al.
    IMDEA Nanosci, Spain.
    Trukhina, Olga
    University of Autonoma Madrid, Spain.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Bottari, Giovanni
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain; University of Autonoma Madrid, Spain.
    Rodriguez-Fernandez, Jonathan
    University of Autonoma Madrid, Spain.
    Martin-Jimenez, Alberto
    IMDEA Nanosci, Spain.
    Islyaikin, Mikhail K.
    Ivanovo State University of Chemistry and Technology, Russia.
    Otero, Roberto
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain.
    Gallego, Jose M.
    CSIC, Spain.
    Miranda, Rodolfo
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain.
    Torres, Tomas
    IMDEA Nanosci, Spain; University of Autonoma Madrid, Spain; University of Autonoma Madrid, Spain.
    Ecija, David
    IMDEA Nanosci, Spain.
    Long-Range Orientational Self-Assembly, Spatially Controlled Deprotonation, and Off-Centered Metalation of an Expanded Porphyrin2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 40, p. 14129-14136Article in journal (Refereed)
    Abstract [en]

    Expanded porphyrins are large-cavity macro cycles with enormous potential in coordination chemistry, anion sensing, photodynamic therapy, and optoelectronics. In the last two decades, the surface science community has assessed the physicochemical properties of tetrapyrrolic-like macrocydes. However, to date, the sublimation, self-assembly and atomistic insights of expanded porphyrins on surfaces have remained elusive. Here, we show the self-assembly on Au(111) of an expanded aza-porphyrin, namely, an "expanded hemi-spatially-controlled porphyrazine", through a unique growth mechanism based on deprotonation long-range orientational self-assembly. Furthermore, a spatially controlled "writing" protocol on such self-assembled architecture is presented based on the STM tip-induced deprotonation of the inner protons of individual macrocydes. Finally, the capability of these surface-confined macrocydes to host lanthanide elements is assessed, introducing a novel off-centered coordination motif. The presented findings represent a milestone in the fields of porphyrinoid chemistry and surface science, revealing a great potential for novel surface patterning, opening new avenues for molecular level information storage, and boosting the emerging field of surface-confined coordination chemistry involving f-block elements.

  • 9.
    Cornil, J
    et al.
    University of Mons, Belgium.
    dos Santos, DA
    University of Mons, Belgium.
    Crispin, X
    University of Mons, Belgium.
    Silbey, R
    MIT, USA.
    Bredas, JL
    University of Mons, Belgium.
    Influence of interchain interactions on the absorption and luminescence of conjugated oligomers and polymers: A quantum-chemical characterization1998In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 120, no 6, p. 1289-1299Article in journal (Refereed)
    Abstract [en]

    Correlated quantum-chemical calculations are used to investigate the influence of interchain interactions on the absorption and emission of pi-conjugated chains. The results are discussed in relation to the utilization of conjugated materials as active elements in electro-optic devices; they provide guidelines on how to prevent a substantial decrease in luminescence yield in solid films. In high-symmetry cofacial configurations, interchain interactions lead to a blue shift of the lowest optical transition compared to that calculated for an isolated chain; the appearance of an additional red-shifted component is expected when positional disorder is considered. The absence of any significant oscillator strength in the transition between the ground state and the lowest excited state in highly symmetric complexes implies that the luminescence emission will be strongly quenched. This picture is. however, modified when one takes account of the relaxation processes which occur in the lowest excited state. The nature of the most stable photogenerated species and the role played by chemical impurities are also addressed.

  • 10.
    Crispin, X
    et al.
    University of Mons, Belgium;.
    Lazzaroni, R
    University of Mons, Belgium; .
    Geskin, V
    University of Mons, Belgium; .
    Baute, N
    University of Liege, Belgium;.
    Dubois, P
    University of Liege, Belgium; .
    Jerome, R
    University of Liege, Belgium; .
    Bredas, JL
    University of Mons, Belgium; .
    Controlling the electrografting of polymers onto transition metal surfaces through solvent vs monomer adsorption1999In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 121, no 1, p. 176-187Article in journal (Refereed)
    Abstract [en]

    Electropolymerization of methacrylic monomers opens the possibility of chemically grafting a wide range of polymers onto transition metal surfaces. In this work, the electropolymerization of polyacrylonitrile and polyethyl acrylate is studied in different solvents; we experimentally confirm that the choice of solvent is a critical parameter for obtaining electrografted polymers. A density-functional theory-based study modeling the interaction of solvent (acetonitrile, dimethylformamide, and pyridine) or monomer (acrylonitrile and ethyl acrylate) molecules with the Ni(100) metal surface provides the means to classify the organic molecules with respect to their ability to interact with the surface. The surface binding-energy difference between monomer and solvent is introduced in a Frumkin-type isotherm. This allows us to rationalize the experimental observations in terms of a competitive adsorption at the metal surface between the monomer and the solvent. The first step in the electrografting mechanism thus appears to be the chemisorption of the monomer at the electrode surface before cathodic polarization is applied; the chemisorbed monomer is therefore the first species reduced, giving rise to an adsorbed reactive intermediate, which is thus able to start the polymerization of a grafted chain.

  • 11.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Cornil, J.
    Université de Mons-Hainaut.
    Friedlein, Rainer
    Linköping University, Department of Physics, Chemistry and Biology.
    Okudaira, K. K.
    Chiba University.
    Lemaur, V
    Université de Mons-Hainaut.
    Crispin, Annica
    Linköping University, Department of Physics, Chemistry and Biology.
    Kestemont, G.
    Université Libre de Bruxelles.
    Lehmann, M.
    Université Libre de Bruxelles.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lazzaroni, R.
    Université de Mons-Hainaut.
    Geerts, Y
    Université Libre de Bruxelles.
    Wendin, G.
    Chalmers University of Technology.
    Ueno, N.
    Chiba University.
    Brédas, J.-L.
    Université de Mons-Hainaut.
    Salaneck, William R
    Linköping University, Department of Physics, Chemistry and Biology.
    Electronic delocalization in discotic liquid crystals: A joint experimental and theoretical study2004In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 38, p. 11889-11899Article in journal (Refereed)
    Abstract [en]

    Discotic liquid crystals emerge as very attractive materials for organic-based (opto)electronics as they allow efficient charge and energy transport along self-organized molecular columns. Here, angle-resolved photoelectron spectroscopy (ARUPS) is used to investigate the electronic structure and supramolecular organization of the discotic molecule, hexakis(hexylthio)diquinoxalino[2,3-a:2′,3′-c]phenazine, deposited on graphite. The ARUPS data reveal significant changes in the electronic properties when going from disordered to columnar phases, the main feature being a decrease in ionization potential by 1.8 eV following the appearance of new electronic states at low binding energy. This evolution is rationalized by quantum-chemical calculations performed on model stacks containing from two to six molecules, which illustrate the formation of a quasi-band structure with Bloch-like orbitals delocalized over several molecules in the column. The ARUPS data also point to an energy dispersion of the upper π-bands in the columns by some 1.1 eV, therefore highlighting the strongly delocalized nature of the π-electrons along the discotic stacks.

  • 12.
    Crispin, Xavier
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Geskin, V.
    Crispin, Annica
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Cornil, J.
    Lazzaroni, R.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Bredas, J.-L.
    Characterization of the interface dipole at organic/metal interfaces2002In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 124, no 27, p. 8131-8141Article in journal (Refereed)
    Abstract [en]

    In organics-based (opto)electronic devices, the interface dipoles formed at the organic/metal interfaces play a key role in determining the barrier for charge (hole or electron) injection between the metal electrodes and the active organic layers. The origin of this dipole is rationalized here from the results of a joint experimental and theoretical study based on the interaction between acrylonitrile, a p-conjugated molecule, and transition metal surfaces (Cu, Ni, and Fe). The adsorption of acrylonitrile on these surfaces is investigated experimentally by photoelectron spectroscopies, while quantum mechanical methods based on density functional theory are used to study the systems theoretically. It appears that the interface dipole formed at an organic/metal interface can be divided into two contributions: (i) the first corresponds to the "chemical" dipole induced by a partial charge transfer between the organic layers and the metal upon chemisorption of the organic molecules on the metal surface, and (ii) the second relates to the change in metal surface dipole because of the modification of the metal electron density tail that is induced by the presence of the adsorbed organic molecules. Our analysis shows that the charge injection barrier in devices can be tuned by modulating various parameters: the chemical potential of the bare metal (given by its work function), the metal surface dipole, and the ionization potential and electron affinity of the organic layer.

