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  • 1.
    Abrahamsson, Malin L. A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Berglund Baudin, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Tran, A.
    Philouze, C.
    Berg, K.
    Raymond-Johansson, Mary Katherine
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Sun, L.
    Åkermark, B.
    Styring, S.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Ruthenium-Manganese Complexes for Artificial Photosynthesis: Factors Controlling Intramolecular Electron Transfer and Excited State Quenching Reactions2002In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 41, no 6, p. 1534-1544Article in journal (Refereed)
    Abstract [en]

    Continuing our work toward a system mimicking the electron-transfer steps from manganese to P(680)(+) in photosystem II (PS II), we report a series of ruthenium(II)-manganese(II) complexes that display intramolecular electron transfer from manganese(II) to photooxidized ruthenium(III). The electron-transfer rate constant (k(ET)) values span a large range, 1 x 10(5)-2 x 10(7) s(-1), and we have investigated different factors that are responsible for the variation. The reorganization energies determined experimentally (lambda = 1.5-2.0 eV) are larger than expected for solvent reorganization in complexes of similar size in polar solvents (typically lambda approximately 1.0 eV). This result indicates that the inner reorganization energy is relatively large and, consequently, that at moderate driving force values manganese complexes are not fast donors. Both the type of manganese ligand and the link between the two metals are shown to be of great importance to the electron-transfer rate. In contrast, we show that the quenching of the excited state of the ruthenium(II) moiety by manganese(II) in this series of complexes mainly depends on the distance between the metals. However, by synthetically modifying the sensitizer so that the lowest metal-to-ligand charge transfer state was localized on the nonbridging ruthenium(II) ligands, we could reduce the quenching rate constant in one complex by a factor of 700 without changing the bridging ligand. Still, the manganese(II)-ruthenium(III) electron-transfer rate constant was not reduced. Consequently, the modification resulted in a complex with very favorable properties.

  • 2.
    Abrahamsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Becker, Hans-Christian
    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.
    Bonnefous, Celine
    Chamchoumis, Charles
    Thummel, Randolph
    Six-membered Ring Chelate Complexes of Ru(II): Structural and photophysical effects2007In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 24, p. 10354-10364Article in journal (Refereed)
    Abstract [en]

    The structural and photophysical properties of Ru(II)−polypyridyl complexes with five- and six-membered chelate rings were studied for two bis-tridentate and two tris-bidentate complexes. The photophysical effect of introducing a six-membered chelate ring is most pronounced for the tridentate complex, leading to a room-temperature excited-state lifetime of 810 ns, a substantial increase from 180 ns for the five-membered chelate ring model complex. Contrasting this, the effect is the opposite in tris-bidentate complexes, in which the lifetime decreases from 430 ns to around 1 ns in going from a five-membered to six-membered chelate ring. All of the complexes were studied spectroscopically at both 80 K and ambient temperatures, and the temperature dependence of the excited-state lifetime was investigated for both of the bis-tridentate complexes. The main reason for the long excited-state lifetime in the six-membered chelate ring bis-tridentate complex was found to be a strong retardation of the activated decay via metal-centered states, largely due to an increased ligand field splitting due to the complex having a more-octahedral geometry.

  • 3.
    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, p. 9580-9586Article 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.

  • 4.
    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, p. 3540-3548Article 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.

  • 5.
    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, p. 3215-3225Article in journal (Refereed)
  • 6. 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, p. 7389-7403Article 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.

  • 7. 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, p. 6082-6093Article 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.

  • 8. 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, p. 1417-1429Article 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.

  • 9.
    Andres, Julien
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Borbas, K. Eszter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Expanding the Versatility of Dipicolinate-Based Luminescent Lanthanide Complexes: A Fast Method for Antenna Testing2015In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, no 17, p. 8174-8176Article in journal (Refereed)
    Abstract [en]

    A dipicolinate (dpa)-based platform for the rapid testing of potential lanthanide-sensitizing antennae was developed; 4-methyl-7-O-alkylcoumarin-appended dpa could sensitize four lanthanides. The platform could be used to estimate the photophysical properties of a more difficult-to-prepare 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid based structure carrying the same antenna.

  • 10.
    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, p. 3044-3054Article 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.

  • 11. Bacchi, Marine
    et al.
    Berggren, Gustav
    Niklas, Jens
    Veinberg, Elias
    Mara, Michael W.
    Shelby, Megan L.
    Poluektov, Oleg G.
    Chen, Lin X.
    Tiede, David M.
    Cavazza, Christine
    Field, Martin J.
    Fontecave, Marc
    Artero, Vincent
    Cobaloxime-Based Artificial Hydrogenases2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, no 15, p. 8071-8082Article in journal (Refereed)
    Abstract [en]

    Cobaloximes are popular H2 evolution molecular catalysts but have so far mainly been studied in nonaqueous conditions. We show here that they are also valuable for the design of artificial hydrogenases for application in neutral aqueous solutions and report on the preparation of two well-defined biohybrid species via the binding of two cobaloxime moieties, {Co(dmgH)2} and {Co(dmgBF2)2} (dmgH2 = dimethylglyoxime), to apo Sperm-whale myoglobin (SwMb). All spectroscopic data confirm that the cobaloxime moieties are inserted within the binding pocket of the SwMb protein and are coordinated to a histidine residue in the axial position of the cobalt complex, resulting in thermodynamically stable complexes. Quantum chemical/molecular mechanical docking calculations indicated a coordination preference for His93 over the other histidine residue (His64) present in the vicinity. Interestingly, the redox activity of the cobalt centers is retained in both biohybrids, which provides them with the catalytic activity for H2 evolution in near-neutral aqueous conditions.

  • 12. Benson, Daryn
    et al.
    Li, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Luo, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Svensson, Gunnar
    Haussermann, Ulrich
    Lithium and Calcium Carbides with Polymeric Carbon Structures2013In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, no 11, p. 6402-6406Article in journal (Refereed)
    Abstract [en]

    We studied the binary carbide systems Li2C2 and CaC2 at high pressure using an evolutionary and ab initio random structure search methodology for crystal structure prediction. At ambient pressure Li2C2 and CaC2 represent salt-like acetylides consisting of C-2(2-) dumbbell anions. The systems develop into semimetals (P (3) over bar m1-Li2C2) and metals (Cmcm-Li2C2, Cmcm-CaC2, and Immm-CaC2) with polymeric anions (chains, layers, strands) at moderate pressures (below 20 GPa). Cmcm-CaC2 is energetically closely competing with the ground, state structure. Polyanionic forms of carbon 4 stabilized by electrostatic interactions with surrounding cations add a new feature to carbon chemistry. SemimetallicP (3) over bar m1-Li2C2 displays an electronic structure close to that of graphene. The pi* band, however, is hybridized with Li-sp states and changed into a bonding valence band. Metallic forms are predicted to be superconductors. Calculated critical temperatures may exceed 10 K for equilibrium volume structures.

  • 13.
    Berggren, Gustav
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Anderlund, Magnus F.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Styring, Stenbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    FTIR Study of Manganese Dimers with Carboxylate Donors As Model Complexes for the Water Oxidation Complex in Photosystem II2012In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 51, no 4, p. 2332-2337Article in journal (Refereed)
    Abstract [en]

    The carboxylate stretching frequencies of two high-valent, di-mu-oxido bridged, manganese dimers has been studied with IR spectroscopy in three different oxidation states. Both complexes contain one monodentate carboxylate donor to each Mn ion, in one complex, the carboxylate is coordinated perpendicular to the Mn-(mu-O)(2)-Mn plane, and in the other complex, the carboxylate is coordinated in the Mn-(mu-O)(2)-Mn plane. For both complexes, the difference between the asymmetric and the symmetric carboxylate stretching frequen-cies decrease for both the Mn-2(IV,IV) to Mn-2(III,IV) transition and the Mn-2(III,IV) to Mn-2(III,III) transition, with only minor differences observed between the two arrangements of the carboxylate ligand versus the Mn-(mu-O)(2)-Mn plane. The IR spectra also show that both carboxylate ligands are affected for each one electron reduction, i.e., the stretching frequency of the carboxylate coordinated to the Mn ion that is not reduced also shifts. These results are discussed in relation to FTIR studies of changes in carboxylate stretching frequencies in a one electron oxidation step of the water oxidation complex in Photosystem II.

