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  • 1.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Ekborg, Margareta
    School of Education, Malmö university.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chemistry in crisis?: Perspectives on teaching and learning chemistry in Swedish upper secondary schools2011In: NorDiNa: Nordic Studies in Science Education, ISSN 1504-4556, E-ISSN 1894-1257, Vol. 7, no 1, p. 43-60Article in journal (Refereed)
    Abstract [en]

    Explanations for a decline in the number of students studying chemistry at advanced level all over the world have been sought for quite some time. Many students do not find chemistry relevant and meaningful and there have been difficulties in developing school chemistry courses that engage students sufficiently and tempt them to further studies in the field. In this study, Swedish upper secondary school students (Ns=372) and their teachers (Nt=18) answered a questionnaire on their experiences of the content and the working methods of their chemistry course. They were also given the opportunity to express ideas on how to make chemistry courses more interesting and meaningful. The results point out some subject areas as both easy and interesting, e.g. atomic structure; while other areas are hard to understand but still interesting, e.g. biochemistry. The students find chemistry lessons teacher-centred, something they appreciate. When teachers and students gave suggestions on how to improve the relevance of chemistry education at upper secondary level, more laboratory work and connections to everyday life were the most common proposals. But on the whole, these students seem quite satisfied with their chemistry courses.

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    Broman 2011
  • 2.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Engineering students going “flipped”: a new teaching approach in organic chemistry to increase students’ interest and value2019In: 7:e utvecklingskonferensen för Sveriges ingenjörsutbildningar, Luleå tekniska universitet , 2019Conference paper (Other academic)
    Abstract [en]

    This paper presents a longitudinal design-based research study where a university organic chemistry course has changed teaching and learning focus, from more conventional teaching into flipped teaching. Engineering students have been followed with surveys, observations, interviews and analysis of how the teaching material was used; results on students’ perceived interest and value are discussed. The project shows that flipped learning with peer instruction is an applicable way to increase students’ interest in organic chemistry and perceived value of the problem-solving process and peer instruction when learning chemistry. Moreover, the paper also discusses the design-based aspect, and how researchers and practitioners can collaborate to develop university teaching with an aim to enhance students’ higher-order thinking and deep learning.

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    fulltext
  • 3.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Flipped Learning as a New Approach for University Organic Chemistry2018In: 14th European Conference on Research in Chemical Education: Book of Abstracts, 2018, p. 20-20Conference paper (Refereed)
    Abstract [en]

    Flipped learning approaches have emerged since the beginning of the 21st century to make students’ learning environments more active and thereby improve learning outcomes as well as student engagement [1]. In the US, several flipped projects have focused on university chemistry courses, normally the student groups are large, from hundreds up to thousands of students [2], while some research also is found on smaller groups [3]. Here we study an organic chemistry university course both quantitatively and qualitatively during two years when changing from a more traditional teaching method to a new pedagogical approach (i.e., flipped learning), for empirical data see Table 1. In Sweden, flipped learning approaches are uncommon compared to the US and a Swedish university chemistry department had intentions improve students’ learning outcomes and increase students’ engagement in chemistry. The organic course has been perceived difficult and, according to previous course evaluations, also been ascribed as having bad quality in general. Therefore, a change was requested both from students and teachers.

    From the empirical data we will elaborate on students’ opinions when meeting a new teaching and learning approach. Students’ challenges with the organic chemistry course are discussed relating to their opinions about chemistry in general and flipped learning in specific. How students used the different learning material and how they made use of each other through peer interaction when solving problems in class will be discussed according to both constructivist and socio-cultural perspectives. Furthermore, students’ own perception of how they used the course material related to an exact analysis of how the material actually was adapted will be presented together to explore how flipped learning have been applied within the course.