  • 13. De, S.
    et al.
    Pascher, T.
    Maiti, M.
    Kesti, T.
    Zhang, Fengling
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Inganäs, Olle
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics.
    Yartsev, A.
    Sundstrom, V.
    Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 27, p. 8466-8472Article in journal (Refereed)
    Abstract [en]

    By measuring excited state and charge dynamics in blends of an alternating polyfluorene copolymer and fullerene derivative over nine orders in time and two orders in light intensity, we have monitored the light-induced processes from ultrafast charge photogeneration to much slower decay of charges by recombination. We find that at low light intensities relevant to solar cell operation relatively fast (∼30 ns) geminate recombination is the dominating charge decay process, while nongeminate recombination has a negligible contribution. The conclusion of our work is that under solar illumination conditions geminate recombination of charges may be directly competing with efficient charge collection in polymer/fullerene solar cells. © 2007 American Chemical Society.

  • 14. Demers, LM
    et al.
    Östblom, Mattias
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Zhang, Hanmin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Jang, NH
    Liedberg, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Mirkin, CA
    Thermal desorption behavior and binding properties of DNA bases and nucleosides on gold2002In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 124, no 38, p. 11248-11249Article in journal (Refereed)
  • 15.
    Dolphin, Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    A designed branched three-helix bundle protein dimer2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 22, p. 7287-7290Article in journal (Refereed)
    Abstract [en]

    The ultimate goals of de novo protein design are the construction of novel tertiary structures and functions. Here is presented the design and synthesis of a uniquely branched three-helix bundle that folds into a well-folded dimeric protein. The branching of this protein was performed by the method of native chemical ligation, which provides a chemoselective and stable amide bond between the unprotected fragments. This ligation strategy was possible by the presented facile preparation of a peptide (43 amino acids) with a specific side chain thioester, which is synthesized by general Fmoc solid phase peptide synthesis. From the presented structural analysis, it is seen that the folded protein is present as a stable and highly helical dimer, thus forming a six-helix bundle. This unique tertiary structure, composed of a dimer of three individual a-helices branched together, offers different possibilities for protein engineering, such as metal and cofactor binding sites, as well as for the construction of novel functions. © 2006 American Chemical Society.

  • 16.
    Durbeej, Bo
    et al.
    Uppsala University, Sweden.
    Eriksson, Leif A.
    Uppsala University, Sweden.
    Thermodynamics of the photoenzymic repair mechanism studied by density functional theory2000In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 122, no 41, p. 10126-10132Article in journal (Refereed)
    Abstract [en]

    The thermodynamics of the different steps in the photoenzymic fragmentation of a thymine dimer is investigated using density functional theory (DFT) methods, including time-dependent (TD) DFT for calculating electronic transition energies, employing a model system consisting of different thymine derivatives and enzymatic cofactors (FADH, 8-HDF, and MTHF). It is found that the crucial electron-transfer steps, as well as the overall reaction, are exothermic and that the splitting of the C6−C6’ bond in a thymine dimer radical anion is slightly exothermic (2.4 kcal mol−1 ) with a 2.3 kcal mol−1 energy barrier. The reaction energies assigned to the different steps are generally in good agreement with the corresponding energies from previous estimates that have constituted the foundation of the proposed reaction mechanism. On the basis of this comparison, the results support the proposed model. Moreover, the excellent agreement between theoretical excitation energies and experimental data shows that TDDFT can be successfully applied to large organic molecules.

  • 17.
    Eckstein, Brian J.
    et al.
    Northwestern University, IL 60208 USA.
    Melkonyan, Ferdinand S.
    Northwestern University, IL 60208 USA.
    Manley, Eric F.
    Northwestern University, IL 60208 USA; Argonne National Lab, IL 60439 USA.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering. Northwestern University, IL 60208 USA.
    Moua, Aidan R.
    Northwestern University, IL 60208 USA.
    Chen, Lin X.
    Northwestern University, IL 60208 USA; Argonne National Lab, IL 60439 USA.
    Facchetti, Antonio
    Northwestern University, IL 60208 USA; Flexterra Corp, IL 60077 USA.
    Marks, Tobin J.
    Northwestern University, IL 60208 USA.
    Naphthalene Bis(4,8-diamino-1,5-dicarboxyl)amide Building Block for Semiconducting Polymers2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 41, p. 14356-14359Article in journal (Refereed)
    Abstract [en]

    We report a new naphthalene bis(4,8-diamino-1,5-dicarboxyl)amide (NBA) building block for polymeric semiconductors. Computational modeling suggests that regio-connectivity at the 2,6- or 3,7-NBA positions strongly modulates polymer backbone torsion and, therefore, intramolecular pi-conjugation and aggregation. Optical, electrochemical, and X-ray diffraction characterization of 3,7- and 2,6-dithienyl-substituted NBA molecules and, corresponding isomeric NBA, bithiophene copolymers P1 and P2, respectively, reveals the key role of regio-connectivity. Charge transport measurements demonstrate that while the twisted 3,7-NDA-based P1 is a poor semiconductor, the planar 2,6-functionalized NBA polymers (P2-P4) exhibit ambipolarity, with mu(e) and mu(h) of up to 0.39 and 0.32 cm(2)/(V.s), respectively.

  • 18.
    Enander, Karin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Dolphin, Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Baltzer, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Designed, functionalized helix-loop-helix motifs that bind human carbonic anhydrase II: a new class of synthetic receptor molecules2004In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 14, p. 4464-4465Article in journal (Refereed)
    Abstract [en]

    Polypeptides designed to fold into helix−loop−helix motifs and to dimerize to form four-helix bundles were functionalized by the introduction of a sulfonamide derivative known to bind human carbonic anhydrase II (HCAII) and one or both of the dansyl- and methoxycoumarin fluorescent probes. The 42-residue sequence DC that carries all three substituents in solvent-exposed positions was found to bind HCAII with a dissociation constant of 5 nM in aqueous solution at pH 7. At 2 μM concentration, DC was mainly dimeric in aqueous solution but bound HCAII as a monomer. Upon addition of a large excess of a helix−loop−helix motif without a high-affinity ligand, KE2-Q, a ternary complex was formed between HCAII, DC, and KE2-Q. Hydrophobic interactions between DC and HCAII and coordination of the sulfonamide group to the zinc ion of HCAII contributed cooperatively to binding in a demonstration of the usefulness of folded polypeptide−small organic molecule chimera as novel protein receptors. The DC homodimer was found to be a very sensitive biosensor component due to intermolecular quenching of its fluorescence that was inhibited upon binding to HCAII.

  • 19.
    Fang, Junfeng
    et al.
    University of Cambridge, England.
    Wallikewitz, Bodo H.
    University of Cambridge, England.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Tu, Guoli
    University of Cambridge, England; Huazhong University of Science and Technology, Peoples R China.
    Mueller, Christian
    University of Cambridge, England.
    Pace, Giuseppina
    University of Cambridge, England.
    Friend, Richard H.
    University of Cambridge, England.
    Huck, Wilhelm T. S.
    University of Cambridge, England; Radboud University of Nijmegen, Netherlands.
    Conjugated Zwitterionic Polyelectrolyte as the Charge Injection Layer for High-Performance Polymer Light-Emitting Diodes2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 4, p. 683-685Article in journal (Refereed)
    Abstract [en]

    A new zwitterionic conjugated polyelectrolyte without free counterions has been used as an electron injection material in polymer light-emitting diodes. Both the efficiency and maximum brightness were considerably improved in comparison with standard Ca cathode devices. The devices showed very fast response times, indicating that the improved performance is, in addition to hole blocking, due to dipoles at the cathode interface, which facilitate electron injection.

  • 20.
    Feng, Guitao
    et al.
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Li, Junyu
    DSM DMSC RandD Solut, Netherlands.
    Colberts, Fallon J. M.
    Eindhoven University of Technology, Netherlands.
    Li, Mengmeng
    Eindhoven University of Technology, Netherlands; Eindhoven University of Technology, Netherlands.
    Zhang, Jianqi
    National Centre Nanosci and Technology, Peoples R China.
    Yang, Fan
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Jin, Yingzhi
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands; Eindhoven University of Technology, Netherlands.
    Li, Cheng
    Chinese Academic Science, Peoples R China.
    Li, Weiwei
    Chinese Academic Science, Peoples R China.
    “Double-Cable” Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 51, p. 18647-18656Article in journal (Refereed)
    Abstract [en]

    A series of "double-cable" conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly(benzodithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a "face-on" orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential pi-pi stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the high-up to 80%-internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.