  • 14.
    Berggren, Gustav
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Huang, Ping
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Eriksson, Lars
    Styring, Stenbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Anderlund, Magnus F.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Mechanistic Studies on the Water-Oxidizing Reaction of Homogeneous Manganese-Based Catalysts: Isolation and Characterization of a Suggested Catalytic Intermediate2011In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, no 8, p. 3425-3430Article in journal (Refereed)
    Abstract [en]

    The synthesis, isolation, and characterization of two high-valent manganese dimers with isomeric ligands are reported. The complexes are synthesized and crystallized from solutions of low-valent precursors exposed to tert-butyl hydroperoxide. The crystal structures display centrosymmetric complexesconsisting of Mn2 IV,IV(μ-O)2 cores, with one ligand coordinating to each manganese. The ligands coordinate with the diaminoethane backbone, the carboxylate, and one of the two pyridines, while the second pyridine is noncoordinating. The activity of these complexes, under water oxidation conditions, is discussed in light of a proposed mechanism for water oxidation, in which this type of complexes have been suggested as a key intermediate.

  • 15.
    Bonn, Annabell G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Univ Basel, Dept Chem, St Johanns Ring 19, CH-4056 Basel, Switzerland..
    Yushchenko, Oleksandr
    Univ Geneva, Dept Phys Chem, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland..
    Vauthey, Eric
    Univ Geneva, Dept Phys Chem, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland..
    Wenger, Oliver S.
    Univ Basel, Dept Chem, St Johanns Ring 19, CH-4056 Basel, Switzerland..
    Photoinduced Electron Transfer in an Anthraquinone-[Ru(bpy)(3)](2+)-Oligotriarylamine-[Ru(bpy)(3)](2+)-Anthraquinone Pentad2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 6, p. 2894-2899Article in journal (Refereed)
    Abstract [en]

    A molecular pentad comprised of a central multielectron donor and two flanking photosensitizer-acceptor moieties was prepared in order to explore the possibility of accumulating two positive charges at the central donor, using visible light as an energy input. Photoinduced charge accumulation in purely molecular systems without sacrificial reagents is challenging, because of the multitude of energy-wasting reaction pathways that are accessible after excitation with two photons. As expected, the main photoproduct in our pentad is a simple electron hole pair, and it is tricky to identify the desired two-electron oxidation product on top of the stronger signal resulting from one-electron oxidation.

  • 16.
    Borgström, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Johansson, Olof
    Lomoth, Reiner
    Berglund-Baudin, Helena
    Wallin, Staffan
    Sun, Licheng
    Åkermark, Björn
    Hammarström, Leif
    Electron Donor-Acceptor Dyads and Triads Based on Tris(bipyridine) Ruthenium(II) and Benzoquinone: Synthesis, Characterization, and Photoinduced Electron Transfer Reactions2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, p. 5173-5184Article in journal (Refereed)
  • 17.
    Borgström, Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry. Fysikalisk kemi.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry. Analytisk kemi.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Johansson, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Photoinduced energy transfer coupled to charge separation in a Ru(II)-Ru(II)-acceptor triad.2006In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 45, no 12, p. 4820-4829Article in journal (Refereed)
  • 18. Brandt, Peter
    et al.
    Norrby, Thomas
    Åkermark, Björn
    Norrby, Per-Ola
    Molecular Mechanics (MM3) Parameters for Ruthenium(II)-Polypyridyl Complexes.1998In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 37, no 16, p. 4120-4127Article in journal (Refereed)
    Abstract [en]

    We have developed molecular mechanics parameters for Ru(II)-polypyridyl coordination compounds with the MM3 force field in MacroModel. X-ray structures, together with a B3LYP frequency calculation on a model system, have been utilized in the parametrization. The performance of the force field and the quality of each parameter is analyzed. A clear qualitative correlation have been found between coordination geometry and emission properties for the ruthenium polypyridyl complexes examined in this paper.

  • 19.
    Cedervall, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nonnet, Elise
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Werwinski, Miroslaw
    Institute of Molecular Physics, Polish Academy of Sciences.
    Edström, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Department of Materials Theory, ETH Zürich.
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of cobalt substitution on the magnetic properties of Fe5PB22018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 2, p. 777-784Article in journal (Other academic)
    Abstract [en]

    In this study the effects of cobalt substitutions in Fe5PB2 have been studied. An increased cobalt content reduces the magnetic exchange interactions. This has been concluded from a large, linear decrease in both the Curie temperature as well as the saturated magnetic moment. At high cobalt concentrations, cobalt prefers to order at the M(2) position in the crystal structure. A tunable Curie transition like this shows some prerequisites for magnetic cooling applications.

    The substitutional effects of cobalt in (Fe1–xCox)5PB2 have been studied with respect to crystalline structure and chemical order with X-ray diffraction and Mössbauer spectroscopy. The magnetic properties have been determined from magnetic measurements, and density functional theory calculations have been performed for the magnetic properties of both the end compounds, as well as the chemically disordered intermediate compounds. The crystal structure of (Fe1–xCox)5PB2 is tetragonal (space group I4/mcm) with two different metal sites, with a preference for cobalt atoms in the M(2) position (4c) at higher cobalt contents. The substitution also affects the magnetic properties with a decrease of the Curie temperature (TC) with increasing cobalt content, from 622 to 152 K for Fe5PB2 and (Fe0.3Co0.7)5PB2, respectively. Thus, the Curie temperature is dependent on composition, and it is possible to tune TC to a temperature near room temperature, which is one prerequisite for magnetic cooling materials.

  • 20. Corden, Vincent A.
    et al.
    Duhme-Klair, Anne-K
    Hostachy, Sarah
    Perutz, Robin N.
    Reddig, Nicole
    Becker, Hans-Christian
    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.
    Spectroscopic and Structural Investigations Reveal the Signaling Mechanism of a Luminescent Molybdate Sensor2011In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, no 3, p. 1105-1115Article in journal (Refereed)
    Abstract [en]

    A heteroditopic ligand H(2)-L consisting of a dihydroxybenzene (catechol)-unit linked via an amide bond to a pyridyl-unit and its methyl-protected precursor Me(2)-L were synthesized, characterized, and their photophysical properties investigated. The three accessible protonation states of the ligand, H(3)-L(+), H(2)-L, and H-L(-), showed distinct (1)H NMR, absorption and emission spectroscopic characteristics that allow pH-sensing. The spectroscopic signatures obtained act as a guide to understand the signaling mechanism of the luminescent pH and molybdate sensor [Re-(bpy)(CO)(3)(H(2)-L)](+). It was found that upon deprotonation of the 2-hydroxy group of H(2)-L, a ligand-based absorption band emerges that overlaps with the Re(d pi)-> bpy metal-to-ligand charge transfer (MLCT) band of the sensor, reducing the quantum yield for emission on excitation in the 370 nm region. In addition, deprotonation of the catechol-unit leads to quenching of the emission from the Re(d pi)-> bpy (3)MLCT state, consistent with photoinduced electron transfer from the electron-rich, deprotonated catecholate to the Re-based luminophore. Finally, reaction of 2 equiv of [Re(bpy)(CO)(3)(H(2)-L)](+) with molybdate was shown to give the zwitterionic Mo(VI) complex [MoO(2){Re(CO)(3)-(bpy)(L)}(2)], as confirmed by electrospray ionization (ESI) mass spectrometry and X-ray crystallography. The crystal structure determination revealed that two fully deprotonated sensor molecules are bound via their oxygen-donors to a cis-dioxo-MoO(2) center.

