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  • 151. Hagfeldt, Anders
    et al.
    Cappel, U.B.
    Boschloo, G.
    Sun, L.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Pettersson, H.
    Gibson, E.A.
    Dye-sensitized Photoelectrochemical Cells2012In: Practical Handbook of Photovoltaics Findamentals and Applications, 2nd Edition / [ed] A. McEvoy, T. Markvart, L.Castaner, Oxford: Academic Press, 2012, 2, p. 479-542Chapter in book (Refereed)
    Abstract [en]

    As part of the growing sustainable and renewable energy movement, the design, manufacture and use of photovoltaic devices is increasing in pace and frequency. The Handbook of Photovoltaics will be a 'benchmark' publication for those involved in the design, manufacture and use of these devices. The Handbook covers the principles of solar cell function, the raw materials, photovoltaic systems, standards, calibration, testing, economics and case studies. The editors have assembled a cast of internationally-respected contributors from industry and academia. The report is essential reading for: Physicists, electronic engineers, designers of systems, installers, architects, policy-makers relating to photovoltaics.

  • 152.
    Halldin Stenlid, Joakim
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden.

    In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface.

    An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces.

    Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology.

  • 153.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Extending the σ-Hole Concept to Metals: An Electrostatic Interpretation of the Nanostructural Effects in Gold and Platinum Catalysis2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126Article in journal (Refereed)
    Abstract [en]

    Crystalline surfaces of gold are chemically inert, whereas nanoparticles of gold are excellent catalysts for many reactions. The catalytic properties of nanostructured gold have been connected to increased binding affinities of reactant molecules to low-coordinated Au atoms. Here we show that the high reactivity at these sites is a consequence of the formation of σ-holes, i.e. maxima in the surface electrostatic potential (Vs,max) due to the overlap of mainly the valence s-orbitals when forming the bonding σ-orbitals. The σ-holes are binding sites for Lewis bases, and binding energies correlate with magnitudes of the Vs,max. For symmetrical Au clusters, of varying size, the most positive Vs,max are found at corners, edges, and surfaces (facets) and decreasing in that order. This is in agreement with the experimentally and theoretically observed dependence of catalytic activity on local structure. The density of σ-holes can explain the increasing catalytic activity with decreasing particle size also for other transition metal catalysts, such as platinum.

  • 154.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johaness
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    σ-Holes on Transition Metal Nanoclusters and Their Influence on the Local Lewis Acidity2017In: Crystals, ISSN 2073-4352, Vol. 7, article id 222Article in journal (Refereed)
    Abstract [en]

    Understanding the molecular interaction behavior of transition metal nanoclusters lies at the heart of their efficient use in, e.g., heterogeneous catalysis, medical therapy and solar energy harvesting. For this purpose, we have evaluated the applicability of the surface electrostatic potential [VS(r)] and the local surface electron attachment energy [ES(r)] properties for characterizing the local Lewis acidity of a series of low-energy TM13 transition metal nanoclusters (TM = Au, Cu, Ru, Rh, Pd, Ir, Pt, Co), including also Pt7Cu6. The clusters have been studied using hybrid Kohn–Sham density functional theory (DFT) calculations. The VS(r) and ES(r), evaluated at 0.001 a.u. isodensity contours, are used to analyze the interactions with H2O. We find that the maxima of VS(r), σ-holes, are either localized or diffuse. This is rationalized in terms of the nanocluster geometry and occupation of the clusters’s, p and d valence orbitals. Our findings motivate a new scheme for characterizing σ-holes as σs (diffuse), σp (localized) or σd (localized) depending on their electronic origin. The positions of the maxima in VS(r) (and minima in ES(r)) are found to coincide with O-down adsorption sites of H2O, whereas minima in VS(r) leads to H-down adsorption. Linear relationships between VS,max (and ES,min) and H2O interaction energies are further discussed.

  • 155.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    The Local Electron Attachment Energy and the Electrostatic Potential as Descriptors of Surface- Adsorbate InteractionsManuscript (preprint) (Other academic)
  • 156.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Local Lewis Acidity of (TiO2)n n=7-10 Nanoparticles Characterized by DFT-Based DescriptorsManuscript (preprint) (Other academic)
  • 157.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    Swedish Nuclear Fuel and Waste Management Co (SKB).
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Searching for the thermodynamic limit - a DFT study of the step-wise water oxidation of the bipyramidal Cu-7 cluster2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 6, p. 2452-2464Article in journal (Refereed)
    Abstract [en]

    Oxidative degradation of copper in aqueous environments is a major concern in areas such as catalysis, electronics and construction engineering. A particular challenge is to systematically investigate the details of this process for non-ideal copper surfaces and particles under the conditions found in most real applications. To this end, we have used hybrid density functional theory to study the oxidation of a Cu-7 cluster in water solution. Especially, the role of a large water coverage is explored. This has resulted in the conclusion that, under atmospheric H-2 pressures, the thermodynamically most favored state of degradation is achieved upon the generation of four H-2 molecules (i.e. Cu-7 + 8H(2)O -> Cu-7(OH)(8) + 4H(2)) in both condensed and gas phases. This state corresponds to an average oxidation state below Cu(I). The calculations suggest that the oxidation reaction is slow at ambient temperatures with the water dissociation as the rate-limiting step. Our findings are expected to have implication for, among other areas, the copper catalyzed water-gas shift reaction, and for the general understanding of copper corrosion in aqueous environments.

  • 158.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    sigma-Holes and sigma-lumps direct the Lewis basic and acidic interactions of noble metal nanoparticles: introducing regium bonds2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 4, p. 2676-2692Article in journal (Refereed)
    Abstract [en]

    Using local DFT-based probes for electrostatic as well as charge transfer/polarization interactions, we are able to characterize Lewis basic and acidic sites on copper, silver and gold nanoparticles. The predictions obtained using the DFT-probes are compared to the interaction energies of the electron donating (CO, H2O, NH3 and H2S) and the electron accepting (BH3, BF3, HCl [H-down] and Na+) compounds. The probes include the local electron attachment energy [E(r)], the average local ionization energy [% I(r)], and the electrostatic potential [V(r)] and are evaluated on isodensity surfaces located at distances corresponding to typical interaction distances. These probes have previously been successful in characterizing molecular interactions. Good correlations are found between Lewis acidity and maxima in V(r), appearing as a consequence of sigma-holes, as well as minima in E(r), of the noble metal nanoparticles. Similarly are Lewis basic sites successfully described by surface minima in V(r) and % I(r); the former are indicative of sigma-lumps, i.e. regions of enhanced sigma-density. The investigated probes are anticipated to function as reliable tools in nanoparticle reactivity and interaction characterization, and may act as suitable descriptors in large-scale screenings for materials of specific properties, e.g. in heterogeneous catalysis. Because of the similarity between the noble metal nanoparticle's interactions with Lewis bases and the concepts of halogen and hydrogen bonding, a new class of bonds is introduced - regium bonds - taking place between a sigma-hole of a Cu, Ag or Au compound and an electron donor.

