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  • 51. Belda, O.
    et al.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Bispyridylamides - coordination chemistry and applications in catalytic reactions2005Inngår i: Coordination chemistry reviews, ISSN 0010-8545, E-ISSN 1873-3840, Vol. 249, nr 06-maj, s. 727-740Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Complexes of bis(2-pyridylamides) with most metal ions have been described. A variety of coordination modes, with the neutral or the deprotonated amide functions binding either via the carbonyl oxygen atom or the amide nitrogen atom have been identified. The modular technique used for the preparation of the compounds permits facile access to ligands with substituted pyridine nuclei and ligands with different backbones. Moreover, symmetric as well as asymmetric compounds, with equal or different pyridine rings and with symmetric or non-symmetric amines, can conveniently be prepared. Chiral derivatives are easily obtained starting from chiral diamines. Several metal complexes have been studied as mimics of biological systems. In recent years a variety of metal complexes have also been employed in catalysis. Oxidations of alkanes and alkenes have been particularly well studied, although modest reactivity has usually been encountered. Other applications include their use as ligands in Lewis acid catalyzed processes. Recently, it was shown that complexes with molybdenum catalyze highly regio- and enantioselective allylic alkylations.

  • 52. Beletskaya, I.
    et al.
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Element-element additions to unsaturated carbon-carbon bonds catalyzed by transition metal complexes2006Inngår i: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 106, nr 6, s. 2320-2354Artikkel, forskningsoversikt (Fagfellevurdert)
  • 53. Beller, M.
    et al.
    Centi, G.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Chemistry Future: Priorities and Opportunities from the Sustainability Perspective2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 1, s. 6-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To celebrate the 10 year anniversary of ChemSusChem, we as the chairmen of the editorial board are writing this Essay to summarize important scientific contributions to our journal during the past decade in terms of sustainable science and technology. Bibliometric analysis of published papers show that biorefinery, solar energy conversion, energy-storage materials, and carbon dioxide utilizations attracted most attention in this area. According to our own knowledge and understanding and from the sustainability point of view, we are also pointing out those research directions that we believe can play key roles in the future chemistry to meet the grand challenges in energy and environment. Hopefully, these perspective aspects will provide the readers with new angles to look at the chemistry in the coming decades and inspire the development of new technologies to make our society sustainable.

  • 54.
    Bellini, Rosalba
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Magre, Marc
    Biosca, Maria
    Norrby, Per-Ola
    Pamies, Oscar
    Dieguez, Montserrat
    Moberg, Christina
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Conformational Preferences of a Tropos Biphenyl Phosphinooxazoline-a Ligand with Wide Substrate Scope2016Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, nr 3, s. 1701-1712Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Excellent enantioselectivities are observed in palladium-catalyzed allylic substitutions of a wide range of substrate types and nucleophiles using a bidentate ligand composed of oxazoline and chirally flexible biaryl phosphite elements. This unusually wide substrate scope is shown by experimental and theoretical studies of its eta(3)-allyl and eta(2)-olefin complexes not to be a result of configurational interconversion of the biaryl unit, since the ligand in all reactions adopts an S-a,S configuration on coordination to palladium, but rather the ability of the ligand to adapt the size of the substrate-binding pocket to the reacting substrate. This ability also serves as an explanation to its excellent performance in other types of catalytic processes.

  • 55.
    Berasategui, Aileen
    et al.
    Dep. of Biochemistry, Max Planck institute for Chemical Ecology.
    Axelsson, Karolin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Nordlander, Göran
    Dep. of Ecology, SLU.
    Schmidt, Axel
    Max Planck Institute for Chemical Ecology.
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Gershenzon, Jonathan
    Dep of Biochemistry, Max Planck institute for Chemical Ecology.
    Terenius, Olle
    Dep of Ecology, SLU.
    Kaltenpoth, Martin
    Insect Symbiosis Research Group, Max Planck institute for Chemical Ecology.
    The Gut microbiota of the pine weevil is similar across Europe and resembles that of other conifer-feeding beetles2016Inngår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 25, nr 16, s. 4014-4031Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pine weevil (Hylobius abietis, Coleoptera: Curculionidae) is an important pest of conifer seedlings in Europe. Despite its economic importance, little is known about the composition of its gut microbial community and the role it plays in mediating the weevil's ability to utilize conifers as a food source. Here, we characterized the gut bacterial communities of different populations of H. abietis across Europe and compared them to those of other beetles that occupy similar ecological niches. We demonstrate that the microbial community of H. abietis is similar at higher taxonomic levels (family and genus) across locations in Europe, with Wolbachia as the dominant microbe, followed by Enterobacteria and Firmicutes. Despite this similarity, we observed consistent differences between countries and locations, but not sexes. Our meta-analysis demonstrates that the gut bacterial community of the pine weevil is very similar to that of bark beetles that also exploit conifers as a food source. The Enterobacteriaceae symbionts of both host taxa are especially closely related phylogenetically. Conversely, the microbiota of H. abietis is distinct from that of closely related weevils feeding on non-conifer food sources, suggesting that the microbial community of the pine weevil is determined by the environment and may be relevant to host ecology. Furthermore, several H. abietis-associated members of the Enterobacteriaceae family are known to contain genes involved in terpenoid degradation. As such, we hypothesize that the gut microbial community is important for the utilization of conifer seedlings as a food source, either through the detoxification of plant secondary metabolites or supplementation of essential nutrients.

