uu.seUppsala University Publications
Change search
Refine search result
1234567 1 - 50 of 1323
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1. Aabloo, A
    et al.
    Klintenberg, M
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Molecular dynamics simulation of a polymer-inorganic interface.2000In: Electrochim.Acta, Vol. 45, 1425- p.Article in journal (Refereed)
  • 2. Aabloo, A.
    et al.
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Molecular dynamics simulation of lithium ion mobility in a PEO surface.2001In: Solid State Ionics, Vol. 143, 83- p.Article in journal (Refereed)
  • 3.
    Aabloo, A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Molecular dynamics simulation of Nd3+ ions in a crystalline PEO surface1998In: ELECTROCHIMICA ACTA, ISSN 0013-4686, Vol. 43, no 10-11, 1361-1364 p.Article in journal (Other scientific)
    Abstract [en]

    Poly(ethylene oxide) based electrolytes are systems in which ionic salts are dissolved into an amorphous EO matrix. Potentials developed earlier to model crystalline and amorphous bulk PEO systems are here used for the MD simulation at 400 K of the behavi

  • 4.
    Aabloo, A
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Molecular dynamics simulations of a poly(ethylene oxide) surface1997In: POLYMER, ISSN 0032-3861, Vol. 38, no 18, A47-A51 p.Article in journal (Refereed)
    Abstract [en]

    Potentials developed earlier for crystalline and amorphous bulk PEO systems have been used for the MD simulation of a PEO surface model. The surface comprises the outer region of a 122 Angstrom-thick sheet of PEO in which the PEO, -(CH2-CH2-O)(n)- chains

  • 5.
    Aarik, J.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. oorganisk kemi.
    Aidla, A.
    Mändar, H.
    Uustare, T.
    Schuisky, M.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. oorganisk kemi.
    Hårsta, A.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. oorganisk kemi.
    Atomic layer growth of epitaxial TiO2 thin films from TiCl4 and H2O on a-Al2O3 substrates2002In: J. Cryst. Growth, no 242, 189-198 p.Article in journal (Refereed)
  • 6.
    Aarik, J.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. oorganisk kemi.
    Sundqvist, J.
    Aidla, A.
    Lu, J.
    Sajavaara, T.
    Kukli, K.
    Hårsta, Anders
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. oorganisk kemi.
    Hafnium tetraiodide and oxygen as precursors for atomic layer deposition of hafnium oxide thin films2002In: Thin Solid Films, Vol. 418, 69-72 p.Article in journal (Refereed)
  • 7. Abbrent, S
    et al.
    Plestil, J
    Hlavata, D
    Lindgren, Jan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Tegenfeldt, Jörgen
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Wendsjö, Å
    Crystallinity and morphology of PVdF-HFP based gel electrolytes.2001In: Polymer, Vol. 42, 1407- p.Article in journal (Refereed)
  • 8.
    Abrahamsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Tocher, Derek
    Nag, Samik
    Datta, Dipankar
    Modulation of the lowest metal-to-ligand charge-transfer state in [Ru(bpy)(2)(N-N)](2+) systems by changing the N-N from hydrazone to azine: Photophysical Consequences2006In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 45, no 23, 9580-9586 p.Article in journal (Refereed)
    Abstract [en]

    Two Ru( II) complexes, [ Ru( bpy) L-2]( ClO4) 2 ( 1) and [ Ru( bpy)(2)L']( BF4) 2 ( 2), where bpy is 2,2'-bipyridine, L is diacetyl dihydrazone, and L' 1: 2 is the condensate of L and acetone, are synthesized. From X-ray crystal structures, both are found to contain distorted octahedral RuN62+ cores. NMR spectra show that the cations in 1 and 2 possess a C-2 axis in solution. They display the expected metal-to-ligand charge transfer ( (MLCT)-M-1) band in the 400 - 500 nm region. Complex 1 is nonemissive at room temperature in solution as well as at 80 K. In contrast, complex 2 gives rise to an appreciable emission upon excitation at 440 nm. The room-temperature emission is centered at 730 nm ( lambda(max)(em)) with a quantum yield ( em) of 0.002 and a lifetime ( tau(em)) of 42 ns in an air-equilibrated methanol - ethanol solution. At 80 K, Phi(em) = 0.007 and tau(em)= 178 ns, with a lambda(max)(em) of 690 nm, which is close to the 0 - 0 transition, indicating an (MLCT)-M-3 excited-state energy of 1.80 eV. The radiative rate constant ( 5 x 10(4) s(-1)) at room temperature and 80 K is almost temperature independent. From spectroelectrochemistry, it is found that bpy is easiest to reduce in 2 and that L is easiest in 1. The implications of this are that in 2 the lowest (MLCT)-M-3 state is localized on a bpy ligand and in 1 it is localized on L. Transient absorption results also support these assignments. As a consequence, even though 2 shows a fairly strong and long-lived emission from a Ru( II) -> bpy CT state, the Ru( II) -> L CT state in 1 shows no detectable emission even at 80 K.

  • 9.
    Abrahamsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Lundqvist, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Wolpher, Henriette
    Johansson, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Eriksson, Lars
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Rasmussen, Torben
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Becker, Hans-Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Norrby, Per-Ola
    Åkermark, Björn
    Persson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands.2008In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, no 9, 3540-3548 p.Article in journal (Refereed)
    Abstract [en]

    The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2'-bipyridyl)](2-pyridyl)methane (1) and 2-[6-(2,2'-bipyridyl)]-2-(2-pyridyl)propane (2). A homoleptic ([Ru(2)(2)](2+)) and a heteroleptic complex ([Ru(ttpy)(2)](2+)) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru(1)(2)](2+). The excited-state lifetime of the homoleptic Ru-II complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru-II complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central Ru-II ion less octahedral in [Ru(2)(2)](2+) than in [Ru(1)(2))(2+). Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer ((MLCT)-M-3) and metal-centered ((MC)-M-3) excited states. The large difference in measured excited-state lifetimes for the two homoleptic Ru-II complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from (MLCT)-M-3 states to short-lived (MC)-M-3 states.

  • 10.
    Abrahamsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Accelerator mass spectrometry group. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Wolpher, Henriette
    Johansson, Olof
    Larsson, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Kritikos, Mikael
    Eriksson, Lars
    Norrby, Per-Ola
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Sun, Licheng
    Åkermark, Björn
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    A New Strategy for the Improvement of Photophysical Properties in Ruthenium(II) Polypyridyl Complexes: Synthesis and Photophysical and Electrochemical Characterization of Six Mononuclear Ruthenium(II) Bisterpyridine-Type Complexes2005In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 44, no 9, 3215-3225 p.Article in journal (Refereed)
  • 11. Agarwala, Hemlata
    Bidirectional non-​innocence of the β-​diketonato ligand 9-​oxidophenalenone (L-​) in [Ru([9]​aneS3)​(L)​(dmso)​]​n, [9]​aneS3 = 1,​4,​7-​trithiacyclononane2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, 3939-3948 p.Article in journal (Refereed)
    Abstract [en]

    The new compound [RuII([9]aneS3)(L)(dmso)]ClO4 ([1]ClO4) ([9]aneS3 = 1,4,7-trithiacyclononane, HL =9-hydroxyphenalenone, dmso = dimethylsulfoxide) has been structurally characterised to reveal almostequal C–O bond distances of coordinated L−, suggesting a delocalised bonding situation of the β-diketonatoligand. The dmso ligand is coordinated via the sulfur atom in the native (1+) and reduced states(1 and 1−) as has been revealed by X-ray crystallography and by DFT calculations. Cyclic voltammetry of1+ exhibits two close-lying one-electron oxidation waves at 0.77 V and 0.94 V, and two similarly closeone-electron reduction processes at −1.43 V and −1.56 V versus SCE in CH2Cl2. The electronic structuresof 1n in the accessible redox states have been analysed via experiments (EPR and UV-vis-NIR spectroelectrochemistry)and by DFT/TD-DFT calculations, revealing the potential for bidirectional non-innocent behaviourof coordinated L•/−/•2−. Specifically, the studies establish significant involvement of L basedfrontier orbitals in both the oxidation and reduction processes: [([9]aneS3)(dmso)RuIII–L•]3+ (13+) ⇌ [([9]-aneS3)(dmso)RuIII–L−]2+/[([9]aneS3)(dmso)RuII–L•]2+ (12+) ⇌ [([9]aneS3)(dmso)RuII–L−]+ (1+) ⇌ [([9]aneS3)-(dmso)RuII–L•2−] (1) ⇌ [([9]aneS3)(dmso)RuII–L3−]−/[([9]aneS3)(dmso)RuI–L•2−]− (1−).