  • 4.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Flipped organic chemistry: in the light of Corona2021In: Book of abstracts: 9th European Variety in University Chemistry Education Conference EUROVARIETY 2021, University of Ljubljana , 2021, p. -62Conference paper (Refereed)
  • 5.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Flipping the class: University chemistry students' experiences from a new teaching and learning approach2019In: Chemistry Teacher International, ISSN 2569-3263, Vol. 1, no 1, article id 20180004Article in journal (Refereed)
    Abstract [en]

    University chemistry courses have for a long time had a similar conventional approach to teaching, with chem- istry professors lecturing in a traditional manner. Today, flipped learning approaches have found their ways into higher education with positive results. In particular, US innovations in this area have made positive im- pressions on Swedish university chemistry educators, resulting in an interest and curiosity in integrating a flipped model into the course curricula. The rationale behind flipped learning is to incorporate an active learn- ing approach into lecture, thereby increasing both student engagement and learning outcomes. In this paper, an implementation project where an organic chemistry course has changed focus from traditional teaching to flipped learning, will be presented. The focus in this mixed-methods study will be on students’ cognitive and affective responses when meeting a new teaching and learning approach. Through following a project where a conventional approach to an organic chemistry course is changed into a more student-active focus, we elaborate on implications for course development of chemistry curricula.

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    fulltext
  • 6.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Flipping the class: university chemistry students' experiences from a new teaching approach2017In: Universitetspedagogiska konferensen 2017: undervisning i praktiken – föreläsning, flexibelt eller mitt emellan?, Umeå: Universitetspedagogik och lärandestöd (UPL), Umeå universitet , 2017, p. 14-18Conference paper (Refereed)
    Abstract [en]

    University chemistry courses have for a long time had a similar approach to teaching, with chemistry professors lecturing in a traditional manner. Today, flipped learning approaches have found their ways into higher education and positive results from for example the US have been spread and made Swedish university chemistry teachers interested and curious to develop their courses. The rationale of flipped learning is to incorporate an active learning approach in the lecture halls and thereby hopefully both increase student engagement and learning outcomes. In this study, an implementation project where an organic chemistry course has changed focus from traditional teaching to flipped learning will be presented. The focus will be on students’ experiences when meeting a new teaching and learning approach. 

  • 7.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Organic chemistry going ‘flipped’ – university students’ perceptions of a new teaching and learning approach2019In: European Variety In Chemistry Education 2019: Abstract Booklet, 2019, p. 32-32Conference paper (Refereed)
  • 8.
    Broman, Karolina
    et al.
    Umeå University.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    To flip or not to flip: Students’ use of the learning material in a flipped university organic chemistry course2017Conference paper (Other academic)
    Abstract [en]

    University chemistry courses have had a similar approach to teaching for a long time, with chemistry professors lecturing in a traditional manner. Today, flipped learning approaches have found their ways into higher education and positive results from for example the US have been spread and made Swedish university chemistry teachers interested and curious to develop their courses. The rationale of flipped learning is to incorporate an active learning approach in the lecture halls and thereby hopefully both increase student engagement and learning outcomes. In this presentation, an implementation project where an organic chemistry course has changed focus from traditional teaching to flipped learning will be presented.

  • 9.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Mårell-Olsson, Eva
    Umeå University, Faculty of Social Sciences, Department of applied educational science, Interactive Media and Learning (IML).
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Virtual and augmented reality – a way to develop university students; spatial ability in organic chemistry2019In: European Variety In Chemistry Education 2019: Abstract Booklet, 2019, p. 24-24Conference paper (Refereed)
  • 10.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Mårell-Olsson, Eva
    Umeå University, Faculty of Social Sciences, Department of applied educational science, Interactive Media and Learning (IML).
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, C. David
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Chorell, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Boström, Jonas
    Norrby, Magnus
    Spatial Ability in Organic Chemistry: Can Virtual and Augmented Reality be Valuable?2019In: 7:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar, Luleå tekniska universitet , 2019Conference paper (Other academic)
    Abstract [en]

    In this paper, the roles of digital technologies as Virtual Reality (VR), and Augmented Reality (AR), are discussed to explore how biotechnology engineering students develop their spatial ability in organic chemistry. We have, through stereochemistry workshops, followed how students, in specific, visualise and rotate molecular representations and how the use of digital tools influences the students’ interest.