  • 159.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    σ-Holes and σ-Lumps Direct the Lewis Basic and Acidic Interactions of Noble Metal Nanoparticles: Introducing Regium BondsManuscript (preprint) (Other academic)
  • 160.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Aqueous Solvation and Surface Oxidation of the Cu7 Nanoparticle: Insights from Theoretical Modeling2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 3, p. 1977-1988Article in journal (Refereed)
    Abstract [en]

    The current understanding on: the behavior of nano particles in solution is limited. We have studied tho effects of the aqueous environment on the anoxic oxidation of a Cu-7 riannpartide using a range of different computational solvation models. On the basis of a series of hydroxylated Cu-7(H2O)(y)(OH)x structures, the performance of standard continuum models have been compared to discrete models including up to, and beyond, the second solvation layer. Both full quantum chemical 4 (DFT: PBEO-D3) and QM/MM (PBEO/EPP1) computations were employed in the analysis. The Cu-7 structures were solvated in water nanodroplets and studied by molecular dynamics simulations. On the basis of the simulations, we were able to identify new modes of H2O interactions with the Cu(7)particle, modes that were previously considered unbeneficial. All solvation models favor the "Same equilibrium oxidation state corresponding to a Cu(I)OH surface species. However, for quantitative energy comparison of similar- systems, our results suggest the use of a combined water cinst07cniftinuum model including at least a first explicit solvation shell for energetic comparisons. Nevertheless, the second solvatiOn:thell is -important for identifying representative inner solvation shell structures.

  • 161.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Adam Johannes
    Leygraf, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Computational Analysis of the Early Stage of Cuprous Oxide Sulphidation: A Top-Down Process2017In: Corrosion Engineering, Science and Technology, ISSN 1478-422X, E-ISSN 1743-2782, Vol. 52, no S1, p. 50-53Article in journal (Refereed)
    Abstract [en]

    The initial steps of Cu2O sulphidation to Cu2S have been studied using plane-wave density functional theory at the PBE-D3+U level of sophistication. Surface adsorption and dissociation of H2S and H2O, as well as the replacement reaction of lattice oxygen with sulphur, have been investigated for the most stable (111) and (100) surface facets under oxygen-lean conditions. We find that the (100) surface is more susceptible to sulphidation than the (111) surface, promoting both H2S adsorption, dissociation and the continued oxygen–sulphur replacement. The results presented in this proceeding bridge previous results from high-vacuum experiments on ideal surface to more realistic corrosion conditions and set the grounds for future mechanistic studies. Potential implications on the long-term final disposal of spent nuclear fuel are discussed.

  • 162.
    Halldin Stenlid, Joakim
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Johansson, A. J.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Reactivity at the Cu2O(100):Cu-H2O interface: a combined DFT and PES study2016In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, no 44, p. 30570-30584Article in journal (Refereed)
    Abstract [en]

    The water-cuprite interface plays an important role in dictating surface related properties. This not only applies to the oxide, but also to metallic copper, which is covered by an oxide film under typical operational conditions. In order to extend the currently scarce knowledge of the details of the water-oxide interplay, water interactions and reactions on a common Cu2O(100):Cu surface have been studied using high-resolution photoelectron spectroscopy (PES) as well as Hubbard U and dispersion corrected density functional theory (PBE-D3+U) calculations up to a bilayer water coverage. The PBE-D3+U results are compared with PBE, PBE-D3 and hybrid HSE06-D3 calculation results. Both computational and experimental results support a thermodynamically favored, and H2O coverage independent, surface OH coverage of 0.25-0.5 ML, which is larger than the previously reported value. The computations indicate that the results are consistent also for ambient temperatures under wet/humid and oxygen lean conditions. In addition, both DFT and PES results indicate that the initial (3,0; 1,1) surface reconstruction is lifted upon water adsorption to form an unreconstructed (1 x 1) Cu2O(100) structure.

  • 163. Hammer, Stephan C.
    et al.
    Syrén, Per-Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hauer, Bernhard
    Substrate Pre-Folding and Water Molecule Organization Matters for Terpene Cyclase Catalyzed Conversion of Unnatural Substrates2016In: CHEMISTRYSELECT, ISSN 2365-6549, Vol. 1, no 13, p. 3589-3593Article in journal (Refereed)
    Abstract [en]

    Terpene cyclase enzymes have recently been challenged with terpene substrate derivatives to generate additional chemical complexity beyond to what is currently found in nature. Herein, molecular dynamics and biocatalysis are used to shed light on the flexibility and inherent limitation of a triterpene cyclase in converting unnatural substrates. Our studies suggest that populating binding modes which allows for concerted reaction pathways is a key element towards an expanded substrate scope and new chemistries displayed by terpene cyclases. Additionally, we show that the spatial organization of water, which is influenced by both the substrate architecture as well as the active site geometry, controls the product selectivity. This highlights that activity and selectivity displayed by terpene cyclases acting on unnatural substrates is particularly difficult to predict, since they depend on various parameters.

  • 164. Hao, Yan
    et al.
    Saygili, Yasemin
    Cong, Jiayan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Eriksson, Anna
    Yang, Wenxing
    Zhang, Jinbao
    Polanski, Enrico
    Nonomura, Kazuteru
    Zakeeruddin, Shaik Mohammed
    Gratzel, Michael
    Hagfeldt, Anders
    Boschloo, Gerrit
    Novel Blue Organic Dye for Dye-Sensitized Solar Cells Achieving High Efficiency in Cobalt-Based Electrolytes and by Co-Sensitization2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 48, p. 32797-32804Article in journal (Refereed)
    Abstract [en]

    Blue and green dyes as well as NIR-absorbing dyes have attracted great interest because of their excellent ability of absorbing the incident photons in the red and near-infrared range region. A novel blue D-pi-A dye (Dyenamo Blue), based on the diketopyrrolopyrrole (DPP)-core, has been designed and synthesized. Assembled with the cobalt bipyridine-based electrolytes, the device with Dyenamo Blue achieved a satisfying efficiency of 7.3% under one sun (AM1.5 G). The co-sensitization strategy was further applied on this blue organic dye together with a red D-pi-A dye (D35). The successful co-sensitization outperformed a panchromatic light absorption and improved the photocurrent density; this in addition to the open-circuit potential result in an efficiency of 8.7%. The extended absorption of the sensitization and the slower recombination reaction between the blue dye and TiO2 surface inhibited by the additional red sensitizer could be the two main reasons for the higher performance. In conclusion, from the results, the highly efficient cobalt-based DSSCs could be achieved with the co-sensitization between red and blue D-pi-A organic dyes with a proper design, which showed us the possibility of applying this strategy for future high-performance solar cells.