  • 21. Fortage, Jerome
    et al.
    Boixel, Julien
    Blart, Errol
    Becker, Hans Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Odobel, Fabrice
    Very Fast Single-Step Photoinduced Charge Separation in Zinc Porphyrin Bridged to a Gold Porphyrin by a Bisethynyl Quaterthiophene2009In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 48, no 2, p. 518-526Article in journal (Refereed)
    Abstract [en]

    A new heterometallic dyad composed of a zinc porphyrin linked by bisethynyl quaterthiophene to a gold porphyrin was synthesized according to a stepwise modular approach. The latter dyad and the parent reference compounds (porphyrin-ethynylquatedhiophene) were characterized by electrochemistry, spectroelectrochemistry, and femtosecond transient absorption spectrocopy. We showed that light excitation of the zinc or the gold porphyrin induces a very fast and quantitative charge separation over a distance of 25 angstrom which occurs through a superexchange mechanism. The lifetime of the charge-separated state is 3.3 ns in toluene and 100 ps in dichloromethane, and it recombines to the ground state in both solvents.

  • 22.
    Gebresenbut, Girma H.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Mikael S.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Gomez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tailoring Magnetic Behavior in the Tb-Au-Si Quasicrystal Approximant System2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 5, p. 2001-2008Article in journal (Refereed)
    Abstract [en]

    A novel synthesis method, "arc-melting-self-flux", has been developed and a series of five Tsai-type 1/1 approximant crystals in the Tb-Au-Si system have been synthesized. The synthesis method, by employing a temperature program which oscillates near the melting and nucleation points of the approximants, has provided high-quality and large single crystals in comparison to those obtained from the standard arc-melting-annealing and self-flux methods. The atomic structures of the approximants have been determined from single-crystal X-ray diffraction data and described using concentric atomic clusters with icosahedral symmetry. The compounds are nearly isostructural with subtle variations; two types of atomic clusters which mainly vary at their cluster centers are observed. One type contains a Tb site at the center, and the other contains a disordered tetrahedron decorated with Au/Si mixed sites. Both cluster types can be found coexisting in the approximants. The compounds have different average weighted ratios of central Tb to disordered tetrahedron in the bulk material. Furthermore, a strategy for chemically tuning magnetic behavior is presented. Magnetic property measurements on the approximants revealed that the magnetic transition temperature (T-c) decreases as the occupancy of the central Tb site increases. T-c decreased from 11.5 K for 0% occupancy of the central Tb to 8 K for 100% occupancy. Enhanced magneto crystalline anisotropy is observed for the approximants with higher central Tb occupancy in comparison to their low central Tb occupancy counterparts. Hence, the previously reported "ferrimagnetic-like" magnetic structure model remains valid.

  • 23.
    Gogoll, Adolf
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Polavarapu, Prasad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Enhanced Silver Ion Binding to a Rigid Bisarene Molecular Cleft with Formation of Nonpolar Pleated Sheets through Non-Ionic Intermolecular Forces2007In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 13, p. 5271-5275Article in journal (Refereed)
    Abstract [en]

    Silver ion complexation to bisarene ligands is enhanced by providing a conformationally rigid molecular cleft in the (Z)-acenaphthylene dimer 1. NMR titrations were used to determine complexation constants K for a series of ligands in tetrahydrofuran solution, with K = 4.9 M-1 for the Z dimer 1 and 0.4 M-1 for the E dimer 2. Higher values of K were observed in CDCl3/CD3OD 9:1 with K = 38 M-1 for 1 and K = 4.1 M-1 for 2. In the solid state, isolated clusters of [1·(AgCF3SO3)2]2 form a novel, pleated-sheet motif based on non-ionic interactions between clusters.

  • 24.
    Gond, Ritambhara
    et al.
    Indian Inst Sci, Bangalore .
    Meena, Sher Singh
    Bhabha Atom Res Ctr, Bombay .
    Yusuf, S. M.
    Bhabha Atom Res Ctr, Bombay .
    Shukla, Vivekanand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Jena, Naresh K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Okada, Shigeto
    Kyushu Univ, Japan.
    Barpanda, Prabeer
    Indian Inst Sci, Bangalore.
    Enabling the Electrochemical Activity in Sodium Iron Metaphosphate [NaFe(PO3)(3)] Sodium Battery Insertion Material: Structural and Electrochemical Insights2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 10, p. 5918-5929Article in journal (Refereed)
    Abstract [en]

    Sodium-ion batteries are widely pursued as an economic alternative to lithium-ion battery technology, where Fe- and Mn-based compounds are particularly attractive owing to their elemental abundance. Pursuing phosphate-based polyanionic chemistry, recently solid-state prepared NaFe(PO3)(3) metaphosphate was unveiled as a novel potential sodium insertion material, although it was found to be electrochemically inactive. In the current work, employing energy-savvy solution combustion synthesis, NaFe2+(PO3)(3) was produced from low-cost Fe3+ precursors. Owing to the formation of nanoscale carbon-coated product, electrochemical activity was enabled in NaFe(PO3)(3) for the first time. In congruence with the first principles density functional theory (DFT) calculations, an Fe3+/Fe2+ redox activity centered at 2.8 V (vs Na/Na+) was observed. Further, the solid-solution metaphosphate family Na(Fe1-xMnx)(PO3)(3) (x = 0-1) was prepared for the first time. Their structure and distribution of transition metals (TM = Fe/Mn) was analyzed with synchrotron diffraction, X-ray photoelectron spectroscopy, and Mossbauer spectroscopy. Synergizing experimental and computational tools, NaFe(PO3)(3) metaphosphate is presented as an electrochemically active sodium insertion host material.

  • 25.
    Gupta, Arvind Kumar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Akkarasamiyo, Sunisa
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Rich Coordination Chemistry of pi-Acceptor Dibenzoarsole Ligands2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 8, p. 4504-4511Article in journal (Refereed)
    Abstract [en]

    A series of dibenzoarsole (also known as 9-arsafluorene) derivatives have been prepared, and their coordination chemistry has been investigated. The different ligand topology and the arsenic substituents govern the reactivity of the ligands. We report various crystal structures of palladium and platinum complexes derived from this family of ligands. The biphenyl backbone of the bridged bidentate ligands allows very flexible coordination. We have also studied the application of an allylic Pd complex in nucleophilic substitution reactions, revealing that the benzoarsole substituent is susceptible to metal insertion.

