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  • 1. Adnan, Muhammad
    et al.
    Iqbal, Javed
    Bibi, Shamsa
    Hussain, Riaz
    Akhtar, Muhammad Nadeem
    Rashid, Muhammad Abid
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ayub, Khurshid
    Fine Tuning the Optoelectronic Properties of Triphenylamine Based Donor Molecules for Organic Solar Cells2017In: Zeitschrift fur physikalische Chemie (Munchen. 1991), ISSN 0942-9352, Vol. 231, no 6, p. 1127-1139Article in journal (Refereed)
    Abstract [en]

    Geometrical parameters, electronic structures and photophysical properties of three new triphenylamine (TPA) and diphenylamine (DPA) based electron donor materials M1-M3 (for organic solar cells) have been investigated through density functional theory (DFT) methods at the B3LYP/6-31G(d) level of the theory. TPA and DPA are used as donor moieties due to their electron donating ability while benzothiazole, cyanide and cyanomethylacetate (CMA) moieties have been taken as acceptor moieties. The time dependent-DFT (TD-DFT) method has been employed [TD-B3LYP/6-31G (d)] for the computation of excited state properties in the gas phase and in solvent (chloroform). The polarization continuum model is applied for calculations in the solvent phase. The designed molecules exhibited broad absorption in the visible and near infra-red region of spectrum with respect to a reference molecule "R" of a similar class of compounds. Based on reorganization energies calculations, these materials could act as excellent hole transport materials.

  • 2.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Karlsson, Leif
    AkzoNobel.
    de Wit, Paul
    AkzoNobel.
    Svedberg, Anna
    MoRe Research.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Activation of dissolving celluloses pulp for viscose and cellulose ether production2016Conference paper (Other academic)
    Abstract [en]

    Mercerisation of cellulose by alkali treatment is the most common procedure used to activate natural cellulose fibres into many commercial cellulosic materials. During mercerisation, the NaOH solution enters the cellulose fibres, transforming them into a swollen and a highly reactive material called alkali cellulose (Na-Cell). In case NaOH is completely washed out of the cellulose structure, Na-Cell turns into Cellulose II upon drying.

    Traditionally the cellulose is mercerised by suspending it in a 15-20 % NaOH solution. The result is a high (15-25 mol/mol) NaOH: Anhydroglucose  molar ratio (r) and mercerisation in these conditions have been extensively studied. However, in modern production of cellulose ethers, the mercerisation conditions are often very different. The main reason is that any excess of water and OH--ions used during the mercerisation can later react with different chemicals in the process, thus forming unwanted by-products e.g. methanol. One way to avoid this kind of side reaction is by using low-water-content mercerisation conditions, i.e. low (r) = 0.8-1.8 mol/mol and high NaOH concentration (45-55% w/w). The traditional mercerisation is a suspension process while the cellulose during the latter process, i.e low-water-content mercerisation conditions, remains quite “dry”. Thus, although the chemical reaction principles of activation of cellulose for both viscose and cellulose ethers processes are the same, the activation conditions used are often very different. Therefore, the different dependencies of process parameters as well as any similarities between the processes are interesting.

    The presentation summarises the findings presented in two papers which described the influence of the different parameters on the mercerisation/activation of softwood Sulphite dissolving pulp in viscose production conditions (Albán Reyes et al. 2016) and cellulose derivatives production conditions (Albán Reyes et al.) respectively. In the individual studies this has been done by analysing the degree of transformation (DoT) of dissolving pulp to Na-cellulose (or more correctly cellulose II after washing and upon drying) as a function of simultaneous variation of [NaOH], temperature, and reaction time varied using design of experiment. Also the (r) was varied for samples mercerised at dry conditions. A combination of Raman imaging and multivariate data analysis have been used to study the DoT to Cellulose II.

    It was found that the mercerisation under the different conditions was dependent on different parameters. For traditional mercerisation, on the one hand, the temperature was shown to be important for the DoT and showed negative correlation with the data, while [NaOH] showed a positive correlation. On the other hand, at low-water-content mercerisation conditions the (r) was overall most important while the temperature showed no statistical importance in a Partial least squares analysis. Traditional mercerisation gave much higher DoT than the low-water-content mercerisation. Thus,  the data for low-water-content mercerisation was further examined at the different (r). The same chemistry is always expected and the different influences of the parameters seen is understood and discussed in terms of the different physical reaction mechanisms.  

  • 3.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Skoglund, Nils
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, no 2, p. 1061-1072Article in journal (Refereed)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

  • 4.
    Albán Reyes, Diana Carolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sundman, Ola
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schröder, Ulf
    AkzoNobel.
    Karlsson, Leif
    AkzoNobel.
    de Wit, Paul
    AkzoNobel.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Activation of dissolving cellulose pulp at low water content2015In: 4th EPNOE International Polysaccharide Conference: Polysaccharides and polysaccharide-based advance materials: from science to industry, 2015Conference paper (Other academic)
    Abstract [en]

    Mercerisation of cellulose by alkali treatment is the first step in modifying natural cellulose fibres into many commercial cellulosic materials. During treatment, the fiber transforms into a reactive and highly swollen material called alkali cellulose (Na-Cell). In case NaOH is washed out of the cellulose structure, Na-Cell turn into Cellulose II upon drying (Langan et al. 2001).

     

    The aim of the present study was to gain a better understanding of the mercerisation of dissolving cellulose pulp at low water content. This has been done by spraying NaOH onto milled cellulose in a kneader, then washing the cellulose to neutrality to stop the reaction. After drying the transformation degree to cellulose II was analysed. The experiments include variation of temperature (30-60°C), reaction time (5 and 25 min), [NaOH] (45-55%), and NaOH:Cellulose molar ratio (0.8- 1.8). A combination of NIR Raman imaging and multivariate data analysis have been used to study the transformation degree.

     

    To the authors’ knowledge, this is the first time the influence of NaOH: Cellulose molar ratio on the mercerisation process has been studied in a single model together with temperature, reaction time and [NaOH]. Our results indicate that increased NaOH: Cellulose molar ratio has a significant positive influence on transformation degree of dissolving cellulose pulp at low water content.

  • 5.
    Boman, Patrik
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Grimm, Russell A
    Staley, Stuart W
    Bond shift and charge transfer dynamics in methylene- and dimethylsilyl-bridged dicyclooctatetraene dianions2001In: Journal of the Chemical Society Perkin Transactions 2, p. 1130-8Article in journal (Refereed)
    Abstract [en]

    The rate constants for bond shift in dicyclooctatetraenylmethane (1), dicyclooctatetraenyldimethylsilane (2), and their dianions (12– and 22–) in [2H8]THF, have been determined from the temperature dependence of their 13C NMR linewidths. The corresponding parameters for intramolecular electron and cation transfer (charge transfer) between the dinegative and neutral rings have been measured by 13C NMR spin saturation transfer experiments for the dipotassium salts of 1 and 2. Selected structural features of the neutral compounds and the dianions are discussed on the basis of 13C NMR chemical shifts and ab initio molecular orbital calculations at the HF/6-31G* and HF/3-21G(*) levels of theory. Energy contributions to the ring flattening in the bond shift process are calculated by molecular mechanics methods. The measured rate constants for both bond shift and charge transfer are larger for the methylene-bridged dianion. Approximately half of this difference is due to the greater ease of gating (i.e., ring flattening and distortion to the bond shift transition state) in 12––2K+. A significant portion of the remainder is attributed to a greater inter-ring through-space interaction in 12–, although mediation by the cation and/or through-bridge interactions probably also contribute to some extent. A temperature-dependent differential 13C NMR line broadening is observed for the dianion ring carbons of the dipotassium salts. Possible mechanisms for this counterion-specific line broadening, which occurs only for carbons with large HOMO coefficients, are discussed.