  • 56.
    Bergman, J.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Engman, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sidén, J.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tetra-and higher-valent (hypervalent) derivatives of selenium and tellurium2010Inngår i: Organic Selenium and Tellurium Compounds (1986), John Wiley & Sons, 2010, Vol. 1, s. 517-558Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 57. Bernhardt, Paul V.
    et al.
    Boschloo, Gerrit K.
    Bozoglian, Fernando
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Martinez, Manuel
    Sienrad, Beatriz
    Tailoring mixed-valence Co-III/Fe-II complexes for their potential use as sensitizers in dye sensitized solar cells2008Inngår i: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 32, nr 4, s. 705-711Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dinuclear class II Co-III/Fe-II mixed-valence complexes of type [LnCo (III)(mu-NC) Fe-II(CN)(3)L-2](m-) (where L-n represents a pentadentate macrocycle and L-2 a bpy ligand or two cyanides) have electronic properties that make them possible sensitizers in DSSC ( dye sensitized solar cells). For this purpose the new complex Na-2[{trans-L14COOCo III( m-NC)} Fe II( CN) 5] has been prepared and characterized by the usual methods and its sensitizer properties compared with those of the already known [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(5)](2-)(CN)(3)(bipy)(eq,ax)](ClO4). The complex [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(5)](2-) has been designed for the actuation of an electron injection from the cobalt centre on MMCT, while the [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(3)(bipy)](+) structure can produce a tuned injection from the iron centre via an MLCT electronic state, as described for similar systems. The characterization on solid oxide semiconductor supports has been carried out for these two complexes and the results have been compared with the behaviour observed in aqueous solution and in solvents of varying polarities. Their use in DSSC has been checked and, while a sensitizer response is observed for [{trans-L14COOCo (III)(mu-NC)}Fe-II(CN)(5)](2-), complex [{trans-L14COOCoIII(mu-NC)}Fe-II(CN)(3)(bipy)(eq,ax)](+) does not produce any electrical current on illumination. The low efficiency of the built DSSC can be easily related both with the very low value of the extinction coefficient of the MMCT band responsible for the electron injection, and with the small driving force for the reduction of the complex with the standard I-2/I-3 (-) system used after electron injection.

  • 58. Bi, D.
    et al.
    Xu, Bo
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. Dalian University of Technology (DUT), China.
    Gao, P.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. Dalian University of Technology (DUT), China.
    Grätzel, M.
    Hagfeldt, A.
    Facile synthesized organic hole transporting material for perovskite solar cell with efficiency of 19.8%2016Inngår i: Nano Energy, ISSN 2211-2855, Vol. 23, s. 138-144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The exploration of alternative molecular hole-transporting materials (HTMs) specifically for high performance perovskite solar cells (PSCs) is a relatively recent research area. Aiming for further increasing the 'efficiency-cost ratio' of PSCs, we developed a spiro[fluorene-9,9'-xanthene] based HTM (X59) via two-step synthesis from commercial precursors for perovskite solar cells (PSCs) that works as effectively as the well-known HTM-Spiro-OMeTAD-based device under the same conditions. The molecular structure was analyzed by X-ray crystallography indicating a similar packing regime as for Spiro-OMeTAD. An impressive PCE of 19.8% was achieved by using X59 as HTM in PSC, which can compete with the record PCE of 20.8% by using the state-of-the-art-HTM Spiro-OMeTAD (Tress et al., 2016) [1]. The optimized devices employing X59 as HTM exhibited minimized hysteresis, excellent reproducibility and reasonable stability under dark and dry conditions. The present finding highlights the potential of spiro-type HTM for high performance PSCs and paves the way to a much deceased fabrication cost for potential commercialization of perovskite solar panels.

  • 59. Bichao, H.
    et al.
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Araujo, J.
    Mustaparta, H.
    Five types of olfactory receptor neurons in the strawberry blossom weevil Anthonomus rubi: Selective responses to inducible host-plant volatiles2005Inngår i: Chemical Senses, ISSN 0379-864X, E-ISSN 1464-3553, Vol. 30, nr 2, s. 153-170Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plants release hundreds of volatiles that are important in the interaction with herbivorous animals, but which odorants are detected by which species? In this study, single receptor neurons on the antenna of the oligophagous strawberry blossom weevil Anthonomus rubi were screened for sensitivity to naturally produced plant compounds by the use of gas chromatography linked to electrophysiological recordings from single cells. The narrow tuning of the neurons was demonstrated by responses solely to a few structurally related sesquiterpenes, aromatics or monoterpene hydrocarbons out of hundreds of plant constituents tested. We present five olfactory receptor neuron types, identified according to one primary odorant i.e. the compound to which the neurons are most sensitive. These odorants, (-)-germacrene D, (-)-beta-caryophyllene, methyl salicylate, E-beta-ocimene and (3E)-4,8-dimethyl-1,3,7-nonatriene, present in the intact strawberry plant, are induced in higher amounts by weevil feeding. This suggests that these compounds can provide information about the presence of conspecifics. We used protocols especially designed to allow comparison with previously investigated species. Striking similarities, but also differences, are demonstrated between receptor neuron specificity in the strawberry weevil and moths.

  • 60. Bichao, H.
    et al.
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Wibe, A.
    Araujo, J.
    Mustaparta, H.
    Molecular receptive ranges of olfactory receptor neurones responding selectively to terpenoids, aliphatic green leaf volatiles and aromatic compounds, in the strawberry blossom weevil Anthonomus rubi2005Inngår i: Chemoecology, ISSN 0937-7409, E-ISSN 1423-0445, Vol. 15, nr 4, s. 211-226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important question in insect-plant interactions is which of the numerous plant compounds contribute to the perception of odour qualities in herbivorous insects and are likely to be used as cues in host-searching behaviour. In order to identify which plant-produced volatiles the strawberry blossom weevil Anthonomus rubi detects, we have used electrophysiological recordings from single olfactory neurones linked to gas chromatography and mass spectrometry. We here present 15 receptor neurone types specialised for naturally produced compounds present in the host and nonhost plants and two types for two aggregation pheromone components. The active compounds were terpenoids, aromatic and aliphatic esters, alcohols and aldehydes, some of which are induced by feeding activity of the weevils. The neurones were characterised by a strong response to one or two primary odorants and weaker responses to a few others having similar chemical structure. With one exception, the molecular receptive range of each neurone type was within one chemical group. Enantiomers of linalool separated on a chiral column activated two neurone types with different enantioselectivity. Inhibition by linalool of another neurone type, excited by alpha-pinene, indicated an additional mechanism for coding the information about this compound. Altogether, detection of 54 compounds by olfactory receptor neurones is shown, of which 40 have been chemically identified in this study. Thus A. rubi has the ability to detect a large number of odorants that may be used in host selection behaviour.

  • 61.
    Blid, Jan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The thesis describes the realization of an asymmetric [2,3]-sigmatropic rearrangement of achiral allylic amines. It is divided into two parts; the first part deals with the development of a Lewis acid-mediated [2,3]-sigmatropic rearrangement and the second the asymmetric version thereof. Quaternization of an -amino amide with various Lewis acids established BBr3 and BF3 to be the most appropriate ones. Various allylic amines were subsequently rearranged into the corresponding homoallylic amines in good to excellent syn-diastereoselectivities, revealing the endo-transition state to be the preferred pathway. The structures of the intermediate Lewis acid-amine complexes were confirmed by NMR spectroscopy studies and DFT calculations.