  • 26.
    Göransson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Boixel, Julien
    Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), Nantes, France.
    Fortage, Jérôme
    Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), Nantes, France.
    Jacquemin, Denis
    Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), Nantes, France.
    Becker, Hans-Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Blart, Errol
    Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), Nantes, France.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Odobel, Fabrice
    Université de Nantes, CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), Nantes, France.
    Long-Range Electron transfer in Zinc-Phthalocyanine-oligo(phenylene-ethynylene)-based donor-bridge-acceptor dyads2012In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 51, no 21, p. 11500-11512Article in journal (Refereed)
    Abstract [en]

    In the context of long-range electron transfer for solar energy conversion, we present the synthesis, photophysical, and computational characterization of two new zinc(II) phthalocyanine oligophenylene-ethynylene based donor-bride-acceptor dyads: ZnPc-OPE-AuP+ and ZnPc-OPE-C60. A gold(III) porphyrin and a fullerene has been used as electron accepting moieties, and the results have been compared to a previously reported dyad with a tin(IV) dichloride porphyrin as the electron acceptor (Fortage et al. Chem. Commun.2007, 4629). The results for ZnPc-OPE-AuP+ indicate a remarkably strong electronic coupling over a distance of more than 3 nm. The electronic coupling is manifested in both the absorption spectrum and an ultrafast rate for photoinduced electron transfer (kPET = 1.0 × 1012 s–1). The charge-shifted state in ZnPc-OPE-AuP+ recombines with a relatively low rate (kBET = 1.0 × 109 s–1). In contrast, the rate for charge transfer in the other dyad, ZnPc-OPE-C60, is relatively slow (kPET = 1.1 × 109 s–1), while the recombination is very fast (kBET ≈ 5 × 1010 s–1). TD-DFT calculations support the hypothesis that the long-lived charge-shifted state of ZnPc-OPE-AuP+ is due to relaxation of the reduced gold porphyrin from a porphyrin ring based reduction to a gold centered reduction. This is in contrast to the faster recombination in the tin(IV) porphyrin based system (kBET = 1.2 × 1010 s–1), where the excess electron is instead delocalized over the porphyrin ring.

  • 27.
    Göransson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Boixel, Julien
    Monnereau, Cyrille
    Blart, Errol
    Pellegrin, Yann
    Becker, Hans-Christian
    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.
    Odobel, Fabrice
    Photoinduced Electron Transfer in Zn(II)porphyrin-Bridge-Pt(II)acetylide Complexes: Variation in Rate with Anchoring Group and Position of the Bridge2010In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 49, no 21, p. 9823-9832Article in journal (Refereed)
    Abstract [en]

    The synthesis and photophysical characterization of two sets of zinc porphyrin platinum acetylide complexes are reported. The two sets of molecules differ in the way the bridging phenyl-ethynyl unit is attached to the porphyrin ring. One set is attached via an ethynyl unit on the beta position, while the other set is attached via a phenyl unit on the meso position of the porphyrin. These were compared with previously studied complexes where attachment was made via an ethynyl unit on the meso position. Femtosecond transient absorption measurements showed in all systems a rapid quenching of the porphyrin singlet state. Electron transfer is suggested as the quenching mechanism, followed by an even faster recombination to form both the porphyrin ground and triplet excited states. This is supported by the variation in quenching rate and porphyrin triplet yield with solvent polarity, and the observation of an intermediate state in the meso-phenyl linked systems. The different linking motifs between the dyads resulted in significant variations in electron transfer rates.

  • 28.
    Hermansson, Kersti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Wojcik, Mark
    Sjoberg, Stefan
    o-, m-, and p-carboranes and their anions: Ab initio calculations of structures, electron affinities, and acidities1999In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 38, no 26, p. 6039-6048Article in journal (Refereed)
    Abstract [en]

    Ab initio geometry optimizations have been performed for o-, m-, and p-C2B10H12 carborane cages and their mono- and dianions at the Hartree-Fock 3-21G*, 6-31G*, and 6-31G** levels. The para-compound is the most stable with a calculated Delta H(para-meta) value of -10 kJ/mol and a calculated Delta G(975K)(para-meta) value of -3 kJ/mol. These small calculated energy differences disagree with the experimental heats of formation, which suggest Delta H to be ca. -65 kJ/mol, but they agree with equilibrium gas mixture measurements at 975 K, which suggest a Delta G value of ca. -1 kJ/mol. Electron distributions, electron affinities, and acidic properties of the carboranes are presented. The structures of the mono- and dianions were determined by optimization, starting from the three neutral carborane cages; we find three energy minima for the C2B10H122- ion. The lowest-energy dianion is a nido-structure topped by a six-membered ring with the two C atoms in the meta position. The captured electrons become distributed over all the H atoms.

  • 29.
    Hjelm, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Handel, Robyn W.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Constable, Edwin C.
    Housecroft, Catherine E.
    Forster, Robert J.
    Conducting polymers containing in-chain metal centers: Electropolymerization of oligothienyl-substituted {M(tpy)2} complexes and in-situ conductivity studies, M = Os(II), Ru(II)2005In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 44, no 4, p. 1073-1081Article in journal (Refereed)
    Abstract [en]

    The electropolymerization of a series of Ru and Os bis-terpyridine complexes that form rodlike polymers with bithienyl, quaterthienyl, or hexathienyl bridges has been studied. Absorption spectroscopy, scanning electron microscopy, and cyclic voltammetry have been used to characterize the monomers and resulting polymer films. The absolute dc conductivity of the quaterthienyl-bridged {Ru(tpy)2} and {Os(tpy)2} polymers is unusually large and independent of the identity of the metal center at 1.6 × 10-3 S cm-1. The maximum conductivity occurs at the formal potential of each redox process, which typically is observed for systems where redox conduction is the dominant charge transport mechanism. Significantly, the dc conductivity of the metal-based redox couple observed in these polymers is 2 orders of magnitude higher than that of a comparable nonconjugated system.

  • 30.
    Ivanov, Sergey A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10,K-64, Moscow 105064, Russia.
    Bush, Alexander A
    Moscow State Inst Radio Engn Elect & Automat, RU-119434 Moscow, Russia.
    Stash, Adam I
    Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10,K-64, Moscow 105064, Russia.
    Kamentsev, Konstantin E
    Moscow State Inst Radio Engn Elect & Automat, RU-119434 Moscow, Russia.
    Shkuratov, Valerii Ya
    Moscow State Inst Radio Engn Elect & Automat, RU-119434 Moscow, Russia.
    Kvashnin, Yaroslav O
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Autieri, Carmine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Di Marco, Igor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Polar Order and Frustrated Antiferromagnetism in Perovskite Pb2MnWO6 Single Crystals.2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 6, p. 2791-2805Article in journal (Refereed)
    Abstract [en]

    Single crystals of the multiferroic double-perovskite Pb2MnWO6 have been synthesized and their structural, thermal, magnetic and dielectric properties studied in detail. Pure perovskite-phase formation and stoichiometric chemical composition of the as-grown crystals are confirmed by X-ray single-crystal and powder diffraction techniques as well as energy-dispersive X-ray and inductively coupled plasma mass spectrometry. Detailed structural analyses reveal that the crystals experience a structural phase transition from the cubic space group (s.g.) Fm3̅m to an orthorhombic structure in s.g. Pn21a at about 460 K. Dielectric data suggest that a ferrielectric phase transition takes place at that same temperature, in contrast to earlier results on polycrystalline samples, which reported a transition to s.g. Pnma and an antiferroelectric low-temperature phase. Magnetic susceptibility measurements indicate that a frustrated antiferromagnetic phase emerges below 8 K. Density functional theory based calculations confirm that the cationic order between Mn and W is favorable. The lowest total energy was found for an antiferromagnetically ordered state. However, analyses of the calculated exchange parameters revealed strongly competing antiferromagnetic interactions. The large distance between the magnetic atoms, together with magnetic frustration, is shown to be the main reason for the low value of the ordering temperature observed experimentally. We discuss the structure-property relationships in Pb2MnWO6 and compare these observations to reported results on related Pb2BWO6 perovskites with different B cations.