  • 6.
    Carlsson, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Desroches, Cedric
    Lindgren, Mikael
    Lopes, Cesar
    Parola, Stephane
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Synthesis of di(arylethynyl)bis(tributylphosphine) platinum(II) complexes and preparation of organic-inorganic hybrid silica glass for nonlinear absorption of lightManuscript (preprint) (Other (popular science, discussion, etc.))
  • 7.
    Carlsson, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    One-pot synthesis of trans mono- or diarylalkynyl substituted platinum(II) compounds with tertiary phosphine or phosphite ligands2006In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 25, no 22, p. 5500-5502Article in journal (Refereed)
    Abstract [en]

    An efficient one-pot synthesis has been developed for preparation of trans-mono- or diarylalkynyl bisphosphine or bisphosphite Pt(II) compounds. In the procedure, the alkyne and the tertiary phosphorus ligands are mixed with PtCl2 in tetrahydrofuran and triethylamine solution. CuI is added for synthesis of disubstituted complexes, but the catalyst is not used for preparation of monosubstituted complexes. Microwave irradiation is preferably employed to give the trans-mono- or diarylalkynyl Pt(II) compound in short time and high yield.

  • 8.
    Chateau, Denis
    et al.
    Laboratoire de Chimie, Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, CNRS UMR5182, Lyon 69364, France.
    Chaput, Frederic
    Laboratoire de Chimie, Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, CNRS UMR5182, Lyon 69364, France.
    Lopes, Cesar
    Information Systems, Swedish Defence Research Agency (FOI), Linköping SE-581 11, Sweden.
    Lindgren, Mikael
    Department of Physics, Norwegian University of Science and Technology, Trondheim NO-7491, Norway.
    Brännlund, Carl
    Information Systems, Swedish Defence Research Agency (FOI), Linköping SE-581 11, Sweden.
    Öhgren, Johan
    Information Systems, Swedish Defence Research Agency (FOI), Linköping SE-581 11, Sweden.
    Djourelov, Nikolay
    Institut de Physique Nucléaire, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France.
    Nedelec, Patrick
    Institut de Physique Nucléaire, Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Villeurbanne, France.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lerouge, Frederic
    Laboratoire de Chimie, Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, CNRS UMR5182, Lyon 69364, France.
    Andraud, Chantal
    Laboratoire de Chimie, Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, CNRS UMR5182, Lyon 69364, France.
    Parola, Stephane
    Laboratoire de Chimie, Université de Lyon, Université Claude Bernard Lyon 1, ENS Lyon, CNRS UMR5182, Lyon 69364, France.
    Silica hybrid sol-gel materials with unusually high concentration of Pt-organic molecular guests: Studies of luminescence and nonlinear absorption of light2012In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 5, p. 2369-2377Article in journal (Refereed)
    Abstract [en]

    The development of new photonic materials is a key step towards improvement of existing optical devices and for the preparation of a new generation of systems. Therefore synthesis of photonic hybrid materials with a thorough understanding and control of the microstructure-to-properties relationships is crucial. In this perspective, a new preparation method based on fast gelation reactions using simple dispersion of dyes without strong covalent bonding between dye and matrix has been developed. This new sol-gel method is demonstrated through synthesis of monolithic siloxane-based hybrid materials highly doped by various platinum(II) acetylide derivatives. Concentrations of the chromophores as high as 400 mM were obtained and resulted in unprecedented optical power limiting (OPL) performance at 532 nm of the surface-polished solids. Static and time-resolved photoluminescence of the prepared hybrid materials were consistent with both OPL data and previous studies of similar Pt(II) compounds in solution. The impacts of the microstructure and the chemical composition of the matrix on the spectroscopic properties, are discussed.

  • 9. Glimsdal, Eirik
    et al.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Minaev, Boris
    Lindgren, Mikael
    Excited States and Two-Photon Absorption of Some Novel Thiophenyl Pt(II)-Ethynyl Derivatives2007In: JOURNAL OF PHYSICAL CHEMISTRY A, Vol. 111, p. 244-50Article in journal (Refereed)
    Abstract [en]

    The photophysical characterization of two new compounds related to bis((4-(phenylethynyl)phenyl)ethynyl)bis(tributylphosphine)platinum(II), here abbreviated Pt1, is reported. For the first new compound ATP1, the inner phenyl rings (closer to the Pt atom) in Pt1 are replaced by thiophene rings bridging at the 2,5-positions. In compound ATP2, the outer phenyl groups are replaced by thiophene rings bonded at the 2-position. Specifically, we report on the fluorescence quantum yield, two-photon absorption, triplet decay times and two-photon absorption induced emission spectra of the molecules in THF solutions. The results were compared with those of Pt1 and Pt1 capped with an acetonide-protected 2,2-bis(methylol)propionic acid (bis-MPA) ester group (Pt1-G1). The photophysical properties of the organic dye 7-(diethylamino)coumarin (Coumarin 110) were determined and used as a reference material. The two-photon absorption cross section around 720-740 nm of ATP1 and ATP2 was found to be of the same order of magnitude as for Pt1-G1, i.e., between 5 and 10 GM, but slightly larger for ATP1 than for ATP2 (1 GM = 1 Goppert-Mayer = 10(-50) (cm(4) s)/photon). The fluorescence decay time of all compounds was found to be very short (subnanosecond) with quantum yields 0.0045, 0.0007, 0.0011 and 0.0020 for ATP1, ATP2, Pt1-G1 and Pt1, respectively, measured at excitation wavelength 373 nm. Just as Pt1 and Pt1-G1, both thiophenyl derivatives showed large intersystem crossing capabilities and phosphorescence, characteristic for a triplet state that can enhance the nonlinear absorption and optical power limiting by triplet state absorption. The phosphorescence emission of the thiophenyl derivatives was red-shifted in comparison with Pt1 and Pt1-G1, and the phosphorescence decay times were on the order of 200-500 ns, as for the Pt1 compound.

  • 10.
    Glimsdal, Eirik
    et al.
    Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kindahl, Tomas
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindgren, Mikael
    Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
    Lopes, Cesar
    Division of Information Systems, Swedish Defence Research Agency (FOI), Linköping, Sweden.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Luminescence, singlet oxygen production, and optical power limiting of some diacetylide platinum(II) diphosphine complexes2010In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 114, no 10, p. 3431-3442Article in journal (Refereed)
    Abstract [en]

    A series of four new trans-diphosphine Pt(II) diacetylide complexes, with a thiophene and two benzenoid rings in each acetylide ligand, have been synthesized and characterized with respect to optical absorption, spectrally and time-resolved luminescence, and optically nonlinear properties such as two-photon absorption cross section and optical power limiting. Density functional theory (DFT) calculations of a few ground state conformations of three Pt(II) diacetylide structures showed similar total energy for each geometry-optimized rotamer but some differences in the vertical excitation energies and in the ligand-to-metal charge-transfer character. The wavelengths of the calculated excitations were found to be red-shifted compared with peaks in the optical absorption spectra, but the general trends and shifts of wavelengths between the different structures are well reproduced. Static emission spectra for degassed samples in THF solution of the larger compounds showed small Stokes shifts and low fluorescence quantum yields, indicating fast intersystem crossing to the triplet manifold. More pronounced differences between the compounds were displayed in the phosphorescence data, in terms of spectral emission wavelengths and decay times. For instance, the phosphorescence decay of the compound with the thiophene ring close to the Pt center was found to be significantly faster than for the other compounds. A possible relationship between triplet lifetime and conformation of the compounds is discussed. It was also demonstrated that the quenching of the excited triplet states in air-saturated samples involves energy transfer to the oxygen triplet state, and subsequent generation of singlet oxygen showing the typical emission at approximately 1275 nm. The amount of produced singlet oxygen followed the phosphorescence yields of the solute molecules. Two-photon absorption cross sections (sigma(2)) were measured and showed values on the order of 10 GM at 780 nm for all compounds. Optical power limiting measurements of the new complexes in THF using 5 ns pulses, showed only slightly better performance at the wavelength of 532 nm compared to that of similar platinum compounds with only two aryl rings in each ligand. At 600 nm the complexes with three aryl rings were significantly better optical limiters than the smaller compounds with two aryl rings in the ligands.