  • 165. Hao, Yan
    et al.
    Yang, Xichuan
    Cong, Jiayan
    Tian, Haining
    Hagfeldt, Anders
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Efficient near infrared D-pi-A sensitizers with lateral anchoring group for dye-sensitized solar cells2009In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 27, p. 4031-4033Article in journal (Refereed)
    Abstract [en]

    A new strategy in which the anchoring group is separated from the acceptor groups of the dyes was developed; among these dyes, the HY103 dye gives a maximum IPCE value of 86% at 660 nm and an eta value of 3.7% in the NIR region reported in DSCs.

  • 166.
    Hedberg, Jonas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Skoglund, Sara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Karlsson, Maria-Elisa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Sequential Studies of Silver Released from Silver Nanoparticles in Aqueous Media Simulating Sweat, Laundry Detergent Solutions and Surface Water2014In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, no 13, p. 7314-7322Article in journal (Refereed)
    Abstract [en]

    From an increased use of silver nanoparticles (Ag NPs) as an antibacterial in consumer products follows a need to assess the environmental interaction and fate of their possible dispersion and release of silver. This study aims to elucidate an exposure scenario of the Ag NPs potentially released from, for example, impregnated clothing by assessing the release of silver and changes in particle properties in sequential contact with synthetic sweat, laundry detergent solutions, and freshwater, simulating a possible transport path through different aquatic media. The release of ionic silver is addressed from a water chemical perspective, compared with important particle and surface characteristics. Released amounts of silver in the sequential exposures were significantly lower, approximately a factor of 2, than the sum of each separate exposure. Particle characteristics such as speciation (both of Ag ionic species and at the Ag NP surface) influenced the release of soluble silver species present on the surface, thereby increasing the total silver release in the separate exposures compared with sequential immersions. The particle stability had no drastic impact on the silver release as most of the Ag NPs were unstable in solution. The silver release was also influenced by a lower pH (increased release of silver), and cotransported zeolites (reduced silver in solution).

  • 167.
    Hendrikse, N. M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stromberg, P.
    Nordling, E.
    Syrén, Per-Olof
    KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Redesign of biosynthetic enzymes using ancestral sequence reconstruction2017In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 284, p. 86-87Article in journal (Refereed)
  • 168. Henry, Christophe
    et al.
    Norrfors, K. Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Karlsruhe Institute of Technology, Germany.
    Olejnik, Michal
    Bouby, Muriel
    Luetzenkirchen, Johannes
    Wold, Susanna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Karlsruhe Institute of Technology, Germany.
    Minier, Jean-Pierre
    A refined algorithm to simulate latex colloid agglomeration at high ionic strength2016In: Adsorption, ISSN 0929-5607, E-ISSN 1572-8757, Vol. 22, no 4-6, p. 503-515Article in journal (Refereed)
    Abstract [en]

    This study is focussed on the simulation of particle agglomeration at relatively high ionic strength using a refined stochastic algorithm developed in the context of parcel-tracking approaches. For that purpose, experimental data of both diffusion-limited and reaction-limited aggregation of latex particles were obtained using dynamic light scattering techniques for different initial particle sizes (diameters ranging from 24 to 495 nm) and at various chemical conditions (ionic strength between 0.5 and 2 M with NaCl or CaCl2 solutions). The experimental data collected have been compared to numerical results obtained with the refined parcel-tracking algorithm for particle agglomeration which has been developed. Results show that the evolution of the aggregate diameters over time can be properly captured by the present model with the value of the aggregate fractal dimension that is extracted from experimental data.

  • 169. Hermans, Joen J.
    et al.
    Keune, Katrien
    van Loon, Annelies
    Corkery, Robert W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Iedema, Piet D.
    The molecular structure of three types of long-chain zinc(II) alkanoates for the study of oil paint degradation2014In: Polyhedron, ISSN 0277-5387, E-ISSN 1873-3719, Vol. 81, p. 335-340Article in journal (Refereed)
    Abstract [en]

    The molecular structures of three types of zinc(II) alkanoates (Zn(C-n)(2), ZnNa2(C-n)(4) and ZaK(2)(C-n)(4), C-n = CH3(CH2)(n-2)COO-, n = 8-18) were investigated by Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) to aid the study of degradation phenomena in oil paint. Each type of complex forms a homologous series in the studied chain length range. For (Zn(C-n)(2) and ZnNa2(C-n)(4), these homologous series indicate that the long-chain complexes have structures highly similar to those published for short-chain single-crystal analogs. Moreover, we introduce a chain tilt factor F-tilt to derive information about alkanoate chain angles from highly accurate PXRD long spacing values. The complex ZnK2(C-n)(4) has not been reported before. It consists of metal sheets containing tetrahedrally coordinated Zn atoms and octahedrally coordinated K atoms bridged by effectively monodentate carboxylate groups, and alkanoate chains that are tilted relative to the long axis.

  • 170.
    Heydari, Golrokh
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tyrode, Eric
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Stenroos, Christian
    Koivuluoto, Heli
    Tuominen, Mikko
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ultralow ice adhesion on hydrophilic and molecularly smooth mica surfacesManuscript (preprint) (Other academic)
    Abstract [en]

    Despite much research on designing surfaces for combating icing, no permanent solution has been achievedusing solid materials. Inspired by the slippery surface of ice, attributed to the presence of a quasi-liquid layeracting as a natural lubricant, we hypothesize that flat hydrophilic surfaces with a hydration layer remaining inthe liquid-like state at the solid-ice interface could result in low ice adhesion. Utilizing temperature-controlledice adhesion measurements on the molecularly smooth basal plane of muscovite mica, we observed the lowestreported ice adhesion on solid surfaces down to temperatures of -35 ºC. The ice adhesion is dramatically higheron flat hydrophilic silica surfaces. We discuss these findings in terms of what is known about mica-water andmica-ice interactions.

  • 171.
    Heydari, Golrokh
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Tyrode, Eric
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Visnevskij, Ceslav
    Makuska, Ricardas
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Temperature-Dependent Deicing Properties of ElectrostaticallyAnchored Branched Brush Layers of Poly(ethylene oxide)2016In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 32, no 17, p. 4194-4202Article in journal (Refereed)
    Abstract [en]

    The hydration water of hydrophilic polymersfreezes at subzero temperatures. The adsorption of suchpolymers will result in a hydrophilic surface layer that stronglybinds water. Provided this interfacial hydration water remainsliquidlike at subzero temperatures, its presence could possiblyreduce ice adhesion, in particular, if the liquidlike layer isthicker than or comparable to the surface roughness. Toexplore this idea, a diblock copolymer, having one branchedbottle-brush block of poly(ethylene oxide) and one linear cationic block, was electrostatically anchored on flat silica surfaces. Theshear ice adhesion strength on such polymer-coated surfaces was investigated down to −25 °C using a homebuilt device. Inaddition, the temperature dependence of the ice adhesion on surfaces coated with only the cationic block, only the branchedbottle-brush block, and with linear poly(ethylene oxide) was investigated. Significant ice adhesion reduction, in particular, attemperatures above −15 °C, was observed on silica surfaces coated with the electrostatically anchored diblock copolymer.Differential scanning calorimetry measurements on bulk polymer solutions demonstrate different thermal transitions of waterinteracting with branched and linear poly(ethylene oxide) (with hydration water melting points of about −18 and −10 °C,respectively). This difference is consistent with the low shear ice adhesion strength measured on surfaces carrying branchedbottle-brush structured poly(ethylene oxide) at −10 °C, whereas no significant adhesion reduction was obtained with linearpoly(ethylene oxide) at this temperature. We propose a lubrication effect of the hydration water bound to the branched bottlebrushstructured poly(ethylene oxide), which, in the bulk, does not freeze until −18 °C.