    Based on this investigation a chiral diazaborolidine was chosen as Lewis acid and was shown to efficiently promote the asymmetric [2,3]-sigmatropic rearrangement furnishing homoallylic amines in good yields and excellent enantiomeric excesses. In contrast to the achiral rearrangement mediated by BBr3 and BF3, the asymmetric version gave the opposite major diastereomer, revealing a preference for the exo-transition state in the asymmetric rearrangement. To account for the observed selectivities, a kinetic and thermodynamic pathway was presented. On the basis of a deuterium exchange experiment on a rearranged Lewis acid-amine complex and an NMR spectroscopic investigation, the kinetic pathway was shown to be favored.

  • 62.
    Blid, Jan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Fischer, Andreas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Oorganisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Asymmetric [2,3]-Sigmatropic Rearrangement of Allylic Ammonium Ylides: Scope and Mechanistic InvestigationManuskript (Annet vitenskapelig)
  • 63.
    Blid, Jan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Panknin, Olaf
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Asymmetric [2,3]-sigmatropic rearrangement of allylic ammonium ylides2005Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, nr 26, s. 9352-9353Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An asymmetric Lewis acid-mediated [2,3]-sigmatropic rearrangement of allylic amines has been developed, affording the corresponding homoallylic amines in good yield and excellent enantioselectivities. The rearrangement proceeds by complexation of the chiral Lewis acid to the amine followed by deprotonation and rearrangement.

  • 64.
    Blid, Jan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Panknin, Olaf
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tuzina, Pavel
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Lewis acid mediated asymmetric 2,3 -sigmatropic rearrangement of allylic amines. Scope and mechanistic investigation2007Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, nr 4, s. 1294-1300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    [GRAPHIC] The first asymmetric [2,3]-sigmatropic rearrangement of achiral allylic amines has been realized by quaternization of the amines with an enantiomerically pure diazaborolidine and subsequent treatment with Et3N. The resultant homoallylic amines were obtained in good yields and excellent ee's. The observed diastereo- and enantioselectivities were rationalized by invoking a kinetically controlled process, and support for this model was obtained from an NMR spectroscopic investigation of the chiral Lewis acid-substrate complex. The structure of the Lewis acid-product complex was established by X-ray crystallographic analysis and supported the proposed mechanism.

  • 65.
    Bo, Xu
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Advanced Organic Hole Transport Materials for Solution-Processed Photovoltaic Devices2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Solution-processable photovoltaic devices (PVs), such as perovskite solar cells (PSCs) and solid-state dye-sensitized solar cells (sDSCs) show great potential to replace the conventional silicon-based solar cells for achieving low-cost and large-area solar electrical energy generation in the near future, due to their easy manufacture and high efficiency. Organic hole transport materials (HTMs) play important roles in both PSCs and sDSCs, and thereby can well facilitate the hole separation and transportation, for obtaining high performance solar cells.

    The studies in this thesis aimed to develop advanced small-molecule organic HTMs with low-cost, high hole mobility and conductivity for the achievement of highly efficient, stable and reproducible sDSCs and PSCs. In order to achieve these objectives, two different strategies were utilized in this thesis: the development of new generation HTMs with simple synthetic routes and the introduction of cost-effective p-type dopants to control the charge transport properties of HTMs.

    In Chapter 1 and Chapter 2, a general introduction of the solution-processed sDSCs and PSCs, as well as the characterization methods that are used in this thesis were presented.

    In Chapter 3 and Chapter 4, a series of novel triphenylamine- and carbazole- based HTMs with different oxidation potential, hole mobility, conductivity and molecular size were designed and synthesized, and then systematically applied and investigated in sDSCs and PSCs.

    In Chapter 5, two low-cost and colorless p-type dopants AgTFSI and TeCA were introduced for the organic HTM-Spiro-OMeTAD, which can significantly increase the conductivity of the Spiro-OMeTAD films. The doping effects on the influence of sDSC and PSC device performances were also systematically investigated.

  • 66. Bohman, B.
    et al.
    Nordlander, G.
    Nordenhem, H.
    Sunnerheim, K.
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Unelius, C. R.
    Structure-activity relationships of phenylpropanoids as antifeedants for the pine weevil Hylobius abietis2008Inngår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 34, nr 3, s. 339-352Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ethyl cinnamate has been isolated from the bark of Pinus contorta in the search for antifeedants for the pine weevil, Hylobius abietis. Based on this lead compound, a number of structurally related compounds were synthesized and tested. The usability of the Topliss scheme, a flow diagram previously used in numerous structure-activity relationship (SAR) studies, was evaluated in an attempt to find the most potent antifeedants. The scheme was initially followed stepwise; subsequently, all compounds found in the scheme were compared. In total, 51 phenylpropanoids were tested and analyzed for SARs by using arguments from the field of medicinal chemistry (rational drug design). Individual Hansch parameters based on hydrophobicity, steric, and electronic properties were examined. The effects of position and numbers of substituents on the aromatic ring, the effects of conjugation in the molecules, and the effects of the properties of the parent alcohol part of the esters were also evaluated. It proved difficult to find strong SARs derived from single physicochemical descriptors, but our study led to numerous new, potent, phenylpropanoid antifeedants for the pine weevil. Among the most potent were methyl 3-phenylpropanoates monosubstituted with chloro, fluoro, or methyl groups and the 3,4-dichlorinated methyl 3-phenylpropanoate.

  • 67. Boonyavong, Narumon
    et al.
    Suwanruji, Potjanart
    Hannongbua, Supa
    Li, Fei
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Karpkird, Thitinun M.
    Synthesis, electrochemistry and photo-induced electron transfer of unsymmetrical dinuclear ruthenium osmium 2,2 '-bipyridine complexes2014Inngår i: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, E-ISSN 1873-2666, Vol. 287, s. 40-48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Four unsymmetric dinuclear ruthenium and osmium complexes, Os(bpy)(3)-viologen-Ru(bpy)(3) (1; bpy= 2,2'-bipyridyl), Ru(bpy)(3)-viologen-Ru(bpy)(dcbpy)(2) (2; dcbpy= 4,4'-dicarboxy1-2,2-bipyridyl), Os(bpy)(3)-viologen-Ru(bpy)(dcbpy)(2) (3) and rotaxane 1 subset of CB[7] (CB[7] = cucurbit[7]uril), were successfully synthesized. The NMR, electrochemistry and photochemistry studies of these complexes were performed in non-aqueous solutions. The results show that the CB[7] host mainly locates at the butyl linker part of the osmium side in an acetonitrile solution. This binding lowers the oxidation potential of osmium whereas the oxidation potential of ruthenium does not change. The oxidation potential of ruthenium in complexes 2 and 3 is higher due to the electron withdrawing property of carboxylic anchor groups. Analysis with UV-vis spectra shows the viologen radical formation and reversed process of these complexes in non-aqueous solutions.