  • 11.
    Glimsdal, Eirik
    et al.
    Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Dragland, Ingunn
    Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Melø, Thor Bernt
    Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Lindgren, Mikael
    Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Triplet excited states of some thiophene and triazole substituted platinum(II) acetylide chromophores2009In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 113, no 14, p. 3311-3320Article in journal (Refereed)
    Abstract [en]

    The photophysical properties of a series of platinum(II) acetylide compounds (trans-Pt(PBu(3))(2)(CC-R)(2)) with the R group consisting of two or three aryl rings (phenyl, phenyl/thiophenyl, phenyl/triazolyl) linked together with ethynyl groups were systematically investigated. Four new structurally similar compounds are reported with: (i) a bithiophene unit in the ligands, (ii) methyl or (iii) methoxy substituents on the aryl ring ligands that promote a more twisted conformation along the long axis of the molecule, and (iv) with two different alkynylaryl ligands giving rise to an asymmetric substitution with respect to the photoactive metal ion center. The spectroscopic studies include optical absorption, spectrally and time-resolved luminescence, as well as transient absorption spectra. The ground-state UV absorption between 300 and 420 nm gave rise to fluorescence with quantum efficiencies in the range of 0.1-1% and efficient intersystem crossing to triplet states. Phosphorescence decay times were in the order of 10-500 mus in oxygen-evacuated samples. The triplet states also lead to strong broadband triplet-triplet absorption between 400 and 800 nm. The complex with asymmetric substitution was found to populate two triplet states of different structure and energy.

  • 12. Gromov, Sergey P
    et al.
    Vedernikov, Artem I
    Ushakov, Evgeny N
    Kuz'mina, Lyudmila G
    Feofanov, Alexei V
    Avakyan, Vitaly G
    Churakov, Andrei V
    Alaverdyan, Yurii S
    Malysheva, Ekaterina V
    Alfimov, Michael V
    Howard, Judith A K
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis, Structure, Spectroscopic Studies, and Complexation of Novel Crown Ether Butadienyl Dyes2002In: Helvetica Chimica Acta, Vol. 85, no 1, p. 60-81Article in journal (Refereed)
    Abstract [en]

    Butadienyl dyes of the benzothiazole series with various fragments of benzocrown ethers 1a-c were synthesized for the first time. The structures and spectral properties of crown-containing butadienyl dyes and their complexes with alkali and alkaline-earth metal cations were studied by X-ray diffraction analysis and 1H-NMR, UV/VIS, and resonance Raman spectroscopy. To interpret the experimental results, quantum-chemical calculations were performed. In the case of Sr2+ and Ba2+ ions, the formation of strong sandwich complexes [M(1b)2]2+ of an unusual structure involving stacking interactions was established; the dye molecules are arranged one above another in the complex according to the head-to-head' pattern.

  • 13.
    Gräsvik, John
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Halogen-free ionic liquids and their utilization as cellulose solvents2012In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1028, p. 156-163Article in journal (Refereed)
    Abstract [en]

    This work demonstrates a novel synthesis route to halogen-free ionic liquids. A one-pot synthetic reaction route avoiding the use of toxic and high-energetic alkyl halides was developed to reduce the environmental impact of the synthesis process of ionic liquids. However, the elimination of halogens and alkyl halides in the preparation of ionic liquids is not just an environmental issue: the aforementioned species are also among the most common and persistent contaminants in today’s Ionic Liquids (ILs). Thus, this paper introduces a range of quaternized nitrogen based ionic liquids, including both aromatic and non-aromatic components, all prepared without alkyl halides in any step of the process. Moreover, bio-renewable precursors such as (bio-)alcohols and carboxylic acids were employed as anion sources and alkylation media, thus avoiding halogen contamination or halogen-containing anions. The IL’s prepared were designed to dissolve cellulose, some of which was included in a cellulose dissolution study using a sulphite cellulose from the company Domsjö.

  • 14.
    Iqbal, Javed
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Chemistry, University of Agriculture, Faisalabad 38040, Pakistan.
    Enevold, Jenny
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Larsen, Christian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wang, Jia
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Revoju, Srikanth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Barzegar, Hamid Reza
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    An arylene-vinylene based donor-acceptor-donor small molecule for the donor compound in high-voltage organic solar cells2016In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 155, p. 348-355Article in journal (Refereed)
    Abstract [en]

    A donor-acceptor-donor (D-A-D) molecule has been designed and synthesized for use as the electron donating material in solution-processed small-molecule organic solar cells (OSCs). The D-A-D molecule comprises a central electron-accepting (2Z,2'Z)-2,2'-(2,5-bis(octyloxy)-1,4-phenylene)bis(3-(thiophen-2-yl)acry lonitrile) (ZOPTAN) core, which is chemically connected to two peripheral and electron-donating triphenylamine (TPA) units. The ZOPTAN-TPA molecule features a low HOMO level of -5.2 eV and an optical energy gap of 2.1 eV. Champion OSCs based on a solution-processed and non-annealed active material blend of [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) and ZOPTAN-TPA in a mass ratio of 2:1 exhibits a power conversion efficiency of 1.9% and a high open-circuit voltage of 1.0 V. 

  • 15. Irfan, Muhammad
    et al.
    Eliason, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mahr, Muhammad Shabir
    Iqbal, Javed
    Tuning the Optoelectronic Properties of Naphtho-Dithiophene-Based A-D-A Type Small Donor Molecules for Bulk Hetero-Junction Organic Solar Cells2018In: ChemistrySelect, ISSN 2365-6549, Vol. 3, no 8, p. 2352-2358Article in journal (Refereed)
    Abstract [en]

    Four acceptor-donor-acceptor (A-D-A) type small molecules using naphtho-dithiophene as central building block, trithiophene as -bridges, malononitrile and 2-Thioxo-thiazolidin-4-one as end acceptor groups were designed by using density functional theory (DFT) and investigated as donor materials for organic solar cells (OSCs). The effects of end acceptor groups on absorption, charge transport, morphology, energy level and photovoltaic properties of the molecules were investigated and compared with reference molecule (R1= NDTP-CNCOO). These designed molecules showed relatively low HOMO levels of -5.46 to -5.56eV, strong absorption between 440-650nm by using chloroform as solvent. The designed donor molecules have an excellent electron mobility from 0.0161 to 0.0201V, hole mobility from 0.0275 to 0.0307V and open circuit voltage (Voc) from 1.76 to 1.86V. This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.

  • 16. Irfan, Muhammad
    et al.
    Iqbal, Javed
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ayub, Khurshid
    Rana, Usman Ali
    Khan, Salah Ud-Din
    Benchmark study of UV/Visible spectra of coumarin derivatives by computational approach2017In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1130, p. 603-616Article in journal (Refereed)
    Abstract [en]

    A benchmark study of UV/Visible spectra of Simple coumarins and Furanocoumarins derivatives was conducted by employing the Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) approaches. In this study the geometries of ground and excited states, excitation energy and absorption spectra were estimated by using the DFT functional CAM-B3LYP, WB97XD, HSEH1PBE, MPW1PW91 and TD-B3LYP with 6-31 + G (d,p) basis set. CAM-B3LYP functional was found to have close agreement with the experimental values of Furranocoumarin class of coumarins while MPW1PW91 gave close results for simple coumarins. This study provided an insight about the electronic characteristics of the selected compounds and provided an effective tool for developing and designing the better UV absorber compounds.

  • 17. Irfan, Muhammad
    et al.
    Iqbal, Javed
    Sadaf, Sana
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rana, Usman Ali
    Ud-din Khan, Salah
    Ayub, Khurshid
    Design of donor-acceptor-donor (D-A-D) type small molecule donor materials with efficient photovoltaic parameters2017In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 117, no 10, article id e25363Article in journal (Refereed)
    Abstract [en]

    Four Donor-Acceptor-Donor (D-A-D) type of donor molecules (M1-M4) with triphenylamine (TPA) as donor moiety, thiophene as bridge, and thiazolothiazole as acceptor unit were designed and its photovoltaic parameters were equated with reference molecule R. DFT functional CAM-B3LYP/6-31G (d,p) was found best for geometry optimization and TD-CAM-B3LYP/6-31G (d,p) was found suitable for excited state calculations. Among designed donor molecules, M4 manifests suitable lowest band gap of 4.73 eV, frontier molecular orbital energy levels as well as distinctive broad absorption of 455.3 nm due to the stronger electron withdrawing group. The electron-withdrawing substituents contribute to red shifts of absorption spectra and better stabilities for designed molecules. The theoretically determined reorganization energies of designed donor molecules suggested excellent charge mobility property. The lower (e) values in comparison with (h) illustrated that these four donor materials would be ideal for electron transfer and M4 would be best amongst the investigated molecules with lowest (e) of 0.0177. Furthermore, the calculated Voc of M4 is 2.04 V with respect to PC60BM (phenyl-C61-butyric acid methyl ester). This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.