  • 172. Hogberg, Daniel
    et al.
    Soberats, Bartolome
    Yoshio, Masafumi
    Mizumura, Yurika
    Uchida, Satoshi
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Segawa, Hiroshi
    Kato, Takashi
    Self-Assembled Liquid-Crystalline Ion Conductors in Dye-Sensitized Solar Cells: Effects of Molecular Sensitizers on Their Performance2017In: CHEMPLUSCHEM, ISSN 2192-6506, Vol. 82, no 6, p. 834-840Article in journal (Refereed)
    Abstract [en]

    Dye-sensitized solar cells employing nonvolatile liquid-crystalline (LC) electrolytes that form nanostructures capable of efficient ion transport are reported. The LC electrolyte consists of a cyclic carbonate-functionalized mesogen and an iodide-based ionic liquid that nanosegregates into lamellar structures exhibiting over four times higher ion conductivities parallel to the layers than perpendicular to the layers. The self-assembled ion pathways allow efficient ion transport in the semi-solid LC state. When used together with organic dyes, DSSCs employing these LC electrolytes show higher power conversion efficiency (PCE) than metal-organic dyes. This behavior is not observed for devices containing standard liquid electrolytes. The higher PCEs of the LC-based devices can be attributed to longer electron lifetimes (t) and higher electron densities in the photoelectrodes. The high concentration of iodide ions in the nanostructured pathways of the LC electrolyte is thought to induce reductive quenching of the ruthenium-based sensitizer, which competes with the electron injection process and lowers the t and electron densities of the TiO2.

  • 173.
    Hua, Yong
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Cheng, Ming
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    High conductivity Ag-based metal organic complexes as dopant-free hole-transport materials for perovskite solar cells with high fill factors2016In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 7, no 4, p. 2633-2638Article in journal (Refereed)
    Abstract [en]

    Hole-transport materials (HTMs) play an important role as hole scavenger materials in the most efficient perovskite solar cells (PSCs). Here, for the first time, two Ag-based metal organic complexes (HA1 and HA2) are employed as a new class of dopant-free hole-transport material for application in PSCs. These HTMs show excellent conductivity and hole-transport mobility. Consequently, the devices based on these two HTMs exhibit unusually high fill factors of 0.76 for HA1 and 0.78 for HA2, which are significantly higher than that obtained using spiro-OMeTAD (0.69). The cell based on HA1-HTM in its pristine form achieved a high power conversion efficiency of 11.98% under air conditions, which is comparable to the PCE of the cell employing the well-known doped spiro-MeOTAD (12.27%) under the same conditions. More importantly, their facile synthesis and purification without using column chromatography makes these new silver-based HTMs highly promising for future commercial applications of PSCs. These results provide a new way to develop more low-cost and high conductivity metal-complex based HTMs for efficient PSCs.

  • 174.
    Hua, Yong
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Zhang, J.
    Xu, Bo
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Cheng, Ming
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Johansson, E. M. J.
    Sveinbjörnsson, K.
    Aitola, K.
    Boschloo, G.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD. Dalian University of Technology (DUT), China.
    Facile synthesis of fluorene-based hole transport materials for highly efficient perovskite solar cells and solid-state dye-sensitized solar cells2016In: Nano Energy, ISSN 2211-2855, Vol. 26, p. 108-113Article in journal (Refereed)
    Abstract [en]

    Two novel low-cost fluorene-based hole transport materials (HTMs) HT1 and HT2 as alternatives to the expensive HTM Spiro-OMeTAD have been designed and synthesized for the application in perovskite solar cells (PSCs) and solid-state dye-sensitized solar cell (ssDSCs). The two HTMs were prepared through a facile two-step reaction from cheap starting material and with a total yield higher than 90%. These HTMs exhibit good solubility and charge-transport ability. PSCs based on HT2 achieved power conversion efficiency (PCE) of 18.04% under air conditions, which is comparable to that of the cell employing the commonly used Spiro-OMeTAD (18.27%), while HT1-based cell showed a slightly worse performance with a PCE of 17.18%. For ssDSCs, the HT2-based device yielded a PCE of 6.35%, which is also comparable to that of a cell fabricated based on Spiro-OMeTAD (6.36%). We found that the larger dimensional structure and molecular weight of HT2 enable better photovoltaic performance than that of the smaller one HT1. These results show that easily synthesized fluorene-based HTMs have great potential to replace the expensive Spiro-OMeTAD for both PSCs and ssDSCs. © 2016 Elsevier Ltd.

  • 175. Högberg, D.
    et al.
    Soberats, B.
    Yatagai, R.
    Uchida, S.
    Yoshio, M.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Segawa, H.
    Kato, T.
    Liquid-crystalline dye-sensitized solar cells: Design of two-dimensional molecular assemblies for efficient ion transport and thermal stability2016In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 28, no 18, p. 6493-6500Article in journal (Refereed)
    Abstract [en]

    Nanostructured liquid-crystalline (LC) electrolytes have been developed for efficient and stable quasi-solid-state dye-sensitized solar cells (DSSCs). Two types of ionic LC assemblies for electrolytes have been designed: (i) noncovalent assemblies of two-component mixtures consisting of I2-doped imidazolium ionic liquids and carbonate-terminated mesogenic compounds (noncovalent type) and (ii) single-component mesogenic compounds covalently bonding an imidazolium moiety doped with I2 (covalent type). These mesogenic compounds are designed with flexible oligooxyethylene spacers connecting the mesogenic and the polar moieties. The oligooxyethylene-based material design inhibits crystallization and leads to enhanced ion transport as compared to alkyl-linked analogues due to the higher flexibility of the oligooxyethylene spacer. The noncovalent type mixtures exhibit a more than 10 times higher I3- diffusion coefficient compared to the covalent type assemblies. DSSCs containing the noncovalent type liquid crystals show power conversion efficiencies (PCEs) of up to 5.8 ± 0.2% at 30 °C and 0.9 ± 0.1% at 120 °C. In contrast, solar cells containing the covalent type electrolytes show significant increase in PCE up to 2.4 ± 0.1% at 120 °C and show superior performance to the noncovalent type-based devices at temperature above 90 °C. Furthermore, the LC-DSSCs exhibit excellent long-term stability over 1000 h. These novel electrolyte designs open unexplored paths for the development of DSSCs capable of efficient conversion of light to electricity in a wide range of temperatures.