  • 68.
    Borg, Tessie
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Stereoselective Nucleophilic Additions to Aldehydes and Development of New Methodology in Organic Synthesis2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is divided into four separate parts with nucleophilic addition to aldehydes as the common feature in three of them.

    The first part deals with the investigation of the stereochemical induction and elucidation of the factors that dictate the p-facial selectivities in Mukaiyama aldol addition to a- and a,b-heteroatom substituted aldehydes. An explanation for the unexpected shift from 1,2-anti to 1,2-syn selectivity seen in the reaction when applying nucleophiles of different sizes in the addition to a-chloro aldehydes is offered.

    The next two parts describes the addition of 1,3-bis(silyl)propenes and C3 substituted 1,3-bis(silyl)propenes to aldehydes and the development of two highly stereoselective new methodologies for the construction of 1,3-dienes and 2,3,4,5-tetrasubstituted tetrahydrofuranes, respectively.

    The last part describes the attempts made towards the total synthesis of (±)-aspidophylline A, where the intention was to apply a domino carbopalladation-carbonylation reaction as the key step in the synthetic route.

  • 69.
    Borg, Tessie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Danielsson, Jakob
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Mohiti, Maziar
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Restorp, Per
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Diastereoselective Nucleophilic Addition to Aldehydes with Polar alpha- and alpha,beta-Substituents2011Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, nr 11-12, s. 2022-2036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The stereoselectivities obtained in Lewis acid-promoted Mukaiyama aldol additions and Sakurai allylations of mono-, and syn- and anti-disubstituted aldehydes possessing various polar alpha- and beta-substituents under non-chelating conditions are presented. The stereochemical outcome in the nucleophilic addition to alpha-substituted aldehydes containing an alpha-benzyloxy, alpha-fluoro or alpha-sulfonamide substituent are accurately predicted by current stereoinduction models. In contrast, the selectivitites obtained from addition of sterically demanding nucleophiles to alpha-chloro-substituted aldehydes cannot be rationalized by the same models and an alternative is discussed. The stereochemichal outcome in the additions to alpha, beta-disubstituted aldehydes is more complex and cannot be predicted using current models.

  • 70.
    Borg, Tessie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Danielsson, Jakob
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Mukaiyama aldol addition to α-chloro-substituted aldehydes. Origin of the unexpected syn selectivity.2010Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, nr 8, s. 1281-1283Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The addition of sterically demanding enolsilanes to alpha-chloro aldehydes results unexpectedly in preferential formation of the anti-PFA product (1,2-syn), while the addition of the corresponding boron enolate furnishes the expected polar Felkin-Anh product (1,2-anti). A stereoinduction model explaining these observations is proposed.

  • 71.
    Borg, Tessie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Restorp, Per
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    ORGN 988-Diastereoselective addition of nucleophiles to aldehydes having polar - and -substituents2007Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234Artikkel i tidsskrift (Annet vitenskapelig)
  • 72.
    Borg, Tessie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Timmer, Brian
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    Diastereoselective formation of 2,3,4,5-tetrasubstituted tetrahydrofurans by a Lewis acid promoted addition of C3-substituted 1,3-bis(silyl)propenes to aldehydes2013Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 54, nr 30, s. 3916-3918Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mild, efficient, Lewis acid promoted addition of C3-substituted 1,3-bis(silyl)propenes to aldehydes to provide the corresponding 2,3,4,5-tetrasubstituted tetrahydrofurans in excellent stereoselectivity is reported.

  • 73.
    Borg, Tessie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Timmer, Brian
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Diastereoselective formation of 2,3,4,5-tetrasubstituted tetrahydrofurans by a Lewis acid promoted addition of C3-substituted 1,3-bis(silyl)propenes to aldehydes2010Manuskript (preprint) (Annet vitenskapelig)
  • 74.
    Borg, Tessie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Tuzina, Pavel
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Somfai, Peter
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Lewis Acid-Promoted Addition of 1,3-Bis(silyl)propenes to Aldehydes: A Route to 1,3-Dienes2011Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, nr 19, s. 8070-8075Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Lewis acid-promoted addition of 1,3-bis(silyl)-propenes to aldehydes to provide the corresponding (E)-1,3-dienes in excellent stereoselectivity and good to excellent yields is reported. The procedure is mild, base-free, and operationally straightforward.

  • 75.
    Borg-Karlson, Anna-Karin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Nordlander, R.
    Mudalige, A.
    Nordenhem, H.
    Unelius, C. R.
    Antifeedants in the feces of the pine weevil Hylobius abietis: Identification and biological activity2006Inngår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 32, nr 5, s. 943-957Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Egg-laying females of the pine weevil, Hylobius abietis (L.), regularly deposit feces adjacent to each egg. Egg cavities are gnawed in the bark of roots of recently dead conifer trees. After egg deposition, the cavity is sealed by feces and a plug of bark fragments. Root bark containing egg cavities with feces is avoided as food by pine weevils, which indicates the presence of natural antifeedants. Here we present the first results of the isolation and chemical analyses of antifeedant compounds in the feces of H. abietis. In feeding bioassays, methanol extracts of the feces revealed strong antifeedant properties. Methanol extracts were fractionated by medium-pressure liquid chromatography and the antifeedant effects were mainly found in the fractions of highest polarity. Volatile compounds in the active fractions were identified by gas chromatography-mass spectrometry (GC-MS) and the nonvolatile compounds were characterized by pyrolysis-GC-MS. Based on mass spectra, a number of compounds with various chemical structures were selected to be tested for their antifeedant properties. Antifeedant effects were found among compounds apparently originating from lignin: e.g., a methylanisol, guaiacol, veratrol, dihydroxybenzenes, and dihydroconiferyl alcohol. A weak effect by fatty acid derivatives was found. The types of naturally occurring antifeedant compounds identified in this study may become useful for the protection of planted conifer seedlings against damage by H. abietis.