  • 18.
    Kindahl, Tomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ellingsen, Pal Gunnar
    Lopes, Cesar
    Brannlund, Carl
    Lindgren, Mikael
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Photophysical and DFT Characterization of Novel Pt(II)-Coupled 2,5-Diaryloxazoles for Nonlinear Optical Absorption2012In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 116, no 47, p. 11519-11530Article in journal (Refereed)
    Abstract [en]

    Several new bis-phosphine platinum(II) complexes with 2,5-diaryl-substituted oxazole-containing alkyne ligands have been synthesized and optically characterized in solution. Measurements of nonlinear absorption showed strong attenuation of laser light at 532 and 600 nm. The light absorption of the Pt complexes was shifted from the near-UV region for the ground state to the red region for the excited triplet state, and was associated with large extinction coefficients. The optical limiting effect can be explained by triplet-triplet excited state absorption in conjunction with fast excited singlet to-triplet intersystem crossing and slow triplet to-ground-state decay, in comparison with the pulse length of the laser. DFT calculations show good predictability of the S-0-S-1 and S-0-T-1 energy gaps and offer insight into the interaction strength between Pt and the alkyne ligands. The use of this type of ligand, with weak absorption for the Pt(II) complexes in the visual wavelength range as a key feature, enables the possibility to further improve these molecular systems for nonlinear absorption applications.

  • 19.
    Kindahl, Tomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Öhgren, Johan
    Lopes, Cesar
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis, optical power limiting, and DFT calculations of triplet–triplet absorption of three novel Pt(II)-diacetylide chromophores2013In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 54, no 19, p. 2403-2408Article in journal (Refereed)
    Abstract [en]

    Three novel rod-like Pt(II)-diacetylides have been synthesized. When subjected to intense laser light, all three compounds showed strong optical power limiting at 532 and 600 nm. DFT calculated triplet–triplet electronic excitations were found to correlate with the nonlinear absorption.

  • 20.
    Lind, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Boström, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Eriksson, Anders
    Glimsdal, Eirik
    Lindgren, Mikael
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics, Energy Technology and Thermal Process Chemistry.
    Structural, photophysical, and nonlinear absorption properties of trans-di-arylalkynyl Platinum(II) Complexes with Phenyl and Thiophenyl Groups2007In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 111, no 9, p. 1598-1609Article in journal (Refereed)
    Abstract [en]

    Optical power limiting and luminescence properties of two Pt(II) complexes with thiophenyl and phenyl groups in the ligands, trans-Pt(P(n-Bu)3)2(C[triple bond]C-Ar)2, where Ar = -C4H2S-C[triple bond]C-p-C6H4-n-C5H11 (1) and -p-C6H4-C[triple bond]C-C4H3S (2), have been investigated. The fluorescence lifetimes were found to be on the sub-nanosecond time scale, and the quantum yields were low, in accord with fast intersystem crossing from the excited singlet to triplet manifold. The phosphorescence lifetimes of 1 and 2 were shorter than that of a Pt(II) complex having two phenyl groups in the ligands. In order to elucidate the C-Pt bonding nature in the ground state, the 13C NMR chemical shift of the carbon directly bonded to Pt, the coupling constants 1JPtC, 2JPtC, and 1JPtP, and IR νC[triple bond]C wavenumbers were obtained for 1, 2, and three other trans-diarylalkynyl Pt(II) complexes. X-ray diffraction data of 1 and 2 and density functional theory calculated geometries of models of 1, 2, and trans-Pt(P(n-Bu)3)2(C[triple bond]C-p-C6H4-C[triple bond]C-C6H5)2 (3) show that 1 preferably exists in a different conformation from that of 2 and 3. The variations in photophysical, NMR, and IR data can be rationalized by differences in geometry and pi-backbonding from Pt to the alkynyl ligand.

  • 21. Manzoor, Farah
    et al.
    Iqbal, Javed
    Zara, Zeenat
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mahr, Muhammad Shabir
    Ayub, Khurshid
    Theoretical Calculations of the Optical and Electronic Properties of Dithienosilole- and Dithiophene-Based Donor Materials for Organic Solar Cells2018In: ChemistrySelect, ISSN 2365-6549, Vol. 3, no 5, p. 1593-1601Article in journal (Refereed)
    Abstract [en]

    Six Acceptor-Donor-Acceptor (A-D-A) types molecules with dimethyl dithieno[3, 2-b:2',3'-d]silole) -2,6-diyl (DTS) (M-1-M-3) and dimethyl cyclopenta [2, 1-b;3,4-b]-dithiophene (CPDT) (M-4-M-6) core flanged by different acceptor units through methylthiophene bridge are evaluated as donor materials for photovoltaic applications. The photovoltaic properties of M-1-M-3 and M-4-M-6 are compared with standard RaRc and R-b,R-d respectively. Geometry optimization was performed with CAM-B3LYP/6-31G (d) level of theory. TD-CAM-B3LYP has been employed for the estimation of excited state properties of the molecules. M-1, M-2, M-3 and M-4, M-5, M-6 symbolized suitable frontier molecular orbital's (FMO's) energy levels with broad absorption spectra. The electron withdrawing substituents impart red shift in absorption spectra along with good consistancy of designed donor molecules. Reorganization energies of donor molecules (M-1-M-6) showed ideal properties of charge mobility. M-1 and M-4 illustrated lowest le values as compared to lambda(h), thus dictated that designed donor molecules are of good choice for their electron donating ability. Furthermore, M-2 and M-6 demonstrated shortest Eg of 3.7 and 3.72 eV among HOMO and LUMO energy levels.

  • 22. Parola, Stephane
    et al.
    Zieba, Roman
    Desroches, Cedric
    Chaput, Frederic
    Malmstrom, Eva
    Lindgren, Mikael
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lopes, Cesar
    Hybrid materials for optical limiting applications2006In: Optical Materials in Defence Systems Technology III, Stockholm, Sweden, 2006, Vol. 6401, no 1, p. 64010D-8Conference paper (Refereed)
    Abstract [en]

    Optical limiting materials are developed for applications in protection of optical sensors against laser aggressions. We have studied functionalised macrocycles (thiacalixarenes) and alkynylplatinum(H) derivatives for optical limiting applications. Glass materials based on alkynylplatinum(H) derivatives and macrocycles were prepared through the sol-gel process. The molecular species were grafted to the matrix in order to maximise the concentration and the stability of the final solid-state material. The glass materials were cut and polished to approximately 1.5 mm. The glass materials show broadband optical limiting in the visible wavelength region, for nanosecond laser pulses.

  • 23. Parola, Stephane
    et al.
    Öertenblad, Marcus
    Chaput, Frédéric
    Desroches, Cédric
    Baldeck, Patrice L.
    Malmström, Eva
    Lindgren, Mikael
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eriksson, Anders
    Lopes, Cesar
    Hybrid materials for nonlinear absorption2005Conference paper (Refereed)
    Abstract [en]

    Alkynylplatinum derivatives and thiacalixarenes were trapped in solid transparent matricesprepared by the sol-gel process. By using functionalyzed silicon alkoxides,molecular species were grafted to the gel matrix giving ahigh doping concentration and chemically stable materials. In this communicationwe present broadband optical limiting performance in the visible wavelengthregion observed in the prepared materials.

  • 24.
    Revoju, Srikanth
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Biswas, Subhayan
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sharma, Ganesh D.
    Asymmetric triphenylamine–phenothiazine based small molecules with varying terminal acceptors for solution processed bulk-heterojunction organic solar cells2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 9, p. 6390-6400Article in journal (Refereed)
    Abstract [en]

    Three compounds consisting of the electron-donating triphenylamine–phenothiazine conjugate backbone and each of the electron-withdrawing groups 3-ethylrhodanine, malononitrile and 1,3-indandione have been synthesized and used as donors in blends with [6,6]-phenyl-C70-butyric acid methyl ester (PC71BM) for organic solar cell devices. After improvements of the active layer structure by a selected donor-to-acceptor weight ratio and a two-step solvent and thermal annealing, the organic solar cells showed power conversion efficiency (PCE) values in the range of 4.79–7.25%. The highest PCE was obtained for the bulk heterojunction device with the indandione compound, which can be attributed to its better absorption profile, higher crystallinity, more balanced electron and hole transport, higher charge collection efficiency and reduced recombination, in comparison with the photovoltaic cells from the other two compounds. DFT-calculated characteristics, absorption spectra and cyclic voltammetry of the compounds, along with X-ray diffraction patterns of the blend films, are used to validate the photovoltaic results.