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    fulltext
  • 11.
    Broman, Karolina
    et al.
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education. Umeå University, Faculty of Science and Technology, Umeå Mathematics Education Research Centre (UMERC).
    Silfver, Eva
    Umeå University, Faculty of Science and Technology, Department of Science and Mathematics Education.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Swine flu and Tamiflu®: context-based chemistry in Swedish upper secondary school2011Conference paper (Refereed)
  • 12. Gromov, S P
    et al.
    Vedernikov, A I
    Fedorov, Yu V
    Fedorova, O A
    Andryukhina, E N
    Shepel, N E
    Strelenko, Yu A
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Saltiel, J
    Alfimov, M V
    Self-assembly of a (benzothiazolyl)ethenylbenzocrown ether into a sandwich complex and stereoselective [2+2] photocycloaddition2005In: RUSSIAN CHEMICAL BULLETIN, ISSN 1066-5285, Vol. 54, no 7, p. 1569-79Article in journal (Refereed)
    Abstract [en]

    In the presence of Ba2+ ions, (benzothiazolyl)ethenylbenzocrown ether forms the stable sandwich complex 2L center dot Ba2+ with an unusual structure, in which the benzothiazole fragments are arranged one above the other. Irradiation of the sandwich complex with visible light induces stereoselective [2+2] cycloaddition giving rise to two "head-to-head" isomers of biscrown-cyclobutane. The addition of dibasic dicarboxylic acids that additionally stabilize the sandwich complex in a favorable conformation affects the isomer ratio of the cyclobutanes formed. The conformational equilibria for the sandwich complex and cyclobutanes were studied by H-1 N MR spectroscopy.

  • 13. Gromov, Sergey P
    et al.
    Ushakov, Evgeny N
    Fedorova, Olga A
    Baskin, Igor I
    Buevich, Alexei V
    Andryukhina, Elena N
    Alfimov, Michael V
    Johnels, Dan
    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
    Novel Photoswitchable Receptors: Synthesis and Cation-Induced Self-Assembly into Dimeric Complexes Leading to Stereospecific [2+2]-Photocycloaddition of Styryl Dyes Containing a 15-Crown-5 Ether Unit2003In: The Journal of Organic Chemistry, Vol. 68, no 16, p. 6115-25Article in journal (Refereed)
    Abstract [en]

    Styryl dyes 4a-e containing a 15-crown-5 ether unit and a quinoline residue with a sulfonatoalkyl or sulfonatobenzyl N-substituent were synthesized. The relationship between the photochemical behavior of these dyes and their aggregates derived from complexation with Mg2+ in MeCN was studied using 1H NMR and absorption spectroscopy. The E-isomers of 4a-e were shown to form highly stable dimeric (2:2) complexes with Mg2+. Upon irradiation with visible light, the dimeric complexes undergo two competing photoreactions, viz., geometric E Z isomerization, resulting in an anion-capped 1:1 complex of the Z-isomer with Mg2+ and stereospecific syn-head-to-tail [2+2]-cycloaddition, affording a single isomer of bis-crown-containing cyclobutane. The N-substituent in the dye has a dramatic effect on the photochemical behavior of the dimeric complex. Molecular dynamics and semiempirical quantum-chemical calculations were carried out to interpret the observed photocycloaddition in the dimer. Conformational equilibria for the dimer of (E)-4b were analyzed using 1H NMR spectroscopy.

  • 14. Gromov, SP
    et al.
    Vedernikov, AI
    Ushakov, EN
    Lobova, NA
    Botsmanova, AA
    Kuz'mina, LG
    Churakov, AV
    Strelenko, YA
    Alfimov, MV
    Howard, JAK
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Novel supramolecular charge-transfer systems based on bis(18-crown-6)stilbene and viologen analogues bearing two ammonioalkyl groups2005In: NEW JOURNAL OF CHEMISTRY, ISSN 1144-0546, Vol. 29, no 7, p. 881-94Article in journal (Refereed)
    Abstract [en]

    A series of new viologen analogues bearing two ammonioalkyl groups (2-4) were synthesized in order to study their complexation with bis(18-crown-6)stilbene (1b). Electronic spectroscopy and H-1 NMR measurements show that in acetonitrile, bis( crown) stilbene 1b forms highly stable 1 : 1 and 2 : 1 charge-transfer (CT) complexes with pi-acceptors 2-4 owing to host-guest bonding. The influence of geometric and electronic factors on the complex formation constants are discussed. The structures of the supramolecular CT complexes are analyzed on the basis of H-1 and C-13 NMR data obtained in solution and in the solid state. X-Ray diffraction data for 1b and for model tetramethoxystilbene are also reported.