  • 76. Borgstrom, M.
    et al.
    Blart, E.
    Boschloo, Gerrit
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Mukhtar, E.
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Hammarstrom, L.
    Odobel, F.
    Sensitized hole injection of phosphorus porphyrin into NiO: Toward new photovoltaic devices2005Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, nr 48, s. 22928-22934Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the preparation and the characterization of a photovoltaic cell based on the sensitization of a wide band gap p-type semiconductor (NiO) with a phosphorus porphyrin. A photophysical study with femtosecond transient absorption spectroscopy showed that light excitation of the phosphorus porphyrin chemisorbed on NiO particles induces a very rapid interfacial hole injection into the valence band of NiO, occurring mainly on the 2-20 ps time scale. This is followed by a recombination in which ca. 80% of the ground-state reactants are regenerated within 1 ns. A photoelectrochernical device, prepared with a nanocrystalline NiO electrode coated with the phosphorus porphyrin, yields a cathodic photocurrent indicating that electrons indeed flow from the NiO electrode toward the solution. The low incident-to-photocurrent efficiency (IPCE) can be rationalized by the rapid back recombination reaction between the reduced sensitizer and the injected hole which prevents an efficient regeneration of the sensitizer ground state from the iodide/triiodide redox mediator. To the best of our knowledge, this work represents the first example of a photovoltaic cell in which a mechanism of hole photoinjection has been characterized.

  • 77. Boschloo, G.
    et al.
    Marinado, T.
    Nonomura, K.
    Edvinsson, T.
    Agrios, A. G.
    Hagberg, D. P.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Quintana, M.
    Karthikeyan, C. S.
    Thelakkat, M.
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    A comparative study of a polyene-diphenylaniline dye and Ru(dcbpy)(2)(NCS)(2) in electrolyte-based and solid-state dye-sensitized solar cells2008Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 20, s. 7214-7217Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A small organic sensitizer, the polyene-diphenylaniline dye D5, was compared with the standard sensitizer N719 (Ru(dcbPY)(2)(NCS)(2)) in a dyesensitized solar cell investigation. In solar cells with relatively thin layers of mesoporous TiO2 (< 3 mu m) D5 outperformed N719 because of its high extinction coefficient. D5 showed also better performance than N719 in the case of sensitization of mesoporous ZnO. In solid-state solar cells, where the iodide/triiodide electrolyte was replaced by an amorphous hole conductor (spiro-OMeTAD), D5 gave promising preliminary results. The hole conductivity, observed in monolayers of D5 adsorbed at TiO2, may possibly lead to improved performance in such cells.

  • 78.
    Boschloo, Gerrit
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Activation energy of electron transport in dye-sensitized TiO2 solar cells2005Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, nr 24, s. 12093-12098Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Various characteristics of dye-sensitized nanostructured TiO2 solar cells, such as electron transport and electron lifetime, were studied in detail using monochromatic illumination conditions. The electron transport was found to be a thermally activated process with activation energies in the range of 0.10-0.15 eV for light intensities that varied 2 orders of magnitude. Electron lifetimes were determined using a new method and found to be significantly larger (> 1 s) than previously determined. An average potential was determined for electrons in the nanostructured TiO2 under illumination in short-circuit conditions. This potential is about 0.2 V lower than the open-circuit potential at the same light intensity. The electron transport time varies exponentially with the internal potential at short-circuit conditions, indicating that the gradient in the electrochemical potential is the driving force for electron transport in the nanostructured TiO2 film. The applicability of the conventionally used trapping/detrapping model is critically analyzed. Although experimental results can be fitted using a trapping/detrapping model with an exponential distribution of traps, the distribution parameters differ significantly between different types of experiment. Furthermore, the experimental activation energies for electron transport are smaller than those expected in a trapping/detrapping model.

  • 79.
    Boschloo, Gerrit
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Photoinduced absorption spectroscopy as a tool in the study of dye-sensitized solar cells2008Inngår i: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 361, nr 3, s. 729-734Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Photoinduced absorption (PIA) spectroscopy, where the excitation is provided by a square-wave modulated (on/off) monochromatic light source, is a versatile tool in the study of dye-sensitized solar cells. Spectra of transient species, such as the oxidized dye, can easily be obtained and their kinetics can be explored using frequency or time-resolved techniques. Experimental PIA conditions can be kept close to typical solar cell operating conditions, allowing extraction of relevant time constants. PIA is also a suitable method to study the quality of pore filling in case of solid hole conductors. Dye molecules that are not in direct contact with the hole conductor will have long lifetimes in their oxidized state and appear clearly in the PIA spectrum. The basic principles of PIA are explained using the example of electron injection and recombination in dye-sensitized TiO2 in the absence of redox electrolyte.

  • 80.
    Boschloo, Gerrit
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Haggman, L.
    Hagfeldt, Anders
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Quantification of the effect of 4-tert-butylpyridine addition to I-/I-3(-) redox electrolytes in dye-sensitized nanostructured TiO2 solar cells2006Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 110, nr 26, s. 13144-13150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Addition of 4-tert-butylpyridine (4TBP) to redox electrolytes used in dye- sensitized TiO2 solar cells has a large effect on their performance. In an electrolyte containing 0.7 M LiI and 0.05 M I-2 in 3-methoxypropionitrile, addition of 0.5 M 4TBP gave an increase of the open-circuit potential of 260 mV. Using charge extraction and electron lifetime measurements, this increases could be attributed to a shift of the TiO2 band edge toward negative potentials (responsible for 60% of the voltage increase) and to an increase of the electron lifetime (40%). At a lower 4TBP concentration the shift of the band edge was similar, but the effect on the electron lifetime was less pronounced. The working mechanism of 4TBP can be summarized as follows: (1) 4TBP affects the surface charge of TiO2 by decreasing the amount of adsorbed protons and/or Li+ ions. ( 2) It decreases the recombination of electrons in TiO2 with triiodide in the electrolyte by preventing triiodide access to the TiO2 surface and/or by complexation with iodine in the electrolyte.