  • 25.
    Revoju, Srikanth
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Biswas, Subhayan
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sharma, Ganesh D.
    Effect of acceptor strength on optical, electrochemical and photovoltaic properties of phenothiazine-based small molecule for bulk heterojunction organic solar cells2018In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 149, p. 830-842Article in journal (Refereed)
    Abstract [en]

    Two new acceptor–π(donor)–donor–π(donor)-acceptor small molecules SM1 and SM2 with benzodithiophene (BDT) donor core unit linked via phenothiazine (PTZ) donor units with 1,3–indanedione and malononitrile end capping units, respectively, have been designed and synthesized and used as electron donor along with PC71BM as acceptor for solution-processed bulk heterojunction organic solar cells. The influence of these end-capping groups on their thermal, optical, electrochemical properties and photovoltaic performance was investigated. After the optimization of the donor to acceptor weight ratio and solvent vapor annealing, the organic solar cells based on SM1:PC71BM and SM2:PC71BM active layers showed the power conversion efficiency (PCE) of 6.20% and 7.45%, respectively. Hence, the end-capping acceptor units for the two small molecules revealed a significant influence on the PCE of the organic solar cells, which resulted from differences in film absorption, molecular packing and charge transport properties.

  • 26. Sahar,
    et al.
    Bari, Alina
    Irfan, Muhammad
    Zara, Zeenat
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ayub, Khurshid
    Iqbal, Javed
    Benchmark study of bond dissociation energy of Si-X (X=F, Cl, Br, N, O, H and C) bond using density functional theory (DFT)2017In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1143, p. 8-19Article in journal (Refereed)
    Abstract [en]

    A benchmark study of Bond Dissociation Energies (BDEs) of various chemical bonds is carried out by Density Functional theory (DFT) method. The aim of the present research study was to find out the best suited functional and basis set to calculate BDEs of selected bonds of silicon with halogens (F, Cl, Br), N, H, C and O. Six different functionals (CAM/B3LYP, B3LYP, B3PW91, PBEPBE, TPSSTPSS) were applied on 36 molecules of different nature. Furthermore, six different basis sets 3-21G, aug-cc-pVTZ, 6-31G, aug-cc-pVDZ, DGDZVP and DGDZVP2 were also applied on these molecules with the best suited functional CAM/B3LYP. After rigorous effort it can be safely said that the best basis set for calculating BDEs for Si H, Si-C, Si-N bonds using CAM-B3LYP functional is 3-21G and for Si-halogens,aug-cc-pVTZ was found to be best basis set.

  • 27. Sahar, Anum
    et al.
    Ali, Shaukat
    Hussain, Tanveer
    Irfan, Muhammad
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Iqbal, Javed
    UV absorbers for cellulosic apparels: A computational and experimental study2018In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 188, p. 355-361Article in journal (Refereed)
    Abstract [en]

    Two triazine based Ultra Violet (UV) absorbers Sulfuric acid mono-(2-{4-[4-chloro-6-(4-{4-chloro-6-[4-(2-sulfooxy-ethanesulfonyl)-phenylamino]-[1,3,5] triazin-2-ylamino-phenylamino)-[1,3,5]triazin-2-ylamino]-benzenesulfonyl}-ethyl) ester (1a) and 4-{4-chloro-6-[4-(2-sulfooxy-ethanesulfonyl)-phenylamino]-[1,3,5] triazin-2-ylamino}-2-[4-chloro-6-(2-sulfooxy-ethanesulfonyl)-[1,3,5]triazin-2-ylamino]-benzenesulfonic acid (2a) with different substituents were designed computationally. The influence of different substituents on the electrochemical properties and UV spectra of the absorbers was investigated. The presence of electron deficient unit in 1a to the molecular core significantly reduces the LUMO levels and energy gap. The designed absorbers were synthesized via condensation reaction and characterized by UV–Vis, FT-IR, MS studies. The performance of synthesized compounds as UV absorbers and their fastness properties were assessed by finishing the cotton fabric through exhaust method at different concentration and results appeared in good range.

  • 28. Shahzadi, Iram
    et al.
    Shaukat, Aqsa
    Zara, Zeenat
    Irfan, Muhammad
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ayub, Khurshid
    Iqbal, Javed
    Estimation of optical rotation of gamma-alkylidenebutenolide, cyclopropylamine, cyclopropyl-methanol and cyclopropenone based compounds by a Density Functional Theory (DFT) approach2017In: Chirality, ISSN 0899-0042, E-ISSN 1520-636X, Vol. 29, no 10, p. 634-647Article in journal (Refereed)
    Abstract [en]

    Computing the optical rotation of organic molecules can be a real challenge, and various theoretical approaches have been developed in this regard. A benchmark study of optical rotation of various classes of compounds was carried out by Density Functional Theory (DFT) methods. The aim of the present research study was to find out the best-suited functional and basis set to estimate the optical rotations of selected compounds with respect to experimental literature values. Six DFT functional LSDA, BVP86, CAM-B3LYP, B3PW91, and PBE were applied on 22 different compounds. Furthermore, six different basis sets, i.e., 3-21G, 6-31G, aug-cc-pVDZ, aug-cc-pVTZ, DGDZVP, and DGDZVP2 were also applied with the best-suited functional B3LYP. After rigorous effort, it can be safely said that the best combination of functional and basis set is B3LYP/aug-cc-pVTZ for the estimation of optical rotation for selected compounds.

  • 29. Staley, Stuart W
    et al.
    Grimm, Russell A
    Boman, Patrik
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Bond shift and charge transfer dynamics in methylene- and dimethylsilyl-bridged dicyclooctatetraene dianions2001In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2001, p. U153-U153Conference paper (Other academic)
  • 30. Staley, Stuart W
    et al.
    Vignon, Scott A
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Conformational Analysis and Kinetics of Ring Inversion for Methylene- and Dimethylsilyl-Bridged Dicyclooctatetraene2001In: Journal of Organic Chemistry, Vol. 66, no 11, p. 3871-7Article in journal (Refereed)
    Abstract [en]

    Dicyclooctatetraenylmethane (1) and dicyclooctatetraenyldimethylsilane (2) in THF-d8 at 272 K exist as mixtures of diastereomers in ratios of 1:0.8 and 1:1, respectively. Nine energy minima (four meso and five racemic conformers) were located for each compound by geometry optimization at the HF/6-31G* level of theory. The effects of torsional strain, steric interactions and dynamic electron correlation were analyzed. The diastereomeric ratios for 1 and 2 were reproduced reasonably well from the total energy calculated for each conformer corrected for its conformational enthalpy and entropy contributions. The ratio of rate constants for bond shift (BS) (kBS(1)/kBS(2)) is three times greater than the corresponding ratio for ring inversion. This suggests that additional substituent effects, such as interactions, are operative in the transition state for BS.

  • 31. Staley, Stuart W
    et al.
    Vignon, Scott A
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Conformational analysis and ring inversion in methylene- and dimethylsilyl-bridged dicyclooctatetraenes: Vignon2001In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2001, p. U177-U177Conference paper (Other academic)
  • 32.
    Strunk, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hägglund, Curt
    Agnemo, Roland
    The influence of properties in cellulose pulps on the reactivity in viscose manufacturing2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 1, p. 81-89Article in journal (Refereed)
    Abstract [en]

    This paper describes properties in cellulose pulps to adress the increased quality demands on pulps for viscose production. Several grades of cellulose pulps were selected to investigate their chemical reactivity based on pulping process, original wood type and intrinsic viscosity. In total, six sulfite pulps and four sulfate pulps were chosen, of which all but one sulfate pulp were of dissolving grade. The physical and chemical properties of the pulps were tested. The influence of these properties on xanthation and viscose manufacturing as well as their correlation to each of the three selection criteria was investigated by the use of multivariate data analyses. Two methods to describe cellulose reactivity were used: a laboratory scale viscose test method for cellulose reactivity (Fock) and a filter clogging test for viscose dope. It was shown that all pulps chosen in this investigation formed groups according to all three selection criteria using principal component analysis. The analysis shows that sulfite pulps, from both wood types, are strongly correlated to the variables Fock reactivity, pore size and concentration of extractives. Sulfate pulps, however, are separated into two groups, hardwood and softwood. Hardwood sulfate pulps are strongly described by the variables permeability, content of hemicelluloses and filter clogging value. Softwood sulfate pulps, on the other hand, are described by variables such as alpha cellulose content, R10 and R18. Partial least square regression showed that Fock reactivity is influenced by the following cellulose pulp properties, in order of importance: absorption rate with caustic, pore area, permeability and pore diameter. The main property affecting the filter clogging value of the viscose dope is pulp permeability, followed by pore diameter, content of hemicelluloses, R18 and pore area.