  • 31.
    Jacobsson, T. Jesper
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Absorption and Fluorescence Spectroscopy of Growing ZnO Quantum Dots: Size and Band Gap Correlation and Evidence of Mobile Trap States2011In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 50, no 19, p. 9578-9586Article in journal (Refereed)
    Abstract [en]

    ZnO nanoparticles constitute a convenient model system for fundamental studies with many possible technical applications in, for example, sensors and the field of catalysis and optoelectronics. A large set of ZnO quantum dots in the size range 2.5-7 nm have been synthesized and analyzed in detail. Time resolved in situ UV-vis absorption measurements were used to monitor the growth of these particles in solution by correlating the optical band gap to particle size given from X-ray diffraction (XRD) measurements. The particles formed were isotropic in shape, but small initial deviations gave indications of a transition from thermodynamic to kinetically controlled growth for particles around 4 nm in diameter. On the basis of this, the behavior and mechanisms for the particle growth are discussed. The fluorescence dependence on particle size was investigated by combining fluorescence and UV-vis measurements on growing particles. This revealed that the positions of the fluorescence trap states are mobile toward the conduction- and valence band. A broadening of the trap states was also found, and a surface dependent mechanism of the trap state shift and broadening is proposed.

  • 32.
    Jacobsson, T. Jesper
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Schwan, L. Josef
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Determination of Thermal Expansion Coefficients and Locating the Temperature-Induced Phase Transition in Methylammonium Lead Perovskites Using X-ray Diffraction2015In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, no 22, p. 10678-10685Article in journal (Refereed)
    Abstract [en]

    Lead halogen perovskites, and particularly methylammonium lead iodine, CH3NH3PbI3, have recently attracted considerable interest as alternative solar cell materials, and record solar cell efficiencies have now surpassed 20%. Concerns have, however, been raised about the thermal stability of methylammonium lead iodine, and a phase transformation from a tetragonal to a cubic phase has been reported at elevated temperature. Here, this phase transition has been investigated in detail using temperature-dependent X-ray diffraction measurements. The phase transformation is pinpointed to 54 degrees C, which is well within the normal operating range of a typical solar cell. The cell parameters were extracted as a function of the temperature, from which the thermal expansion coefficient was calculated. The latter was found to be rather high (alpha(v) = 1.57 X 10(-4) K-1) for both the tetragonal and cubic phases. This is 6 times higher than the thermal expansion coefficient for soda lime glass and CIGS and 11 times larger than that of CdTe. This could potentially be of importance for the mechanical stability of perovskite solar cells in the temperature cycling experienced under normal day night operation. The experimental knowledge of the thermal expansion coefficients and precise determination of the cell parameters can potentially also be valuable while conducting density functional theory simulations on these systems in order to deliver more accurate band structure calculations.

  • 33. Johansson, Anh
    et al.
    Abrahamsson, Malin
    Magnuson, Ann
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Huang, Ping
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Mårtensson, J
    Styring, Stenbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Sun, Licheng
    Åkermark, Björn
    Synthesis and Photophysics of One Mononuclear Mn(III) and One Dinuclear Mn(III,III) Complex Covalently Linked to a Ruthenium(II) tris-Bipyridyl Complex.2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, no 23, p. 7502-7511Article in journal (Refereed)
  • 34. Johansson, Olof
    et al.
    Borgström, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
    Lomoth, Reiner
    Palmblad, Magnus
    Bergquist, Jonas
    Hammarström, Leif
    Sun, Licheng
    Åkermark, Björn
    Electron Donor-Acceptor Dyads Based on Ruthenium(II) Bipyridine and Terpyridine Complexes Bound to Naphtalenediimide2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, p. 2908-2918Article in journal (Refereed)
  • 35.
    Johansson, Olof
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Molecular hysteresis in a rigid dinuclear ruthenium polypyridyl complex incorporating a ligand-bound ambidentate motif2008In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, no 13, p. 5531-5533Article in journal (Refereed)
    Abstract [en]

    Two alternative Ru-2(2+/3+) mixed-valence states are formed in the first dinuclear Ru complex with a ligand-bound ambidentate motif. The hysteretic electrochemical response follows a double-square scheme where the structure of the mixed-valence state depends on the previous isovalent state. The Ru3+ state of the pyrrolidine-substituted bisterpyridine unit is characterized by intense ligand-to-metal charge-transfer absorptions that provide a distinctive signature of the corresponding mixed-valence state.

  • 36.
    Johnstone, Erik V.
    et al.
    Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA.;Univ Sheffield, Dept Mat Sci & Engn, Sheffield S1 3JD, S Yorkshire, England..
    Poineau, Frederic
    Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA..
    Todorova, Tanya K.
    UPMC, CNRS, Coll France, Lab Chim Proc Biol,UMR 8229, 11 Pl Marcelin Berthelot, F-75231 Paris 05, France..
    Forster, Paul M.
    Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA..
    Sørensen, Lasse K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Fernández Galván, Ignacio
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Lindh, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Czerwinski, Kenneth R.
    Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA..
    Sattelberger, Alfred P.
    Univ Nevada, Dept Chem, Las Vegas, NV 89154 USA.;Argonne Natl Lab, Argonne, IL 60439 USA..
    Molecular and Electronic Structure of Re2Br4(PMe3)(4)2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 14, p. 7111-7116Article in journal (Refereed)
    Abstract [en]

    The dinuclear rhenium(II) complex Re2Br4(PMe3)(4) was prepared from the reduction of [Re2Br8](2-) with (n-Bu4N)BH4 in the presence of PMe3 in propanol. The complex was characterized by single-crystal X-ray diffraction (SCXRD) and UV-visible spectroscopy. It crystallizes in the monoclinic C2/c space group and is isostructural with its molybdenum and technetium analogues. The Re-Re distance (2.2521(3) angstrom) is slightly longer than the one in Re2Cl4(PMe3)(4) (2.247(1) angstrom). The molecular and electronic structure of Re2X4(PMe3)(4) (X = Cl, Br) were studied by multiconfigurational quantum chemical methods. The computed ground-state geometry is in excellent agreement with the experimental structure determined by SCXRD. The calculated total bond order (2.75) is consistent with the presence of an electron-rich triple bond and is similar to the one found for Re2Cl4(PMe3)(4). The electronic absorption spectrum of Re2Br4(PMe3)(4) was recorded in benzene and shows a series of low-intensity bands in the range 10 000-26 000 cm(-1). The absorption bands were assigned based on calculations of the excitation energies with the multireference wave functions followed by second-order perturbation theory using the CASSCF/CASPT2 method. Calculations predict that the lowest energy band corresponds to the delta* -> sigma* transition, while the next higher energy bands were attributed to the delta* -> pi*, delta -> sigma*, and delta -> pi* transitions.

  • 37.
    Jäger, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Kumar, Rohan John
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Görls, Helmar
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Johansson, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Facile synthesis of bistridentate Ru(II) complexes based on 2,6-di(quinolin-8-yl)pyridyl ligands: sensitizers with microsecond 3MLCT excited state lifetimes2009In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 48, no 7, p. 3228-3238Article in journal (Refereed)
    Abstract [en]

    Synthetic routes to meridional bistridentate ruthenium(II) complexes based on 2,6-di(quinolin-8-yl)pyridyl (dqp) ligands have been investigated. Microwave-assisted synthesis at 200 degrees C allowed the high yield (49-87%) preparation of homoleptic meridional [Ru(dqp)(2)](2+)-based complexes containing inert functional groups. Applying this protocol for the synthesis of mer-[Ru(dqp)(2)](2+) (mer-1) but lowering the temperature to 180 degrees C and shorter reaction times revealed the formation of the facial isomers cis,fac-1 and trans,fac-1 (56% and 12% yields, respectively). The facial isomers were characterized by NMR spectroscopy and X-ray diffraction analysis. In a stepwise protocol, the reaction of Ru(dqp)Cl(3) or Ru(dqp)(L)Cl(2) (L = MeCN or DMSO) and a second equivalent dqp gave mer-1 in 12-26% yields and N(5)Cl-coordinated [Ru(dqp)(2)Cl](+) (28-46%). [Ru(dqp(2))Cl](+) was photochemically, or thermally in the presence of Ag(I), converted to mer-1. By using mer-[Ru(dqp)(MeCN)(3)] (2+), which was crystallographically characterized, a wide range of homo- and heteroleptic meridional [Ru(dqp)(2)](2+)-based complexes was synthesized in up to 77% yield. The synthetic utility of meridional [Ru(dqp)(2)](2+)-based complexes as building blocks was demonstrated by palladium-catalyzed homocoupling of mer-[Ru(dqp)(dqpPhBr)](2+) to form a dinuclear complex. The redox and photophysical properties of the meridional complexes are discussed.