  • 21.
    Fitie, Carel F. C.
    et al.
    Eindhoven University of Technology, Netherlands.
    Christian Roelofs, W. S.
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Eindhoven University of Technology, Netherlands.
    Sijbesma, Rint P.
    Eindhoven University of Technology, Netherlands.
    Remnant Polarization in Thin Films from a Columnar Liquid Crystal2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 20, p. 6892-+Article in journal (Refereed)
    Abstract [en]

    Ferroelectric switching is demonstrated in a hydrogen bonded columnar liquid crystalline (LC) material. Polar order induced in the LC phase can be frozen by crystallization of the alkyl chains in the periphery of the columns yielding thin films with remnant polarization and an unprecedented high surface potential as shown by scanning Kelvin probe microscopy.

  • 22.
    Garcia-Iglesias, Miguel
    et al.
    Eindhoven University of Technology, Netherlands.
    de Waal, Bas F. M.
    Eindhoven University of Technology, Netherlands.
    Gorbunov, Andrey V.
    Eindhoven University of Technology, Netherlands.
    Palmans, Anja R. A.
    Eindhoven University of Technology, Netherlands.
    Kemerink, Martijn
    Linköping University, Department of Physics, Chemistry and Biology, Complex Materials and Devices. Linköping University, Faculty of Science & Engineering. Eindhoven University of Technology, Netherlands.
    Meijer, E. W.
    Eindhoven University of Technology, Netherlands.
    A Versatile Method for the Preparation of Ferroelectric Supramolecular Materials via Radical End-Functionalization of Vinylidene Fluoride Oligomers2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 19, p. 6217-6223Article in journal (Refereed)
    Abstract [en]

    A synthetic method for the end-functionalization of vinylidene fluoride oligomers (OVDF) via a radical reaction between terminal olefins and I-OVDF is described. The method shows a wide substrate scope and excellent conversions, and permits the preparation of different disc-shaped cores such as benzene-1,3,5-tricarboxamides (BTAs), perylenes bisimide and phthalocyanines (Pc) bearing three to eight ferroelectric oligomers at their periphery. The formation, purity, OVDF conformation, and morphology of the final adducts has been assessed by a combination of techniques, such as NMR, size exclusion chromatography, differential scanning calorimetry, polarized optical microscopy, and atomic force microscopy. Finally, PBI-OVDF and Pc-OVDF materials show ferroelectric hysteresis behavior together with high remnant polarizations, with values as high as P-r approximate to 37 mC/m(2) for Pc-OVDF. This work demonstrates the potential of preparing a new set of ferroelectric materials simply by attaching OVDF oligomers to different small molecules. The use of carefully chosen small molecules paves the way to new functional materials in which ferroelectricity and electrical conductivity or light-harvesting properties coexist in a single compound.

  • 23.
    Hansen, Alexandar L
    et al.
    University of Toronto.
    Lundström, Patrik
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Velyvis, Algirdas
    University of Toronto.
    Kay, Lewis E
    University of Toronto.
    Quantifying Millisecond Exchange Dynamics in Proteins by CPMG Relaxation Dispersion NMR Using Side-Chain H-1 Probes2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 6, p. 3178-3189Article in journal (Refereed)
    Abstract [en]

    A Carr-Purcell-Meiboom-Gill relaxation dispersion experiment is presented for quantifying millisecond time-scale chemical exchange at side-chain H-1 positions in proteins. Such experiments are not possible in a fully protonated molecule because of magnetization evolution from homonuclear scalar couplings that interferes with the extraction of accurate transverse relaxation rates. It is shown, however, that by using a labeling strategy whereby proteins are produced using {C-13,H-1}-glucose and D2O a significant number of isolated side-chain H-1 spins are generated, eliminating such effects. It thus becomes possible to record H-1 dispersion profiles at the beta positions of Ass, Cys, Ser, His, Phe, Tyr, and Trp as well as the gamma positions of Glx, in addition to the methyl side-chain moieties. This brings the total of amino acid side-chain positions that can be simultaneously probed using a single H-1 dispersion experiment to 16. The utility of the approach is demonstrated with an application to the four-helix bundle colicin E7 immunity protein, Im7, which folds via a partially structured low populated intermediate that interconverts with the folded, ground state on the millisecond time-scale. The extracted H-1 chemical shift differences at side-chain positions provide valuable restraints in structural studies of invisible, excited states, complementing backbone chemical shifts that are available from existing relaxation dispersion experiments.

  • 24.
    Hansen, D. Flemming
    et al.
    University of Toronto, Canada.
    Vallurupalli, Pramodh
    University of Toronto, Canada.
    Lundström, Patrik
    University of Toronto, Canada.
    Neudecker, Philipp
    University of Toronto, Canada.
    Kay, Lewis E.
    University of Toronto, Canada.
    Probing chemical shifts of invisible states of proteins with relaxation dispersion NMR spectroscopy: How well can we do?2008In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, no 8, p. 2667-2675Article in journal (Refereed)
    Abstract [en]

    Carr−Purcell−Meiboom−Gill relaxation dispersion NMR spectroscopy has evolved into a powerful approach for the study of low populated, invisible conformations of biological molecules. One of the powerful features of the experiment is that chemical shift differences between the exchanging conformers can be obtained, providing structural information about invisible excited states. Through the development of new labeling approaches and NMR experiments it is now possible to measure backbone 13Cα and 13CO relaxation dispersion profiles in proteins without complications from 13C−13C couplings. Such measurements are presented here, along with those that probe exchange using 15N and 1HN nuclei. A key experimental design has been the choice of an exchanging system where excited-state chemical shifts were known from independent measurement. Thus it is possible to evaluate quantitatively the accuracy of chemical shift differences obtained in dispersion experiments and to establish that in general very accurate values can be obtained. The experimental work is supplemented by computations that suggest that similarly accurate shifts can be measured in many cases for systems with exchange rates and populations that fall within the range of those that can be quantified by relaxation dispersion. The accuracy of the extracted chemical shifts opens up the possibility of obtaining quantitative structural information of invisible states of the sort that is now available from chemical shifts recorded on ground states of proteins.

  • 25.
    Haq, S Raza
    et al.
    Uppsala University.
    Chi, Celestine N
    Uppsala University.
    Bach, Anders
    University of Copenhagen.
    Dogan, Jakob
    Uppsala University.
    Engstrom, Ake
    Uppsala University.
    Hultqvist, Greta
    Uppsala University.
    Karlsson, O Andreas
    Uppsala University.
    Lundström, Patrik
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Montemiglio, Linda C
    University of Roma La Sapienza.
    Stromgaard, Kristian
    University of Copenhagen.
    Gianni, Stefano
    University of Roma La Sapienza.
    Jemth, Per
    Uppsala University.
    Side-Chain Interactions Form Late and Cooperatively in the Binding Reaction between Disordered Peptides and PDZ Domains2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 1, p. 599-605Article in journal (Refereed)
    Abstract [en]

    Intrinsically disordered proteins are very common and mediate numerous protein-protein and protein-DNA interactions. While it is clear that these interactions are instrumental for the life of the mammalian cell, there is a paucity of data regarding their molecular binding mechanisms. Here we have used short peptides as a model system for intrinsically disordered proteins. Linear free energy relationships based on rate and equilibrium constants for the binding of these peptides to ordered target proteins, PDZ domains, demonstrate that native side-chain interactions form mainly after the rate-limiting barrier for binding and in a cooperative fashion. This finding suggests that these disordered peptides first form a weak encounter complex with non-native interactions. The data do not support the recent notion that the affinities of intrinsically disordered proteins toward their targets are generally governed by their association rate constants. Instead, we observed the opposite for peptide-PDZ interactions, namely, that changes in K-d correlate with changes in k(off).

  • 26.
    Hederos, Markus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Synthesis of the Trypanosoma cruzi LPPG heptasaccharyl myo-inositol2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 10, p. 3414-3419Article in journal (Refereed)
    Abstract [en]

    Synthesis of the heptasaccharyl myo-inositol found in Trypanosoma cruzi lipopeptidophosphoglycan was accomplished using a convergent assembly of three building blocks. The target compound is the first complete 2-aminoethyl phosphonic acid substituted glycan related to the glycosylphosphatidylinositol anchor family to be synthesized. The order of assembly enables synthesis of phosphoinositol oligosaccharides related to other glycosylinositolphospholipids in Tr. cruzi, the protozoan parasite causing Chagas' disease, which is endemic in South America.