  • 15.
    Hedenström, Mattias
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterization of Hydrogenated Fullerenes by NMR Spectroscopy2010In: Fulleranes: The Hydrogenated Fullerenes / [ed] Franco Cataldo, Susana Iglesias-Groth, Dordrecht: Springer Netherlands, 2010, Vol. 2, p. 171-202Chapter in book (Other academic)
    Abstract [en]

    NMR spectroscopy is so far the only analytical technique that has been used to get a detailed structural characterization of hydrogenated fullerenes. A substantial amount of information derived from different NMR experiments can thus be found in the literature for a number of fullerenes hydrogenated to various degrees. These studies have benefitted from the fact that chemical shifts of H-1 and C-13 and in some cases also He-3 can be used to obtain structural information of these compounds. Such results, together with discussions about different NMR experiments and general considerations regarding sample preparations, are summarized in this chapter. The unique information, both structural and physicochemical, that can be derived from different NMR experiments ensures that this technique will continue to be of central importance in characterization of hydrogenated fullerenes.

  • 16.
    Johnels, Dan
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Günther, Harald
    Solid state NMR spectroscopy in organolithium chemistry2004In: The Chemistry of Organolithium Compounds, 2 volume set, The Chemistry of Organolithium Compounds, Wiley , 2004Chapter in book (Refereed)
  • 17.
    Mercier, Guillaume
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Klechikov, Alexey
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hedenstrom, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Baburin, Igor A.
    Seifert, Gotthard
    Mysyk, Roman
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Porous Graphene Oxide/Diboronic Acid Materials: Structure and Hydrogen Sorption2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 49, p. 27179-27191Article in journal (Refereed)
    Abstract [en]

    Solvothermal reaction of graphite oxide (GO) with benzene-1,4-diboronic acid (DBA) was reported previously to result in formation of graphene oxide framework (GOP) materials. The theoretical structure of GOFs consists of graphene layers separated by benzene-diboronic "pillars" with similar to 1 nm slit pores thus providing the opportunity to use it as a model material to verify the effect of a small pore size on hydrogen adsorption. A set of samples with specific surface area (SSA) in the range of similar to 50-1000 m(2)/g were prepared using variations of synthesis conditions and GO/DBA proportions. Hydrogen storage properties of GOF samples evaluated at 293 and 77 K were found to be similar to other nanocarbon trends in relation to SSA values. Structural characterization of GO/DBA samples showed all typical features reported as evidence for formation of a framework structure such as expanded interlayer distance, increased temperature of thermal exfoliation, typical features in FTIR spectra, etc. However, the samples also exhibited reversible swelling in polar solvents which is not compatible with the idealized GOF structure linked by benzenediboronic molecular pillars. Therefore, possible alternative nonframework models of structures with pillars parallel and perpendicular to GO planes are considered.

  • 18.
    Persson, Per-Axel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Ove
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    High-pressure polymerized C601996In: Extended Abstracts of Carbon´96, European Carbon Conference, Newcastle-upon-Tyne 1996, volume 2, The British Carbon Group , 1996, p. 746-747Conference paper (Other academic)
  • 19.
    Persson, Per-Axel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fransson, Åke
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Inaba, Akira
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Meingast, Christoph
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Physical properties of pressure polymerized C601996In: High Pressure Science and Technology: Proceedings of the Joint XV AIRAPT and XXXIII EHPRG International Conference, Warsaw 1995, Singapore: World Scientific , 1996, p. 716-718Conference paper (Refereed)
    Abstract [en]

    The properties of C60 have been studied after treatment at high temperature and high pressure (1.1 GPa and 565 K for 2 h). The treated material is insoluble in organic solvents. We present results obtained in NMR and Raman studies and measured data for the specific heat and the thermal expansion. Our results show clearly that there are no covalent bonds and no molecular rotation, but suggest that the molecules are slightly deformed and held together by weak pi-type bonds.

  • 20.
    Persson, Per-Axel
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    NMR and Raman characterization of pressure polymerized C-601996In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 258, no 5-6, p. 540-546Article in journal (Refereed)
    Abstract [en]

    Bulk C60 has been treated at 1.1 GPa and 550–585 K, producing a dense insoluble material which on heating to above 600 K reverts to normal C60. Raman and IR studies on modified material show a large number of new lines, and the Raman pentagon pinch mode shifts from 1469 to 1458 cm−1 as on photopolymerization. MAS NMR shows one broadened line at the original C60 shift 144 ppm and a small peak at about 77 ppm due to the bridging carbons. None of the new resonances observed for C60 polymerized by other methods were observed. The results verify previously suggested polymeric structures where the fullerence cages are connected by four-membered rings.