  • 176.
    Högberg, Daniel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Soberats, Bartolome
    Uchida, Satoshi
    Yoshio, Masafumi
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Segawa, Hiroshi
    Kato, Takashi
    Nanostructured Two-Component Liquid-Crystalline Electrolytes for High-Temperature Dye-Sensitized Solar Cells2014In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 26, no 22, p. 6496-6502Article in journal (Refereed)
    Abstract [en]

    Nanostructured liquid-crystalline (LC) ion transporters have been developed and applied as new electrolytes for dye-sensitized solar cells (DSSCs). The new electrolytes are two-component liquid crystals consisting of a carbonate-based mesogen and an ionic liquid that self-assemble into two-dimensional (2D) nanosegregated structures forming well-defined ionic pathways suitable for the I-/I-3(-) redox couple transportation. These electrolytes are nonvolatile and they show LC phases over wide temperature ranges. The DSSCs containing these electrolytes exhibit exceptional open-circuit voltages (V-oc) and improved power conversion efficiencies with increasing temperature. Remarkably, these solar cells operate at temperatures up to 120 degrees C, which is, to the best of our knowledge, the highest working temperature reported for a DSSC. The nature of the LC electrolyte and the interactions at the TiO2 electrode/electrolyte interface lead to a partial suppression of electron recombination reactions, which is key in the exceptional features of these LC-DSSCs. Thus, this type of solar cells are of interest, because they can produce electricity efficiently from light at elevated temperatures.

  • 177.
    Ito, Mika
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Novel Approach for Identifying Key Residues in Enzymatic Reactions: Proton Abstraction in Ketosterbid Isomerase2014In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 118, no 46, p. 13050-13058Article in journal (Refereed)
    Abstract [en]

    We propose a computationally efficient approach for evaluating the individual contributions of many different residues to the catalytic efficiency of an enzymatic reaction. This approach is based on the fragment molecular orbital (FMO) method, and it defines the energy of a deletion form, i.e., the energy of the system when a particular residue is deleted. Using this approach, we found that, among 10 investigated residues, three, Tyr14, Asp99, and Tyr55, in this order, significantly reduce the activation energy of the proton abstraction from a substrate, cyclopent-2-enone, catalyzed by ketosteroid isomerase (KSI). The relative activation energies estimated in this study are in good agreement with available previous experimental and theoretical data obtained for the similar proton abstraction with a native substrate and substitution mutants of KSI. It was thus indicated that the new approach is efficient for rationally evaluating the catalytic effects of multiple residues on an enzymatic reaction.

  • 178.
    Johansson, Adam Johannes
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Inga Fischer-Hjalmars (1918-2008): Swedish pharmacist, humanist, and pioneer quantum chemist2012In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 89, no 10, p. 1274-1279Article in journal (Other academic)
    Abstract [en]

    A wide variety of questions can be asked about the molecules that compose the physical reality around us and constitute biological life. Some of these questions are answered by the science called biology, others find their answer in chemistry, whereas the answers to the most fundamental questions are only to be found in the theories of physics. Inga Fischer-Hjalmars (born Fischer) belonged to the rare group of scientists who asked questions of all these kinds. Her life and career is a fascinating story of devotion, strive, and an unyielding curiosity about nature. As a young pharmacist, she had a central role in the development of the local anesthetic Xylocaine (also known as lidocaine), but the major part of her career was dedicated to explain the biological, chemical, and physical properties of molecules using the most fundamental principles available: quantum mechanics. Inga Fischer-Hjalmars was a pioneer in applying quantum mechanics to chemical problems, and she became the first female professor in theoretical physics in Sweden. Beside her scientific work, Inga Fischer-Hjalmars was a human rights activist dedicated to the freedom of oppositional and Jewish scientists in the Soviet Union. For this engagement, she was awarded with the New York Academy of Science's Human Rights of Scientists Award in 1990.

  • 179.
    Johansson, Adam Johannes
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Teaching the jahn-teller theorem: A simple exercise that illustrates how the magnitude of distortion depends on the number of electrons and their occupation of the degenerate energy level2013In: Journal of Chemical Education, ISSN 0021-9584, E-ISSN 1938-1328, Vol. 90, no 1, p. 63-69Article in journal (Refereed)
    Abstract [en]

    Teaching the Jahn-Teller theorem offers several challenges. For many students, the first encounter comes in coordination chemistry, which can be difficult due to the already complicated nature of transition-metal complexes. Moreover, a deep understanding of the Jahn-Teller theorem requires that one is well acquainted with quantum mechanics and group theory. A comparatively simple way to illustrate the anatomy of the Jahn-Teller effect is presented here. Chemistry teachers are reminded of a sometimes forgotten aspect, namely, that the orbital degeneracy itself is not a sufficient criterion for the Jahn-Teller effect to appear, it is necessary that the occupation of the degenerate energy level is asymmetric. The article can serve as an introduction to the Jahn-Teller theorem, either as a lecture or as a computational exercise.

  • 180. Johansson, Jimmy
    et al.
    Blom, Åsa
    Dvinskikh, Sergey
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    NMR-measurements for determination of local moisture content of coated wood2013In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 10, no 5, p. 601-607Article in journal (Refereed)
    Abstract [en]

    Local increased moisture content (MC) in wood constructions may result in different kinds of mechanical and, especially, biological degrading problems. Therefore, it is of great importance to control the MC of the material. However, there is at present no appropriate method for determining local MC in wood without destroying the product itself. Nondestructive measurements of local MC in wood is significant for the possibility of, for instance, monitoring the in situ MC in wood constructions over time, and thereby predicting potential problems. The nuclear magnetic resonance (NMR) technique has been shown to be valuable for the measurement of MC in wood. In this study, the possibility of utilizing this technique for local MC measurement in wood has been tested on wood samples exposed to water absorption for 72 h. The samples came from three different wood species treated with paint systems available on the market. In the wood samples an artificial "crack" had been created in the paint to introduce an area where the water could easily gain access to the wood. The results show the possibility of using the NMR technique for local MC measurements in wood. The measurement area, however, must be related to the properties of the material. In the case of wood, the measurement spot must be related to the early/latewood proportions. Further, a calibration of the NMR measurement must be made in relation to the expected density variations of the material.

  • 181.
    Johansson, Viktor
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ellis-Gibbings, Lilian
    Clarke, Trevor
    Gorlov, Mikhail
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Andersson, Gunther G.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    On the correlation between dye coverage and photoelectrochemical performance in dye-sensitized solar cells2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 2, p. 711-718Article in journal (Refereed)
    Abstract [en]

    Concentration depth profiles of the ruthenium based dyes Z907 and N719 adsorbed onto titania are measured directly and used for determining the adsorption isotherm of the dyes. Dye layers formed by both grow in islands on the titania which do not cover the entire titania surface even at the maximum coverage. Impedance spectroscopy in conjunction with the adsorption isotherms shows that recombination losses mainly appear between the dye and the electrolyte solution. The short circuit current and the efficiency increase linearly with the dye coverage. The open circuit voltage slightly increases with increasing dye coverage which is interpreted as most likely to be a consequence of the higher charge in the particles upon higher dye loading on the TiO2 surface.