  • 27.
    Heidebrecht, Tatjana
    et al.
    Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
    Fish, Alexander
    Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
    von Castelmur, Eleonore
    Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
    Johnson, Kenneth A
    Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas, United States.
    Zaccai, Giuseppe
    Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France.
    Borst, Piet
    Division of Molecular Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
    Perrakis, Anastassis
    Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
    Binding of the J-binding protein to DNA containing glucosylated hmU (base J) or 5-hmC: evidence for a rapid conformational change upon DNA binding2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 32, p. 13357-13365Article in journal (Refereed)
    Abstract [en]

    Base J (β-D-glucosyl-hydroxymethyluracil) was discovered in the nuclear DNA of some pathogenic protozoa, such as trypanosomes and Leishmania, where it replaces a fraction of base T. We have found a J-Binding Protein 1 (JBP1) in these organisms, which contains a unique J-DNA binding domain (DB-JBP1) and a thymidine hydroxylase domain involved in the first step of J biosynthesis. This hydroxylase is related to the mammalian TET enzymes that hydroxylate 5-methylcytosine in DNA. We have now studied the binding of JBP1 and DB-JBP1 to oligonucleotides containing J or glucosylated 5-hydroxymethylcytosine (glu-5-hmC) using an equilibrium fluorescence polarization assay. We find that JBP1 binds glu-5-hmC-DNA with an affinity about 40-fold lower than J-DNA (~400 nM), which is still 200 times higher than the JBP1 affinity for T-DNA. The discrimination between glu-5-hmC-DNA and T-DNA by DB-JBP1 is about 2-fold less, but enough for DB-JBP1 to be useful as a tool to isolate 5-hmC-DNA. Pre-steady state kinetic data obtained in a stopped-flow device show that the initial binding of JBP1 to glucosylated DNA is very fast with a second order rate constant of 70 μM(-1) s(-1) and that JBP1 binds to J-DNA or glu-5-hmC-DNA in a two-step reaction, in contrast to DB-JBP1, which binds in a one-step reaction. As the second (slower) step in binding is concentration independent, we infer that JBP1 undergoes a conformational change upon binding to DNA. Global analysis of pre-steady state and equilibrium binding data supports such a two-step mechanism and allowed us to determine the kinetic parameters that describe it. This notion of a conformational change is supported by small-angle neutron scattering experiments, which show that the shape of JBP1 is more elongated in complex with DNA. The conformational change upon DNA binding may allow the hydroxylase domain of JBP1 to make contact with the DNA and hydroxylate T's in spatial proximity, resulting in regional introduction of base J into the DNA.

  • 28.
    Herland, Anna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Nilsson, K. Peter R.
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Olsson, Johan D. M.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hammarström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Konradsson, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Synthesis of a regioregular zwitterionic conjugated oligoelectrolyte, usable as an optical probe for detection of amyloid fibril formation at acidic pH2005In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 7, p. 2317-2323Article in journal (Refereed)
    Abstract [en]

    Changes of the optical properties of conjugated polyelectrolytes have been utilized to monitor noncovalent interactions between biomolecules and the conjugated polyelectrolytes in sensor applications. A regioregular, zwitterionic conjugated oligoelectrolyte was synthesized in order to create a probe with a defined set of optical properties and hereby facilitate interpretation of biomolecule−oligoelectrolyte interactions. The synthesized oligoelectrolyte was used at acidic pH as a novel optical probe to detect amyloid fibril formation of bovine insulin and chicken lysozyme. Interaction of the probe with formed amyloid fibrils results in changes of the geometry and the electronic structure of the oligoelectrolyte chains, which were monitored with absorption and emission spectroscopy.

  • 29.
    Iavicoli, Patrizia
    et al.
    CSIC.
    Xu, Hong
    Katholieke University Leuven.
    Feldborg, Lise N.
    CSIC.
    Linares, Mathieu
    University of Mons.
    Paradinas, Markos
    CSIC.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Ocal, Carmen
    CSIC.
    Len Nieto-Ortega, Be
    University Malaga.
    Casado, Juan
    University Malaga.
    Lopez Navarrete, Juan T.
    University Malaga.
    Lazzaroni, Roberto
    University of Mons.
    De Feyter, Steven
    Katholieke University Leuven.
    Amabilino, David B.
    CSIC.
    Tuning the Supramolecular Chirality of One- and Two-Dimensional Aggregates with the Number of Stereogenic Centers in the Component Porphyrins2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 27, p. 9350-9362Article in journal (Refereed)
    Abstract [en]

    A synthetic strategy was developed for the preparation of porphyrins containing between one and four stereogenic centers, such that their molecular weights vary only as a result of methyl groups which give the chiral forms. The low-dimensional nanoscale aggregates of these compounds reveal the profound effects of this varying molecular chirality on their supramolecular structure and optical activity. The number of stereogenic centers influences significantly the self-assembly and chiral structure of the aggregates of porphyrin molecules described here. A scanning tunneling microscopy study of monolayers on graphite shows that the degree of structural chirality with respect to the surface increases almost linearly with the number of stereogenic centers, and only one handedness is formed in the monolayers, whereas the achiral compound forms a mixture of mirror-image domains at the surface. In solution, four hydrogen bonds induce the formation of an H-aggregate, and circular dichroism measurements and theoretical studies indicate that the compounds self-assemble into helical structures. Both the chirality and stability of the aggregates depend critically on the number of stereocenters. The chiral porphyrin derivatives gelate methylcyclohexane at concentrations dependent on the number and position of chiral groups at the periphery of the aromatic core, reflecting the different aggregation forces of the molecules in solution. Increasing the number of stereogenic centers requires more material to immobilize the solvent, in all likelihood because of the greater solubility of the porphyrins. The vibrational circular dichroism spectra of the gels show that all compounds have a chiral environment around the amide bonds, confirming the helical model proposed by calculations. The morphologies of the xerogels (studied by scanning electron microscopy and scanning force microscopy) are similar, although more fibrous features are present in the molecules with fewer stereogenic centers. Importantly, the presence of only one stereogenic center, bearing a methyl group as the desymmetrizing ligand, in a molecule of considerable molecular weight is enough to induce single-handed chirality in both the one- and two-dimensional supramolecular self-assembled structures.

  • 30.
    Kroon, Renee
    et al.
    University of S Australia, Australia Chalmers, Sweden .
    Diaz de Zerio Mendaza, Amaia
    Chalmers, Sweden .
    Himmelberger, Scott
    Stanford University, CA 94305 USA .
    Bergqvist, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Backe, Olof
    Chalmers, Sweden .
    Couto Faria, Gregorio
    Stanford University, CA 94305 USA University of Sao Paulo, Brazil .
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Obaid, Abdulmalik
    Wake Forest University, NC 27106 USA .
    Zhuang, Wenliu
    Chalmers, Sweden .
    Gedefaw, Desta
    Chalmers, Sweden .
    Olsson, Eva
    Chalmers, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Salleo, Alberto
    Stanford University, CA 94305 USA .
    Muller, Christian
    Chalmers, Sweden .
    Andersson, Mats R.
    University of S Australia, Australia Chalmers, Sweden .
    A New Tetracyclic Lactam Building Block for Thick, Broad-Bandgap Photovoltaics2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 33, p. 11578-11581Article in journal (Refereed)
    Abstract [en]

    A new tetracyclic lactam building block for polymer semiconductors is reported that was designed to combine the many favorable properties that larger fused and/or amide-containing building blocks can induce, including improved solid-state packing, high charge carrier mobility, and improved charge separation. Copolymerization with thiophene resulted in a semicrystalline conjugated polymer, PTNT, with a broad bandgap of 2.2 eV. Grazing incidence wide-angle X-ray scattering of PTNT thin films revealed a strong tendency for face-on pi-stacking of the polymer backbone, which was retained in PTNT:firllerene blends. Corresponding solar cells featured a high open-circuit voltage of 0.9 V, a fill factor around 0.6, and a power conversion efficiency as high as 596 for greater than200 nm thick active layers, regardless of variations in blend stoichiometry and nanostructure. Moreover, efficiencies of greater than4% could be retained when thick active layers of similar to 400 rim were employed. Overall, these values are the highest reported for a conjugated polymer with such a broad bandgap and are unprecedented in materials for tandem and particularly ternary blend photovoltaics. Hence, the newly developed tetracyclic lactam unit has significant potential as a conjugated building block in future organic electronic materials.

  • 31.
    Li, Qing
    et al.
    Soochow Univ, Peoples R China.
    Yang, Biao
    Soochow Univ, Peoples R China.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Zhong, Qigang
    Soochow Univ, Peoples R China; Justus Liebig Univ Giessen, Germany.
    Ju, Huanxin
    Univ Sci and Technol China, Peoples R China.
    Zhang, Junjie
    Soochow Univ, Peoples R China.
    Cao, Nan
    Soochow Univ, Peoples R China.
    Shi, Ziliang
    Soochow Univ, Peoples R China.
    Zhang, Haiming
    Soochow Univ, Peoples R China.
    Ebeling, Daniel
    Justus Liebig Univ Giessen, Germany.
    Schirmeisen, Andre
    Justus Liebig Univ Giessen, Germany.
    Zhu, Junfa
    Univ Sci and Technol China, Peoples R China.
    Chi, Lifeng
    Soochow Univ, Peoples R China.
    Hierarchical Dehydrogenation Reactions on a Copper Surface2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 19, p. 6076-6082Article in journal (Refereed)
    Abstract [en]

    Hierarchical control of chemical reactions is being considered as one of the most ambitious and challenging topics in modern organic chemistry. In this study, we have realized the one-by-one scission of the X-H bonds (X = N and C) of aromatic amines in a controlled fashion on the Cu(lll) surface. Each dehydrogenation reaction leads to certain metal-organic supramolecular structures, which were monitored in single-bond resolution via scanning tunneling microscopy and noncontact atomic force microscopy. Moreover, the reaction pathways were elucidated from X-ray photoelectron spectroscopy measurements and density functional theory calculations. Our insights pave the way for connecting molecules into complex structures in a more reliable and predictable manner, utilizing carefully tuned stepwise on-surface synthesis protocols.