  • 81. Brudvig, G. W.
    et al.
    Reek, J. N. H.
    Sakai, K.
    Spiccia, L.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology (DUT), China.
    Catalytic Systems for Water Splitting2016Inngår i: ChemPlusChem, ISSN 2192-6506, Vol. 81, nr 10, s. 1017-1019Artikkel i tidsskrift (Fagfellevurdert)
  • 82.
    Brulé, Emilie
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Hii, K K
    de Miguel, Y R
    Polymer-supported manganese porphyrin catalysts - peptide-linker promoted chemoselectivity2005Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 3, nr 10, s. 1971-1976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Manganese porphyrin catalysts were tethered to polymer-supports via peptide linkers. The reactivity and chemoselectivity of the catalysts were assessed in the epoxidation of limonene. It was found that the inclusion of a peptide linker incorporating a donor heteroatom which could act as an axial ligand led to a supported manganese porphyrin catalyst with unprecedented selectivity and stability.

  • 83. Buda, Vincas
    et al.
    Mozuraitis, Raimondas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Kutra, Jonas
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    p-Cresol: A Sex Pheromone Component Identified from the Estrous Urine of Mares2012Inngår i: Journal of Chemical Ecology, ISSN 0098-0331, E-ISSN 1573-1561, Vol. 38, nr 7, s. 811-813Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Previously it was shown that m- and p-cresols in the urine of mares exhibits a temporally reproducible pattern that is dependent on ovarian activity and, thus, provides information about the timing of ovulation. New behavioral data demonstrate 1) that stallions spend significantly more time sniffing p-cresol as compared to o-, and m-cresols, and, 2) that the extent of stallions' erections differ significantly in response to different types of samples. The lowest erection level was recorded for the pure-water control, a moderate erection level was elicited by the urine of diestrous mares, and the highest erection level was elicited by urine of a diestrous mare containing synthetic p-cresol at a quantity equivalent to half of the amount of p-cresol found in the urine of estrous mares. Consequently, p-cresol is at least one of the components of a horse sex pheromone.

  • 84. Canton, S. E.
    et al.
    Zhang, X.
    Liu, Y.
    Zhang, J.
    Papai, M.
    Corani, A.
    Smeigh, A. L.
    Smolentsev, G.
    Attenkofer, K.
    Jennings, G.
    Kurtz, C. A.
    Li, F.
    Harlang, T.
    Vithanage, D.
    Chabera, P.
    Bordage, A.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ott, S.
    Warnmark, K.
    Sundstrom, V.
    Watching the dynamics of electrons and atoms at work in solar energy conversion2015Inngår i: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498, Vol. 185, s. 51-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The photochemical reactions performed by transition metal complexes have been proposed as viable routes towards solar energy conversion and storage into other forms that can be conveniently used in our everyday applications. In order to develop efficient materials, it is necessary to identify, characterize and optimize the elementary steps of the entire process on the atomic scale. To this end, we have studied the photoinduced electronic and structural dynamics in two heterobimetallic ruthenium-cobalt dyads, which belong to the large family of donor-bridge-acceptor systems. Using a combination of ultrafast optical and X-ray absorption spectroscopies, we can clock the light-driven electron transfer processes with element and spin sensitivity. In addition, the changes in local structure around the two metal centers are monitored. These experiments show that the nature of the connecting bridge is decisive for controlling the forward and the backward electron transfer rates, a result supported by quantum chemistry calculations. More generally, this work illustrates how ultrafast optical and X-ray

  • 85.
    Caraballo, Remi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Rahm, Martin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Vongvilai, Pornrapee
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Phosphine-catalyzed disulfide metathesis2008Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 48, s. 6603-6605Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The reaction between disulfides and phosphines generates a reversible disulfide metathesis process.

  • 86.
    Caraballo, Rémi
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dynamic Sulfur Chemistry: Screening, Evaluation and Catalysis2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with the design, formation and evaluation of dynamic systems constructed by means of sulfur-containing reversible reactions, in organic and aqueous media and under mild conditions.

    In a first part, the synthesis of thioglycoside derivatives, constituting the biologically relevant starting components of the dynamic systems, is described. In addition, the pD-profile of the mutarotation process in aqueous media for a series of 1-thioaldoses is reported and revealed an astonishing beta-anomeric preference for all the carbohydrate analogs under acidic or neutral conditions.

    In a second part, the phosphine-catalyzed or -mediated disulfide metathesis for dynamic system generation in organic or aqueous media is presented, respectively. The direct in situ 1H STD-NMR resolution of a dynamic carbohydrate system in the presence of a target protein (Concanavalin A) proved the suitability and compatibility of such disulfide metathesis protocols for the discovery of biologically relevant ligands.

    In a third part, hemithioacetal formation is demonstrated as a new and efficient reversible reaction for the spontaneous generation of a dynamic system, despite a virtual character of the component associations in basic aqueous media. The direct in situ 1H STD-NMR identification of the best dynamic beta-galactosidase inhibitors from the dynamic HTA system was performed and the results were confirmed by inhibition studies. Thus, the HTA product formed from the reaction between 1-thiogalactopyranose and a pyridine carboxaldehyde derivative provided the best dynamic inhibitor.

    In a fourth and final part, a dynamic drug design strategy, where the best inhibitors from the aforementioned dynamic HTA system were used as model for the design of non-dynamic (or “static”) beta-galactosidase inhibitors, is depicted. Inhibition studies disclosed potent leads among the set of ligands.

  • 87.
    Caraballo, Rémi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Deng, Lingquan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Amorim, Luis
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Brinck, Tore
    KTH, Skolan för kemivetenskap (CHE), Kemi, Fysikalisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    pH-Dependent Mutarotation of 1-Thioaldoses in Water. Unexpected Behavior of (2S)-D-Aldopyranoses2010Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, nr 18, s. 6115-6121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pH-dependent mutarotation of 1-thioaldopyranoses in aqueous media has been investigated. Anomerization readily occurred at lower and neutral pH for all aldopyranoses studied, whereas mainly for (2S)-D-aldopyranoses at higher pH. 1-Thio-D-mannopyranose and 1-thio-D-altropyranose showed very strong pH dependence where the anomeric equilibrium ratios changed dramatically from a preference for the beta-anomer at lower pH to the alpha-anomer at higher pH.

  • 88.
    Caraballo, Rémi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Dong, Hai
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ribeiro, Joao P.
    Jimenez-Barbero, Jesus
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Direct STD NMR Identification of beta-Galactosidase Inhibitors from a Virtual Dynamic Hemithioacetal System2010Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, nr 3, s. 589-593Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

     The formation of a dynamic hemithioacetal system and its application toward the discovery of ß-galactosidase inhibitors were successfully investigated. The designed dynamic system, which has a virtual character in neutral aqueous media, was subjected to a direct in situ identification of the best inhibitors by 1H STD NMR spectroscopy (ONPC : o-nitrophenyl-β-galactopyranoside).