  • 33.
    Strunk, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindgren, Åsa
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agnemo, Roland
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Properties of cellulose pulps and their influence on the production of a cellulose ether2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 1, p. 24-34Article in journal (Refereed)
    Abstract [en]

    Several grades of cellulose pulps were investigated for their influence on the product quality of a cellulose ether, ethyl hydroxyethyl cellulose (EHEC). The selection of the pulps was based on pulping process, original wood type and intrinsic viscosity. In total, five sulfite pulps and four sulfate pulps were chosen, of which all but one sulfate pulp were of dissolving grade. The physical and chemical properties of the pulps were analyzed as well as important qualitative parameters of the final product EHEC. The influence of pulp properties on EHEC quality was investigated by multivariate data analyses.Principal component analysis showed that due to the influence of all variables, the pulps aligned in groups in accordance to the selection criteria pulping process and wood type. Partial least square regression revealed that high gel formation in EHEC is explained by the pulp properties high intrinsic viscosity and high Mw in combination with high caustic absorption rate and high total caustic absorption. The amount of hemicelluloses, in particular xylose, also contributed to gel formation. High cloud point for an EHEC solution was explained by a high MSEO and low DSEt of the EHEC molecules, where in turn a high MSEO could be predicted by a high pore area, high PD and a low caustic absorption rate. A low DSEt could on the other hand be predicted by a low hemicellulose content and hence a high R18. In a separate model, the same pulp properties explaining MSEO and DSEt also predicted cloud point directly. Fock reactivity and viscose dope filterability, both test methods originating from the viscose manufacturing, were shown to predict cloud point but have low predictability on other EHEC quality parameters.The models achieved can thus be utilized to predict final EHEC product qualities for new pulps within the design set of the chosen pulps.

  • 34.
    Strunk, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lindgren, Åsa
    AkzoNobel Functional Chemicals AB, Stenungsund, Sweden.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Agnemo, Roland
    DomInnova, Domsjö Fabriker AB, Örnsköldsvik, Sweden.
    Chemical changes of cellulose pulps in the processing to viscose dope2012In: Cellulose Chemistry and Technology, ISSN 0576-9787, Vol. 46, no 9-10, p. 559-569Article in journal (Refereed)
    Abstract [en]

    A selection of cellulose pulps was investigated for their chemical changes during the required process steps to viscose dope. The selection of the pulps was based on pulping process, original wood type and intrinsic viscosity. In total, five sulfite pulps and four sulfate pulps were chosen, of which all but one sulfate pulp were of dissolving grades. The physical and chemical properties of the pulps were analyzed as well as important qualitative parameters of the cellulose intermediates during mercerization, pre-aging and in the final viscose dope. Pre-aging curves were reported as a measure of each pulp's reactivity with respect to oxidative degradation, where high hemicellulose content and small pore area and pore diameter were found to hamper cellulose degradation. The correlations in pre-aged pulps of intrinsic viscosity to Mz, Mv and Mw were found to be ambiguous and show the need for a description of total molecular weight distribution of the alkali celluloses to better understand the degradation behavior of each pulp, instead of only intrinsic viscosity. It was also shown that R18 and R10 are insufficient analyses to determine pulp, and to predict viscose quality. Further, many pulps, independently of initial hemicellulose content, reached the same level of hemicellulose content after mercerization. The presence of crystalline hemicelluloses could be a possible cause for this level-off behavior, combined with hemicelluloses resistant to caustic lye treatment. The change of both low-molecular-weight celluloses and PD in the process to viscose dope was investigated due to the importance of these variables on dope spinnability and viscose fiber strength. Caustic resistance of cellulose and hemicelluloses and a more rigid fiber structure in some pulps are suggested to contribute to the different degradation behavior.

  • 35.
    Strunk, Peter
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Öman, Tommy
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gorzsás, András
    Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), Umeå, Sweden.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterization of dissolving pulp by multivariate data analysis of FT-IR and NMR spectra2011In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 26, no 4, p. 398-409Article in journal (Refereed)
    Abstract [en]

    Several grades of dissolving pulps have been analyzed using FT-IR, solid state13C NMR and two dimensional1H-13C HSQC NMR spectroscopy to obtain an extensive data set for further characterization. The selection of the dissolving pulps with high cellulose purity was based on pulping process, wood type and, intrinsic pulp viscosity. Multivariate data analysis was used to investigate how information derived from the spectroscopic data correlate to each of the selection criterion: wood type, process type and viscosity. The spectroscopic methods were also compared with common dissolving pulp analyses to see to what extent spectroscopy can predict pulp analyses.

    Correlations were found between the spectroscopic data and the pulp characteristics process type and wood type, but not for intrinsic viscosity. A reason for a good correlation to wood type appears to be the hemicelluloses composition, expressed as the xylose:mannose ratio by 2D NMR spectroscopy. For process type, 2D NMR showed the most characteristic property to be the amount of reducing ends in the cellulosic samples, which in turn strongly correlates to lower molecular weight for the sulfite samples as determined by molecular weight distribution.

    Many common, yet expensive and time consuming, pulp analyses could also be predicted by the achieved models. It can be concluded that investigations of dissolving pulp characteristics, especially concerning different wood and process types, can take advantage of the methods and models presented in this study.

  • 36. Ushakov, Evgeny N
    et al.
    Gromov, Sergey P
    Vedernikov, Artem I
    Malysheva, Ekaterina V
    Botsmanova, Asya A
    Alfimov, Michael V
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Whitesell, James K
    Fox, Marye Anne
    Self-Organization of Highly Stable Electron Donor-Acceptor Complexes via Host-Guest Interactions2002In: The Journal of Physical Chemistry A, Vol. 106, no 10, p. 2020-3Article in journal (Refereed)
    Abstract [en]

    Biscrown stilbene S forms complexes of 1:1 and 2:1 composition with bisammonium viologen salt V4+ in acetonitrile solution. Both of the complexes exhibit spectroscopic behavior typical of molecular electron donor-acceptor complexes. The 1:1 complex [S·V]4+ has a very high thermodynamic stability (log K = 9.08), which is due to simultaneous interaction of the two ammonium groups of V4+ with the two 18-crown-6-ether units of S. The 2:1 complex (log K = 12.28) [S·V·S]4+ likely has a sandwich-type layered structure in which the acceptor salt is located between two complexed molecules of the biscrown stilbene.

  • 37. Vestberg, R.
    et al.
    Westlund, R.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Glimsdal, E.
    Ortengren, J.
    Lindgren, M.
    Malmstrom, E.
    Photophysical properties of dendronized platinum(II) acetylides for optical power limiting2005In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, ISSN 0065-7727, Vol. 229Article in journal (Other academic)
    Abstract [en]

    Meeting Abstract

  • 38. Vestberg, Robert
    et al.
    Nilsson, Christina
    Lopes, Cesar
    Lind, Per
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Malmstrom, Eva
    Thiophene-cored 2,2-bis(methylol)propionic acid dendrimers for optical-power-limiting applications2005In: JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY, ISSN 0887-624X, Vol. 43, no 6, p. 1177-87Article in journal (Refereed)
    Abstract [en]

    The synthesis and characterization of dendron-coated 2,5-bis(phenylethynyl)thiophene chromophores are described. The dendrimers were grown divergently on the arylthiophene core with the versatile anhydride of 2,2-bis(methylol)propionic acid. The arylthiophene core was synthesized with Sonogashira coupling reactions. Structurally well-defined dendrimers up to the fourth generation were grown, as confirmed by size exclusion chromatography, NMR, and matrix-assisted laser desorption/ionization time-of-flight analysis. The different dendritic substitution did not influence the absorption spectra of the compounds in or near the visible region. Solutions of arylthiophenes had good transparency at wavelengths greater than 400 nm. The dendritic thiophenes exhibited an optical-power limit at the laser wavelength of 532 nm. However, the magnitude of the optical-power limit of these compounds was slightly lower than that of a nondendritic arylthiophene with n-pentyl substituents. (C) 2005 Wiley Periodicals, Inc.