  • 38.
    Jäger, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Smeigh, Amanda
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Lombeck, Florian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Gorls, Helmar
    Collin, Jean-Paul
    Sauvage, Jean-Pierre
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Johansson, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Molecular Biomimetics.
    Cyclometalated Ru-II Complexes with Improved Octahedral Geometry: Synthesis and Photophysical Properties2010In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 49, no 2, p. 374-376Article in journal (Refereed)
    Abstract [en]

    Cyclometalated bis-tridentate ruthenium(II) complexes incorporating 2,6-diquinolin-8-ylpyridine ligands and exhibiting broad visible absorptions are described. A [Ru(N boolean AND N boolean AND N)(N boolean AND C boolean AND N)](+) complex based only on ligands with expanded bite angles has a metal-to-ligand charge-transfer excited-state lifetime of 16 ns, which is attributed to a strong ligand field and therefore reduced deactivation via metal-centered states.

  • 39.
    Karlsson, Dennis
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Ek, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden..
    Zlotea, Claudia
    Univ Paris Est, Inst Chim & Mat Paris Est, CNRS, UPEC,UMR7182, 2-8 Rue Henri Dunant, F-94320 Thiais, France..
    Moller, Kasper Trans
    Aarhus Univ, Ctr Mat Crystallog, iNANO, Langelandsgade 140, DK-8000 Aarhus, Denmark.;Aarhus Univ, Dept Chem, Langelandsgade 140, DK-8000 Aarhus, Denmark..
    Hansen, Thomas Christian
    Inst Laue Langevin, 71 Ave Martyrs, Grenoble, France..
    Bednarcik, Jozef
    DESY, Photon Sci, Hamburg, Germany.
    Paskevicius, Mark
    Aarhus Univ, Ctr Mat Crystallog, iNANO, Aarhus, Denmark.;Aarhus Univ, Dept Chem, Langelandsgade 140, DK-8000 Aarhus, Denmark..
    Sorby, Magnus Helgerud
    Inst Energy Technol, Phys Dept, Kjeller, Norway.
    Jensen, Torben Rene
    Aarhus Univ, Ctr Mat Crystallog, iNANO, Aarhus, Denmark.;Aarhus Univ, Dept Chem, Langelandsgade 140, DK-8000 Aarhus, Denmark..
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Structure and Hydrogenation Properties of a HfNbTiVZr High-Entropy Alloy2018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 4, p. 2103-2110Article in journal (Refereed)
    Abstract [en]

    A high-entropy alloy (HEA) of HfNbTiVZr was synthesized using an arc furnace followed by ball milling. The hydrogen absorption mechanism was studied by in situ X-ray diffraction at different temperatures and by in situ and ex situ neutron diffraction experiments. The body centered cubic (BCC) metal phase undergoes a phase transformation to a body centered tetragonal (BCT) hydride phase with hydrogen occupying both tetrahedral and octahedral interstitial sites in the structure. Hydrogen cycling of the alloy at 500 degrees C is stable. The large lattice strain in the HEA seems favorable for absorption in both octahedral and tetrahedral sites. HEAs therefore have potential as hydrogen storage materials because of favorable absorption in all interstitial sites within the structure.

  • 40.
    Karlsson, Susanne
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Modin, Judit
    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.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    How Close Can You Get?: Studies of Ultrafast Light-Induced Processes in Ruthenium-[60] Fullerene Dyads with Short Pyrazolino and Pyrrolidino Links2008In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, no 16, p. 7286-7294Article in journal (Refereed)
    Abstract [en]

    Two pyrazoline- and one pyrrolidine-bridged Ru(II)bipyridine-[60]fullerene dyads have been prepared and studied by ultrafast time-resolved spectroscopy. A silver-assisted synthesis route, in which Ag(I) removes the chlorides from the precursor complex Ru(bpy)(2)Cl-2 facilitates successful coordination of the [60]fullerene-substituted third ligand. Upon light excitation of the ruthenium moiety, the emission was strongly quenched by the fullerene. The main quenching mechanism is an exceptionally fast direct energy transfer (k(obs) > , 1 x 10(12) s(-1) in the pyrazoline-bridged dyads), resulting in population of the lowest excited triplet state of fullerene. No evidence for electron transfer was found, despite the extraordinarily short donor-acceptor distance that could kinetically favor that process. The observations have implications on the ongoing development of devices built from Ru-polypyridyl complexes and nanostructured carbon, such as C-60 or nanotubes.

  • 41.
    Katea, Sarmad Naim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hajduk, Spela
    Natl Inst Chem, Hajdrihova 19, SI-1001 Ljubljana, Slovenia.
    Orel, Zorica Crnjak
    Natl Inst Chem, Hajdrihova 19, SI-1001 Ljubljana, Slovenia.
    Westin, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Low Cost, Fast Solution Synthesis of 3D Framework ZnONanosponges2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 24, p. 15150-15158Article in journal (Refereed)
    Abstract [en]

    An efficient, template-free solution-chemical route to nanostructured ZnO sponges is presented: A mixture of Zn(NO3)(2)center dot 6H(2)O, Zn(OAc)(2).2H(2)O, and triethanolamine in methanol was evaporated to a highly viscous liquid and rapidly heated to >200 degrees C for 1-3 min to achieve highly porous, nanocrystalline sponges of ZnO. The viscous precursor concentrate obtained on evaporation in air was characterized by TG, DSC, and IR spectroscopy, and the product ZnO sponges by XRD, SEM, TEM, and IR spectroscopy. The fast reaction forming ZnO started at 140 degrees C and finished within a few seconds. Scherrer analysis of the XRD peak broadening showed average crystallite sizes of 8 to 11 nm for ZnO prepared by annealing at 200-450 degrees C (3 min), while grain growth to 134 nm was observed from 500 to 900 degrees C (3 min). The ZnO powders obtained at 200-900 degrees C had cell dimensions of a = 3.25 angstrom and b = 5.21 angstrom, matching the ZnO literature data well. SEM and TEM analyses showed highly porous, bread-like 3D nanostructures built by ca. 30-70 nm thick walls of ZnO crystallites of the approximate average sizes given by the XRD Scherrer analysis. It seems that the crystal growth above 450 degrees C takes place within the ZnO 3D structure obtained at lower temperatures without much sintering of the larger porous structure.