  • 89.
    Caraballo, Rémi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sakulsombat, Morakot
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Phosphine-Mediated Disulfide Metathesis in Aqueous Media2010Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, nr 44, s. 8469-8471Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Dynamic carbohydrate systems have been efficiently generated through phosphine-mediated disulfide metathesis in aqueous media. The protein compatibility and binding features of the dynamic systems were demonstrated in situ using H-1 STD NMR.

  • 90.
    Caraballo, Rémi
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Sakulsombat, Morakot
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Ramström, Olof
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Towards Dynamic Drug Design: Identification and Optimization of β-Galactosidase Inhibitors from a Dynamic Hemithioacetal System2010Inngår i: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 11, nr 11, s. 1600-1606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A discovery strategy relying on the identification of fragments through resolution of a constitutional dynamic system, coupled to subsequent static ligand design and optimization, is demonstrated. The strategic design and synthesis of the best molecular fragments identified from a dynamic hemithioacetal system into static ligand structures yielded a range of -galactosidase inhibitors. Two series of structures mimicking the hemithioacetal motif were envisaged: thioglycosides and C-glycosides. Inhibition studies provided important structural information for the two groups, and 1-thiobenzyl--D-galactopyranoside demonstrated the best inhibitory effects.

  • 91. Carlsson, Mikael A.
    et al.
    Bisch-Knaden, Sonja
    Schaepers, Alexander
    Mozuraitis, Raimondas
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Hansson, Bill S.
    Janz, Niklas
    Odour Maps in the Brain of Butterflies with Divergent Host-Plant Preferences2011Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 6, nr 8, s. e24025-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Butterflies are believed to use mainly visual cues when searching for food and oviposition sites despite that their olfactory system is morphologically similar to their nocturnal relatives, the moths. The olfactory ability in butterflies has, however, not been thoroughly investigated. Therefore, we performed the first study of odour representation in the primary olfactory centre, the antennal lobes, of butterflies. Host plant range is highly variable within the butterfly family Nymphalidae, with extreme specialists and wide generalists found even among closely related species. Here we measured odour evoked Ca(2+) activity in the antennal lobes of two nymphalid species with diverging host plant preferences, the specialist Aglais urticae and the generalist Polygonia c-album. The butterflies responded with stimulus-specific combinations of activated glomeruli to single plant-related compounds and to extracts of host and non-host plants. In general, responses were similar between the species. However, the specialist A. urticae responded more specifically to its preferred host plant, stinging nettle, than P. c-album. In addition, we found a species-specific difference both in correlation between responses to two common green leaf volatiles and the sensitivity to these compounds. Our results indicate that these butterflies have the ability to detect and to discriminate between different plant-related odorants.

  • 92. Casari, B. M.
    et al.
    Wingstrand, Erica
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Langer, V.
    New mixed-valence chromium structure type: NH4Cr(CrO4)(2)2006Inngår i: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 179, nr 1, s. 296-301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Synthesis and crystal structure of a new structure type of mixed Cr(III)/Cr(VI) chromates is reported. NH4Cr(CrO4)(2) was prepared from CrO3 in the presence of (NH4)(2)Ce(NO3)(6). Since this is the first preparation of mixed valence ternary chromium oxides from aqueous solution, a reaction pathway for this synthesis is suggested. The crystal structure of NH4Cr(CrO4)2 has been determined from three-dimensional X-ray data collected at low temperature, 173 K. The structure belongs to the orthorhombic space group Pnma, with a = 14.5206(10), b = 5.4826(4), c = 8.7041(7) angstrom and Z = 4. The title compound consists of corner-sharing chromium(III) octahedra and chromium(VI) tetrahedra forming a three-dimensional network with the composition [Cr(CrO4)(2]n)(n-), containing channels in which zigzag rows of ammonium ions balance the net charge.

  • 93.
    Chen, Cheng
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Cheng, Ming
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Liu, Peng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Gao, Jiajia
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Kloo, Lars
    KTH, Skolan för kemivetenskap (CHE), Kemi, Tillämpad fysikalisk kemi.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Application of benzodithiophene based A-D-A structured materials in efficient perovskite solar cells and organic solar cells2016Inngår i: Nano Energy, ISSN 2211-2855, Vol. 23, s. 40-49Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, we have designed and synthesized a novel molecular material, BDT-C1, in which the core unit, benzodithiophene (BDT), was functionalized by thiophene (TP) and benzo-[c][1,2,5]-thiadiazole (BTZ) derivatives to generate extended pi-conjugation. BDT-C1 shows high hole mobility and high conductivity in its pristine form, in combination with appropriate energy level alignment with respect to [CH3NH3]PbI3 and PC70BM, qualifying the material as a good candidate for application both in perovskite solar cells (PSCs) as dopant-free hole transport material (HTM) and in OSCs as donor material. The champion PSCs based on BDT-C1 show an average conversion efficiency (PCE) of 13.4% (scan forward: 13.9%; scan backward: PCE=12.9%, scan rate: 10 mV/s). Although the average efficiency obtained is slightly lower than that of reference devices based on the well-known doped HTM Spiro-OMeTAD (13.7%), the BDT-C1 based devices exhibit better stability. Moreover, BDT-C1 as a donor material in OSCs also shows good performance in combination with PC70BM as acceptor material, and an efficiency of 6.1% was obtained. The present results demonstrate that BDT-C1 works well as both donor material in OSCs as well as dopant-free HTMs for efficient PSCs.

  • 94. Chen, Cheng
    et al.
    Yang, Xichuan
    Cheng, Ming
    Zhang, Fuguo
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Degradation of Cyanoacrylic Acid-Based Organic Sensitizers in Dye-Sensitized Solar Cells2013Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 6, nr 7, s. 1270-1275Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Organic dyes have become widely used in dye-sensitized solar cells (DSSCs) because of their good performance, flexible structural modifications, and low costs. To increase the photostability of organic dye-based DSSCs, we conducted a full study on the degradation mechanism of cyanoacrylic acid-based organic sensitizers in DSSCs. The results showed that with the synergy between water and UV light, the sensitizer could desorb from the TiO2 surface and the cyanoacrylic acid unit of the sensitizer was transformed into the aldehyde group. It was also observed that the water content had a great effect on the degradation process. Our experiments conducted using O-18-labeled water demonstrated that the oxygen atom of the aldehyde group identified in the degraded dye came from the solvent water in the DSSCs. Therefore, controlling the water content during DSSC fabrication, good sealing of cells, and filtering the UV light are crucial to produce DSSCs that are more durable and robust.