  • 32.
    Li, Zhaojun
    et al.
    Chalmers, Sweden.
    Xu, Xiaofeng
    Chalmers, Sweden.
    Zhang, Wei
    Lund University, Sweden.
    Meng, Xiangyi
    Xi An Jiao Tong University, Peoples R China.
    Ma, Wei
    Xi An Jiao Tong University, Peoples R China.
    Yartsev, Arkady
    Lund University, Sweden.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mats. R.
    University of South Australia, Australia.
    Janssen, Rene A. J.
    Eindhoven University of Technology, Netherlands; Eindhoven University of Technology, Netherlands.
    Wang, Ergang
    Chalmers, Sweden.
    High Performance All-Polymer Solar Cells by Synergistic Effects of Fine-Tuned Crystallinity and Solvent Annealing2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 34, p. 10935-10944Article in journal (Refereed)
    Abstract [en]

    Growing interests have been devoted to the design of polymer acceptors as potential replacement for fullerene derivatives for high-performance all polymer solar cells (all-PSCs). One key factor that is limiting the efficiency of all-PSCs is the low fill factor (FF) (normally amp;lt;0.65), which is strongly correlated with the mobility and film morphology of polymer:polymer blends. In this work, we find a facile method to modulate the crystallinity of the well-known naphthalene diimide (NDI) based polymer N2200, by replacing a certain amount of bithiophene (2T) units in the N2200 backbone by single thiophene (T) units and synthesizing a series of random polymers PNDI-Tx, where x is the percentage of the single T. The acceptor PNDI-T10 is properly miscible with the low band gap donor polymer PTB7-Th, and the nanostructured blend promotes efficient exciton dissociation and charge transport. Solvent annealing (SA) enables higher hole and electron mobilities, and further suppresses the bimolecular recombination. As expected, the PTB7-Th:PNDI-T10 solar cells attain a high PCE of 7.6%, which is a 2-fold increase compared to that of PTB7-Th:N2200 solar cells. The FF of 0.71 reaches the highest value among all-PSCs to date. Our work demonstrates a rational design for fine-tuned crystallinity of polymer acceptors, and reveals the high potential of all-PSCs through structure and morphology engineering of semicrystalline polymer:polymer blends.

  • 33.
    Liu, Jiang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. null.
    Engquist, Isak
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. null.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology. null.
    Double-Gate Light-Emitting Electrochemical Transistor: Confining the Organic p-n Junction2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 33, p. 12224-12227Article in journal (Refereed)
    Abstract [en]

    In conventional light-emitting electrochemical cells (LECs), an off-centered p-n junction is one of the major drawbacks, as it leads to exciton quenching at one of the charge-injecting electrodes and results in performance instability. To combat this problem, we have developed a new device configuration, the double-gate light-emitting electrochemical transistor (DG-LECT), in which the location of the light-emitting p-n junction can be precisely defined via the position of the two gate terminals. Based on a planar LEC structure, two gate electrodes made from an electrochemically active conducting polymer are employed to predefine the p- and n-doped area of the light-emitting polymer. Thus, a p-n junction is formed in between the p-doped and n-doped regions. We demonstrate a homogeneous and centered p-n junction as well as other predefined junction patterns in these DG-LECT devices. Additionally, we report an electrical model that explains the operation of the DG-LECTs. The DG-LECT device provides a new tool to study the fundamental physics of LECs, as it dissects the key working process of LEC into decoupled p-doping, n-doping, and electroluminescence.

  • 34.
    Liu, Jiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Engquist, Isak
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Crispin, Xavier
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Spatial Control of p-n Junction in an Organic Light-Emitting Electrochemical Transistor2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 2, p. 901-904Article in journal (Refereed)
    Abstract [en]

    Low-voltage-operating organic electrochemical light-emitting cells (LECs) and transistors (OECTs) can be realized in robust device architectures, thus enabling easy manufacturing of light sources using printing tools. In an LEC, the p-n junction, located within the organic semiconductor channel, constitutes the active light-emitting element. It is established and fixated through electrochemical p- and n-doping, which are governed by charge injection from the anode and cathode, respectively. In an OECT, the electrochemical doping level along the organic semiconducting channel is controlled via the gate electrode. Here we report the merger of these two devices: the light-emitting electrochemical transistor, in which the location of the emitting p-n junction and the current level between the anode and cathode are modulated via a gate electrode. Light emission occurs at 4 V, and the emission zone can be repeatedly moved back and forth within an interelectrode gap of 500 mu m by application of a 4 V gate bias. In transistor operation, the estimated on/off ratio ranges from 10 to 100 with a gate threshold voltage of -2.3 V and transconductance value between 1.4 and 3 mu S. This device structure opens for new experiments tunable light sources and LECs with added electronic functionality.

  • 35.
    Lundström, Patrik
    et al.
    Lund University, Department of Biophysical Chemistry.
    Akke, Mikael
    Lund University, Department of Biophysical Chemistry.
    Quantitative analysis of conformational exchange contributions to H-1-N-15 multiple-quantum relaxation using field-dependent measurements. Time scale and structural characterization of exchange in a calmodulin C-terminal domain mutant2004In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, ISSN 0002-7863, Vol. 126, no 3, p. 928-935Article in journal (Refereed)
    Abstract [en]

    Multiple-quantum spin relaxation is a sensitive probe for correlated conformational exchange dynamics on microsecond to millisecond time scales in biomolecules. We measured differential H-1-N-15 multiple-quantum relaxation rates for the backbone amide groups of the E140Q mutant of the C-terminal domain of calmodulin at three static magnetic field strengths. The differential multiple-quantum relaxation rates range between -88.7 and 92.7 s(-1), and the mean and standard deviation are 7.0 24 s(-1), at a static magnetic field strength of 14.1 T. Together with values of the H-1 and N-15 chemical shift anisotropies (CSA) determined separately, the field-dependent data enable separation of the different contributions from dipolar-dipolar, CSA-CSA, and conformational exchange cross-correlated relaxation mechanisms to the differential multiple-quantum relaxation rates. The procedure yields precise quantitative information on the dominant conformational exchange contributions observed in this protein. The field-dependent differences between double- and zero-quantum relaxation rates directly benchmark the rates of conformational exchange, showing that these are fast on the chemical shift time scale for the large majority of residues in the protein. Further analysis of the differential H-1-N-15 multiple-quantum relaxation rates using previously determined exchange rate constants and populations, obtained from N-15 off-resonance rotating-frame relaxation data, enables extraction of the product of the chemical shift differences between the resonance frequencies of the H-1 and N-15 spins in the exchanging conformations, deltasigma(H)deltasigma(N). Thus, information on the H-1 chemical shift differences is obtained, while circumventing complications associated with direct measurements of conformational exchange effects on H-1 single-quantum coherences in nondeuterated proteins. The method significantly increases the information content available for structural interpretation of the conformational exchange process, partly because deltasigma(H)deltasigma(N) is a signed quantity, and partly because two chemical shifts are probed simultaneously. The present results support the hypothesis that the exchange in the calcium-loaded state of the E140Q mutant involves conformations similar to those of the wild-type apo (closed) and calcium-loaded (open) states.