  • 39. Vestberg, Robert
    et al.
    Westlund, Robert
    Eriksson, Anders
    Lopes, Cesar
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Glimsdal, Eirik
    Lindgren, Mikael
    Malmström, Eva
    Dendron Decorated Platinum(II) Acetylides for Optical Power Limiting2006In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 39, no 6, p. 2238-2246Article in journal (Refereed)
    Abstract [en]

    The effect of dendritic substituents on a nonlinear optical chromophore for optical power limiting (OPL) has been investigated. Synthesis and characterization of bis((4-(phenylethynyl)phenyl)ethynyl)bis(tributylphosphine)platinum(II) with dendritic end groups are described. Polyester dendrimers up to the fourth generation were grown divergently using the anhydride of 2,2-bis(methylol)propionic acid (bis-MPA). The introduction of the dendritic moieties onto the NLO chromophore enables further processing of the materials using polymeric and related techniques. OPL measurements performed at 532, 580, and 630 nm show that the OPL properties improve with increasing size of the dendritic substituent. It is also shown that the addition of the dendrons increase the OPL as compared to the nondecorated bis((4-(phenylethynyl)phenyl)ethynyl)bis(tributylphosphine)platinum(II). By use of femtosecond z-scan measurements carried out at different pulse-repetition frequencies, it is shown that the two-photon absorption cross section is ~10 GM. Using pulse repetition frequencies (100 kHz-4.75 MHz) so that the time between the pulses is comparable with the triplet excited lifetime, the z-scans become dominated by excited-state absorption of excited triplet states.

  • 40. Vestherg, R.
    et al.
    Nystrom, AM.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Nilsson, C.
    Eriksson, A.
    Lopes, Cesar
    Lindgren, M.
    Malmstrom, E.
    Dendron decorated chromophores for optical power limiting applications2005In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, ISSN 0065-7727, Vol. 229Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Meeting Abstract

  • 41.
    Wang, Jia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Resist-free laser patterning of perfluoro-alkyl functionalized fullerene films: attaining pattern and stability by order2010In: Organic electronics, ISSN 1566-1199, E-ISSN 1878-5530, Vol. 11, no 10, p. 1595-1604Article in journal (Refereed)
    Abstract [en]

    We report that it is possible to establish well-defined semiconducting patterns in a perfluoro-alkyl functionalized fullerene (C60-F) film using a straightforward, benign and scalable method. The patterning technique comprises a direct laser light exposure of pre-select film areas, and a subsequent development in a heptane developer solution that selectively removes the non-exposed areas of the film. It is notable that no sacrificial photo-resist material is utilized, and that the remaining patterned C60-F material exhibits high electron mobility (>4 × 10−2 cm2/Vs, as quantified in transistor experiments) and improved ambient stability, both in comparison to the pristine material and to the more commonly utilized fullerene PCBM. We demonstrate that the patterning process has left the remaining C60-F material chemically unaltered, but that its degree of crystallinity has increased. The latter rationalizes the high electron mobility, the improved air stability, and the decreased solubility in the developer solution.

  • 42.
    Wågberg, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Liu, Bin
    Natl Univ Singapore, Dept Chem & Biomol Engn.
    Orädd, Greger
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Edman, Ludvig
    Umeå University, Faculty of Science and Technology, Physics.
    Cationic polyfluorene: conformation and aggregation in a "good" solvent2009In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, ISSN 0014-3057, Vol. 45, no 11, p. 3228-3233Article in journal (Refereed)
    Abstract [en]

    The conjugated polyelectrolyte (CPE) poly{9,9'-bis[6 ''-(N,N,N-trimethylammonium)-hexylfluorene-alt-co-phenylene] dibromide} (PFPN+Br-) demonstrates a high solubility in methanol in comparison to other more hydrophilic or hydrophobic solvents. We have employed a combination of pulsed-field-gradient-NMR, photoluminescence (PL), and Raman spectroscopy to establish the conformation and aggregation behavior of PFPN+Br- in methanol, with the aim to attain information on how to design CPEs with a high solubility in a preferred solvent. We find that the diffusion coefficient and PL spectrum of PFPN+Br-, as well as the Raman-active methyl rocking mode of methanol, all exhibit a strong dependence on PFPN+Br- concentration. We rationalize our findings with a model in which PFPN+Br- forms aggregates via ∏-∏ interactions between main-chain segments, while the ionic side chains are surrounded and electrostatically screened by the methanol solvent. Accordingly, the notably high solubility of PFPN+Br- in methanol is rationalized by favorable interactions between the ionic side chains and the methanol molecules. We propose that an appropriate design of a high-solubility CPE should consider a matching of the mixed hydrophobic/hydrophilic character of the ionic side chain with that of the preferred solvent.

  • 43. Zara, Zeenat
    et al.
    Iqbal, Javed
    Ayub, Khurshid
    Irfan, Muhammad
    Mahmood, Athar
    Khera, Rasheed Ahmad
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A comparative study of DFT calculated and experimental UV/Visible spectra for thirty carboline and carbazole based compounds2017In: Journal of Molecular Structure, ISSN 0022-2860, E-ISSN 1872-8014, Vol. 1149, p. 282-298Article in journal (Refereed)
    Abstract [en]

    A comparative study of UV/Visible spectra of carboline and carbazole derivatives was conducted by employing the Density Functional Theory (DFT) approach. In this study, the geometries of ground and excited states, excitation energy and absorption spectra were estimated by using seven different DFT functional; CAM-B3LYP, B3LYP, MPW1PW91, PBE, B3PW91, WB97XD and HSE06 with 6-31G basis set. Moreover, five different basis sets 3-21G, 6-31G, DGDZVP, DGTZVP and SDD were also investigated with the CAM-B3LYP and WB97XD functional to take out the best combination of functional and basis set. CAM-B3LYP/6-31G and WB97XD/DGDZVP combination were found to have closest agreement with the experimental values of 13-carboline derivatives and carbazole derivatives, respectively. This study provided an insight about the electronic characteristics of the selected compounds and provided an effective tool for developing and designing the better UV absorber compounds.

  • 44. Zara, Zeenat
    et al.
    Iqbal, Javed
    Bibi, Shamsa
    Sadaf, Sana
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Designing Benzodithiophene-Based Donor Materials with Favorable Photovoltaic Parameters for Bulk Heterojunction Organic Solar Cells2017In: CHEMISTRYSELECT, ISSN 2365-6549, Vol. 2, no 20, p. 5628-5639Article in journal (Refereed)
    Abstract [en]

    Computational study on four Acceptor-Donor-Acceptor (A-D-A) type of donor molecules namely, dimethyl cyanoacetate terthiophene di(methylthiophene) benzo[1,2-b: 4,5-b'] dithiophene (DMCATDMTBDT) (M1), methylrhodanine terthiophene di (methylthiophene) benzo[1,2-b: 4,5-b'] dithiophene (MRTDMTBDT) (M2), dimethyl cyanoacetate terthiophene di (fluoromethyl thiophene) benzo[1,2-b: 4,5-b'] dithiophene (DMCATDFMTBDT) (M3), and methylrhodanine terthiophene di (fluoromethyl thiophene) benzo[1,2-b: 4,5-b'] dithiophene (MRTDFMTBDT) (M4) was carried out and their photovoltaic properties were associated with methyl cyanoacetate terthiophene di (methoxy) benzo[1,2-b: 4,5-b'] dithiophene (DCAO3TBDT) (R1) and methylrhodanine terthiophene di (methoxy) benzo[1,2-b: 4,5-b'] dithiophene (DR3TBDT) (R2). For the geometry optimization DFT functional CAM B3LYP/6-31G(d) was found to be the best choice, hence TD-CAM B3LYP/631G(d) was opted for the calculation of excited state of the molecules. M3 and M4 represented appropriate frontier molecular orbital energy levels and broad absorption band. The reorganization energies of the designed molecules illustrated excellent charge mobility property. The lower le values as compared to lambda(i) illustrate that the designed donor molecules are better electron donors. M4 was found as champion molecules with the lowest le (0.01601) value. The Voc value of M3 and M4 are 2.74 eV and 2.63 eV respectively with respect to the energy levels of PC60BM (acceptor).