  • 12. Agarwala, Hemlata
    Correspondence of RuIIIRuII and RuIVRuIII Mixed Valent States in a SmallDinuclear Complex2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, 5667-5675 p.Article in journal (Refereed)
    Abstract [en]

    The dirutheniumACHTUNGTRENUNG(III) compound[(m-oxa){RuACHTUNGTRENUNG(acac)2}2] [1, oxa2=oxamidato(2), acac=2,4-pentanedionato]exhibits an S=1 ground statewith antiferromagnetic spin-spin coupling(J=40 cm1). The molecularstructure in the crystal of 1·2C7H8 revealedan intramolecular metal–metaldistance of 5.433 and a notableasymmetry within the bridging ligand.Cyclic voltammetry and spectroelectrochemistry(EPR, UV/Vis/NIR) of thetwo-step reduction and of the two-stepoxidation (irreversible second step)produced monocation and monoanionintermediates (Kc=105.9) with broadNIR absorption bands (e ca.2000m1cm1) and maxima at 1800 (1)and 1500 nm (1+). TD-DFT calculationssupport a RuIIIRuII formulationfor 1 with a doublet ground state. The1+ ion (RuIVRuIII) was calculated withan S=3/2 ground state and the doubletstate higher in energy (DE=694.6 cm1). The Mulliken spin densitycalculations showed little participationof the ligand bridge in the spin accommodationfor all paramagnetic species[(m-oxa){RuACHTUNGTRENUNG(acac)2}2]n, n=+1, 0, 1,and, accordingly, the NIR absorptionswere identified as metal-to-metal (intervalence)charge transfers. Whereasonly one such NIR band was observedfor the RuIIIRuII (4d5/4d6) system 1,the RuIVRuIII (4d4/4d5) form 1+ exhibitedextended absorbance over the UV/Vis/NIR range.

  • 13. Agarwala, Hemlata
    Electronic structure and catalytic aspects of [Ru(tpm)​(bqdi)​(Cl​/H2O)​]​n, tpm = tris(1-​pyrazolyl)​methane and bqdi = o-​benzoquinonediimine2013In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 42, 3721-3734 p.Article in journal (Refereed)
    Abstract [en]

    The diamagnetic complexes [Ru(tpm)(bqdi)(Cl)]ClO4 ([1]ClO4) (tpm = tris(1-pyrazolyl)methane, bqdi =o-benzoquinonediimine) and [Ru(tpm)(bqdi)(H2O)](ClO4)2 ([2](ClO4)2) have been synthesized. Thevalence state-sensitive bond distances of coordinated bqdi [C–N: 1.311(5)/1.322(5) Å in [1]ClO4;1.316(7)/1.314(7) Å in molecule A and 1.315(6)/1.299(7) Å in molecule B of [2](ClO4)2] imply its fullyoxidised quinonediimine (bqdi0) character. DFT calculations of 1+ confirm the {RuII–bqdi0} versus the antiferromagneticallycoupled {RuIII–bqdi˙−} alternative. The 1H NMR spectra of [1]ClO4 in different solventsshow variations in chemical shift positions of the NH (bqdi) and CH (tpm) proton resonances due to theirdifferent degrees of acidity in different solvents. In CH3CN/0.1 mol dm−3 Et4NClO4, [1]ClO4 undergoesone reversible RuII ⇌ RuIII oxidation and two reductions, the reversible first electron uptake being bqdibased (bqdi0/bqdi˙−). The electrogenerated paramagnetic species {RuIII–bqdi0}(12+) and {RuII–Q˙−}(1)exhibit RuIII-type (12+: <g> = 2.211/Δg = 0.580) and radical-type (1: g = 1.988) EPR signals, respectively, asis confirmed by calculated spin densities (Ru: 0.767 in 12+, bqdi: 0.857 in 1). The aqua complex [2](ClO4)2exhibits two one-electron oxidations at pH = 7, suggesting the formation of {RuIVvO} species. The electronicspectral features of 1n (n = charge associated with the different redox states of the chloro complex:2+, 1+, 0) in CH3CN and of 22+ in H2O have been interpreted based on the TD-DFT calculations. The applicationpotential of the aqua complex 22+ as a pre-catalyst towards the epoxidation of olefins has beenexplored in the presence of the sacrificial oxidant PhI(OAc)2 in CH2Cl2 at 298 K, showing the desiredselectivity with a wide variety of alkenes. DFT calculations based on styrene as the model substratepredict that the epoxidation reaction proceeds through a concerted transition state pathway.IntroductionThe well recognized mixing of ruthenium dπ orbitals andπ orbitals of redox non-innocent quinonoid moieties introducesseveral manifestations with respect to the valence distributionat the metal–quinonoid interface, as depicted in Scheme 1.1This makes the electronic structure of such complexes sensitiveto the molecular frameworks, and in many occasions theexperimental results

  • 14. Agarwala, Hemlata
    Electronic structures and selective fluoride sensingfeatures of Os(bpy)2(HL2−) and [{Os(bpy)2}2(μ-HL2−)]2+(H3L: 5-(1H-benzo[d]imidazol-2-yl)-1H-imidazole-4-carboxylic acid)2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, 13932-13947 p.Article in journal (Refereed)
    Abstract [en]