  • 95. Chen, Cheng
    et al.
    Yang, Xichuan
    Cheng, Ming
    Zhang, Fuguo
    Zhao, Jianghua
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Efficient Panchromatic Organic Sensitizers with Dihydrothiazole Derivative as pi-Bridge for Dye-Sensitized Solar Cells2013Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 5, nr 21, s. 10960-10965Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Novel organic dyes CC201 and CC202 with dihydrothiazole derivative as pi-bridge have been synthesizedand applied in the DSSCs. With the synergy electron-withdrawing of dihydrothiazole and cyanoacrylic acid, these two novel dyes CC201 and CC202 show excellent response in the region of 500-800 nm. An efficiency as high as 6.1% was obtained for the device fabricated by sensitizer CC202 together with cobalt electrolyte under standard light illumination (AM 1.5G, 100 mW cm(-2)). These two novel D-pi-A panchromatic organic dyes gave relatively high efficiencies except common reported squaraine dyes.

  • 96. Chen, Cheng
    et al.
    Yang, Xichuan
    Cheng, Ming
    Zhang, Fuguo
    Zhao, Jianghua
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD.
    Highly efficient organic dyes containing a benzopyran ring as a pi-bridge for DSSCs2013Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, nr 31, s. 12688-12693Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A series of novel organic dyes containing a benzopyran ring as a p-bridge have been designed and applied in dye-sensitized solar cells (DSSCs). This series of dyes show the excellent DSSCs' performance, due to their efficient light-to-photocurrent conversion in the region from 380 nm to 600 nm, with the highest IPCE values exceeding 90%. Through modification of the donor units, an efficiency as high as 7.5% has been achieved under standard light illumination (AM 1.5G, 100 mW cm(-2)) by the dye CC103.

  • 97. Chen, H.
    et al.
    Gao, Y.
    Lu, Z.
    Ye, L.
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Centra, Molekylär elektronik, CMD. KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. KTH, Skolan för bioteknologi (BIO), Teoretisk kemi och biologi. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, DUT-KTH Joint Education and Research Center on Molecular Devices, Dalian University of Technology (DUT), Dalian 116024, China.
    Copper Oxide Film In-situ Electrodeposited from Cu(II) Complex as Highly Efficient Catalyst for Water Oxidation2017Inngår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 230, s. 501-507Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water splitting is deemed as an effective pathway for producing ideal clean energy, such as hydrogen. Here, a copper oxide film (Cu-Tris film) was prepared in-situ from a 0.2 M phosphate buffer solution (pH = 12.0) containing 1.0 mM Cu2+ and 2.0 mM Tris via controlled-potential electrodeposition. The Cu-Tris film showed a significantly low overpotential of 390 mV at a current density of 1.0 mA/cm2 for electrocatalytic water oxidation. Simultaneously, a considerably low Tafel slope of 41 mV/decade was achieved. This Cu-Tris film also exhibited a high and stable current density of ca. 7.5 mA/cm2 at 1.15 V vs. NHE for long-term electrocatalysis (10 h). These results demonstrated the superior performance of the developed Cu-Tris film, which should be attributed to the regulating effect of the five coordinated planar structure of the Cu-Tris complex precursor during the process of electrodeposition.

  • 98. Chen, Hu
    et al.
    Gao, Yan
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian University of Technology (DUT), China.
    A Cobalt-Based Film for Highly Efficient Electrocatalytic Water Oxidation in Neutral Aqueous Solution2016Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 8, nr 17, s. 2757-2760Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A cobalt-based film (Co-Hi) for water oxidation was prepared in 2-[4-(2-hydroxyethyl) piperazin-1-yl]ethanesulfonic acid buffer at pH 7.0 through a unique cyclic voltammetry electrodeposition method by applying a wide scan range from 1.40 to -1.00 V versus normal hydrogen electrode (NHE). This catalyst film displayed highly efficient activity during oxygen evolution in neutral aqueous solution. An impressive current density of more than 1.5 mAcm(-2) that was stable over a prolonged time period was obtained with a remarkably low onset overpotential of 230 mV in 0.1 M phosphate buffer (pH 7.0).

  • 99. Chen, Hu
    et al.
    Gao, Yan
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi. Dalian Univ Technol, Peoples R China.
    Highly Active Three-Dimensional NiFe/Cu2O Nanowires/Cu Foam Electrode for Water Oxidation2017Inngår i: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, nr 7, s. 1475-1481Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water splitting is of paramount importance for exploiting renewable energy-conversion and -storage systems, but is greatly hindered by the kinetically sluggish oxygen evolution reaction (OER). In this work, a three-dimensional, highly efficient, and durable NiFe/Cu2O nanowires/Cu foam anode (NiFe/Cu2O NWs/CF) for water oxidation in 1.0m KOH was developed. The obtained electrode exhibited a current density of 10mAcm(-2) at a uniquely low overpotential of =215mV. The average specific current density (j(s)) was estimated, on the basis of the electrocatalytically active surface area, to be 0.163mAcm(-2) at =310mV. The electrode also displayed a low Tafel slope of 42mVdecade(-1). Moreover, the NiFe/Cu2O NWs/CF electrode could maintain a steady current density of 100mAcm(-2) for 50h at an overpotential of =260mV. The outstanding electrochemical performance of the electrode for the OER was attributed to the high conductivity of the Cu foam and the specific structure of the electrode with a large interfacial area.

  • 100. Chen, Lin
    et al.
    Wang, Mei
    Gloaguen, Frederic
    Zheng, Dehua
    Zhang, Peili
    Sun, Licheng
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Multielectron-Transfer Templates via Consecutive Two-Electron Transformations: Iron-Sulfur Complexes Relevant to Biological Enzymes2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 44, s. 13968-13973Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    [FeFe] hydrogenase mimics: Two polynuclear iron-sulfur complexes (1 and 2; see figure) were prepared and structurally characterized. They are potentially effective and stable multielectron-transfer relays for mediating four- and six-electron transformations via a cascade of reversible two-electron redox steps with relatively narrow potential spans.

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