  • 36.
    Lundström, Patrik
    et al.
    University of Toronto, Departments of Biochemistry, Chemistry and Medical Genetics.
    Hansen, D. Flemming
    University of Toronto, Departments of Biochemistry, Chemistry and Medical Genetics.
    Vallurupalli, Parmodh
    University of Toronto, Departments of Biochemistry, Chemistry and Medical Genetics.
    Kay, Lewis E.
    University of Toronto, Departments of Biochemistry, Chemistry and Medical Genetics.
    Accurate Measurement of Alpha Proton Chemical Shifts of Excited Protein States by Relaxation Dispersion NMR Spectroscopy2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 5, p. 1915-1926Article in journal (Refereed)
    Abstract [en]

    Carr-Purcell-Meiboom-Gill relaxation dispersion NMR spectroscopy can provide detailed information about low populated, invisible states of protein molecules, including backbone chemical shifts of the invisible conformer and bond vector orientations that can be used as structural constraints. Notably, the measurement of H-1(alpha) chemical shifts in excited protein states has not been possible to date because, in the absence of suitable labeling, the homonuclear proton scalar coupling network in side chains of proteins leads to a significant degradation in the performance of proton-based relaxation dispersion experiments. Here we have overcome this problem through a labeling scheme in which proteins are prepared with U-H-2 glucose and 50% D2O/50% H2O that results in cleuteration levels of between 50-88% at the C-beta carbon. Effects from residual H-1(alpha)-H-1(beta) scalar couplings can be suppressed through a new NMR experiment that is presented here. The utility of the methodology is demonstrated on a ligand binding exchanging system and it is shown that H-1(alpha) chemical shifts extracted from dispersion profiles are, on average, accurate to 0.03 ppm, an order of magnitude better than they can be predicted from structure using a database approach. The ability to measure H-1(alpha) chemical shifts of invisible conformers is particularly important because such shifts are sensitive to both secondary and tertiary structure. Thus, the methodology presented is a valuable addition to a growing list of experiments for characterizing excited protein states that are difficult to study using the traditional techniques of structural biology.

  • 37.
    Lunell, S
    et al.
    Uppsala universitet, Institutionen för kvantkemi.
    Stashans, A
    Ojamae, L
    Lindström, H
    Uppsala universitet, Fysikalisk-kemiska institutionen.
    Hagfeldt, Anders
    Uppsala universitet, Fysikalisk-kemiska institutionen.
    Li and Na diffusion in TiO2 from quantum chemical theory versus electrochemical experiment1997In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 119, no 31, p. 7374-7380Article in journal (Refereed)
    Abstract [en]

    Diffusion of Li and Na ions in TiO2, anatase, has been studied using theoretical (quantum chemical nb initio periodic Hartree-Fock and a modified semiempirical INDO) as well as electrochemical (chronocoloumetry) methods. On the basis of the theoretical ca

  • 38.
    Naguib, Michael
    et al.
    Drexel University, PA USA .
    Halim, Joseph
    Drexel University, PA USA .
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Cook, Kevin M:
    Drexel University, PA USA .
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gogotsi, Yury
    Drexel University, PA USA .
    Barsoum, Michel E.
    Drexel University, PA USA .
    New Two-Dimensional Niobium and Vanadium Carbides as Promising Materials for Li-Ion Batteries2013In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 43, p. 15966-15969Article in journal (Refereed)
    Abstract [en]

    New two-dimensional niobium and vanadium carbides have been synthesized by selective etching, at room temperature, of Al from Nb2AlC and V2AlC, respectively. These new matrials are promising electrode materials for Li-ion batteries, demonstrating good capability to handle high charge-discharge rates. Reversible capacities of 170 and 260 mA.h.g(-1) at 1 C, and 110 and 125 mA.h.g(-1) at 10 C were obtained for Nb2C and V2C-based electrodes, respectively.

  • 39.
    Oliveras-Gonzalez, Cristina
    et al.
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain.
    Di Meo, Florent
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Gonzalez-Campo, Arantzazu
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain.
    Beljonne, David
    University of Mons, Belgium.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Simon-Sorbed, Maite
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Amabilino, David B.
    Institute Ciencia Mat Barcelona ICMAB CSIC, Spain; University of Nottingham, England.
    Bottom-Up Hierarchical Self-Assembly of Chiral Porphyrins through Coordination and Hydrogen Bonds2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 50, p. 15795-15808Article in journal (Refereed)
    Abstract [en]

    A series of chiral synthetic compounds is reported that shows intricate but specific hierarchical assembly because of varying positions of coordination and hydrogen bonds. The evolution of the aggregates (followed by absorption spectroscopy and temperature-dependent circular dichroism studies in solution) reveal the influence of the proportion of stereogenic centers in the side groups connected to the chromophore ring in their optical activity and the important role of pyridyl groups in the self-assembly of these chiral macrocycles. The optical activity spans 2 orders of magnitude depending on composition and constitution. Two of the aggregates show very high optical activity even though the isolated chromophores barely give a circular dichroism signal. Molecular modeling of the aggregates, starting from the pyridine zinc(II) porphyrin interaction and working up, and calculation of the circular dichroism signal confirm the origin of this optical activity as the chiral supramolecular organization of the molecules. The aggregates show a broad absorption range, between approximately 390 and 475 rim for the transitions associated with the Soret region alone, that spans wavelengths far more than the isolated chromophore. The supramolecular assemblies of the metalloporphyrins in solution were deposited onto highly oriented pyrolitic graphite in order to study their hierarchy in assembly by atomic force microscopy. Zero and one-dimensional aggregates were observed, and a clear dependence on deposition temperature was shown, indicating that the hierarchical assembly took place largely in solution. Moreover, scanning electron microscopy images of porphyrins and metalloporphyrins precipitated under out-of-equilibrium conditions showed the dependence of the number and position of chiral amide groups in the formation of a fibrillar nanomaterial. The combination of coordination and hydrogen bonding in the complicated assembly of these molecules where there is a clear hierarchy for zinc(II)-pyridyl interaction followed by hydrogen-bonding between amide groups, and then van der Waals interactions paves the way for the preparation of molecular materials with multiple chromophore environments.

  • 40.
    Pal, Suman Kalyan
    et al.
    Chemical Physics, Lund University.
    Kesti, Tero
    University of Oulu, Finland.
    Maiti, Manisankar
    Chemical Physics, Lund University.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics . Linköping University, The Institute of Technology.
    Hellström, Stefan
    Chalmers University of Technology.
    Andersson, Mats R
    Chalmers University of Technology.
    Oswald, Frederic
    Universidad de Castilla-La Mancha.
    Langa, Fernando
    Universidad de Castilla-La Mancha.
    Österman, Tomas
    Chemical Physics, Lund University:.
    Pascher, Torbjo¨rn
    Chemical Physics, Lund University.
    Yartsev, Arkady
    Chemical Physics, Lund University.
    Sundström, Villy
    Chemical Physics, Lund University.
    Geminate Charge Recombination in Polymer/Fullerene Bulk Heterojunction Films and Implications for Solar Cell Function2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 35, p. 12440-12451Article in journal (Refereed)
    Abstract [en]

    We have studied the influence of three different fullerene derivatives on the charge generation and recombination dynamics of polymer/fullerene bulk heterojunction (BHJ) solar cell blends. Charge generation in APFO3/[70]PCBM and APFO3/[60]PCBM is very similar and somewhat slower than charge generation in APFO3/[70]BTPF. This difference qualitatively matches the trend in free energy change of electron transfer estimated from the LUMO energies of the polymer and fullerene derivatives. The first order (geminate) charge recombination rate is significantly different for the three fullerene derivatives studied and increases in the order APFO3/[70]PCBM andlt; APFO3/[60]PCBM andlt; APFO3/[70]BTPF. The variation in electron transfer rate cannot be explained from the LUMO energies of the fullerene derivatives and single-step electron transfer in the Marcus inverted region and simple considerations of expected trends for the reorganization energy and free energy change. Instead we suggest that geminate charge recombination occurs from a state where electrons and holes have separated to different distances in the various materials because of an initially high charge mobility, different for different materials. In a BHJ thin film this charge separation distance is not sufficient to overcome the electrostatic attraction between electrons and holes and geminate recombination occurs on the nanosecond to hundreds of nanoseconds time scale. In a BHJ solar cell, we suggest that the internal electric field in combination with polarization effects and the dynamic nature of polarons are key features to overcome electron-hole interactions to form free extractable charges.

  • 41.
    Palma, Carlos-Andres
    et al.
    University of Strasbourg, France.
    Björk, Jonas
    University of Liverpool, UK.
    Bonini, Massimo
    BASF SE..
    Dyer, Matthew S.
    University of Liverpool, UK.
    Llanas-Pallas, Anna
    University of Trieste, Italy.
    Bonifazi, Davide
    University of Trieste, Italy.
    Persson, Mats
    University of Liverpool, UK.
    Samorì, Paolo
    University of Strasbourg, France.
    Tailoring Bicomponent Supramolecular Nanoporous Networks: Phase Segregation, Polymorphism, and Glasses at the Solid−Liquid Interface2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 36, p. 13062-13071Article in journal (Refereed)
    Abstract [en]

    We study the formation of four supramolecular bicomponent networks based on four linear modules (linkers) bridging melamine via triple hydrogen-bonds. We explore at the nanoscale level the phenomena of polymorphism and phase segregation which rule the generation of highly crystalline nanoporous patterns self-assembled at the solid-liquid interface. The investigated linkers include two systems exposing diuracil groups in the R and ω position, naphthalene tetracarboxylic diimide and pyromellitic diimide. In situ scanning tunneling microscopy (STM) investigations revealed that, when blended with melamine, out of the four systems, three are able to form two-dimensional (2D) porous architectures, two of which exhibit highly ordered hexagonal structures, while pyromellitic diimide assembles only into one- dimensional (1D) supramolecular arrays. These bicomponent self-assembled monolayers are used as a test bed to gain detailed insight into phase segregation and polymorphism in 2D supramolecular systems by exploring the contribution of hydrogen-bond energy and periodicity, molecular flexibility, concentration and ratio of the components in solution as well as the effect of annealing via time-dependent and temperature-modulated experiments. These comparative studies, obtained through a joint experimental and computational analysis, offer new insights into strategies toward the bottom-up fabrication of highly ordered tunable nanopatterning at interfaces mediated by hydrogen bonds.