    The article deals with the newly designed mononuclear and asymmetric dinuclear osmium(II) complexesOsII(bpy)2(HL2−) (1) and [(bpy)2OsII(μ-HL2−)OsII(bpy)2](Cl)2 ([2](Cl)2)/[(bpy)2OsII(μ-HL2−)OsII(bpy)2](ClO4)2([2](ClO4)2), respectively, (H3L = 5-(1H-benzo[d]imidazol-2-yl)-1H-imidazole-4-carboxylic acid and bpy = 2,2’-bipyridine). The identity of 1 has been established by its single crystal X-ray structure. The ligand (HL2−)-basedprimary oxidation process (E°298, 0.23 V versus SCE) along with the partial metal contribution (∼20%) in 1 hasbeen revealed by the ligand-dominated HOMO of 1 (HL2−: 88%, Os: 8%), as well as by the Mulliken spindensity distribution of 1+ (HL2−: 0.878, Os: 0.220). Accordingly, 1+ exhibits a free radical type EPR at 77 K witha partial metal-based anisotropic feature (g1 = 2.127, g2 = 2.096, g3 = 2.046; <g> = 2.089; Δg = 0.08).1H-NMR of the dinuclear 22+ in CDCl3 suggests an intimate mixture of two diastereomeric forms in a 1 : 1ratio. The DFT-supported predominantly Os(II)/Os(III)-based couples of asymmetric 22+ at 0.24 V and 0.50 Vversus SCE result in a comproportionation constant (Kc) value of 8.2 × 104. The class I mixed valent state of23+ (S = 1/2) has, however, been corroborated by the Mulliken spin density distribution of Os1: 0.887, Os2:0.005, HL2−: 0.117, as well as by the absence of a low-energy IVCT (intervalence charge transfer) band in thenear-IR region (up to 2000 nm). The appreciable spin accumulation on the bridge in 23+ or 24+ (S = 1, Os1:0.915, Os2: 0.811 and HL2−: 0.275) implies a mixed electronic structural form of [(bpy)2OsIII(μ-HL2−)-OsII(bpy)2]3+(major)/[(bpy)2OsII(μ-HL•−)OsII(bpy)2]3+(minor) or [(bpy)2OsIII(μ-HL2−)OsIII(bpy)2]4+(major)/[(bpy)2-OsIII(μ-HL•−)OsII(bpy)2]4+ (minor), respectively. The mixed valent {OsIII(μ-HL2−)OsII} state in 23+, however, fails toshow EPR at 77 K due to the rapid spin relaxation process. The DFT-supported bpy-based two reductions forboth 1+ and 22+ appear in the potential range of −1.5 V to −1.8 V versus SCE. The electronic transitions in 1nand 2n are assigned by the TD-DFT calculations. Furthermore, the potential anion sensing features of 1 and22+ via the involvement of the available N–H proton in the framework of coordinated HL2− have been evaluatedby different experimental investigations, in conjunction with the DFT calculations, using a wide variety ofanions such as F−, Cl−, Br−, I−, OAc−, SCN−, HSO4− and H2PO4−. This, however, establishes that both 1 and 22+are equally efficient in recognising the F− ion selectively, with log K values of 6.83 and 5.89, respectively.

  • 15. Agarwala, Hemlata
    Four-Center Oxidation State Combinations and Near-Infrared Absorption in[Ru(pap)(Q)2]n (Q=3,5-Di-tert-butyl-N-aryl-1,2-benzoquinonemonoimine,pap=2-Phenylazopyridine)2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, 7384-7394 p.Article in journal (Refereed)
  • 16. Agarwala, Hemlata
    Probing valence and spin situations in selective ruthenium–iminoquinonoidframeworks. An experimental and DFT analysis2011In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 374, 216-225 p.Article in journal (Refereed)
    Abstract [en]

    The ruthenium–iminoquinone complexes, [Ru(tpm)(Cl)(Q)]+ [tpm = tris(1-pyrazolyl)methane, Q = 3,5-di-tert-butyl-N-aryl-1,2-benzoquinonemonoimine, where aryl = C6H5, [1]+; m-(OCH3)2C6H3, [2]+;m-(Cl)2C6H3, [3]+] have been synthesized. The sensitive bond distances of ‘‘Q’’ in [1](ClO4) and[2](ClO4), C–O: 1.294(8), 1.281(2) Å; C–N: 1.352(8), 1.335(2) Å; and C–C(meta): 1.366(10)/1.367(9) Å,1.364(2)/1.353(2) Å, respectively, and other analytical as well as theoretical (DFT) events suggest thevalence configuration of [RuIII(tpm)(Cl)(QSq)]+ for [1]+–[3]+. The paramagnetic [1]+–[3]+ show sharp1H NMR spectra with strikingly small J of 1.8–3.0 Hz. The DFT calculations on [1]+ predict that the triplet(S = 1) state exists above (1004 cm1) the singlet (S = 0) ground state. [1]+ exhibits l = 2.2 BM at 300 Kwhich diminishes to 0.3 BM near 2 K due to the steady decrease in the ratio of triplet to singlet populationwith the lowering of temperature. [1]+–[3]+ exhibit one oxidation and two successive reductions each inCH3CN. Experimental and DFT analyses collectively establish the valence configurations at thenon-innocent {Ru–Q} interface along the redox chain as [(tpm)(Cl)RuIII(QQo)]2+ ([1]2+–[3]2+)?[(tpm)(Cl)RuIII(QSq)]+ ([1]+–[3]+)?[(tpm)(Cl)RuII(QSq)]M[(tpm)(Cl)RuIII(QCat)] (1–3)?[(tpm)(Cl)-RuII(QCat)] ([1]–[3]). The spectral features of [1]n–[3]n (n = +2, +1, 0) have been addressed based onthe TD-DFT calculations on [1]n.

  • 17. Agarwala, Hemlata
    Sensitivity of a Strained C−C Single Bond to Charge Transfer: RedoxActivity in Mononuclear and Dinuclear Ruthenium Complexes ofBis(arylimino)acenaphthene (BIAN) Ligands2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, 7389-7403 p.Article in journal (Refereed)
    Abstract [en]

    The new compounds [Ru(acac)2(BIAN)], BIAN = bis(arylimino)-acenaphthene (aryl = Ph (1a), 4-MeC6H4 (2a), 4-OMeC6H4 (3a), 4-ClC6H4 (4a), 4-NO2C6H4 (5a)), were synthesized and structurally, electrochemically, spectroscopically,and computationally characterized. The α-diimine sections of the compoundsexhibit intrachelate ring bond lengths 1.304 Å < d(CN) < 1.334 and 1.425 Å < d(CC)< 1.449 Å, which indicate considerable metal-to-ligand charge transfer in the groundstate, approaching a RuIII(BIAN•−) oxidation state formulation. The particularstructural sensitivity of the strained peri-connecting C−C bond in the BIAN ligandstoward metal-to-ligand charge transfer is discussed. Oxidation of [Ru(acac)2(BIAN)]produces electron paramagnetic resonance (EPR) and UV−vis−NIR (NIR = near infrared) spectroelectrochemically detectableRuIII species, while the reduction yields predominantly BIAN-based spin, in agreement with density functional theory (DFT)spin-density calculations. Variation of the substituents from CH3 to NO2 has little effect on the spin distribution but affects theabsorption spectra. The dinuclear compounds {(μ-tppz)[Ru(Cl)(BIAN)]2}(ClO4)2, tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine;aryl (BIAN) = Ph ([1b](ClO4)2), 4-MeC6H4 ([2b](ClO4)2), 4-OMeC6H4 ([3b](ClO4)2), 4-ClC6H4 ([4b](ClO4)2), were alsoobtained and investigated. The structure determination of [2b](ClO4)2 and [3b](ClO4)2 reveals trans configuration of thechloride ligands and unreduced BIAN ligands. The DFT and spectroelectrochemical results (UV−vis−NIR, EPR) indicateoxidation to a weakly coupled RuIIIRuII mixed-valent species but reduction to a tppz-centered radical state. The effect of the πelectron-accepting BIAN ancillary ligands is to diminish the metal−metal interaction due to competition with the acceptor bridgetppz.