  • 182.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    An Overview of Interfacial Radiation Chemistry in Nuclear Technology2014In: Israel Journal of Chemistry, ISSN 0021-2148, Vol. 54, no 3, p. 292-301Article, review/survey (Refereed)
    Abstract [en]

    Interfacial radiation chemistry is of key importance in nuclear technology because most materials in the vicinity of radioactive materials in nuclear power plants, reprocessing plants, and repositories for nuclear waste are exposed to ionizing radiation. Corrosion is a crucial issue for the long-term performance and safety of these installations. Nevertheless, this field is still fairly undeveloped. In this paper, the current state of the art with particular focus on reactions between aqueous radiolysis products and metal or metal oxide surfaces is discussed. The general reactivity of hydrogen peroxide and the hydroxyl radical towards oxide surfaces is discussed on the basis of recent experimental results and DFT calculations. More specific discussions on radiation-induced surface processes in a future geological repository for spent nuclear fuel are given as relevant examples. This includes radiation-induced dissolution of spent nuclear fuel in contact with groundwater, radiation-induced corrosion of copper, and radiation-induced alterations of bentonite clay. Current knowledge gaps in these areas are highlighted.

  • 183.
    Josefsson, Leila
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bioanalytical separation using capillary electrophoresis: Applications with microbubbles and proteins2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis the possibilities of using capillary electrophoresis as a separation technique for analysis of proteins and microbubbles is presented.

    A complete analytical process consists of five necessary steps of which one is the actual analysis step. For this step a suitable analytical technique is needed. Capillary electrophoresis (CE) is one of the common analytical separation techniques used for analysis of a diversity of analytes, and can be both used in routine analysis and for research purposes. The reason for using CE, compared to other liquid-based separation techniques, is mainly short analysis time, high resolution, and negligible sample volumes and solvent waste. Depending on the characteristics of the analytes, and the sample matrix, different modes of CE can be used, where capillary zone electrophoresis (CZE) is the most employed one. The basic principle of CZE is separation of the analytes due to differences in total mobility, which is dependent on the charge and size of the analytes, and the electroosmotic flow (EOF). The EOF can be controlled by several parameters e.g. choice of background electrolyte (BGE), and the optimization of the parameters has been discussed throughout the thesis.

    To improve the properties of the BGE, an ethylammonium nitrate (EAN) water solution was used as BGE for CE analysis in Paper I. The precision of the EOF with this method was determined by adjusting the pH of the BGE, the concentration of EAN in the BGE, and the electric field. Model proteins were thereafter analysed using the optimal parameters yielding a precision sufficient for routine control.

    One example of the applications of CE is separation of novel contrast agents, which consist of polyvinyl alcohol microbubbles (PVA-MBs). In Paper II, a method for analysis of PVA-MBs in biological samples using CE with UV-detection was developed. It was also established that intact PVA-MBs could be distinguished from ultrasound degraded PVA-MBs in the same set-up.

  • 184.
    Josefsson, Leila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Larsson, Malin K.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Bjällmark, Anna
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institute, Sweden.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis2016In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 39, no 8, p. 1551-1558Article in journal (Refereed)
    Abstract [en]

    Recently, a new type of ultrasound contrast agent that consists of air-filled microbubbles stabilized with a shell of polyvinyl alcohol was developed. When superparamagnetic nanoparticles of iron oxide are incorporated in the polymer shell, a multimodal contrast agent can be obtained. The biodistribution and elimination pathways of the polyvinyl alcohol microbubbles are essential to investigate, which is limited with today's techniques. The aim of the present study was, therefore, to develop a method for qualitative and quantitative analysis of microbubbles in biological samples using capillary electrophoresis with ultraviolet detection. The analysis parameters were optimized to a wavelength at 260 nm and pH of the background electrolyte ranging between 11.9 and 12. Studies with high-intensity ultrasonication degraded microbubbles in water showed that degraded products and intact microbubbles could be distinguished, thus it was possible to quantify the intact microbubbles solely. Analysis of human blood plasma spiked with either plain microbubbles or microbubbles with nanoparticles demonstrated that it is possible to separate them from biological components like proteins in these kinds of samples.

  • 185.
    Josefsson, Leila
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Verdaasdonk, Thijs
    Bernsteen, Jessica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Emmer, Åsa
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, Superseded Departments (pre-2005), Chemistry.
    Evaluation of ethylammonium nitrate as background electrolyte in capillary electrophoresisManuscript (preprint) (Other academic)
  • 186. Karlsson, Martin
    et al.
    Yang, Lei
    Karlsson, Marlin K.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Boschloo, Gerrit
    Hagfeldt, Anders
    Phenoxazine dyes in solid-state dye-sensitized solar cells2012In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 239, p. 55-59Article in journal (Refereed)
    Abstract [en]

    Several structural modifications have been made to a sensitizer dye based on the phenoxazine core. which was tested in a solid-state dye-sensitized solar cell configuration based on the hole transporting material 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9'-spirofluorene. Light-to-power conversion efficiencies between 2.5% and 4.1% are reported herein. The difference in device performance is significantly related to the variations of dye molecular structure, with dye molecules having surface protecting alkoxy-groups yielding better solar cell devices. The phenoxazine dyes were characterized by their light harvesting capabilities and electronic properties such as electron recombination lifetime and chemical dipole moment.

  • 187.
    Kharkov, Boris
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Molecular Order and Dynamics in Nanostructured Materials by Solid-State NMR2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organic-inorganic nanostructured composites are nowadays integrated in the field of material science and technology. They are used as advanced materials directly or as precursors to novel composites with potential applications in optics, mechanics, energy, catalysis and medicine. Many properties of these complex materials depend on conformational rearrangements in their inherently dynamic organic parts. The focus of this thesis is on the study of the molecular mobility in ordered nanostructured composites and lyotropic mesophases and also on the development of relevant solid-state NMR methodologies.

    In this work, a number of new experimental approaches were proposed for dipolar NMR spectroscopy for characterizing molecular dynamics with atomic-level resolution in complex solids and liquids. A new acquisition scheme for two-dimensional dipolar spectroscopy has been developed in order to expand the spectral window in the indirect dimension while using limited radio-frequency power. Selective decoupling of spin-1 nuclei for sign-sensitive determination of the heteronuclear dipolar coupling has been described. A new dipolar recoupling technique for rotating samples has been developed to achieve high dipolar resolution in a wide range of dipolar coupling strength. The experimental techniques developed herein are capable of delivering detailed model-independent information on molecular motional parameters that can be directly compared in different composites and their bulk analogs.