  • 42.
    Kubin, Markus
    et al.
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Berlin, Germany.
    Guo, Meiyuan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Ekimova, Maria
    Max Born Inst Nichtlineare Opt & Kurzzeitspektros, Berlin, Germany.
    Baker, Michael L.
    Univ Manchester Harwell, Sch Chem, Oxon, England.
    Kroll, Thomas
    SLAG Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA USA.
    Källman, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Kern, Jan
    Lawrence Berkeley Natl Lab, Mol Biophys & Integrated Bioimaging Div, Berkeley, CA USA.
    Yachandra, Vittal K.
    Lawrence Berkeley Natl Lab, Mol Biophys & Integrated Bioimaging Div, Berkeley, CA USA.
    Yano, Junko
    Lawrence Berkeley Natl Lab, Mol Biophys & Integrated Bioimaging Div, Berkeley, CA USA.
    Nibbering, Erik T. J.
    Max Born Inst Nichtlineare Opt & Kurzzeitspektros, Berlin, Germany.
    Lundberg, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
    Wernet, Philippe
    Helmholtz Zentrum Berlin Mat & Energie GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Berlin, Germany.
    Direct Determination of Absolute Absorption Cross Sections at the L-Edge of Dilute Mn Complexes in Solution Using a Transmission Flatjet2018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 9, p. 5449-5462Article in journal (Refereed)
    Abstract [en]

    The 3d transition metals play a pivotal role in many charge transfer processes in catalysis and biology. X-ray absorption spectroscopy at the L-edge of metal sites probes metal 2p–3d excitations, providing key access to their valence electronic structure, which is crucial for understanding these processes. We report L-edge absorption spectra of MnII(acac)2 and MnIII(acac)3 complexes in solution, utilizing a liquid flatjet for X-ray absorption spectroscopy in transmission mode. With this, we derive absolute absorption cross-sections for the L-edge transitions with peak magnitudes as large as 12 and 9 Mb for MnII(acac)2 and MnIII(acac)3, respectively. We provide insight into the electronic structure with ab initio restricted active space calculations of these L-edge transitions, reproducing the experimental spectra with excellent agreement in terms of shapes, relative energies, and relative intensities for the two complexes. Crystal field multiplet theory is used to assign spectral features in terms of the electronic structure. Comparison to charge transfer multiplet calculations reveals the importance of charge transfer in the core-excited final states. On the basis of our experimental observations, we extrapolate the feasibility of 3d transition metal L-edge absorption spectroscopy using the liquid flatjet approach in probing highly dilute biological solution samples and possible extensions to table-top soft X-ray sources.

  • 43. La Macchia, G.
    et al.
    Manni, G. Li
    Todorova, T. K.
    Brynda, M.
    Aquilante, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Roos, B. O.
    Gagliardi, L.
    On the Analysis of the Cr-Cr Multiple Bond in Several Classes of Dichromium Compounds2010In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 49, no 11, p. 5216-5222Article in journal (Refereed)
    Abstract [en]

    Since the discovery of a formal quintuple bond in Ar’CrCrAr’ (CrCr = 1.835 angstrom) by Power and co-workers in 2005, many efforts have been dedicated to isolating dichromium species featuring quintuple-bond character. In the present study we investigate the electronic configuration of several, recently synthesized dichromium species with ligands using nitrogen to coordinate the metal centers. The bimetallic bond distances of Power’s compound and Cr-2-diazadiene (1) (CrCr = 1.803 angstrom) are compared to those found for Cr-2(mu-eta(2)-ArNC(R)NAr)(2) (2) (CrCr = 1.746 angstrom; R = H, Ar = 2,6-Et2C6H3), Cr-2(mu-eta(2)-(ArNC)-N-Xyl(H)NArXyl)(3) (3) (CrCr = 1.740(reduced)/1.817(neutral) angstrom; Ar-Xyl=2,6-C6H3-(CH3)(2)), Cr-2(mu-eta(2)-TippPyNMes)(2) (4) (CrCr = 1.749 angstrom; TippPyNMes = 6-(2,4,6-triisopropylphenyl)pyridin-2-yl (2,4,6-trimethylphenyl)-amide), and Cr-2(mu-eta(2)-DippNC(NMe2)N-Dipp)(2) (5) (CrCr = 1.729 angstrom, Dipp = 2,6-i-Pr2C6H3). We show that the correlation between the CrCr bond length and the effective bond order (EBO) is strongly affected by the nature of the ligand, as well as by the steric hindrance due to the ligand structure (e.g., the nature of the coordinating nitrogen). A linear correlation between the EBO and CrCr bond distance is established within the same group of ligands. As a result, the CrCr species based on the amidinate, aminopyridinate, and guanidinate ligands have bond patterns similar to the Ar’CrCrAr’ compound. Unlike these latter species, the dichromium diazadiene complex is characterized by a different bonding pattern involving Cr-N pi interactions, resulting in a lower bond order associated with the short metal-metal bond distance. In this case the short CrCr distance is most probably the result of the constraints imposed by the diazadiene ligand, implying a Cr2N4 core with a closer CrCr interaction.

  • 44. La Macchia, Giovanni
    et al.
    Aquilante, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Quantum Chemistry.
    Veryazov, Valera
    Roos, Bjorn O.
    Gagliardi, Laura
    Bond Length and Bond Order in One of the Shortest Cr-Cr Bonds2008In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, p. 11455-11457Article in journal (Refereed)
    Abstract [en]

    Multiconfigurational quantum chemical calculations on the R-diimines dichromium compound confirm that the Cr-Cr bond, 1.80 angstrom, is among the shortest Cr-I-Cr-I bonds. However, the bond between the two Cr atoms is only a quadruple bond rather than a quintuple bond. The reason why the bond is so short has to be attributed to the strain in the NCCN ligand moieties.

  • 45. Laakso, Johanna
    et al.
    Rosser, Geraldine A.
    Szijjarto, Csongor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Beeby, Andrew
    Borbas, Eszter K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Synthesis of Chlorin-Sensitized Near Infrared-Emitting Lanthanide Complexes2012In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 51, no 19, p. 10366-10374Article in journal (Refereed)
    Abstract [en]

    Lanthanide (Yb3+, Nd3+) complexes equipped with red-absorbing hydroporphyrin (chlorin) antennae were synthesized and characterized. The syntheses are scalable, highly modular, and enable the introduction of different chlorins functionalized with a single reactive group (COOH or NH2). Absorption maxima were dependent on chlorin substitution pattern (monomeso aryl or dimeso aryl) and metalation state (free base or zinc chelate). The complexes benefit from dual chlorin (610-639 nm) and lanthanide (980 or 1065 nm for Yb- or Nd-complexes, respectively) emission in the biologically relevant red and near IR region of the spectrum.

  • 46. Leidel, Nils
    et al.
    Chernev, Petko
    Havelius, Kajsa G. V.
    Ezzaher, Salah
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Haumann, Michael
    Site-Selective X-ray Spectroscopy on an Asymmetric Model Complex of the [FeFe] Hydrogenase Active Site2012In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 51, no 8, p. 4546-4559Article in journal (Refereed)
    Abstract [en]

    The active site for hydrogen production in [FeFe] hydrogenase comprises a diiron unit. Bioinorganic chemistry has modeled important features of this center, aiming at mechanistic understanding and the development of novel catalysts. However, new assays are required for analyzing the effects of ligand variations at the metal ions. By high-resolution X-ray absorption spectroscopy with narrow-band X-ray emission detection (XAS/XES = XAES) and density functional theory (DFT), we studied an asymmetrically coordinated [FeFe] model complex, [(CO)(3)Fe(I)1-(bdtCl(2))-Fe-2(I)(CO)(Ph2P-CH2-NCH3-CH2-PPh2)] (1, bdt = benzene-1,2-dithiolate), in comparison to iron-carbonyl references. K beta emission spectra (K beta(1,3), K beta') revealed the absence of unpaired spins and the low-spin character for both Fe ions in 1. In a series of low-spin iron compounds, the K beta(1,3) energy did not reflect the formal iron oxidation state, but it decreases with increasing ligand field strength due to shorter iron-ligand bonds, following the spectrochemical series. The intensity of the valence-to-core transitions (K beta(2,5)) decreases for increasing Fe-ligand bond length, certain emission peaks allow counting of Fe-CO bonds, and even molecular orbitals (MOs) located on the metal-bridging bdt group of 1 contribute to the spectra. As deduced from 3d -> 1s emission and 1s -> 3d absorption spectra and supported by DFT, the HOMO-LUMO gap of 1 is about 2.8 eV. K beta-detected XANES spectra in agreement with DFT revealed considerable electronic asymmetry in 1; the energies and occupancies of Fe-d dominated MOs resemble a square-pyramidal F(0) for Fe1 and an octahedral Fe(II) for Fe2. EXAFS spectra for various K beta emission energies showed considerable site-selectivity; approximate structural parameters similar to the crystal structure could be determined for the two individual iron atoms of 1 in powder samples. These results suggest that metal site- and spin-selective XAES on [FeFe] hydrogenase protein and active site models may provide a powerful tool to study intermediates under reaction conditions.