  • 42.
    Palma, Carlos-Andres
    et al.
    Technishe Universität München, Garching, Germany.
    Diller, Katharina
    Technishe Universität München, Garching, Germany.
    Berger, Reinhard
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Welle, Alexander
    Karlsruher Institut für Technologie, Eggenstein-Leopoldshafen, Germany.
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Cabellos, Jose Luis Cabellos
    Universidad del País Vasco UPV/EHU, San Sebastián, Spain.
    Mowbray, Duncan John
    Universidad del País Vasco UPV/EHU, San Sebastián, Spain.
    Papageorgiou, Anthoula C.
    Technishe Universität München, Garching, Germany.
    Ivleva, Natalia P.
    Technische Universität München, München, Germany.
    Matich, Sonja
    Walter Schottky Institut, Garching, Germany.
    Margapoti, Emanuela
    Walter Schottky Institut, Garching, Germany.
    Niesser, Reinhard
    Technische Universität München, Germany.
    Menges, Bernhard
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Reichert, Joachim
    Technishe Universität München, Garching, Germany.
    Feng, Xinliang
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Räder, Hans Joachim
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Klappenberger, Florian
    Technishe Universität München, Garching, Germany.
    Rubio, Angel
    Universidad del País Vasco UPV/EHU, San Sebastián, Spain.
    Müllen, Klaus
    Max-Planck-Institut für Polymerforschung, Mainz, Germany.
    Barth, Johannes V.
    Technishe Universität München, Garching, Germany.
    Photo-induced C-C reactions on insulators towards photolithography of graphene nanoarchitectures2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, p. 4651-4658Article in journal (Refereed)
    Abstract [en]

    On-surface chemistry for atomically precise sp2 macromolecules requires top-down lithographic methods on insulating surfaces in order to pattern the long-range complex architectures needed by the semiconductor industry. Here, we fabricate sp2-carbon nm-thin films on insulators and under ultra-high vacuum (UHV) conditions from photo-coupled brominated precursors. We reveal that covalent coupling is initiated by C-Br bond cleavage through photon energies exceeding 4.4 eV, as monitored by laser desorption ionization (LDI) mass spectrometry (MS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) gives insight into the mechanisms of C-Br scission and C-C coupling processes. Further, unreacted material can be sublimed and the coupled sp2-carbon precursors can be graphitized by e-beam treatment at 500°C, demonstrating promising applications in photolithography of graphene nanoarchitectures. Our results present UV-induced reactions on insulators for the formation of all sp2-carbon architectures, thereby converging top-down lithography and bottom-up on-surface chemistry into technology.

  • 43.
    Parvez, Khaled
    et al.
    Max Planck Institute Polymer Research, Germany .
    Wu, Zhong-Shuai
    Max Planck Institute Polymer Research, Germany .
    Li, Rongjin
    Max Planck Institute Polymer Research, Germany .
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Graf, Robert
    Max Planck Institute Polymer Research, Germany .
    Feng, Xinliang
    Max Planck Institute Polymer Research, Germany Shanghai Jiao Tong University, Peoples R China .
    Muellen, Klaus
    Max Planck Institute Polymer Research, Germany .
    Exfoliation of Graphite into Graphene in Aqueous Solutions of Inorganic Salts2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 16, p. 6083-6091Article in journal (Refereed)
    Abstract [en]

    Mass production of high-quality graphene sheets is essential for their practical application in electronics, optoelectronics, composite materials, and energy-storage devices. Here we report a prompt electrochemical exfoliation of graphene sheets into aqueous solutions of different inorganic salts ((NH4)(2)SO4, Na2SO4, K2SO4, etc.). Exfoliation in these electrolytes leads to graphene with a high yield (greater than85%, less than= 3 layers), large lateral size (up to 44 mu m), low oxidation degree (a C/O ratio of 17.2), and a remarkable hole mobility of 310 cm(2) V-1 s(-1). Further, highly conductive graphene films (11 Omega sq(-1)) are readily fabricated on an A4-size paper by applying brush painting of a concentrated graphene ink (10 mg mL(-1), in N,N-dimethylformamide). All-solid-state flexible supercapacitors manufactured on the basis of such graphene films deliver a high area capacitance of 11.3 mF cm(-2) and an excellent rate capability of 5000 mV s(-1). The described electrochemical exfoliation shows great promise for the industrial-scale synthesis of high-quality graphene for numerous advanced applications.

  • 44.
    Payer, Dietmar
    et al.
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Rauschenbach, Stephan
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Malinowski, Nicola
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Konuma, M
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Virojanadara, Chariya
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Starke, Ulrich
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Dietrich-Buchecker, Christiane
    Université Louis Pasteur, Strasbourg-Cedex, France.
    Collin, Jean-Paul
    Université Louis Pasteur, Strasbourg-Cedex, France.
    Sauvage, Jean-Pierre
    Université Louis Pasteur, Strasbourg-Cedex, France.
    Lin, Nian
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Kern, Klaus
    Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany.
    Toward Mechanical Switching of Surface-Adsorbed [2]Catenane by in Situ Copper Complexation2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, p. 15662-15667Article in journal (Refereed)
    Abstract [en]

    Using scanning tunneling microscopy (STM), electrospray ionization mass spectrometry (ESI-MS), and X-ray photoelectron spectroscopy (XPS), we demonstrate that a free [2]catenane consisting of two interlocking 30-membered rings (cat-30) can be deposited on a Ag(111) surface by vacuum sublimation without decomposition. The deposited cat-30 molecules self-organize as ordered dimer chain structures at the surface, presumably via intermolecular π−π stacking. An in situ addition of Cu atoms to the surface-adsorbed catenanes induces a drastic change in the molecular organization, i.e., from the dimer chain structure to isolated species. The nitrogen core level spectra suggest that the cat-30 phenanthroline units coordinate with Cu, indicating that the free catenane has been transformed into a Cu-complexed [2]catenane. Since it is known that the two interlocked macrocyclic rings of the free ligand cat-30 completely rearrange, i.e., circumrotate, upon complexation to copper, our results reveal that when adsorbed on the silver surface, the two macrocyclic rings of the free [2]catenane can glide within one another so as to generate the corresponding copper complex by in situ Cu complexation. 

  • 45.
    Peng, Xinsheng
    et al.
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    Jeng, Jian
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    Ericsson, Emma
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    Ichinose, Izumi
    National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba.
    General method for ultrathin free-standing films of nanofibrous composite materials2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 27, p. 8625-8633Article in journal (Refereed)
    Abstract [en]

    A simple and general method for the preparation of ultrathin, large-area, free-standing films of nanofibrous composite materials was developed. First, positively charged cadmium hydroxide nanostrands of 1.9 nm in diameter and micrometers in length were prepared by mixing dilute aqueous solutions of cadmium chloride and aminoethanol. Negatively charged dye molecules, proteins, nanoparticles, and water-soluble fullerene or carbon nanotubes were mixed with the nanostrands to give a well-dispersed solution of the corresponding nanofibrous composites. After filtration of the dispersions with a polycarbonate membrane filter, uniform films with a thickness of a few tens to hundreds of nanometers and a diameter of a few centimeters were obtained. The films were readily peeled off from the membrane filter by immersion in ethanol. The resultant free-standing films could be further transferred to other substrates, such as quartz plate, gold electrode, and porous alumina membrane, and were characterized by scanning and transmission electron microscopies. We provide herein various nanofibrous free-standing films with optical, biological, metallic, and magnetic properties.