  • 18. Agarwala, Hemlata
    Sensitivity of the Valence Structure in Diruthenium Complexes As aFunction of Terminal and Bridging Ligands2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, 6082-6093 p.Article in journal (Refereed)
    Abstract [en]

    The compounds [(acac)2RuIII(μ-H2L2−)RuIII(acac)2] (rac, 1, and meso, 1′) and[(bpy)2RuII(μ-H2L•−)RuII(bpy)2](ClO4)3 (meso, [2](ClO4)3) have been structurally, magnetically,spectroelectrochemically, and computationally characterized (acac− = acetylacetonate, bpy= 2,2′-bipyridine, and H4L = 1,4-diamino-9,10-anthraquinone). The N,O;N′,O′-coordinated μ-H2Ln− forms two β-ketiminato-type chelate rings, and 1 or 1′ are connected via NH···Ohydrogen bridges in the crystals. 1 exhibits a complex magnetic behavior, while [2](ClO4)3 is aradical species with mixed ligand/metal-based spin. The combination of redox noninnocentbridge (H2L0 → → → →H2L4−) and {(acac)2RuII} → →{(acac)2RuIV} or {(bpy)2RuII} →{(bpy)2RuIII} in 1/1′ or 2 generates alternatives regarding the oxidation state formulations for the accessible redox states (1n and2n), which have been assessed by UV−vis−NIR, EPR, and DFT/TD-DFT calculations. The experimental and theoretical studiessuggest variable mixing of the frontier orbitals of the metals and the bridge, leading to the following most appropriate oxidationstate combinations: [(acac)2RuIII(μ-H2L•−)RuIII(acac)2]+ (1+) → [(acac)2RuIII(μ-H2L2−)RuIII(acac)2] (1) → [(acac)2RuIII(μ-H2L•3−)RuIII(acac)2]−/[(acac)2RuIII(μ-H2L2−)RuII(acac)2]− (1−) → [(acac)2RuIII(μ-H2L4−)RuIII(acac)2]2−/[(acac)2RuII(μ-H2L2−)RuII(acac)2]2− (12−) and [(bpy)2RuIII(μ-H2L•−)RuII(bpy)2]4+ (24+) → [(bpy)2RuII(μ-H2L•−)RuII(bpy)2]3+/[(bpy)2RuII(μ-H2L2−)RuIII(bpy)2]3+ (23+) → [(bpy)2RuII(μ-H2L2−)RuII(bpy)2]2+ (22+). The favoring of RuIII by σ-donatingacac− and of RuII by the π-accepting bpy coligands shifts the conceivable valence alternatives accordingly. Similarly, theintroduction of the NH donor function in H2Ln as compared to O causes a cathodic shift of redox potentials with correspondingconsequences for the valence structure.

  • 19. Agarwala, Hemlata
    Synthesis, Spectral Characterization, Structures, and Oxidation StateDistributions in [(corrolato)FeIII(NO)]n (n = 0, +1, −1) Complexes2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, 1417-1429 p.Article in journal (Refereed)
    Abstract [en]

    Two novel trans-A2B-corroles and three[(corrolato){FeNO}6] complexes have been prepared andcharacterized by various spectroscopic techniques. In thenative state, all these [(corrolato){FeNO}6] species arediamagnetic and display “normal” chemical shifts in the 1HNMR spectra. For two of the structurally characterized[(corrolato){FeNO}6] derivatives, the Fe−N−O bond anglesare 175.0(4)° and 171.70(3)° (DFT: 179.94°), respectively,and are designated as linear nitrosyls. The Fe−N (NO) bonddistances are 1.656(4) Å and 1.650(3) Å (DFT: 1.597 Å),which point toward a significant FeIII → NO back bonding.The NO bond lengths are 1.159(5) Å and 1.162(3) Å (DFT:1.162 Å) and depict their elongated character. These structural data are typical for low-spin Fe(III). Electrochemicalmeasurements show the presence of a one-electron oxidation and a one-electron reduction process for all the complexes. Theone-electron oxidized species of a representative [(corrolato){FeNO}6] complex exhibits ligand to ligand charge transfer(LLCT) transitions (cor(π) → cor(π*)) at 399 and 637 nm, and the one-electron reduced species shows metal to ligand chargetransfer (MLCT) transition (Fe(dπ) → cor(π*)) in the UV region at 330 nm. The shift of the νNO stretching frequency of arepresentative [(corrolato){FeNO}6] complex on one-electron oxidation occurs from 1782 cm−1 to 1820 cm−1, whichcorresponds to 38 cm−1, and on one-electron reduction occurs from 1782 cm−1 to 1605 cm−1, which corresponds to 177 cm−1.The X-band electron paramagnetic resonance (EPR) spectrum of one-electron oxidation at 295 K in CH2Cl2/0.1 M Bu4NPF6displays an isotropic signal centered at g = 2.005 with a peak-to-peak separation of about 15 G. The in situ generated oneelectronreduced species in CH2Cl2/0.1 M Bu4NPF6 at 295 K shows an isotropic signal centered at g = 2.029. The 99%contribution of corrole to the HOMO of native species indicates that oxidation occurs from the corrole moiety. The results of theelectrochemical and spectroelectrochemical measurements and density functional theory calculations clearly display a preferenceof the {FeNO}6 unit to get reduced during the reduction step and the corrolato unit to get oxidized during the anodic process.Comparisons are presented with the structural, electrochemical, and spectroelectrochemical data of related compounds reportedin the literature, with a particular focus on the interpretation of the EPR spectrum of the one-electron oxidized form.

  • 20. Alami, J.
    et al.
    Eklund, P.
    Emmerlich, J.
    Wilhelmsson, Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Högberg, H.
    Hultman, L.
    Helmersson, U.
    High-power impulse magnetron sputtering of Ti–Si–C thin films from a Ti3SiC2 compound target2006In: Thin Solids Films, ISSN 0040-6090, Vol. 515, no 4, 1731-1736 p.Article in journal (Refereed)
    Abstract [en]

    We have deposited Ti–Si–C thin films using high-power impulse magnetron sputtering (HIPIMS) from a Ti3SiC2 compound target. The as-deposited films were composite materials with TiC as the main crystalline constituent. X-ray diffraction and photoelectron spectroscopy indicated that they also contained amorphous SiC, and for films deposited on inclined substrates, crystalline Ti5Si3Cx. The film morphology was dense and flat, while films deposited with direct-current magnetron sputtering under comparable conditions were rough and porous. We show that, due to the high degree of ionization of the sputtered species obtained in HIPIMS, the film composition, in particular the C content, depends on substrate inclination angle and Ar process pressure.

  • 21. Alfredsson, M
    et al.
    Hermansson, Kersti
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Hartree-Fock and DFT calculations of quadrupole coupling constants in water clusters and ice1999In: CHEMICAL PHYSICS, ISSN 0301-0104, Vol. 242, no 2, 161-175 p.Article in journal (Other scientific)
    Abstract [en]

    Periodic ab initio calculations of the O-17 and H-2 quadrupole coupling constants (QCC) and their shifts have been performed for ice VIII and ice IX. Cluster calculations were done for smaller water clusters and chains. The ice Vm crystal structure was op

  • 22.
    Alfredsson, M
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    OH frequency calculations for the hydroxylated MgO(001) surface2002In: Molecular Simulation, Vol. 28, 663- p.Article in journal (Refereed)
  • 23.
    Alfredsson, M
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Hermansson, Kersti
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Dovesi, R
    Periodic ab initio calculations of the spontaneous polarisation in ferroelectric NaNO2(s).2002In: Phys. Chem. Chem.Phys., 4204- p.Article in journal (Refereed)
  • 24. Alfredsson, Maria
    et al.
    Ojamae, Lars
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    A comparison of Hartree-Fock, MP2, and DFT results for the HCN dimer and crystal1996In: INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Vol. 60, no 3, 767-777 p.Article in journal (Refereed)
    Abstract [en]

    A number of hydrogen-bond related quantities-geometries, interaction energies, dipole moments, dipole moment derivatives, and harmonic vibrational frequencies-were calculated at the Hartree-Fock, MP2, and different DFT levels for the HCN dimer and the pe

  • 25.
    Alm, Oscar
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Technology, Department of Engineering Sciences, Solid State Physics. oorganisk kemi.
    Landström, Lars
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Technology, Department of Engineering Sciences, Solid State Physics. oorganisk kemi.
    Boman, Mats
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Technology, Department of Engineering Sciences, Solid State Physics. oorganisk kemi.
    Granqvist, Claes-Göran
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Technology, Department of Engineering Sciences, Solid State Physics. Fasta tillståndets fysik.
    Heszler, Peter
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Technology, Department of Engineering Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Technology, Department of Engineering Sciences, Solid State Physics. Fasta tillståndets fysik.
    Tungsten oxide nanoparticles synthesised by laser assisted homogeneous gas-phase nucleation2005In: Applied Surface Science, Vol. 247, no 1-4, 262-267 p.Article in journal (Refereed)
    Abstract [en]

    Tungsten oxide nanoparticles were generated by excimer (ArF) laser assisted chemical vapor deposition from WF6/H2/O2/Ar gas mixtures. The deposited particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The deposition rate as a function of the partial pressures of the reactants and of the laser fluence was measured by X-ray fluorescence spectroscopy. The mean diameter of the deposited tungsten oxide particles varied with the experimental parameters and was typically 23 nm. Particles with a higher degree of crystallinity were observed at a laser fluence exceeding 130 mJ/cm2, and X-ray amorphous particles were obtained below 110 mJ/cm2. The amorphous tungsten oxide had a stoichiometry ranging from WO2.7 to WO3. Deposits were formed only when hydrogen was present in the gas mixture.