  • 45. Zara, Zeenat
    et al.
    Iqbal, Javed
    Iftikhar, Sana
    Khan, Salah Ud-Din
    Haider, Sajjad
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ayub, Khurshid
    Designing dibenzosilole and methyl carbazole based donor materials with favourable photovoltaic parameters for bulk heterojunction organic solar cells2018In: Computational and Theoretical Chemistry, ISSN 2210-271X, E-ISSN 2210-2728, Vol. 1142, p. 45-56Article in journal (Refereed)
    Abstract [en]

    Five new Acceptor-Donor-Acceptor (A-D-A) type small donor molecules (M1-M5) namely; Dimethyl cyanoacetate terthiophene di(methylthiophene) dibenzosilole (DMCAO3TBS) (M1), Dimelononitrile terthiophene di(methylthiophene) dibenzosilole (DMCNTBS) (M2), Dimethyl rhodanine terthiophene di(methylthiophene) dibenzosilole (DMRTBS) (M3), Dimelanonitrile terthiophene di(methylthiophene) methyl carbazole (DMCNTCz) (M4) and Dimethyl rhodanine terthiophene di(methylthiophene) methyl carbazole (DMRTCz) (M5) were designed and theoretically explored their electronic, photophysical and geometrical properties via DFT best functional MPW1PW91/6-311G (d,p) with respect to reference molecules Dioctyl cyanoacetate terthiophene di(octylthiophene) dioctylfluorene (DCAO3TF) (Ra) and Dioctyl cyanoacetate terthiophene di(octylthiophene) octylcarbazole (DCAO3TCz) (Rb). Among the designed donor molecules (M1-M5), M2 and M4 represented lowest band gap value (2.480 eV and 2.47 eV) with distinctive broad absorption peak at 598 nm and 601 nm in chloroform. Theoretically estimated reorganization energies of these molecules recommended excellent property of charge mobility. The designed donor molecules (M1-M5), demonstrated lower λe value with reference to their λh, showing that these molecules could be ideal candidates for the transfer of electron while M2 and M4 were found to be best molecules having lowest λe (0.006 eV and 0.005 eV respectively). Additionally the Voc of M2 and M4 are 2.01 eV and 1.85 eV respectively with respect to PCBM.

  • 46.
    Zieba, Roman
    et al.
    Laboratoire des Multimatériaux et Interfaces CNRS 5615 University Claude Bernard Lyon 1 University of Lyon, Villeurbanne, France.
    Desroches, Cédric
    Laboratoire des Multimatériaux et Interfaces CNRS 5615 University Claude Bernard Lyon 1 University of Lyon, Villeurbanne, France.
    Chaput, Frédéric
    Laboratoire des Multimatériaux et Interfaces CNRS 5615 University Claude Bernard Lyon 1 University of Lyon, Villeurbanne, France.
    Carlsson, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lopes, Cesar
    Dep. of Optronic Systems Swedish Defence Research Agency (FOI) Linköping, Sweden.
    Lindgren, Mikael
    Department of Physics Norwegian University of Science and Technology Trondheim, Norway.
    Parola, Stephane
    Laboratoire des Multimatériaux et Interfaces CNRS 5615 University Claude Bernard Lyon 1 University of Lyon, Villeurbanne, France.
    Preparation of functional hybrid glass material from Platinum (II) Complexes for broadband nonlinear absorption of light2009In: Advanced Funcitional Materials, Vol. 19, no 2, p. 235-241Article in journal (Refereed)
    Abstract [en]

    The synthesis of trans-di(arylalkynyl)diphosphine platinum(II) complexes bearing trialkoxysilane groups is described, as well as the preparation of siloxane-based hybrid materials from organometallic chromophores through a modified sol-gel process. Glass materials prepared from trans-[P(n-Bu)3]2Pt[(CC-p-C6H4-CC-p-C6H4-CH2O(CO)NH(CH2)3Si(OC2H5)3]2 generally show spectral transmittance, absorption and luminescence similar to that of solutions reported in the literature. Measurements of optical power limiting for the hybrid glass are carried out, and show broadband nonlinear absorption throughout the whole visible wavelength range with clamping values in the range 0.2-7 µJ at 120 mM chromophore concentration. The sol-gel process using urethane-propyltriethoxysilane-functionalized chromophores as precursors appears to be a valid method for formation of robust silicate materials with grafted diarylethynyl Pt(II) complexes for OPL devices.

  • 47.
    Öberg, Kjell
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Berglund, Anders
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Prediction of nonlinear optical responses of organic compounds2001In: Journal of Chemical Information and Modeling, Vol. 41, no 3, p. 811-4Article in journal (Refereed)
    Abstract [en]

    The nonlinear optical quantities, second and third harmonics ( and ), were predicted using a quantitative structure-property relationship (QSPR) approach. Molecular orbital ab initio calculations were applied to generate easily accessible variables to be used in the partial least-squares analysis. Simplified equations are presented that could be used to predict the experimental and responses, prior to further investigations of potentially interesting molecules for use in optical materials.

  • 48.
    Öberg, Kjell
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Seshadri, Kannan
    Allara, David
    Spectroscopic Characterization of the Bonding, Orientation, and Coverage of Copper Tetraazaphthalocyanine Monolayer Films on SiO2 Surfaces2000In: The Journal of Physical Chemistry B, Vol. 104, no 45, p. 10627-34Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayer films of a metallotetraazaphthalocyanine were prepared using two different reaction conditions. The films were characterized by ellipsometry, AFM, electronic absorption spectroscopy, semiempirical MO calculations, core-level XPS, and projection of a calculated structure of the chromophore onto a surface to obtain its silhouette area for comparison with surface concentration from absorption spectroscopy. A denser packing of the chromophores is found in the SAM film prepared with bromonaphthalene at 250 C as compared with the film from the more polar solvent DMF at 120 C. Data is consistent with an almost vertical orientation of the chromophores in the former film. A different number of bonds connecting the chromophore with the coupling molecule is suggested as an explanation to differences in the absorption bands for the two films.

  • 49.
    Öberg, Kjell
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    A method for screening of coverage and film thickness of monolayers by projection of molecular electron density surface onto a substrate plane2001In: Materials Letters, Vol. 49, no 3-4, p. 147-153Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayer films of a copper tetraazaphthalocyanine have been prepared on quartz and silicon at 120°C in DMF solution and at 250°C in bromonaphthalene solution. A procedure is presented for obtaining film thickness for a sufficiently dense monolayer by fitting the 2D image of the 3D electron density surface of the chromophore in the film to a surface-coverage measure derived from absorption spectroscopy. The film thickness obtained by the electron density projection method is compared to that from ellipsometry. The projection method is expected to be useful for film-screening purposes and can also yield an average angle between the surface and chromophore normals.

  • 50.
    Öberg, Kjell
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Persson, Per
    Umeå University, Faculty of Science and Technology, Chemistry.
    Shchukarev, Andrey
    Umeå University, Faculty of Science and Technology, Chemistry.
    Eliasson, Bertil
    Umeå University, Faculty of Science and Technology, Chemistry.
    Comparison of monolayer films of stearic acid and methyl stearate on an Al2O3 surface2001In: Thin Solid Films, Vol. 397, no 1-2, p. 102-8Article in journal (Refereed)
    Abstract [en]

    Both stearic acid and methyl stearate chemisorbs onto an oxide surface of aluminum with an asymmetric coordination of the carboxylate group as concluded from infrared (IR) spectroscopy data. Similarities in the IR spectra of the films from the two compounds suggest that the ester is bonded in the same way as the acid, and that the ester therefore undergoes hydrolysis during the surface reaction. X-Ray photoelectron spectroscopy (XPS) and IR data are interpreted in terms of self-assembled monolayer formation and a more dense film from the carboxylic acid in comparison with that from the ester.

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