  • 46.
    Pranculis, Vytenis
    et al.
    Centre Phys Science and Technology, Lithuania .
    Infahsaeng, Yingyot
    Lund University, Sweden .
    Tang, Zheng
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Devizis, Andrius
    Centre Phys Science and Technology, Lithuania .
    Vithanage, Dimali A.
    Lund University, Sweden .
    Ponseca, Carlito S. Jr.
    Lund University, Sweden .
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Yartsev, Arkady P.
    Lund University, Sweden .
    Gulbinas, Vidmantas
    Centre Phys Science and Technology, Lithuania .
    Sundstrom, Villy
    Lund University, Sweden .
    Charge Carrier Generation and Transport in Different Stoichiometry APFO3:PC61BM Solar Cells2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 32, p. 11331-11338Article in journal (Refereed)
    Abstract [en]

    In this paper we studied carrier drift dynamics in APFO3:PC61BM solar cells of varied stoichiometry (2:1, 1:1, and 1:4 APFO3:PC61BM) over a wide time range, from subpicoseconds to microseconds with a combination of ultrafast optical electric field probing and conventional transient integrated photocurrent techniques. Carrier drift and extraction dynamics are strongly stoichiometry dependent: the speed of electron or hole drift increases with higher concentration of PC61BM or polymer, respectively. The electron extraction from a sample with 80% PC61BM takes place during hundreds of picoseconds, but slows down to sub-microseconds in a sample with 33% PC61BM. The hole extraction is less stoichiometry dependent: it varies form sub-nanoseconds to tens of nanoseconds when the PC61BM concentration changes from 33% to 80%. The electron extraction rate correlates with the conversion efficiency of solar cells, leading to the conclusion that fast electron motion is essential for efficient charge carrier separation preventing their geminate recombination.

  • 47.
    Razkin, J.
    et al.
    Department of Applied Chemistry, Public University of Navarra, 31006 Pamplona, Navarra, Spain.
    Nilsson, Helena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry .
    Baltzer, L.
    Department of Biochemistry and Organic Chemistry, Uppsala University, Box 576, SE-75123 Uppsala, Sweden.
    Catalysis of the cleavage of uridine 3'-2,2,2-trichloroethylphosphate by a designed helix-loop-helix motif peptide2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 47, p. 14752-14758Article in journal (Refereed)
    Abstract [en]

    A 42-residue peptide that folds into a helix-loop-helix motif and dimerizes to form a four-helix bundle has been designed to catalyze the hydrolysis of phosphodiesters. The active site on the surface of the folded catalyst is composed of two histidine and four arginine residues, with the capacity to provide general acid, general base, and/or nucleophilic catalysis as well as transition state stabilization. Uridine 3'-2,2,2 trichloroethylphosphate (2) is a mimic of RNA with a leaving group pKa of 12.3. Its hydrolysis is energetically less favorable than that of commonly used model substrates with p-nitrophenyl leaving groups and therefore a more realistic model for the design of catalysts capable of cleaving RNA. The second-order rate constant for the hydrolysis of 2 at pH 7.0 by the polypeptide catalyst was 418 × 10-6 M-1 s-1, and that of the imidazole catalyzed reaction was 1.66 × 10-6 M-1 s -1. The pH dependence suggested that catalysis is due to the unprotonated form of a residue with a pKa of around 5.3, and the observed kinetic solvent isotope effect of 1.9 showed that there is significant hydrogen bonding in the transition state, consistent with general acid-base catalysis. The rate constant ratio k2(Pep)/k2(Im) of 252 is probably due to a combination of nucleophilic and general acid-base catalysis, as well as transition state stabilization. Substrate binding was weak since no sign of saturation kinetics was observed for substrate concentrations in the range from 5 to 40 mM. The results provide a platform for the further development of catalysts for RNA cleavage with a potential role in the development of drugs. © 2007 American Chemical Society.

  • 48.
    Ruda, K.
    et al.
    Department of Chemistry, Linkoping University, Linkoping SE-581 83, Sweden.
    Lindberg, J.
    Department of Chemistry, Linkoping University, Linkoping SE-581 83, Sweden.
    Garegg, P.J.
    Department of Chemistry, Linkoping University, Linkoping SE-581 83, Sweden.
    Oscarson, S.
    Department of Chemistry, Linkoping University, Linkoping SE-581 83, Sweden.
    Konradsson, P.
    Department of Chemistry, Linkoping University, Linkoping SE-581 83, Sweden.
    Synthesis of the Leishmania LPG core heptasaccharyl myo-inositol2000In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 122, no 45, p. 11067-11072Article in journal (Refereed)
    Abstract [en]

    Total synthesis of the core heptasaccharyl myo-inositol, Galp(a1-6)Galp(a1-3)Galf(ß1-3)[Glcp(a1-PO4-6)Manp](a1-3)Manp(a1-4)GlcN p(a1-6)Ins-1-PO4, and the corresponding hexasaccharyl myo-inositol, Galp(a1-6)Galp(a1-3)Galf(ß1-3)Manp(a1-3)Manp(a1-4)GlcNp(a1-6)Ins-1-PO4 , found in the lipophosphoglycans of Leishmania parasites are described. The target molecules contain synthetic challenges such as an unusual internal galactofuranosyl residue and an anomeric phosphodiester. The synthesis was accomplished using a convergent block synthetic strategy. Four building blocks, a trigalactoside, a dimannoside, a glucosyl inositolphosphate, and a glucosyl-a-1-H-phosphonate, all appropriately protected, were used. The trigalactoside was linked to the dimannoside followed by glycosylation with the glucosyl inositolphosphate to produce the fully protected hexasaccharyl myo-inositol. Subsequent oxidative coupling of the glucosyl-H-phosphonate formed the anomeric phosphodiester linkage to produce the protected heptasaccharyl myo-inositol. Both the assembly order of the subunits and sequence of deprotection were essential for the successful synthesis of these complex molecules. The deprotection was accomplished by deacetylation and clevage of benzyl ethers with sodium in liquid ammonia, followed by acidic deacetalization/desilylation to produce the target molecules.

  • 49.
    Sekretaryova, Alina N.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail Yu.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony P.F.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Electrocatalytic Currents from Single Enzyme Molecules2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 8, p. 2504-2507Article in journal (Refereed)
    Abstract [en]

    Single molecule enzymology provides an opportunity to examine details of enzyme mechanisms that are not distinguishable in biomolecule ensemble studies. Here we report, for the first time, detection of the current produced in an electrocatalytic reaction by a single redox enzyme molecule when it collides with an ultramicroelectrode. The catalytic process provides amplification of the current from electron-transfer events at the catalyst leading to a measurable current. This new methodology monitors turnover of a single enzyme molecule. The methodology might complement existing single molecule techniques, giving further insights into enzymatic mechanisms and filling the gap between fundamental understanding of biocatalytic processes and their potential for bioenergy production.

  • 50.
    Shchyrba, Aneliia
    et al.
    University of Basel, Switzerland .
    Waeckerlin, Christian
    Paul Scherrer Institute, Villigen, Switzerland .
    Nowakowski, Jan
    Paul Scherrer Institute, Villigen, Switzerland .
    Nowakowska, Sylwia
    University of Basel, Switzerland .
    Björk, Jonas
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Fatayer, Shadi
    University of Basel, Switzerland .
    Girovsky, Jan
    Paul Scherrer Institute, Villigen, Switzerland .
    Nijs, Thomas
    University of Basel, Switzerland .
    Martens, Susanne C.
    University of Basel, Switzerland; Heidelberg University, Germany .
    Kleibert, Armin
    Paul Scherrer Institute, Villigen, Switzerland .
    Stoehr, Meike
    University of Groningen, Netherlands .
    Ballav, Nirmalya
    Indian Institute of Science Education and Research, Pune, India.
    Jung, Thomas A.
    Paul Scherrer Institute, Villigen, Switzerland .
    Gade, Lutz H.
    Heidelberg University, Germany .
    Controlling the dimensionality of on-surface coordination polymers via endo- or exoligation2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 26, p. 9355-9363Article in journal (Refereed)
    Abstract [en]

    The formation of on-surface coordination polymers is controlled by the interplay of chemical reactivity and structure of the building blocks, as well as by the orientating role of the substrate registry. Beyond the predetermined patterns of structural assembly, the chemical reactivity of the reactants involved may provide alternative pathways in their aggregation. Organic molecules, which are transformed in a surface reaction, may be subsequently trapped via coordination of homo- or heterometal adatoms, which may also play a role in the molecular transformation. The amino-functionalized perylene derivative, 4,9-diaminoperylene quinone-3,10-diimine (DPDI), undergoes specific levels of dehydrogenation (-1 H-2 or -3 H-2) depending on the nature of the present adatoms (Fe, Co, Ni or Cu). In this way, the molecule is converted to an endo- or an exoligand, possessing a concave or convex arrangement of ligating atoms, which is decisive for the formation of either ID or 2D coordination polymers.

12 1 - 50 of 61
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