  • 26.
    Alvi, Muhammad Rouf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Jahn, Burkhard O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Tibbelin, Julius
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Baumgartner, Judith
    Institut für Anorganische Chemie, Technische Universität Graz, Stremayrgasse 9, A-8010 Graz, Austria.
    Gómez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Highly Efficient and Convenient Acid Catalyzed Hypersilyl Protection of Alcohols and Thiols by Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide2012Article in journal (Other academic)
    Abstract [en]

    Tris(trimethylsilyl)silyl-N,N-dimethylmethaneamide, herein named hypersilylamide, is a convenient and efficient source of the hypersilyl group in the first widely applicable acid catalyzed protocol for silyl group protection of primary, secondary, tertiary alkyl as well as aryl alcohols and thiols in high yields. The sole by-product is N,N-dimethylformamide (DMF) and a range of solvents can be used, including DMF. A high selectivity in the protection of diols can be achieved, also for diols with very small differences in the steric demands at the two hydroxyl groups. Moreover, in the protection of equivalent alcohol and thiol sites the protection of the alcohol is faster, allowing for selective protection in high yields. Quantum chemical calculations at the M062X hybrid meta density functional theory level give insights on the mechanism for the catalytic process. Finally, the hypersilyl group is easily removed from all protected alcohols and thiols examined herein by irradiation at 254 nm.

  • 27.
    Amft, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Thermally Excited Vibrations in Copper, Silver, and Gold Trimers and Enhanced Binding of CO2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126Article in journal (Other academic)
  • 28.
    Amira, Sami
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry.
    Classical and Car-Parrinello Molecular Dynamics Simulations of Polyvalent Metal Ions in Water2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aqueous solvation of metal ions is one of the long-standing and complex problems in chemistry, with implications for and applications in a broad range of biochemical and electrochemical systems, where water is the all-pervasive medium.

    This thesis describes computer simulations of Al3+(aq), Fe2+(aq), Fe3+(aq) and Cu2+(aq). Various aspects of the solvation of these polyvalent metal ions in water are addressed, at different levels of theory, using Car-Parrinello molecular dynamics, classical molecular dynamics and quantum-mechanical cluster calculations. Polyvalent metal ions are particularly interesting because of their large influence on the solvent structure, dynamics and thermodynamics, as well as on the properties of the individual solvent molecules. Polyvalent metal ions in aqueous solution also constitute a challenging subject for computer simulations since a sophisticated interaction model is needed to incorporate the large many-body effects.

    All the ion-water coordination figures in this thesis are octahedral, except in the Cu2+(aq) solution, where the ion is penta-coordinated with four equatorial neighbours in a plane and one axial neighbour located ~0.45 Å further out from the ion. The equatorial ion-water bonds have covalent character, while the axial water molecule is only electrostatically bound. For all the ions, the OD stretching frequencies of the first-shell water molecules are much more downshifted than in liquid water. In the case of Cu2+(aq), however, only the OD frequencies of the equatorial water molecules are downshifted with respect to bulk water whereas the OD frequencies of the axial water molecule are slightly upshifted.

    Various limitations of the Car-Parrinello molecular dynamics simulations have been explored and compared, such as finite system-size effects and shortcomings in the electronic structure calculations. The Car-Parrinello simulations are found to give reasonable descriptions of the polyvalent metal ions in aqueous solution.

    List of papers
    1. Derivation and evaluation of a flexible SPC model for liquid water
    Open this publication in new window or tab >>Derivation and evaluation of a flexible SPC model for liquid water
    2004 (English)In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 303, no 3, 372-334 p.Article in journal (Refereed) Published
    Abstract [en]

    Molecular dynamics simulations of a new flexible water model are presented. The potential function is based on the simple point charge (SPC) model combined with an accurate experimental quartic intramolecular potential (CCL). This potential not only reproduces the key structural, dynamical and thermodynamical properties of liquid water, but also generates the correct values for both the absolute O–H vibrational frequency and the gas-to-liquid frequency shift. Thus, the model yields a value of ca. 3420 cm−1 for the peak maximum of the anharmonic OH stretching band for liquid water (experiment 3400 cm−1) and a corresponding gas-to-liquid downshift of −300 cm−1 (experiment −310 cm−1). The paper also emphasizes the importance of parameterizing correctly both the harmonic and anharmonic force constants in the gas-phase when developing flexible water models to be used in the liquid state.

    Keyword
    Molecular dynamics, Liquid water, SPC, Flexible
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-92887 (URN)10.1016/j.chemphys.2004.04.024 (DOI)
    Available from: 2005-04-07 Created: 2005-04-07 Last updated: 2017-12-14Bibliographically approved
    2. Molecular Dynamics simulation of Fe2+(aq) and Fe3+(aq)
    Open this publication in new window or tab >>Molecular Dynamics simulation of Fe2+(aq) and Fe3+(aq)
    2004 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 1, 496-502 p.Article in journal (Refereed) Published
    Abstract [en]

    Molecular dynamics simulations of single-ion Fe2+(aq) and Fe3+(aq) solutions have been performed with two rigid-water models (SPC and SPC/E) and a newly constructed SPC-based flexible-water model (SPC+CCL). The SPC+CCL water model in combination with effective Fe2+ and Fe3+ ion-water potentials manages to reproduce many experimental structural and dynamical properties of the solutions. Special attention is given to the large ion-induced frequency shifts of the OH stretching bands, which are also well reproduced by the SPC+CCL model.

    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-92888 (URN)10.1021/jp034855k (DOI)
    Available from: 2005-04-07 Created: 2005-04-07 Last updated: 2017-12-14Bibliographically approved
    3. Car-Parrinello Molecular Dynamics simulation of Fe3+(aq)
    Open this publication in new window or tab >>Car-Parrinello Molecular Dynamics simulation of Fe3+(aq)
    Show others...
    2005 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 29, 14235-14242 p.Article in journal (Refereed) Published
    Abstract [en]

    The optimized geometry and energetic properties of Fe(D2O)n3+ clusters, with n = 4 and 6, have been studied with density-functional theory calculations and the BLYP functional, and the hydration of a single Fe3+ ion in a periodic box with 32 water molecules at room temperature has been studied with Car-Parrinello molecular dynamics and the same functional. We have compared the results from the CPMD simulation with classical MD simulations, using a flexible SPC-based water model and the same number of water molecules, to evaluate the relative strengths and weaknesses of the two MD methods. The classical MD simulations and the CPMD simulations both give Fe-water distances in good agreement with experiment, but for the intramolecular vibrations, the classical MD yields considerably better absolute frequencies and ion-induced frequency shifts. On the other hand, the CPMD method performs considerably better than the classical MD in describing the intramolecular geometry of the water molecule in the first hydration shell and the average first shell···second shell hydrogen-bond distance. Differences between the two methods are also found with respect to the second-shell water orientations. The effect of the small box size (32 vs 512 water molecules) was evaluated by comparing results from classical simulations using different box sizes; non-negligible effects are found for the ion-water distance and the tilt angles of the water molecules in the second hydration shell and for the O-D stretching vibrational frequencies of the water molecules in the first hydration shell.