  • 21.
    Röding, Robert
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Stenmark, Patrik
    Umeå University, Faculty of Science and Technology, Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Structural and vibrational properties of Li- and Na-doped fullerene polymers2004In: Fullerenes, Nanotubes and Carbon Nanostructures vol. 12: Proceedings of 6th biannual International Workshop on Fullerenes and Atomic Clusters (IWFAC'2003), St. Petersburg 2003, London: Taylor & Francis , 2004, p. 319-25Conference paper (Refereed)
    Abstract [en]

    We have studied tetragonal C60 and C60-based polymers doped with Lithium and Sodium. We show that the intercalated phases Li4C60 and Na4C60 both form two-dimensional polymers. X-ray diffraction diagrams for Li4C60 and tetragonal C60 can be accurately indexed assuming tetragonal structures, but for Na4C60 a monoclinic quasi-tetragonal structure is found. We conclude that in Li4C60 the covalent bonds are formed by (2 + 2) cycloadditions, in the same way as in the tetragonal polymer produced by treating pure C60 at high temperature and high pressure, while single C-C bonds connect the fullerene molecules in Na4C60.

  • 22.
    Soldatov, Alexander
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Persson, Per-Axel
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pressure polymerized C60: Raman and NMR studies1996In: Fullerenes and Fullerene Nanostructures: Proceedings of the International Winterschool on Electronic Properties of Novel Materials, Kirchberg, Tyrol, Austria 1996, Singapore: World Scientific , 1996, p. 344-348Conference paper (Refereed)
    Abstract [en]

    The properties of bulk C60 have been studied after treatment at 1.1 GPa and 550-585 K. The treated material is insoluble in both toluene and 1,2-dichlorobenzene. Raman spectroscopy on modified aterial shows a large number of new lines, and the Raman pentagon pinch mode (Ag2) shifts from 1469 to 1458 /cm as on photopolymerization. MAS NMR shows one broadened line at the original C60 shift 144 ppm and a small peak at about 77 ppm due to the bridging carbons. The results verify previous suggested polymeric structures where the fullerene cages are connected by four-membered rings.

  • 23. Soldatov, Alexander V.
    et al.
    Roth, Georg
    Dzyabchenko, Alexander
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Lebedkin, Sergei
    Meingast, Christoph
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Haluska, Miro
    Kuzmany, Hans
    Topochemical polymerization of C70 controlled by monomer crystal packing2001In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 293, no 5530, p. 680-683Article in journal (Refereed)
    Abstract [en]

    Polymeric forms of C60 are now well known, but numerous attempts to obtain C70 in a polymeric state have yielded only dimers. Polymeric C70 has now been synthesized by treatment of hexagonally packed C70 single crystals under moderate hydrostatic pressure (2 gigapascals) at elevated temperature (300°C), which confirms predictions from our modeling of polymeric structures of C70. Single-crystal x-ray diffraction shows that the molecules are bridged into polymeric zigzag chains that extend along the c axis of the parent structure. Solid-state nuclear magnetic resonance and Raman data provide evidence for covalent chemical bonding between the C70 cages.

  • 24.
    Sundqvist, Bertil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Andersson, Ove
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fransson, Åke
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Inaba, Akira
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Launois, Pascale
    Meingast, Christoph
    Moret, Roger
    Moritz, Thomas
    Persson, Per-Axel
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. Umeå University, Faculty of Science and Technology, Department of Physics.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Physical properties of pressure polymerized C601996In: Fullerenes: Recent Advances in the Chemistry and Physics of Fullerenes and Related Materials, volume 3: Proceedings of the 189th ECS Meeting, Symposium Fullerenes: Chemistry, Physics, and New Directions VIII, Los Angeles 1996, Pennington, NJ: The Electrochemical Society , 1996, p. 1014-1028Conference paper (Refereed)
    Abstract [en]

    We present in this paper an overview of the physical properties of the high pressure polymerized C60 phase commonly known as "soft fcc". This phase has been studied by several methods over wide ranges in temperature T and/or pressure, p. We present here experimental information about the specific heat capacity, the thermal expansion coefficient, the lattice structure, and the thermal conductivity, and we also show results obtained by NMR and Raman spectroscopy. All data presented agree with the accepted model that the individual molecules in this phase are covalently bound to form linear molecular chains. In particular, the NMR data show clearly the presence of covalent bonds, and the Raman data exhibit several new lines at very low energies connected with chain vibrations. Thermal conductivity data obtained during polymerization show both the time dependence of the process and that polymerization occurs at lower p and T than observed previously for this phase.