    Solid-state NMR has been applied to study the local molecular dynamics of surfactant molecules in nanostructured organic-inorganic composites of different morphologies. On the basis of the experimental profiles of local order parameters, physical motional models for the confined surfactant molecules were put forward. In layered materials, a number of motional modes of surfactant molecules were observed depending on sample composition. These modes ranged from essentially immobilized rigid states to highly flexible and anisotropically tumbling states. In ordered hexagonal silica, highly dynamic conformationally disordered chains with restricted motion of the segments close to the head group have been found.

    The results presented in this thesis provide a step towards the comprehensive characterization of the molecular states and understanding the great variability of the molecular assemblies in advanced nanostructured organic−inorganic composite materials.

  • 188.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chizhik, V. I.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Low rf power high resolution H-1-C-13-N-14 separated local field spectroscopy in lyotropic mesophases2012In: Journal of magnetic resonance, ISSN 1090-7807, E-ISSN 1096-0856, Vol. 223, p. 73-79Article in journal (Refereed)
    Abstract [en]

    Efficiency of the proton detected (encoded) H-1-C-13-N-14 local field spectroscopy technique at low radiofrequency power is examined when applied to concentrated ionic lyotropic mesophases exhibiting heteronuclear and homonuclear dipolar couplings in kHz range. We demonstrate that highly resolved heteronuclear dipolar spectra can be obtained with limited radiofrequency power corresponding to decoupling B-1 field of 20 kHz and with superior spectral resolution and sensitivity provided by standard solution state probes. To maintain sufficiently large spectral window in indirect dimension, power level alternation scheme for homonuclear decoupling was introduced. In anisotropic mesophases of an ionic surfactant, pair-wise coupling constants in the three-spin system H-1-C-13-N-14 were accurately determined. Relative signs of heteronuclear dipolar couplings to nitrogen were obtained employing frequency selective decoupling.

  • 189.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chizhik, V. I.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sign-sensitive determination of heteronuclear dipolar coupling to spin-1 by selective decoupling2012In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 137, no 23, p. 234902-Article in journal (Refereed)
    Abstract [en]

    This paper presents a theoretical and experimental study of nuclear magnetic resonance technique for sign-sensitive determination of the dipolar couplings of rare spins-1/2 to spin-1 with a strong quadrupolar interaction. The technique is based on low-power transition-selective single-quantum decoupling of spin-1 in the presence of high-power decoupling of abundant (proton) spins. Single-transition operator formalism is employed to calculate the time evolution of the density matrix in the presence of low-power irradiation of spin-1. Generally, the sign of dipolar coupling is unavailable from intrinsically symmetric shapes of dipolar-coupled spectra. Asymmetric dipolar multiplets, resulted from selective decoupling, reveal both the signs and magnitudes of the heteronuclear dipolar couplings. The approach is used to develop the experimental strategy for sign-sensitive measurements of short- and long-range heteronuclear dipolar couplings in highly ordered anisotropic samples. The technique is demonstrated for 13C-2H and 13C-14N spin pairs and for 13C- 2H2 three-spin system in liquid crystals.

  • 190.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. New York University, United States .
    Chizhik, Vladimir I.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. St. Petersburg State University, Russian Federation.
    Broadband cross-polarization-based hetero-nuclear dipolar recoupling for structural and dynamic NMR studies of rigid and soft solids2016In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, p. 034201-Article in journal (Refereed)
    Abstract [en]

    Dipolar recoupling is an essential part of current solid-state NMR methodology for probing atomic-resolution structure and dynamics in solids and soft matter. Recently described magic-echo amplitude- and phase-modulated cross-polarization heteronuclear recoupling strategy aims at efficient and robust recoupling in the entire range of coupling constants both in rigid and highly dynamic molecules. In the present study, the properties of this recoupling technique are investigated by theoretical analysis, spin-dynamics simulation, and experimentally. The resonance conditions and the efficiency of suppressing the rf field errors are examined and compared to those for other recoupling sequences based on similar principles. The experimental data obtained in a variety of rigid and soft solids illustrate the scope of the method and corroborate the results of analytical and numerical calculations. The technique benefits from the dipolar resolution over a wider range of coupling constants compared to that in other state-of-the-art methods and thus is advantageous in studies of complex solids with a broad range of dynamic processes and molecular mobility degrees.

  • 191.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. St. Petersburg State University, Russian Federation .
    Chizhik, Vladimir I.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. St. Petersburg State University, Russian Federation.
    Probing Molecular Mobility in Nanostructured Composites by Heteronuclear Dipolar NMR Spectroscopy2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 48, p. 28308-28313Article in journal (Refereed)
    Abstract [en]

    Conformational and reorientational dynamics of surfactant molecules confined within solid inorganic frameworks of nanostructured composites are studied by solid-state NMR. Since the organic part in the nanocomposites exhibits a great variation in the local molecular mobility, a significant challenge in these materials is to develop an experimental method efficient both for nearly immobilized and for highly dynamic flexible molecules. We introduce a dipolar recoupling NMR technique to study local molecular motion via heteronuclear dipolar spin interactions in a wide range of coupling constant values. The approach is efficient in both rigid and mobile molecules. The method is applied to ordered nanostructured composites to obtain model-independent information on the local molecular dynamics. On the basis of experimentally determined local order parameters of the molecular segments, we put forward physical models for the motion of surfactant molecules in nanoconfined assemblies. In composites with lamellar structure, the hydrocarbon chains adopt well-ordered essentially all-trans conformations and, depending on sample composition, undergo either small-angle wobbling or free rotation around the long molecular axes. In contrast, surfactant molecules in hexagonal mesoporous silica exhibit highly dynamic conformationally disordered chains.

  • 192.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Corkery, Robert W.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Phase Transitions and Chain Dynamics of Surfactants Intercalated into the Galleries of Naturally Occurring Clay Mineral Magadiite2014In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 30, no 26, p. 7859-7866Article in journal (Refereed)
    Abstract [en]

    We investigate conformational dynamics and phase transitions of surfactant molecules confined in the layered galleries of the organo-modified, natural polysilicate clay, magadiite. We have shown that our approach to studying this class of materials is capable of delivering detailed information on the molecular mobility of the confined molecules. From the analysis of the measured heteronuclear dipolar couplings, the orientational order parameters of the C-H bonds along the hydrocarbon chain have been determined. Three phases have been observed in the nanocomposite, characterized by distinct dynamical states of the surfactant. At room temperature, restricted mobility of the molecules led to the adoption of an essentially all-trans conformation by the chains. This behavior can be described by a model incorporating small-angle wobbling around the long molecular axes of the chains. Upon heating, dynamic transformation takes place, resulting in a rotator type solid phase where molecules in extended all-trans conformations undergo fast and unrestricted rotation about their respective symmetry axes. The second phase transition is associated with chain melting and the onset of translational dynamics and results in an essentially liquid-crystalline-like state of the organic component. The mobility of the surfactant is one of the key factors facilitating the efficient penetration of macromolecules in the process of preparing of polymer/organoclay nanocomposites. The exploration of dynamic properties of the fimctionalizing organic layer should provide important input into the improved design of new organic-inorganic hybrid materials.