    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-92889 (URN)10.1021/jp050186u (DOI)
    Available from: 2005-04-07 Created: 2005-04-07 Last updated: 2017-12-14Bibliographically approved
    4. Distorted fivefold coordination of Cu2+(aq) from a Car-Parrinello Molecular Dynamics Simulation
    Open this publication in new window or tab >>Distorted fivefold coordination of Cu2+(aq) from a Car-Parrinello Molecular Dynamics Simulation
    2005 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 7, no 15, 2874-2880 p.Article in journal (Refereed) Published
    Abstract [en]

    The solvation shell structure and dynamics of a single Cu2+ ion in a periodic box with 32 water molecules under ambient conditions has been investigated using Car–Parrinello molecular dynamics simulations in a time-window of 18 ps. Five-fold coordination with four equidistant equatorial water molecules at 2.00 and one axial water molecule at 2.45 from the Cu2+ ion is found. A hole without water molecules is found on the opposite side of the axial water. The ion–water bonding character for the equatorial water molecules is different from that of the axial water molecules, as shown by a localized orbital analysis of the electronic structure. Moreover, the calculated OD stretching vibrational band for the equatorial water molecules lies ca. 175 cm–1 below the axial-water band, in good agreement with experimental data. The equatorial-water band lies below, and the axial-water band above, the pure liquid D2O band, also in agreement with experimental data.

    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-92890 (URN)10.1039/b502427g (DOI)
    Available from: 2005-04-07 Created: 2005-04-07 Last updated: 2017-12-14Bibliographically approved
    5. OD vibrations and hydration structure in an Al3+(aq) solution from a Car-Parrinello Molecular Dynamics Simulation
    Open this publication in new window or tab >>OD vibrations and hydration structure in an Al3+(aq) solution from a Car-Parrinello Molecular Dynamics Simulation
    2006 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 124, no 10, 104501- p.Article in journal (Refereed) Published
    Abstract [en]

    The optimized geometry, energetics, and vibrational properties of Al(D2O) clusters, with n=1,2,4, and 6, have been studied using plane waves, different local basis sets, different methodologies [density-functional theory, MP2, CCSD(T)], and different functionals (BLYP, PBE). Moreover, Car-Parrinello molecular-dynamics (MD) simulations using the BLYP functional, plane waves, and the Vanderbilt ultrasoft pseudopotentials have been performed for an aqueous Al3+ solution with 1 ion and 32 D2O molecules in a periodic box at room temperature, studied for 10 ps. The cluster calculations were performed to pinpoint possible shortcomings of the electronic structure description used in the Car-Parinello MD (CPMD) simulation. For the clusters, the hydration structure and interaction energies calculated with the `BLYP/plane-wave' approach agree well with high-level ab initio methods but the exchange-correlation functional introduces errors in the OD stretching frequencies (both in the absolute values and in the ion-induced shifts). For the aqueous solution, the CPMD simulation yields structural properties in good agreement with experimental data. The CPMD-simulated OD stretching vibrational band for the first-shell water molecules around Al3+ is strongly downshifted by the influence of the ion and is compared with experimental data from the literature. To make such a comparison meaningful, the influences of a number of systematic effects have been addressed, such as the exchange-correlation functional, the fictitious electron mass, anharmonicity effects, and the small box size in the simulation. Each of these factors (except the last one) is found to affect the OD frequency by 100 cm–1 or more. The final "corrected" frequencies agree with experiment within ~30 cm–1 for bulk water but are too little downshifted for the first-shell Al3+(aq) water molecules (by ~200 cm–1).

    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-92891 (URN)10.1063/1.2131062 (DOI)
    Available from: 2005-04-07 Created: 2005-04-07 Last updated: 2017-12-14Bibliographically approved
  • 29.
    Amira, Sami
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Spångberg, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Derivation and evaluation of a flexible SPC model for liquid water2004In: Chemical Physics, ISSN 0301-0104, E-ISSN 1873-4421, Vol. 303, no 3, 372-334 p.Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations of a new flexible water model are presented. The potential function is based on the simple point charge (SPC) model combined with an accurate experimental quartic intramolecular potential (CCL). This potential not only reproduces the key structural, dynamical and thermodynamical properties of liquid water, but also generates the correct values for both the absolute O–H vibrational frequency and the gas-to-liquid frequency shift. Thus, the model yields a value of ca. 3420 cm−1 for the peak maximum of the anharmonic OH stretching band for liquid water (experiment 3400 cm−1) and a corresponding gas-to-liquid downshift of −300 cm−1 (experiment −310 cm−1). The paper also emphasizes the importance of parameterizing correctly both the harmonic and anharmonic force constants in the gas-phase when developing flexible water models to be used in the liquid state.

  • 30.
    Amira, Sami
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Spångberg, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Distorted fivefold coordination of Cu2+(aq) from a Car-Parrinello Molecular Dynamics Simulation2005In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 7, no 15, 2874-2880 p.Article in journal (Refereed)
    Abstract [en]

    The solvation shell structure and dynamics of a single Cu2+ ion in a periodic box with 32 water molecules under ambient conditions has been investigated using Car–Parrinello molecular dynamics simulations in a time-window of 18 ps. Five-fold coordination with four equidistant equatorial water molecules at 2.00 and one axial water molecule at 2.45 from the Cu2+ ion is found. A hole without water molecules is found on the opposite side of the axial water. The ion–water bonding character for the equatorial water molecules is different from that of the axial water molecules, as shown by a localized orbital analysis of the electronic structure. Moreover, the calculated OD stretching vibrational band for the equatorial water molecules lies ca. 175 cm–1 below the axial-water band, in good agreement with experimental data. The equatorial-water band lies below, and the axial-water band above, the pure liquid D2O band, also in agreement with experimental data.

  • 31.
    Amira, Sami
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Spångberg, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    OD vibrations and hydration structure in an Al3+(aq) solution from a Car-Parrinello Molecular Dynamics Simulation2006In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 124, no 10, 104501- p.Article in journal (Refereed)
    Abstract [en]

    The optimized geometry, energetics, and vibrational properties of Al(D2O) clusters, with n=1,2,4, and 6, have been studied using plane waves, different local basis sets, different methodologies [density-functional theory, MP2, CCSD(T)], and different functionals (BLYP, PBE). Moreover, Car-Parrinello molecular-dynamics (MD) simulations using the BLYP functional, plane waves, and the Vanderbilt ultrasoft pseudopotentials have been performed for an aqueous Al3+ solution with 1 ion and 32 D2O molecules in a periodic box at room temperature, studied for 10 ps. The cluster calculations were performed to pinpoint possible shortcomings of the electronic structure description used in the Car-Parinello MD (CPMD) simulation. For the clusters, the hydration structure and interaction energies calculated with the `BLYP/plane-wave' approach agree well with high-level ab initio methods but the exchange-correlation functional introduces errors in the OD stretching frequencies (both in the absolute values and in the ion-induced shifts). For the aqueous solution, the CPMD simulation yields structural properties in good agreement with experimental data. The CPMD-simulated OD stretching vibrational band for the first-shell water molecules around Al3+ is strongly downshifted by the influence of the ion and is compared with experimental data from the literature. To make such a comparison meaningful, the influences of a number of systematic effects have been addressed, such as the exchange-correlation functional, the fictitious electron mass, anharmonicity effects, and the small box size in the simulation. Each of these factors (except the last one) is found to affect the OD frequency by 100 cm–1 or more. The final "corrected" frequencies agree with experiment within ~30 cm–1 for bulk water but are too little downshifted for the first-shell Al3+(aq) water molecules (by ~200 cm–1).