  • 25.
    Sundqvist, Bertil
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jacobsson, Per
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jun, Jan
    Launois, Pascale
    Moret, Roger
    Persson, Per-Axel
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Soldatov, Alexander
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Structural and physical properties of pressure polymerized C601998In: Carbon, vol. 36 issue 5-6: Proceedings of Symposium A: Fullerenes and Carbon Based Materials, of the Joint Meeting of the European Materials Research Society (E-MRS'97) and the International Conference on Advanced Materials (ICAM'97), Strasbourg 1997, Elsevier B.V. , 1998, p. 657-660Conference paper (Refereed)
    Abstract [en]

    We discuss the structural and dynamic properties of C60 polymerized under low-P, low-T conditions, and suggest that the disordered mixed orthorhombic-tetragonal-rhombohedral phases produced under these conditions arise from nucleation of molecular chains in random directions because of the quasi-free molecular rotation under standard reaction conditions in the fcc phase of C60. Polymerization in He gives results qualitatively different from those obtained in other media.

  • 26.
    Talyzin, Alexandr
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Mercier, Guillaume
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Klechikov, Alexey
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wei, Di
    Cotton, Darryl
    Opitz, Andreas
    Moons, Ellen
    Brodie vs Hummers graphite oxides for preparation of multi-layered materials2017In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 115, p. 430-440Article in journal (Refereed)
    Abstract [en]

    Graphite oxides synthesized by one and two step Brodie oxidation (BGO) and Hummers (HGO) methods were analyzed by a variety of characterization methods in order to evaluate the reasons behind the difference in their properties. It is found that the Brodie method results in a higher relative amount of hydroxyl groups and a more homogeneous overall distribution of functional groups over the planar surface of the graphene oxide flakes. The higher number of carbonyl and carboxyl groups in HGO, detected by several methods, including XPS, NMR and FTIR, unavoidably results in defects of the graphene "skeleton", holes and overall disruption of the carbon-carbon bond network, stronger deviation from planar flake shape and poor ordering of the graphene oxide layers. It is also suggested that functional groups in HGO are less homogeneously distributed over the flake surface, forming some nanometer-sized graphene areas. The presence of differently oxidized areas on the GO surface results in inhomogeneous solvation and hydration of HGO and effects of inter- and intra-stratification. The proposed interpretation of the data explains the higher mechanical strength of multi-layered BGO membranes/papers, which are also less affected by humidity changes, thus providing an example of a membrane property superior to that of HGO.

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  • 27.
    Wiklund, Susanne
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Karlsson, Marlene
    Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, SLU, Umeå.
    Antti, Henrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sjöström, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wingsle, Gunnar
    Umeå Plant Science Centre (UPSC), Department of Forest Genetics and Plant Physiology, SLU, Umeå.
    Edlund, Ulf
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    A new metabonomic strategy for analysing the growth process of the poplar tree2005In: Plant Biotechnology Journal, ISSN 1467-7644, E-ISSN 1467-7652, Vol. 3, no 3, p. 353-362Article in journal (Refereed)
    Abstract [en]

    High-resolution, magic angle spinning, proton nuclear magnetic resonance (H-1 HR/MAS NMR) spectroscopy and multivariate data analysis using batch processing (BP) were applied to the analysis of two different genotypes of poplar tree (Populus tremula L. x tremuloides Michx.) containing an antisense construct of PttMYB76 and control (wild-type). A gene encoding a MYB transcription factor, with unknown function, PttMYB76, was selected from a cambial expressed sequence tag (EST) library of poplar tree (Populus tremula L. x tremuloides Michx.) for metabonomic characterization. The PttMYB76 gene is believed to affect different paths in the phenyl propanoid synthetic pathway. This pathway leads to the formation of S- and G-lignin, flavonoids and sinapate esters. Milled poplar samples collected at the internodes of the tree were analysed using H-1 HR/MAS NMR spectroscopy. The application of multivariate BP of the NMR results revealed a growth-related gradient in the plant internode direction, as well as the discrimination between the trees with down-regulated PttMYB76 expression and wild-type populations. This paper focuses on the potential of a new analytical multivariate approach for analysing time-related plant metabonomic data. The techniques used could, with the aid of suitable model compounds, be of high relevance to the detection and understanding of the different lignification processes within the two types of poplar tree. Additionally, the findings highlight the importance of applying robust and organized multivariate data analysis approaches to facilitate the modelling and interpretation of complex biological data sets.