  • 193.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Chain dynamics of surfactants in mesoporous silica2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 42, p. 18620-18626Article in journal (Refereed)
    Abstract [en]

    Mesostructured porous materials possess unique surface, structural, and bulk properties that lead to important practical applications. By retaining structure-directing species in the product material, mesostructured organic-inorganic composites are obtained which are of broad interest for fundamental studies of confinement effects and surface interaction on structural and dynamic properties of organic molecules. In the present study, solid state dipolar C-13-H-1 NMR spectroscopy is applied to quantitatively characterize the conformational dynamics of organic surfactants in the mesostructured composite CTAB-MCM41. Such an approach does not require assumptions and adjustable parameters and reflects the changes in conformational dynamics without relying on specific motional models. The conformational dynamics of the surfactant confined in solid hexagonal arrays is compared to that in hexagonal aggregates formed in a concentrated aqueous solution. The study showed that in cylindrical pores of hexagonal mesoporous silica the order parameter gradually decreases towards the end of the chain. The degree of order and the order parameter profile is similar to that observed in hexagonal liquid crystalline phases. However, the mobility of segments close to the head group is more restricted compared to that in the mesophase, as the result of interaction with the solid silica interface.

  • 194.
    Kharkov, Boris B.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Conformational Dynamics of Surfactant in a Mesolamellar Composite Studied by Local Field NMR Spectroscopy2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 46, p. 24511-24517Article in journal (Refereed)
    Abstract [en]

    Ordered mesostructured materials possess unique surface, structural, and bulk properties that lead to important practical applications. Mesostructured organic inorganic composites are also of broad interest for fundamental studies of confinement effects and surface interaction on structural and dynamic properties of organic molecules. In the present study, solid state dipolar C-13-H-1 NMR spectroscopy is applied to quantitatively characterize the conformational dynamics of a surfactant in a mesolamellar composite. By applying dipolar recoupling and separated local field spectroscopy techniques, the motion of surfactant molecules was studied in a wide range of mobilities from an essentially immobilized rigid state to a highly flexible and anistropically tumbling state. From the analysis of the measured heteronudear dipolar couplings, the orientational order parameters of C-H bonds along the surfactant chain were determined. The study shows that in surfactant bilayers in AIPO layered structure at room temperature the highly ordered chains in all-trans conformation undergo fast rotation about the molecular axis. In a higher temperature phase, the order parameter is gradually decreasing toward the chain end due to conformational transitions; however, the dynamics of the segment in the vicinity of the headgroup is only slightly affected. The conformational dynamics in the surfactant bilayers confined between solid inorganic sheets is also compared to that in fluid bilayers in an aqueous lamellar phase.

  • 195.
    Kleimark, Jonatan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Delanoe, Romain
    Demaire, Alain
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ionization of ammonium dinitramide: decomposition pathways and ionization products2013In: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 132, no 12, p. UNSP 1412-Article in journal (Refereed)
    Abstract [en]

    The decomposition pathways of ionized ammonium dinitramide (ADN) have been analyzed using the B3LYP and the M06-2X density functional theory methods, coupled cluster theory and the composite CBS-QB3 method. Ionization and subsequent decomposition of the major decomposition products have also been studied. The ADN(+) ion dissociates into the stable DN radical and NH4+ with a dissociation enthalpy of 50 kJ/mol. The subsequently formed DN+ ion has an activation enthalpy of 102 kJ/mol for decomposition into N2O, O-2 and NO+. A competing pathway for ionization and decomposition of ADN involves the HDN+ ion, which dissociates into NO2+ and HNNO2 with a barrier of only 17 kJ/mol. The ionization product HNNO2+ is stable toward further decomposition, and the barrier for isomerization to HONNO+ is 167 kJ/mol. The computed adibatic ionization potentials of ADN, HDN, DN and HNNO2 are 9.4, 11.5, 10.2 and 10.9 eV, respectively. The results of the study have implications for the future use of ADN in propellants for electromagnetic space propulsion.

  • 196.
    Klett, Matilda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Giesecke, Marianne
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Nyman, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Hallberg, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wreland Lindström, Rakel
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Furó, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Quantifying mass transport during polarization in a Li Ion battery electrolyte by in situ 7Li NMR imaging2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 36, p. 14654-14657Article in journal (Refereed)
    Abstract [en]

    Poor mass transport in the electrolyte of Li ion batteries causes large performance losses in high-power applications such as vehicles, and the determination of transport properties under or near operating conditions is therefore important. We demonstrate that in situ 7Li NMR imaging in a battery electrolyte can directly capture the concentration gradients that arise when current is applied. From these, the salt diffusivity and Li + transport number are obtained within an electrochemical transport model. Because of the temporal, spatial, and chemical resolution it can provide, NMR imaging will be a versatile tool for evaluating electrochemical systems and methods.

  • 197.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Catenated Compounds - Group 17 - Polyhalides2013In: Comprehensive Inorganic Chemistry II (Second Edition): From Elements to Applications, Elsevier, 2013, 2, Vol. 1, p. 233-249Chapter in book (Refereed)
    Abstract [en]

    The present chapter offers an overview of polyanions of the group 17 as examples of catenation. The main knowledge obtained from the rich literature on polyiodides is summarized, and comparisons are made with other polyhalide systems in order to gain insights into similarities and differences. A detailed analysis of chemical bonding is given, and the special properties of the iodine-based systems are highlighted.

  • 198.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Inorganic chemistry for renewable energy conversion and storage2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, no 40, p. 14924-14925Article in journal (Refereed)
  • 199.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Iodine in Dye-Sensitized Solar Cells2014In: Iodine Chemistry and Applications, Wiley-Blackwell, 2014, Vol. 9781118466292, p. 501-512Chapter in book (Other academic)
    Abstract [en]

    This chapter discusses the role of the iodine-based redox systems in the three components of the dye-sensitized solar cell (DSSC) separately; at the photoelectrode, at the counterelectrode, and finally in the electrolyte. It should be noted that essentially all information communicated refers to n-type DSSC devices, and that similar descriptions regarding the role of iodine is also be made for p-type DSSCs. Regeneration of the oxidized dye at the photoelectrode is a central process in the DSSC. Many different counterelectrode materials may be used in DSSC devices, such as conducting metal oxides, carbon materials, and metals. The DSSC device is conceptually quite simple, but the optimization of the device as a whole is a delicate matter involving several intimate and delicately dependent processes, in particular at the electrode surfaces. Iodide was not the only halide to be used in DSSCs. Bromide, with its oxidized companion-the tribromide ion-represents an alternative.

  • 200.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    On the early development of organic dyes for dye-sensitized solar cells2013In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, no 59, p. 6580-6583Article in journal (Refereed)
    Abstract [en]

    This viewpoint describes the background of the development of organic dyes for dye-sensitized solar cells, the impact of the 2006 ChemComm paper by Sun, Hagfeldt and co-workers regarding the D5 D-pi-A-family of dyes, some recent developments and possible future challenges to meet.

1234567 151 - 200 of 392
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