  • 32.
    Amira, Sami
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Spångberg, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Probst, Michael
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Molecular Dynamics simulation of Fe2+(aq) and Fe3+(aq)2004In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 108, no 1, 496-502 p.Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations of single-ion Fe2+(aq) and Fe3+(aq) solutions have been performed with two rigid-water models (SPC and SPC/E) and a newly constructed SPC-based flexible-water model (SPC+CCL). The SPC+CCL water model in combination with effective Fe2+ and Fe3+ ion-water potentials manages to reproduce many experimental structural and dynamical properties of the solutions. Special attention is given to the large ion-induced frequency shifts of the OH stretching bands, which are also well reproduced by the SPC+CCL model.

  • 33.
    Amira, Sami
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Spångberg, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Zelin, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Probst, Michael
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Car-Parrinello Molecular Dynamics simulation of Fe3+(aq)2005In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 109, no 29, 14235-14242 p.Article in journal (Refereed)
    Abstract [en]

    The optimized geometry and energetic properties of Fe(D2O)n3+ clusters, with n = 4 and 6, have been studied with density-functional theory calculations and the BLYP functional, and the hydration of a single Fe3+ ion in a periodic box with 32 water molecules at room temperature has been studied with Car-Parrinello molecular dynamics and the same functional. We have compared the results from the CPMD simulation with classical MD simulations, using a flexible SPC-based water model and the same number of water molecules, to evaluate the relative strengths and weaknesses of the two MD methods. The classical MD simulations and the CPMD simulations both give Fe-water distances in good agreement with experiment, but for the intramolecular vibrations, the classical MD yields considerably better absolute frequencies and ion-induced frequency shifts. On the other hand, the CPMD method performs considerably better than the classical MD in describing the intramolecular geometry of the water molecule in the first hydration shell and the average first shell···second shell hydrogen-bond distance. Differences between the two methods are also found with respect to the second-shell water orientations. The effect of the small box size (32 vs 512 water molecules) was evaluated by comparing results from classical simulations using different box sizes; non-negligible effects are found for the ion-water distance and the tilt angles of the water molecules in the second hydration shell and for the O-D stretching vibrational frequencies of the water molecules in the first hydration shell.

  • 34. Ananta, M.
    et al.
    Hilborn, Jöns
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Polymer Chemistry.
    Aibibu, D.
    Brown, R. A.
    Mudera, V.
    A Novel Poly(L-Lactide-co-e-Caprolactone)-Collagen Hybrid Construct for Application in Tissue Engineering2007In: Termis-EU Meeting Abstracts, London, UK September 4-7 2007: [Published in Tissue Engineering, vol. 13, nr. 7], Mary Ann Liebert Inc. , 2007, 1637-1637 p.Conference paper (Other academic)
    Abstract [en]

    A biodegradable hybrid construct consisting of a slow degrading poly(L-lactide-co-e-caprolactone) (PLA-e-CL) knitted mesh, plastically compressed (1) between two collagen gels was fabricated and tested in vitro for tissue engineering applications. The polymer mesh was incorporated to give greater mechanical stability to the compressed collagen scaffolds.

    The hybrid construct was characterized for fluid (weight) loss and cell viability during compression and mechanical properties.

    Hybrid constructs embedded and surface layered with human dermal

    fibroblasts (2, Eþ5 per 5 ml) were cultured for up to one week

    in static culture. Quantitative and qualitative data on cell viability

    and proliferation were obtained.

    It was found that the fluid (weight) loss in plastic compression

    of the hybrid construct was time dependent and not weight dependent

    at an applied load of 240 grams. No significant cell death

    was observed during the plastic compression process and a homogenous

    cell distribution was achieved. One week of static culture

    showed that the cultivated hybrid construct retained its

    mechanical properties with no evidence of degradation, and cells

    inside the constructs as well as layered on top of the constructs

    proliferated.

    We found the PLA-e-CL-Collagen hybrid construct a useful

    three-dimensional scaffold for tissue engineering of stratified tissues

    and potential applications in bladder wall, blood vessels and

    skin are currently being explored.

  • 35.
    Andersson, AM
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Edström, Kristina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Chemical Composition and Morphology of the Elevated Temperature SEI-layer on Graphite2001In: J. Electrochem. Soc., Vol. 148, A1100- p.Article in journal (Refereed)
  • 36.
    Andersson, A.M
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Edström, Kristina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Characterisation of the ambient and elevated temperature performance of a graphite electrode1999In: JOURNAL OF POWER SOURCES, ISSN 0378-7753, Vol. 82, 8-12 p.Article in journal (Refereed)
    Abstract [en]

    Thermal stability of the SEI layer on graphite in < Li(liquid electrolyte)graphite > half-cells has been investigated. DSC measurements reveal a two-stage exothermal reaction. The first, corresponding to a breakdown of the SEI layer, begins at 58 degrees

  • 37.
    Andersson, A.M.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Herstedt, Marie
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Bishop, A.
    Edström, Kristina
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    The influence of lithium salt on the interfacial reactions controlling the thermal stability of graphite anodes2002In: Electrochim. Acta, Vol. 47, 1885- p.Article in journal (Refereed)
  • 38.
    Andersson, Anna M
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Henningsson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemically lithiated graphite characterised by photoelectron spectroscopy2003In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 119-121, 522-527 p.Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) has been used to study the depth profile of the solid–electrolyte interphase (SEI) formed on a graphite powder electrode in a Li-ion battery. The morphology of the SEI-layer, formed in a 1 M LiBF4 EC/DMC 2:1 solution, consists of a 900 Å porous layer of polymers (polyethylene oxide) and a 15–20 Å thin layer of Li2CO3 and LiBF4 reduction–decomposition products. Embedded LiF crystals as large as 0.2 μm were found in the polymer matrix. LiOH and Li2O are not major components on the surface but rather found as a consequence of sputter-related reactions. Monochromatised Al Kα XPS-analysis based on the calibration of Ar+ ion sputtering of model compounds combined with a depth profile analysis based on energy tuning of synchrotron XPS can describe the highly complex composition and morphology of the SEI-layer.

  • 39.
    Andersson, A.S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry. strukturkemi. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Kalska, B
    Jönsson, P
    Häggström, L
    Nordblad, P
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry. strukturkemi. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Thomas, John Oswald
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry. strukturkemi. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    The magnetic structure and properties of rhombohedral Li3Fe2(PO4)3.2000In: J. Mater. Chem., Vol. 10, 2542- p.Article in journal (Refereed)
  • 40.
    Andersson, A.S.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    The source of first-cycle capasity loss in LiFePO4.2001In: J. Power Sources, Vol. 97-98, 498- p.Article in journal (Refereed)
  • 41.
    Andersson, A.S.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Thomas, John Oswald
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Kalska, B
    Häggström, L
    Lithium extraction/insertion in LiFePO4: an XRD and Mössbauer spectroscopy Study.2000In: Solid State Ionics, Vol. 130, 41- p.Article in journal (Refereed)
  • 42.
    Andersson, Claes-Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Synthesis and characterization of a ferrocene-linked bis-fullerene[60] dumbbell2012In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, no 8, 2374-2381 p.Article in journal (Refereed)
    Abstract [en]

    A new [60]fullerene dumbbell consisting of two fulleropyrrolidines connected to a central ferrocene unit by amide linkages has been prepared and fully characterized by elemental analysis, 1H NMR, UV/Vis, fluorescence and mass spectrometry. The electrochemical properties as determined by cyclic voltammetry show ground state electronic communication between the ferrocene and the fullerene units. In addition, the preparaton of a ferrocene building block for an alternative linking approach is presented.