  • 47.
    Li, Nana
    et al.
    Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China..
    Manoun, Bouchaib
    Univ Hassan Ler, Lab Sci Mat Milieux & Modelisat LS3M, Khouribga 25000, Morocco..
    Tang, Lingyun
    Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China.;Carnegie Inst Sci, Geophys Lab, High Pressure Synerget Consortium, Argonne, IL 60439 USA..
    Ke, Feng
    Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China..
    Liu, Fengliang
    Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China.;Fudan Univ, State Key Lab Surface Phys, Dept Phys, Shanghai 200433, Peoples R China.;Fudan Univ, Adv Mat Lab, Shanghai 200433, Peoples R China..
    Dong, Haini
    Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China.;Chinese Acad Sci, Inst Geochem, Key Lab High Temp & High Pressure Study Earth Int, Guizhou 550081, Peoples R China..
    Lazor, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.
    Yang, Wenge
    Ctr High Pressure Sci & Technol Adv Res, Shanghai 201203, Peoples R China.;Carnegie Inst Sci, Geophys Lab, High Pressure Synerget Consortium, Argonne, IL 60439 USA..
    Pressure-Induced Structural and Electronic Transition in Sr2ZnWO6 Double Perovskite2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 13, p. 6770-6775Article in journal (Refereed)
    Abstract [en]

    High-pressure structural and electrical properties of Sr2ZnWO6 double perovskite were investigated using in situ angle-dispersive synchrotron X-ray diffraction (XRD), Raman, and alternating current (AC) impedance spectroscopy. A structural transition from monoclinic (P2(1)/n) to triclinic (P (1) over bar) phase around 9 GPa was observed due to the pressure-induced distortion of (W, Zn)O-6 octahedron. In situ high-pressure Raman spectroscopy showed the increasing interaction among O-W-O in WO6 octahedron with pressure and a transition pressure consistent with the XRD results. From the AC impedance spectroscopy measurements, the resistivity increased steeply by similar to 1 order of magnitude around 11 GPa, indicating an electronic transition accompanying the symmetry change. The increase in the interaction among O-W-O enhances the attraction of O2- electrons toward W6+, thus increasing the covalence, which in turn lowers the charge transfer energy between O2- and W6+ and induces the resistivity increase under high pressure.

  • 48.
    Lundberg, Marcus
    et al.
    Department of Physics, Stockholm University, AlbaNova University Center.
    Blomberg, Margareta R. A.
    Siegbahn, Per E. M.
    Oxyl radical required for O-O bond formation in synthetic Mn-catalyst2004In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 43, no 1, p. 264-274Article in journal (Refereed)
    Abstract [en]

    DFT calculations using the B3LYP functional support the suggestion that the [(terpy)(H2O)Mn-IV(mu-O)(2)Mn-III(H2O)-(terpy)](3+) (terpy=2,2':6,2"-terpyridine) complex functions as a synthetic O-2 catalyst. The calculated barrier for O-O bond formation with water is 23 kcal/mol. In this complex, as well as in models of the oxygen evolving complex in PSII, the active species is a Mn-IV-oxyl radical. From comparisons with inactive Mn-V-oxo complexes, it is proposed that radical formation is actually a requirement for O-2 formation activity in Mn-complexes.

  • 49. Löscher, Simone
    et al.
    Schwartz, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Haumann, Michael
    Facilitated hydride binding in an Fe-Fe hydrogenase active-site biomimic revealed by X-ray absorption spectroscopy and DFT calculations2007In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 26, p. 11094-11105Article in journal (Refereed)
    Abstract [en]

    Iron-only hydrogenases are high-efficiency biocatalysts for the synthesis and cleavage of molecular hydrogen. Their active site is a diiron center, which carries CO and CN ligands. Remarkably, the two iron atoms likely are connected by a non-protein azadithiolate (adt = S-CH2-NH-CH2-S). To dwell on the role of the adt in H-2 catalysis, a specific biomimetic diiron compound, 1 = [Fe-2(mu-adt-CH2-Ph)(CO)(4)(PMe3)(2)], with unprecedented positive reduction potential, has been synthesized and crystallized previously. It comprises two protonation sites, the N-benzyl-adt nitrogen that can hold a proton (H) and the Fe-Fe bond that will formally carry a hydride (Hy). We investigated changes in the solution structure of 1 in its four different protonation states (1', [1H](+), [1HHy](2+), and [1Hy](+)) by X-ray absorption spectroscopy at the iron K-edge. EXAFS reveals that already protonation at the adt nitrogen atom causes a change of the ligand geometry involving a significant lengthening of the Fe-Fe distance and CO and PMe3 repositioning, respectively, thereby facilitating the subsequent binding of a bridging hydride. Hydride binding clearly is discernible in the XANES spectra of [1HHy](2+) and [1Hy](+). DIFT calculations are in excellent agreement with the experimentally derived structural parameters and provide complementary insights into the electronic structure of the four protonation states. In the iron-only hydrogenases, protonation of the putative adt ligand may cause the bridging CO to move to a terminal position, thereby preparing the active site for hydride binding en route to H2 formation.

  • 50.
    Ojwang, Dickson O.
    et al.
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Grins, Jekabs
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Wardecki, Dariusz
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renman, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mahmoud, Abdelfattah
    Forschungszentrum Julich, JARA FIT, Julich Ctr Neutron Sci JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, JARA FIT, Peter Grunberg Inst PGI, D-52425 Julich, Germany.;Univ Liege, Inst Phys, Inst Chem B63APTIS, LCIS GREENMAT, B-4000 Liege, Belgium..
    Hermann, Raphael P.
    Forschungszentrum Julich, JARA FIT, Julich Ctr Neutron Sci JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, JARA FIT, Peter Grunberg Inst PGI, D-52425 Julich, Germany.;Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA..
    Svensson, Gunnar
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 12, p. 5924-5934Article in journal (Refereed)
    Abstract [en]

    Copper hexacyanoferrate, Cu-II[Fe-III(CN)(6)](2/3)center dot nH(2)O, was synthesized, and varied amounts of IC ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as Cu-II[Fe-III(CN)(6)](2/3)-nH(2)O + 2x/3K(+) + 2x/3e(-)K(+) <-> K-2x/3 Cu-II[Fe-x(II).Fe-1-x(II),(CN)(6)](2/3)-nH(2)O. Infrared, Raman, and Mossbauer spectroscopy studies show that Fe-II is continuously reduced to Fell with increasing x, accompanied by a decrease of the a-axis of the cubic Fn (3) over barm unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction similar to 10% of the Fe-III, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of similar to 26 wt % upon heating to 180 degrees C, above which the structure starts to decompose. The crystal structures of Cu-III[Fe-III(CN)(6)](2/3)center dot nH(2)O and K2/3Cu[Fe(CN)(6)](2/3)center dot nH(2)O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)(6) groups are vacant, and the octahedron around Cull is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the-Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.

12 1 - 50 of 62
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