  • 28.
    Wågberg, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Goze-Bac, Christophe
    Röding, Robert
    Umeå University, Faculty of Science and Technology, Physics.
    Sundqvist, Bertil
    Umeå University, Faculty of Science and Technology, Physics.
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Chemistry.
    Kataura, Hiromichi
    Bernier, Patric
    13C NMR on intercalated 2D-polymerised C60 and modified peapods.2004In: Electronic Properties of Synthetic Nanostructures: Proceedings of the XVIII International Winter School/Euroconference on Electronic Properties of Novel Materials, Kirchhberg 2004, Melville, NY: American Institute of Physics (AIP) , 2004, p. 238-41Conference paper (Refereed)
    Abstract [en]

    We present 13C NMR results on the intercalated 2D C60-polymers Li4-xNaxC60 (x=0-4 with half integer steps) showing that while Li4C60 forms a tetragonal polymer with double polymer bonds between the molecules, Na4C60 form a monoclinic polymer with single polymer bonds. The chemical shift is much larger for Li-rich samples than for Na-rich samples, indicating perhaps a different type of interaction with the C60 molecules. The crossover between the two structures appears to be at the composition Li2.5Na1.5C60 . We also show NMR data on SWNT filled with C60 molecules, so called peapods, showing that the NMR line of C60 can not be observed when the C60 is inside the tubes. Weinterpret this as resulting from a very long relaxation time, indicating that the dynamics of the C60 molecule is hindered by the nanotube walls.

  • 29.
    Wågberg, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Hedenström, Mattias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Talyzin, Alexandr V
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Sethson, Ingmar
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Tsybin, Yury O
    Purcell, Jeremiah M
    Marshall, Alan G
    Noréus, Dag
    Johnels, Dan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis and Structural Characterization of C70H382008In: Angewandte Chemie International Edition, Vol. 47, no 15, p. 2796-9Article in journal (Refereed)
  • 30.
    Wågberg, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Johnels, Dan
    Chemistry.
    7Li and 23Na MAS solid state NMR studies of Na4C60 and Li4C602006In: Journal of Physics and Chemistry of Solids, Vol. 67, no 5-6, p. 1091-4Article in journal (Refereed)
    Abstract [en]

    We present 7Li and 23Na MAS-NMR measurements of Li4C60 and Na4C60 and discuss structural parameters for these materials. From 7Li NMR on Li4C60, we find good agreement with the recently proposed structure with single polymer bonds in one direction and double ‘pair bonds’ in the other. We observe NMR lines at 1.4 ppm accounting for half the intensity corresponding to two Li-ion in tetrahedral positions and two less symmetric lines at 3.0 and 6.6 ppm which correspond to the occupancy of one Li-ion in each of the sites which are close to the octahedral positions in the former C60 fcc lattice. For the Na4C60 sample, 23Na NMR gives a single line with a center of gravity at −21.3 ppm. As expected, this line shows a stronger quadrupole coupling than the 7Li signal but still the coupling could be considered as quite small which agrees with the occupancy of relatively symmetric tetrahedral sites in the Na4C60 structure.

  • 31.
    Wågberg, Thomas
    et al.
    Umeå University, Faculty of Science and Technology, Physics.
    Johnels, Dan
    Chemistry.
    Peera, Ashgar
    Hedenström, Mattias
    Chemistry.
    Shulga, Yury M.
    Tsybin, Yury O.
    Purcell, J.M.
    Marshall, Alan.G.
    Noreus, Dag
    Sato, Toyoto
    Talyzin, Alexandr V.
    Umeå University, Faculty of Science and Technology, Physics.
    Selective synthesis of the C3v-isomer of C60H182005In: Organic Letters, ISSN 1523-7060, Vol. 7, no 25, p. 5557-60Article in journal (Refereed)
    Abstract [en]

    C60H18 has been produced by hydrogenation of C-60 at 100 bar H-2 pressure and 673 K for 10 h. We have investigated the crude material without any purification by use of H-1 NMR, C-13 NMR, and IR spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. We show that the crude material consists of 95% of the C-3v isomer of C60H18.

1 - 31 of 31
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