  • 43.
    Andersson, Matilda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Högström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Urbonaite, Sigita
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Furlan, Andrej
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Deposition and characterization of magnetron sputtered amorphous Cr-C films2012In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 86, no 9, 1408-1416 p.Article in journal (Refereed)
    Abstract [en]

    Thin films in the Cr-C system with carbon content of 25-85 at.% have been deposited using non-reactive DC magnetron sputtering from elemental targets. Analyses with X-ray diffraction and transmission electron microscopy confirm that the films are completely amorphous. Also, annealing experiment show that the films had not crystallized at 500 degrees C. Furthermore, X-ray spectroscopy and Raman spectroscopy show that the films consist of two phases, an amorphous CrCx phase and an amorphous carbon (a-C) phase. The presence of two amorphous phases is also supported by the electrochemical analysis, which shows that oxidation of both chromium and carbon contributes to the total current in the passive region. The relative amounts of these amorphous phases influence the film properties. Typically, lower carbon content with less a-C phase leads to harder films with higher Young's modulus and lower resistivity. The results also show that both films have lower currents in the passive region compared to the uncoated 316L steel substrate. Finally, our results were compared with literature data from both reactively and non-reactively sputtered chromium carbide films. The comparison reveals that non-reactive sputtering tend to favour the formation of amorphous films and also influence e.g. the sp(2)/sp(3) ratio of the a-C phase. 

  • 44. Andjelkovic, K
    et al.
    Höwing, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Tellgren, Roland
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Jeremic, D
    Ivanovic-Burmazovic, I
    Sladic, D
    Synthesis and Structural Characterization of the Co(III) Complex with 2'-[1-(2-Pyridinyl)-Ethylidene]-Oxamohydrazide (Hapsox): The Crystal Structure of Bis-{2'-[1-(2-Pyridinyl)-Ethylidene]-Oxamohydrazido}Cobalt(III) Perchlorate, [Co(apsox)2]ClO42003In: J. Coord. Chem., Vol. 56, no 7, 611-622 p.Article in journal (Refereed)
  • 45. Andjelkovic, K
    et al.
    Jakovljevic, G
    Zlatovic, M
    Tesic, Z
    Sladic, D
    Höwing, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Tellgren, Roland
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Synthesis and Characterization of Zinc(II), Palladium (II) and Platinum (II) Complex2004In: Journal of the Serbian Chemical Society, Vol. 69, no 8-9, 651-660 p.Article in journal (Refereed)
  • 46. Andjelkovic, Katarina
    et al.
    Höwing, Jonas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Tellgren, Roland
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Jeremić, Dejan
    Ivanović-Burmazović, Ivana
    Sladić, Dušan
    Synthesis and Structural Characterization of the Co(III) Complex with 2'-[1-(2-Pyridinyl)-Ethylidene]-Oxamohydrazide (Hapsox): the Crystal Structure of Bis-{2'-[1-(2-Pyridinyl)-Ethylidene]-Oxamohydrazido} Cobalt(III) Perchlorate, [Co(apsox)2]ClO42003In: Journal of Coordination Chemistry, Vol. 56, no 7, 611-622 p.Article in journal (Refereed)
    Abstract [en]

    The synthesis of a novel ligand 2′-[1-(2-pyridinyl)-ethylidene]-oxamohydrazide (Hapsox), from a series of 2-acetylpyridine acylhydrazones, and its complex with Co(III), which is the first in this series of complexes are described. Both the ligand and the complex were characterized by elemental analysis, IR, 1H-NMR, and 13C-NMR spectra, and the structure of the complex [Co(apsox)2]ClO4 was determined by X-ray structural analysis. It was established that [Co(apsox)2]ClO4 has an octahedral geometry with two tridentate apsox ligands in monoanionic form. Structural characteristics, lengths of the bonds, and angles between the bonds were typical for Co(III) complexes of distorted octahedral geometry. Both direct and template synthesis afforded the same geometrical isomer of the complex with two apsox ligands meridionally bound to the central metal ion, even in the case when equimolar quantities of Co(ClO4)2 and Hapsox were applied.

  • 47.
    André, Benny
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Wiklund, Urban
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Friction and contact resistance of nanocomposite Ti-Ni-C coatings2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 270, no 9-10, 555-566 p.Article in journal (Refereed)
    Abstract [en]

    Ceramic nanocomposite coatings in the Ti-Ni-C were deposited using PVD and studied with respect to tribological properties and contact resistance. It was shown that coatings could be deposited combining of a low contact resistance and a low friction coefficient against silver, making them suitable for use in high performance electrical contacts.Nine coatings with different amounts of C and Ni were deposited. Coatings on flat Ni plated copper substrates were tested in a tribological ball-on-disc setup against ball bearing steel balls. Depending on primarily the amount of carbon the coatings showed very different friction coefficient and wear rate. The coatings were also deposited on cylindrical Ni plated copper substrates. Using geometrically identical silver plated cylinders as counter surface these were evaluated in a test setup better resembling a real life electrical contact. For most coatings a low electrical contact resistance was measured. The evolution of friction coefficient and contact resistance was correlated to wear marks and contact tracks, with their generated tribofilms, as examined after testing using electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy.

  • 48. Antic, B
    et al.
    Rodic, D
    Tellgren, Roland
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Rundlöf, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Materials Chemistry, Structural Chemistry. strukturkemi.
    Neutron diffraction study of the magnetic and structure properties of Co2.50Sb0.50O4 spinel.2000In: Magn. and Magn. Mat., Vol. 219, 41- p.Article in journal (Refereed)
  • 49.
    Arkhypchuk, Anna I.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Borbas, K. Eszter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Synthesis and Characterization of Ferrocenyl Chlorins, 1,1'-Ferrocene-Linked Chlorin Dimers, and their BODIPY Analogues2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 5, 3044-3054 p.Article in journal (Refereed)
    Abstract [en]

    We present the synthesis and characterization of meso-ferrocenyl-substituted hydroporphyrins (chlorins) and 1,1' -linked chlorin dimers. The dipyrromethane chlorin precursors were also transformed into Fc-substituted BODIPYs and 1,1'-ferrocenyl-linked BODIPY dimers. The chlorin dimers were studied by 1D and 2D NMR experiments and DFT calculations, which showed that their solution structures were dependent on the central metal. Monomeric and dimeric Ni(II) chlorins had similar H-1 NMR spectra. Monomeric and dimeric free base, Zn(II), and Pd(II) chlorins, on the other hand, showed significantly more different spectra. The eclipsed conformer of the free base chlorin dimer was calculated to be energetically more favored than the open form. The chlorin and BODIPY fluorescence emissions were quenched in the Fcsubstituted compounds; these could be recovered by oxidation of the Fe(II) center. Cyclic voltammetry showed up to five oxidation waves for the free base chlorin dimer, which suggests that the macrocycles were not behaving independently of each other.

  • 50.
    Arkhypchuk, Anna I.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Svyaschenko, Yurii V.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Versatile Approach to 3-Phosphahexatrienes Bearing Low Coordinated Phosphorus2015In: Phosphorus Sulfur and Silicon and the Related Elements, ISSN 1042-6507, E-ISSN 1563-5325, Vol. 190, no 5-6, 638-646 p.Article in journal (Refereed)
    Abstract [en]

    lambda(3)-phosphahexatrienes were prepared from ethoxyvinyl phosphinophosphonates using the phospha-Wittig-Horner reaction. The title compounds can be easily prepared in three steps starting from dichlorophosphines with good overall yields. Although these were found to be thermally unstable, these can be trapped, for instance, with methanol. The resulting methoxyphosphines are isolated in high yields in case of aldehyde starting materials with more bulky substituents.

1234567 1 - 50 of 1323
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf