Digitala Vetenskapliga Arkivet

Change search
Refine search result
1234567 1 - 50 of 421
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Abbasi, Alireza
    et al.
    Damian Risberg, Emiliana
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Mink, Janos
    Persson, Ingmar
    Sandström, Magnus
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Sidorov, Yurii V.
    Skripkin, Mikhail Yu.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Ullström, Ann-Sofi
    Crystallographic and Vibrational Spectroscopic Studies of Octakis(dimethyl sulfoxide)lanthanoid(III) Iodides2007In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 19, p. 7731-7741Article in journal (Refereed)
    Abstract [en]

    The octakis(DMSO) (DMSO = dimethylsulfoxide) neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III), and lutetium(III) iodides crystallize in the monoclinic space group P21/n (No. 14) with Z = 4, while the octakis(DMSO) iodides of the larger lanthanum(III), cerium(III), and praseodymium(III) ions crystallize in the orthorhombic space group Pbca (No. 61), Z = 8. In all [Ln(OS(Me2)8]I3 compounds the lanthanoid(III) ions coordinate eight DMSO oxygen atoms in a distorted square antiprism. Up to three of the DMSO ligands were found to be disordered and were described by two alternative configurations related by a twist around the metal−oxygen (Ln−O) bond. To resolve the atomic positions and achieve reliable Ln−O bond distances, complete semirigid DMSO molecules with restrained geometry and partial occupancy were refined for the alternative sites. This disorder model was also applied on previously collected data for the monoclinic octakis(DMSO)yttrium(III) iodide. At ambient temperature, the eight Ln−O bond distances are distributed over a range of about 0.1 Å. The average value increases from Ln−O 2.30, 2.34, 2.34, 2.36, 2.38, 2.40 to 2.43 Å (Ln = Lu, Er, Y, Dy, Gd, Sm, and Nd) for the monoclinic [Ln(OSMe2)8]I3 structures, and from 2.44, 2.47 to 2.49 Å (Ln = Pr, Ce, and La) for the orthorhombic structures, respectively. The average of the La−O and Nd−O bond distances remained unchanged at 100 K, 2.49 and 2.43 Å, respectively. Despite longer bond distances and larger Ln−O−S angles, the cell volumes are smaller for the orthorhombic structures (Ln = Pr, Ce, and La) than for the monoclinic structure with Ln = Nd, showing a more efficient packing arrangement. Raman and IR absorption spectra for the [Ln(OS(CH3)2)8]I3 (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Lu, and Y) compounds, also deuterated for La and Y, have been recorded and analyzed by means of normal coordinate methods. The force constants for the Ln−O and S−O stretching modes in the complexes increase with decreasing Ln−O bond distance and show increasing polarization of the bonds for the smaller and heavier lanthanoid(III) ions.

  • 2.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Huang, Zhehao
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    El-Zhory, Ahmed M.
    Haoquan, Zheng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A Fast and Scalable Approach for Synthesis of Hierarchical Porous Zeolitic Imidazolate Frameworks and One-Pot Encapsulation of Target Molecules2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 15, p. 9139-9146Article in journal (Refereed)
    Abstract [en]

    A trimethylamine (TEA)-assisted synthesis approach that combines the preparation of hierarchical porous zeolitic imidazolate framework ZIF-8 nanoparticles and one-pot encapsulation of target molecules is presented. Two dye molecules, rhodamine B (RhB) and methylene blue (MB), and one protein (bovine serum albumin, BSA) were tested as the target molecules. The addition of TEA into the solution of zinc nitrate promoted the formation of ZnO nanocrystals, which rapidly transformed to ZIF-8 nanoparticles after the addition of the linker 2-methylimidazole (Hmim). Hierarchical porous dye@ZIF-8 nanoparticles with high crystallinity, large BET surface areas (1300–2500 m2/g), and large pore volumes (0.5–1.0 cm3/g) could be synthesized. The synthesis procedure was fast (down to 2 min) and scalable. The Hmim/Zn ratio could be greatly reduced (down to 2:1) compared to previously reported ones. The surface areas, and the mesopore size, structure, and density could be modified by changing the TEA or dye concentrations, or by postsynthetic treatment using reflux in methanol. This synthesis and one-pot encapsulation approach is simple and can be readily scaled up. The photophysical properties such as lifetime and photostability of the dyes could be tuned via encapsulation. The lifetimes of the encapsulated dyes were increased by 3–27-fold for RhB@ZIF-8 and by 20-fold for MB@ZIF-8, compared to those of the corresponding free dyes. The synthesis approach is general, which was successfully applied for encapsulation of protein BSA. It could also be extended for the synthesis of hierarchical porous cobalt-based ZIF (dye@ZIF-67).

  • 3.
    Abdelhamid, Hani Nasser
    et al.
    Stockholm Univ, Inorgan & Struct Chem, SE-10691 Stockholm, Sweden;Stockholm Univ, Berzelii Ctr EXSELENT Porous Mat, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Huang, Zhehao
    Stockholm Univ, Inorgan & Struct Chem, SE-10691 Stockholm, Sweden;Stockholm Univ, Berzelii Ctr EXSELENT Porous Mat, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    El-Zohry, Ahmed
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Zheng, Haoquan
    Stockholm Univ, Inorgan & Struct Chem, SE-10691 Stockholm, Sweden;Stockholm Univ, Berzelii Ctr EXSELENT Porous Mat, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Zou, Xiaodong
    Stockholm Univ, Inorgan & Struct Chem, SE-10691 Stockholm, Sweden;Stockholm Univ, Berzelii Ctr EXSELENT Porous Mat, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    A Fast and Scalable Approach for Synthesis of Hierarchical Porous Zeolitic Imidazolate Frameworks and One-Pot Encapsulation of Target Molecules2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 15, p. 9139-9146Article in journal (Refereed)
    Abstract [en]

    A trimethylamine (TEA)-assisted synthesis approach that combines the preparation of hierarchical porous zeolitic, imidazolate framework ZIF-8, nanoparticles and one-pot encapsulation of target molecules is presented. Two dye molecules, rhodamine B (RhB) and methylene blue (MB), and one protein (bovine serum albumin, BSA) were, tested as the target molecules. The addition of TEA into the solution of zinc nitrate promoted the formation of ZnO nanocrystals, which rapidly transformed to ZIF-8 nanoparticles after the addition of the linker 2-methylimidazole (Hmim): Hierarchical porous dye@ZIF-8 nanoparticles with high crystallinity, large BET surface areas (1300-2500 m(2)/g), and large pore Volatiles (0.5-1.0 cm(3)/g) could be synthesized. The synthesis procedure was fast (down to 2 min) and scalable. The Hmim/Zn ratio could be greatly reduced (down to 2:1) compared to previously reported ones. The surface areas, and the mesopore size, structure, and density could be modified by changing the TEA or dye concentrations, or by postsynthetic treatment using reflux in methanol. This synthesis and one-pot encapsulation approach is simple and can be readily scaled Up. The photophysical properties such as lifetime and photostability of the dyes could be tuned via encapsulation. The lifetimes of the encapsulated dyes were increased by 3-27-fold for RhB@ZIF-8 and by 20-fold for MB@ZIF-8, compared to those of the corresponding free dyes. The synthesis approach is general, which was successfully applied for encapsulation of protein BSA. It could also be extended for the synthesis of hierarchical porous cobalt-based ZIP (dye@ZIF-67).

  • 4. Abrahamsson, M. L. A.
    et al.
    Baudin, H. B.
    Tran, A.
    Philouze, C.
    Berg, K. E.
    Raymond-Johansson, M. K.
    Sun, Licheng C.
    Akermark, B.
    Styring, S.
    Hammarstrom, L.
    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 approximate to 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) electrontransfer rate constant was not reduced. Consequently, the modification resulted in a complex with very favorable properties.

  • 5. Abrahamsson, M.
    et al.
    Wolpher, H.
    Johansson, O.
    Larsson, J.
    Kritikos, M.
    Eriksson, L.
    Norrby, P. O.
    Bergquist, J.
    Sun, Licheng C.
    Akermark, B.
    Hammarstrom, L.
    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)
    Abstract [en]

    The synthesis and characterization of six ruthenium(II) bistridentate polypyridyl complexes is described. These were designed on the basis of a new approach to increase the excited-state lifetime of ruthenium(II) bisterpyridine-type complexes. By the use of a bipyridylpyridyl methane ligand in place of terpyridine, the coordination environment of the metal ion becomes nearly octahedral and the rate of deactivation via ligand-field (i.e., metal-centered) states was reduced as shown by temperature-dependent emission lifetime studies. Still, the possibility to make quasi-linear donor-ruthenium-acceptor triads is maintained in the complexes. The most promising complex shows an excited-state lifet me of tau = 15 ns in alcohol solutions at room temperature, which should be compared to a lifetime of tau = 0.25 ns for [Ru(tpy)(2)](2+). The X-ray structure of the new complex indeed shows a more octahedral geometry than that of [Ru(tpy)(2)](2+). Most importantly, the high excited-state energy was retained, and thus, so was the potential high reactivity of the excited complex, which has not been the case with previously published strategies based on bistridentate complexes.

  • 6.
    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.

  • 7.
    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.

  • 8.
    Abrahamsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science, Chemical Physics.
    Tocher, Derek
    Nag, Samik
    Datta, Dipankar
    Modulation of the lowest metal-to-ligand charge-transfer state in [Ru(bpy)(2)(N-N)](2+) systems by changing the N-N from hydrazone to azine: Photophysical Consequences2006In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 45, no 23, 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.

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

  • 10. Abrahamsson, Maria
    et al.
    Wolpher, Henriette
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johansson, Olof
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Larsson, Jan
    Kritikos, Mikael
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Norrby, Per-Ola
    Bergquist, Jonas
    Sun, Licheng
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hammarström, Leif
    A New Strategy for Improvement of Photophysical Properties in Ruthenium(II) Polypyridyl Complexes. Synthesis, Photophysical and Electrochemical characterisation 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)
    Abstract [en]

    The synthesis and characterization of six ruthenium(II) bistridentate polypyridyl complexes is described. These were designed on the basis of a new approach to increase the excited-state lifetime of ruthenium(II) bisterpyridine-type complexes. By the use of a bipyridylpyridyl methane ligand in place of terpyridine, the coordination environment of the metal ion becomes nearly octahedral and the rate of deactivation via ligand-field (i.e., metal-centered) states was reduced as shown by temperature-dependent emission lifetime studies. Still, the possibility to make quasi-linear donor−ruthenium−acceptor triads is maintained in the complexes. The most promising complex shows an excited-state lifetime of τ = 15 ns in alcohol solutions at room temperature, which should be compared to a lifetime of τ = 0.25 ns for [Ru(tpy)2]2+. The X-ray structure of the new complex indeed shows a more octahedral geometry than that of [Ru(tpy)2]2+. Most importantly, the high excited-state energy was retained, and thus, so was the potential high reactivity of the excited complex, which has not been the case with previously published strategies based on bistridentate complexes.

  • 11.
    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)
  • 12. 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.

  • 13. 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.

  • 14. 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.

  • 15. Alammar, Tarek
    et al.
    Hamm, Ines
    Grasmik, Viktoria
    Wark, Michael
    Mudring, Anja-Verena
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Iowa State University, United States; U.S. Department of Energy, United States; Ruhr-Universität Bochum, Germany.
    Microwave-Assisted Synthesis of Perovskite SrSnO3 Nanocrystals in Ionic Liquids for Photocatalytic Applications2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 12, p. 6920-6932Article in journal (Refereed)
    Abstract [en]

    Nanosized SrSnO3 photocatalysts have been successfully synthesized by microwave synthesis in various ionic liquids (ILs) followed by a heat treatment process to optimize the materials' crystallinity. The influence of the ILs with various cations such as 1-butyl-3-methylimidazolium ([C(4)mim](+)), 6-bis(3-methylimidazolium-1-yl)hexane ([C-6(mim)(2)](2+)), butylpyridinium ([C4Py](+)), and tetradecyltrihexylphosphonium ([P-66614](+)) and bis(trifluoromethanesulfonyl)amide ([Tf2N](-)) as the anion on the structure, crystallization, and morphology of the products was investigated. The samples were characterized by X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), surface area analysis by gas adsorption, X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV vis spectroscopy, and Raman and IR spectroscopy. According to structure characterization by XRD and Raman spectroscopy all samples wcrystallized phase-pure in the orthorhombic GdFeO3 perovskite structure type. SEM reveals that, on the basis of the IL, th(e) obtained SrSnO3 nanoparticles exhibit different morphologies and sizes. Rod-shaped particles are formed in [C(4)minn][Tf2N], [C-6(mim)(2)][Tf2N](2), and p [P-66614][Tf2N]. However, the particle dimensions and size distribution vary depending on the IL and range from quite thin and long needlelike partinles with a narrow size distribution obtained in [P-66614] [TfA to relatively larger particles with a broader size distribution obtained in [C-6(mim)(2)][Tf2N](2). In contrast, in [C4Py][Tf2N] nanospheres with a diameter of about 50 nm form. For these particles the highest photocatalytic activity was observed. Our investigations indicate that the improved photocatalytic activity of this material results from the synergistic effect of the relatively large surface area associated with nanosize and an appropriate energy band structure.

  • 16.
    Alammar, Tarek
    et al.
    Department of Chemistry, College of Science, King Faisal University, P.O Box 400, Al-Ahsa, Saudi Arabia.
    Mudring, Anja-Verena
    Umeå University, Faculty of Science and Technology, Department of Physics. Department of Biological & Chemical Engineering, Intelligent Advanced Materials, Aarhus University, Aarhus, Denmark.
    Synthesis and exploration of Barium Stannate-Zirconate BaSn1-xZrxO3 (0 ≤ X ≤ 1) solid solutions as photocatalysts2024In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 63, no 14, p. 6132-6140Article in journal (Refereed)
    Abstract [en]

    Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn1-xZrxO3 solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn1-xZrxO3 samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn0.5Zr0.5O3> BaSn0.8Zr0.2O3> BaSnO3> BaSn0.2Zr0.8O3> BaZrO3. The superior photocatalytic activity of BaSn0.5Zr0.5O3 can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.

    Download full text (pdf)
    fulltext
  • 17.
    Algarra, Andres G.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aullon, Gabriel
    Bemhardt, Paul V.
    Martinez, Manuel
    Computational Insights on the Geometrical Arrangements of Cu(II) with a Mixed-Donor N3S3 Macrobicyclic Ligand2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, no 1, p. 512-521Article in journal (Refereed)
    Abstract [en]

    The macrobicyclic mixed-donor N3S3 cage ligand AMME-N(3)S(3)sar (1-methyl-8-amino-3,13,16-trithia-6,10,19-triazabicyclo[6.6.6]eicosane) can form complexes with Cu(II) in which it acts as hexadentate (N3S3) or tetradentate (N2S2) donor. These two complexes are in equilibrium that is strongly influenced by the presence of halide ions (Br- and Cl-) and the nature of the solvent (DMSO, MeCN, and H2O). In the absence of halides the hexadentate coordination mode of the ligand is preferred and the encapsulated complex (Cu-in(2+)) is formed. Addition of halide ions in organic solvents (DMSO or MeCN) leads to the tetradentate complex (Cu-out(+)) in a polyphasic kinetic process, but no Cu-out(+) complex is formed when the reaction is performed in water. Here we applied density functional theory calculations to study the mechanism of this interconversion as well as to understand the changes in the reactivity associated with the presence of water. Calculations were performed at the B3LYP/(SDD,6-31G**) level, in combination with continuum (MeCN) or discrete-continuum (H2O) solvent models. Our results show that formation of Cu-out(+) in organic media is exergonic and involves sequential halide-catalyzed inversion of the configuration of a N-donor of the macrocycle, rapid halide coordination, and inversion of the configuration of a S-donor. In aqueous solution the solvent is found to have an effect on both the thermodynamics and the kinetics of the reaction. Thermodynamically, the process becomes endergonic mainly due to the preferential solvation of halide ions by water, while the kinetics is influenced by formation of a network of H-bonded water molecules that surrounds the complex.

  • 18.
    Ali, S. K. Imran
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, Reinhard K.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hydrothermal Synthesis of the Oxofluoride FeSbO2F2-An Anti-ferromagnetic Spin S=5/2 Compound2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 8, p. 4662-4667Article in journal (Refereed)
    Abstract [en]

    The new oxofluoride compound FeSbO2F2 was synthesized by hydro thermal techniques at 230 degrees C. Its crystal structure was determined from single-crystal Xray diffraction data. The compound crystallizes in the monoclinic space group C2/c with one crystallographic site for Fe3+ and SP3+, respectively. The crystal structure is made of [FeO2F4] octahedra and seesaw [SbO4] building blocks. These are connected to form [FeO2F2] layers and [SbO2] chains that bond together via the oxygen atoms to form the three-dimensional framework structure. Magnetic susceptibility and heat capacity measurements indicate long-range anti-ferromagnetic ordering below a Neel temperature of similar to 175 K Two-dimensional anti-ferromagnetic short-range order in the square planar net of the Fe3+ cations extends to temperatures far above the Neel temperature.

  • 19.
    Ali, Sk Imran
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Kremer, Reinhard K.
    Johnsson, Mats
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hydrothermal Synthesis and Magnetic Characterization of the Quaternary Oxide CoMo2Sb2O102016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 21, p. 11490-11496Article in journal (Refereed)
    Abstract [en]

    The new quaternary layered oxide CoMo2Sb2O10 was synthesized by hydrothermal synthesis techniques, and its structure was determined from single-crystal X-ray diffraction data. CoMo2Sb2O10 crystallizes in the monoclinic space group C2/c with one Sb3+, Mo6+, and Co2+ atom site per unit cell, respectively. The crystal structure contains building units consisting of [Co2O8](n), [Mo2O8](n), and [SbO2](n) chains. These are connected through corner sharing to form charge neutral [CoMo2Sb2O10](n) layers. Thermal decomposition of CoMo2Sb2O10 starts at 550 degrees C. The magnetic susceptibility follows a Curie Weiss law above 50 K with a Curie constant of C = 3.46 emu K mol(-1) corresponding to an effective moment of mu(eff) = 5.26 mu(B) per cobalt atom and a Curie-Weiss temperature theta = -13.2 K. Short-range anti-ferromagnetic ordering dominates below 5 K. Magnetic susceptibility and heat capacity data can be successfully modeled by the predictions from an Ising linear chain with an intrachain spin exchange of ca. -7.8 K.

  • 20.
    Alonso Mori, Roberto
    et al.
    Universita di Camerino, Italy.
    Paris, E.
    Universita di Camerino, Italy.
    Giuli, G.
    Universita di Camerino, Italy.
    Eeckhout, S.G.
    European Synchrotron Radiation Facility (ESRF).
    Kavčič, M.
    J. Stefan Institute, Slovenia.
    Žitnik, M.
    J. Stefan Institute, Slovenia.
    Bučar, K.
    J. Stefan Institute, Slovenia.
    Pettersson, Lars G.M.
    Stockholm University, Faculty of Science, Department of Physics.
    Glatzel, Pieter
    European Synchrotron Radiation Facility (ESRF).
    Sulfur-Metal Orbital Hybridization in Sulfur-Bearing Compounds Studied by X-ray Emission Spectroscopy2010In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 49, p. 6468-6473Article in journal (Refereed)
    Abstract [en]

     

     

    The electronic structure and ligand environment of sulfur was investigated in various sulfur-containing compounds with different structures and chemical states by using X-ray emission spectroscopy (XES). Calculations were performed using density functional theory (DFT) as implemented in the StoBe code. The sulfur chemical state and atomic environment is discussed in terms of the molecular orbitals and partial charges that are obtained from the calculations. The main spectral features can be modeled using our calculational approach. The sensitivity of the K β

    emission to thecation and the local symmetry is discussed.

  • 21.
    Anasori, Babak
    et al.
    Drexel Univ, PA 19104 USA; Drexel Univ, PA 19104 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rivin, Oleg
    Nucl Res Ctr Negev, Israel.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Voigt, Cooper
    Drexel Univ, PA 19104 USA.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel W.
    Drexel Univ, PA 19104 USA.
    Caspi, Elad N.
    Drexel Univ, PA 19104 USA; Nucl Res Ctr Negev, Israel.
    A Tungsten-Based Nanolaminated Ternary Carbide: (W,Ti)(4)C4-x2019In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 2, p. 1100-1106Article in journal (Refereed)
    Abstract [en]

    Nanolamellar transition metal carbides are gaining increasing interests because of the recent developments of their twodimensional (2D) derivatives and promising performance for a variety of applications from energy storage, catalysis to transparent conductive coatings, and medicine. To develop more novel 2D materials, new nanolaminated structures are needed. Here we report on a tungsten based nanolaminated ternary phase, (W,Ti)(4)C4-x, synthesized by an Al catalyzed reaction of W, Ti, and C powders at 1600 degrees C for 4 h, under flowing argon. X-ray and neutron diffraction, along with Z-contrast scanning transmission electron microscopy, were used to determine the atomic structure, ordering, and occupancies. This phase has a layered hexagonal structure (P6(3)/mmc) with lattice parameters, a = 3.00880(7) angstrom, and c = 19.5633(6) angstrom and a nominal chemistry of (W,Ti)(4)C4-x (actual chemistry, W2.1(1)Ti1.6(1)C2.6(1)). The structure is comprised of layers of pure W that are also twin planes with two adjacent atomic layers of mixed W and Ti, on either side. The use of Al as a catalyst for synthesizing otherwise difficult to make phases, could in turn lead to the discovery of a large family of nonstoichiometric ternary transition metal carbides, synthesized at relatively low temperatures and shorter times.

    Download full text (pdf)
    fulltext
  • 22.
    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.

  • 23.
    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.

  • 24.
    Arkhypchuk, Anna I.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Tran, Thuan T.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Charaf, Rima
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Mechanistic Insights and Synthetic Explorations of the Photoredox-Catalyzed Activation of Halophosphines2023In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 62, no 45, p. 18391-18398Article in journal (Refereed)
    Abstract [en]

    The light-driven activation of halophosphines R2PX (R = alkyl- or aryl, X = Cl, Br) by an IrIII-based photocatalyst is described. It is shown that initially formed secondary phosphines R2PH react readily with the remaining R2PX in a parent–child reaction to form diphosphines R2P–PR2. Aryl-containing diphosphines can be further reduced to secondary phosphines RAr2PH under identical photoredox conditions. Dihalophosphines RPX2 are also activated by the photoredox protocol, giving rise to unusual 3-, 4-, and 5-membered cyclophosphines. Transient absorption studies show that the excited state of the Ir photocatalyst is reductively quenched by the DIPEA (N,N-di-iso-propylethylamine) electron donor. Electron transfer to R2PX is however unexpectedly slow and cannot compete with recombination with the oxidized donor DIPEA•+. As DIPEA is not a perfectly reversible donor, a small proportion of the total IrII population escapes recombination, providing the reductant for the observed transformations.

    Download full text (pdf)
    fulltext
  • 25. 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.

  • 26. Bacher, Felix
    et al.
    Doemoetoer, Orsolya
    Kaltenbrunner, Maria
    Mojovic, Milos
    Popovic-Bijelic, Ana
    Gräslund, Astrid
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Ozarowski, Andrew
    Filipovic, Lana
    Radulovic, Sinisa
    Enyedy, Eva A.
    Arion, Vladimir B.
    Effects of Terminal Dimethylation and Metal Coordination of Proline-2-formylpyridine Thiosemicarbazone Hybrids on Lipophilicity, Antiproliferative Activity, and hR2 RNR Inhibition2014In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, no 23, p. 12595-12609Article in journal (Refereed)
    Abstract [en]

    The nickel(II), copper(II), and zinc(II) complexes of the proline-thiosemicarbazone hybrids 3-methyl-(S)-pyrrolidine-2-carboxylate-2-formylpyridine thiosemicarbazone (l-Pro-FTSC or (S)-H2L1) and 3-methyl-(R)-pyrrolidine-2-carboxylate-2-formylpyridine thiosemicarbazone (d-Pro-FTSC or (R)-H2L1), as well as 3-methyl-(S)-pyrrolidine-2-carboxylate-2-formylpyridine 4,4-dimethyl-thiosemicarbazone (dm-l-Pro-FTSC or (S)-H2L2), namely, [Ni(l-Pro-FTSC-2H)](2) (1), [Ni(d-Pro-FTSC-2H)](2) (2), [Ni(dm-l-Pro-FTSC-2H)](2) (3), [Cu(dm-l-Pro-FTSC-2H)] (6), [Zn(l-Pro-FTSC-2H)] (7), and [Zn(d-Pro-FTSC-2H)] (8), in addition to two previously reported, [Cu(l-Pro-FTSC-2H)] (4), [Cu(d-Pro-FTSC-2H)] (5), were synthesized and characterized by elemental analysis, one- and two-dimensional (1)H and (13)C NMR spectroscopy, circular dichroism, UV-vis, and electrospray ionization mass spectrometry. Compounds 1-3, 6, and 7 were also studied by single-crystal X-ray diffraction. Magnetic properties and solid-state high-field electron paramagnetic resonance spectra of 2 over the range of 50-420 GHz were investigated. The complex formation processes of l-Pro-FTSC with nickel(II) and zinc(II) were studied in aqueous solution due to the excellent water solubility of the complexes via pH potentiometry, UV-vis, and (1)H NMR spectroscopy. The results of the antiproliferative activity in vitro showed that dimethylation improves the cytotoxicity and hR2 RNR inhibition. Therefore, introduction of more lipophilic groups into thiosemicarbazone-proline backbone becomes an option for the synthesis of more efficient cytotoxic agents of this family of compounds.

  • 27. Baranets, Sviatoslav
    et al.
    Ovchinnikov, Alexander
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). University of Delaware, United States of America.
    Bobev, Svilen
    Complex Structural Disorder in the Zintl Phases Yb10MnSb9 and Yb21Mn4Sb182021In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 60, no 9, p. 6702-6711Article in journal (Refereed)
    Abstract [en]

    A systematic investigation of the ternary system Yb-Mn-Sb led to the discovery of the novel phase Yb10MnSb9. Its crystal structure was characterized by single-crystal X-ray diffraction and found to be complex and highly disordered. The average Yb10MnSb9 structure can be considered to represent a defect modification of the Ca10LiMgSb9 type and to crystallize in the tetragonal P4(2)/mnm space group (No. 136) with four formula units per cell. The structural disorder can be associated with both occupational and positional effects on several Yb and Mn sites. Similar traits were observed for the structure of the recently reported Yb21Mn4Sb18 phase (monoclinic space group C2/c, No. 15), which was reevaluated as part of this study as well. In both structures, distorted Sb-6 octahedra centered by Yb atoms and Sb-4 tetrahedra centered by Mn atoms form disordered fragments, which appear as the hallmark of the structural chemistry in this system. Discussion along the lines of how difficult, and important, it is to distinguish Yb10MnSb9 from the compositionally similar binary Yb11Sb10 and ternary Yb14MnSb11 compounds is also presented. Preliminary transport measurements for polycrystalline Yb10MnSb9 indicate high values of the Seebeck coefficient, approaching 210 mu V K-1 at 600 K, and a semiconducting behavior with a room-temperature resistivity of 114 m Omega cm.

  • 28. Baranov, A. I.
    et al.
    Isaeva, A. A.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Popovkin, B. A.
    New metal-rich sulfides Ni6SnS2 and Ni9Sn2S2 with a 2D metal framework: Synthesis, crystal structure, and bonding2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, no 21, p. 6667-6672Article in journal (Refereed)
    Abstract [en]

    Two new, metal-rich nickel-tin sulfides Ni6SnS2 and Ni9Sn2S2 were found by establishing phase relations in the ternary Ni-Sn-S system at 540 degreesC. Their single crystals were prepared by means of chemical vapor transport reactions. Single crystal X-ray diffraction was used for the determination of their crystal structures. Both compounds crystallize in a tetragonal system (/4/mmm, No. 139, Z = 2, a = 3.646(1) Angstrom, c = 18.151(8) Angstrom for Ni6SnS2, and a = 3.678(1) Angstrom, c = 25.527(8) Angstrom for Ni9Sn2S2). Their crystal structures represent a new structure type and can be considered as assembled from bimetallic nickel-tin and nickel-sulfide slabs alternating along the crystallographic c axis. DFT band structure calculations showed the bonding within the bimetallic slabs to have a delocalized, multicenter nature, typical for metallic systems, and predominantly classical, pairwise bonding between nickel and sulfur.

  • 29. Baranov, A. I.
    et al.
    Kloo, Lars A.
    KTH, Superseded Departments (pre-2005), Chemistry.
    Olenev, A. V.
    Popovkin, B. A.
    Romanenko, A. I.
    Quasi-1D cations (1)(infinity) Ni8Bi8S (n+) of variable charge: Infinite columns (1)(infinity) Ni8Bi8S (2+) in the novel compound Ni(8)Bi(8)Sl(2)2003In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, no 13, p. 3988-3993Article in journal (Refereed)
    Abstract [en]

    The new compound Ni(8)Bi(8)Sl(2) has been synthesized and its crystal structure determined by X-ray crystallography. The structure contains one-dimensional (1D) cations (1)(infinity)[Ni8Bi8S](2+) separated by iodine anions. The geometry of the columns is similar to that of the recently reported (1)(infinity)[Ni8Bi8S](+), and the main difference between them is only their formal charge. Electronic structure calculations and physical properties measurements were performed to analyze the influence of the number of valence electrons on the bonding and properties of compounds containing these 1D cations. It was shown that the removal of one electron (i.e., (1)(infinity)[Ni8Bi8S](+) --> (1)(infinity)[Ni8Bi8S](2+)) mainly affects the Ni-S bonding within the cation and essentially has no influence on the intermetallic Ni-Bi bonding. It was found that Ni(8)Bi(8)Sl(2) containing double-charged columns has conductivity properties more similar to a pure 1D metal than the congener Ni(8)Bi(8)Sl containing mono-charged columns.

  • 30. Basnayake, Sajani A.
    et al.
    Su, Jie
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Balkus, Kenneth J., Jr.
    Carbonate-Based Zeolitic Imidazolate Framework for Highly Selective CO2 Capture2015In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, no 4, p. 1816-1821Article in journal (Refereed)
    Abstract [en]

    In this study, we report the formation of a new crystal structure, ZIF-CO3-1, which results from the reaction of Zn2+, 2-methylimidazole, and carbonate. ZIF-CO3-1 can be synthesized solvothermally in N,N-dimethylformamide (DMF)/water (H2O) or by utilizing of CO2 gas at various temperatures in DMF/H2O or H2O. This reaction selectively consumes CO2 because CO2 is incorporated in the ZIF as carbonate. CO2 can be quantitatively released by acidifying the ZIF. Powder X-ray diffraction, single-crystal X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, elemental analysis, and thermogravimetric analysis were used to characterize the ZIF structure. ZIF-CO3-1 (chemical formula C9H(10)N4O(3)Zn(2)), crystallizes in the orthorhombic crystal system with noncentrosymmetric space group Pba2.

  • 31.
    Bell, Thomas
    et al.
    Univ Cologne, Dept Chem, D-50939 Cologne, Germany..
    Smetana, Volodymyr
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Mudring, Anja-Verena
    Stockholm Univ, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden..
    Meyer, Gerd
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry. Univ Cologne, Dept Chem, D-50939 Cologne, Germany..
    Binary Intermetallics in the 70 atom % R Region of Two R-Pd Systems (R = Tb and Er): Hidden, Obscured, or Nonexistent?2020In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 59, no 15, p. 10802-10812Article in journal (Refereed)
    Abstract [en]

    Although rare-earth-metal-transition-metal (R/T) phase diagrams have been explored extensively, our recent studies have uncovered new previously nonexistent binary intermetallics. These compounds belong to a narrow region between 70 and 71.4 atom % of the rare-earth metal but represent four different structure types. The binaries Tb7Pd3 and Er17Pd7 are compositionally approaching (less than 1 atom % difference) the previously reported R2.16Pd0.89 (R = Tb and Er), and apparently form by peritectoid transformation, thus, being hard to detect by fast cooling. Tb7Pd3 (1) crystallizes in the Th7Fe3 structure type (hP20, P6(3)mc, a = 9.8846(4) angstrom, c = 6.2316(3) angstrom, Z = 2) while Er17Pd7 (2) belongs to the Pr17Co7 type being its second reported representative (cP96, P2(1)3, a = 13.365(2) degrees, Z = 4). Er17Pd7 (2) is overlapping with the cubic F-centered Er2.11Pd0.89 (3b, Fd (3) over barm, a = 13.361(1) angstrom, Z = 32) with practically identical unit cell parameters but a significantly different structure. Electronic structure calculations confirm that heteroatomic R-T bonding strongly dominates in all structures; T-T bonding interactions are individually strong but do not play a significant role in the total bonding.

  • 32. Bell, Thomas
    et al.
    Smetana, Volodymyr
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Mudring, Anja-Verena
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Meyer, Gerd H.
    Binary Intermetallics in the 70 atom % R Region of Two R-Pd Systems (R = Tb and Er): Hidden, Obscured, or Nonexistent?2020In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 59, no 15, p. 10802-10812Article in journal (Refereed)
    Abstract [en]

    Although rare-earth-metal-transition-metal (R/T) phase diagrams have been explored extensively, our recent studies have uncovered new previously nonexistent binary intermetallics. These compounds belong to a narrow region between 70 and 71.4 atom % of the rare-earth metal but represent four different structure types. The binaries Tb7Pd3 and Er17Pd7 are compositionally approaching (less than 1 atom % difference) the previously reported R2.16Pd0.89 (R = Tb and Er), and apparently form by peritectoid transformation, thus, being hard to detect by fast cooling. Tb7Pd3 (1) crystallizes in the Th7Fe3 structure type (hP20, P6(3)mc, a = 9.8846(4) angstrom, c = 6.2316(3) angstrom, Z = 2) while Er17Pd7 (2) belongs to the Pr17Co7 type being its second reported representative (cP96, P2(1)3, a = 13.365(2) degrees, Z = 4). Er17Pd7 (2) is overlapping with the cubic F-centered Er2.11Pd0.89 (3b, Fd (3) over barm, a = 13.361(1) angstrom, Z = 32) with practically identical unit cell parameters but a significantly different structure. Electronic structure calculations confirm that heteroatomic R-T bonding strongly dominates in all structures; T-T bonding interactions are individually strong but do not play a significant role in the total bonding.

  • 33. Benecke, Jannik
    et al.
    Svensson Grape, Erik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Fuß, Alexander
    Wöhlbrandt, Stephan
    Engesser, Tobias A.
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Stock, Norbert
    Reinsch, Helge
    Polymorphous Indium Metal-Organic Frameworks Based on a Ferrocene Linker: Redox Activity, Porosity, and Structural Diversity2020In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 59, no 14, p. 9969-9978Article in journal (Refereed)
    Abstract [en]

    The metallocene-based linker molecule 1,1'-ferrocenedicarboxylic acid (H(2)FcDC) was used to synthesize four different polymorphs of composition [In(OH)(FeC12H8O4)]. Using conventional solvent-based synthesis methods and varying the synthetic parameters such as metal source, reaction temperature, and solvent, two different MOFs and one ID-coordination polymer denoted as CAU-43 (1), In-MIL-53-FcDC_a (2), and InFcDC (3) were obtained. Furthermore, thermal treatment of CAU-43 (1) at 190 degrees C under vacuum yielded a new polymorph of 2, In-MIL-53-FcDC_b (4). Both MOFs 2 and 4 crystallize in a MIL-53 type structure, but in different space groups C2/m for 2 and P (1) over bar for 4. The structures of the four title compounds were determined by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), or a combination of three-dimensional electron diffraction measurements (3D ED) and PXRD. N-2 sorption experiments of 1, 2, and 4 showed specific surface areas of 355 m(2) g(-)(1), 110 m(2) g(-1), and 140 m(2) g(-)(1), respectively. Furthermore, the electronic properties of the title compounds were characterized via Mossbauer and EPR spectroscopy. All Mossbauer spectra showed the characteristic doublet, proving the persistence of the ferrocene moiety. In the cases of 1, 3, and 4, appreciable impurities of ferrocenium ions could be detected by electron paramagnetic resonance spectroscopy. Cyclovoltammetric experiments were performed to demonstrate the accessible redox activity of the linker molecule of the title compounds. A redox process of FcDC(2-) with oxidation (between 0.86 and 0.97 V) and reduction wave (between 0.69 and 0.80 V) was observed.

  • 34. Benson, D.
    et al.
    Li, Y.
    Luo, Wei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden .
    Ahuja, Rajeev
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, SE-751 20 Uppsala, Sweden .
    Svensson, G.
    Häussermann, U.
    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 C2 2- dumbbell anions. The systems develop into semimetals (P3Ì...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 stabilized by electrostatic interactions with surrounding cations add a new feature to carbon chemistry. Semimetallic P3Ì...m1-Li2C 2 displays an electronic structure close to that of graphene. The π* 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.

  • 35. 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.

  • 36. Benson, Daryn
    et al.
    Li, Yanling
    Luo, Wei
    Ahuja, Rajeev
    Svensson, Gunnar
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Häussermann, Ulrich
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    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.

    Download full text (pdf)
    Polymeric Carbon Structures
  • 37.
    Berger, Gilles
    et al.
    Univ Libre Bruxelles, Fac Pharm, Microbiol Bioorgan & Macromol Chem, B-1050 Brussels, Belgium.;Harvard Med Sch, Brigham & Womens Hosp, Dept Neurosurg, Harvey Cushing Neurooncol Labs, Boston, MA 02115 USA.;MIT, Dept Chem, Cambridge, MA 02139 USA..
    Wach, Anna
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, PL-01224 Warsaw, Poland..
    Szlachetko, Jakub
    Polish Acad Sci, Inst Nucl Phys, PL-31342 Krakow, Poland..
    Reduction Mechanisms of Anticancer Osmium(VI) Complexes Revealed by Atomic Telemetry and Theoretical Calculations2021In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 60, no 9, p. 6663-6671Article in journal (Refereed)
    Abstract [en]

    Resonant X-ray emission spectroscopy (RXES) has developed in the past decade as a powerful tool to probe the chemical state of a metal center and in situ study chemical reactions. We have used it to monitor spectral changes associated with the reduction of osmium(VI) nitrido complexes to the osmium(III) ammine state by the biologically relevant reducing agent, glutathione. RXES difference maps are consistent with the proposed DFT mechanism and the formation of two stable osmium(IV) intermediates, thereby supporting the overall pathway for the reduction of these high-valent anticancer metal complexes for which reduction by thiols within cells may be essential to the antiproliferative activity.

  • 38.
    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.

  • 39. Berggren, Gustav
    et al.
    Thapper, Anders
    Huang, Ping
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Styring, Stenbjörn
    Ander, Magnus F.
    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 complexes consisting of Mn(2)(IV,IV)(mu-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.

  • 40.
    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.

  • 41. Bi, L. -H
    et al.
    Al-Kadamany, G.
    Chubarova, Elena V.
    Jacobs University, United States .
    Dickman, M. H.
    Chen, L.
    Gopala, D. S.
    Richards, R. M.
    Kelta, B.
    Nadjo, L.
    Jaensch, H.
    Mathys, G.
    Kortz, U.
    Organo-ruthenium supported heteropolytungstates: synthesis, structure, electrochemistry, and oxidation catalysis2009In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 48, no 21, p. 10068-10077Article in journal (Refereed)
    Abstract [en]

    The reaction of [Ru(arene)Cl2]2 (arene = benzene, p-cymene) with [X2W22O74(OH)2] 12- (X = SbIII, BiIII) In buffer medium resulted In four organo-ruthenium supported heteropolytungstates, [Sb 2W20O70(RuC6H6) 2]10 (1), [Bi2W20O 70(RuC6H6)2]10- (2), [Sb2W20O7o(RuC10H14) 2]10- (3), and [Bi2W20O 70(RuC10H14)2]10- (4), which have been characterized in solution by multinuclear (183W, 13C, 1H) NMR, UV-vis spectroscopy, electrochemistry, and in the solid state by single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and elemental analysis. Polyanions 1, 2, and 4 crystallize in the triclinic system, space group P1 with the following unit cell parameters: K5Na5[Sb2W20O 7o(RuC6H6)2]·22H 2O (KNa-1), a= 12.1625(2)Å, b = 13.1677(2) Å, C= 16.0141(3)Å α = 78.9201 (7)°, β = 74.4442(8)°, γ = 78.9019(8)°, and Z= 1 ; Cs2Na8[Bi2W 20O7o(RuC6H6)2] · 30H2O (CsNa-2), a = 11.6353(7) Å b = 13.3638(7) Å, C= 16.7067(8) Å, a = 79.568(2)°, β = 71.103(2)°, γ = 80.331(2)°, and Z= 1; Na10[Bi2W20O 70(RuC10H14)2]-35H20 (Na-4), a = 15.7376(12) Å b = 15.9806(13) Å, c = 24.2909(19) Å, α = 92.109(4)°, β = 101.354(4)°, γ = 97.365(3)°, and Z= 2. Polyanions 1-4 consist of two (L)Ru2+ (L = benzene or p-cymene) units linked to a [X2W20O70]14 (X=Sb III BiIII fragment via Ru-O(W) bonds resulting in an assembly with idealized C2h symmetry. Polyanions 1-4 are stable in solution as indicated by the expected 183W, 13C, and 1H NMR spectra. The electrochemistry of 1-4 is described by considering the reduction and the oxidation processes. The nature of the arene In Ru(arene) has practically no influence on the formal potentials of the W-centers, which are more sensitive to the Sb or Bi hetera atoms. The results suggest that the respective Sb- and Bi derivatives have very different pK a values, with the reduced form of 1 being the most basic, thus permitting the observation of two well-developed voltammetric waves at pH 6. In contrast, the identity of the arene influences the oxidation processes, thus permitting to distinguish them. A strong electrocatalytic water oxidation peak is observed that is more positive than the one corresponding to the Ru(arene) oxidation process. Also a stepwise oxidation of the Ru(benzene) group could be observed at pH 3. The catalytic efficiency, on the other hand, of 1-4 toward the oxidation of n-hexadecane and p-xylene illustrated the effect of ruthenium substitution on the polyanion catalytic performance.

  • 42.
    Bibik, Yurii S.
    et al.
    Department of Chemistry, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., 01601 Kyiv, Ukraine.
    Shova, Sergiu
    “Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, 700487 Iaşi, Romania.
    Rotaru, Aurelian
    Faculty of Electrical Engineering and Computer Science & MANSiD Research Center, Ştefan cel Mare University, Universitatii St. 13, 720229 Suceava, Romania.
    Shylin, Sergii I.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Fritsky, Igor O.
    Department of Chemistry, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., 01601 Kyiv, Ukraine.
    Lampeka, Rostyslav D.
    Department of Chemistry, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., 01601 Kyiv, Ukraine.
    Gural’skiy, Il’ya A.
    Department of Chemistry, Taras Shevchenko National University of Kyiv, 64 Volodymyrska St., 01601 Kyiv, Ukraine.
    Cooperative Spin Crossover above Room Temperature in the Iron(II) Cyanoborohydride–Pyrazine Complex2022In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 61, no 37, p. 14761-14769Article in journal (Refereed)
    Abstract [en]

    Hysteretic spin crossover in coordination complexes of 3d-metal ions represents one of the most spectacular phenomena of molecular bistability. In this paper we describe a self-assembly of pyrazine (pz) and Fe(BH3CN)2 that afforded the new 2D coordination polymer [Fe(pz)2(BH3CN)2]. It undergoes an abrupt, hysteretic spin crossover (SCO) with a T1/2 of 338 K (heating) and 326 K (cooling) according to magnetic susceptibility measurements. Mössbauer spectroscopy revealed a complete transition between the low-spin (LS) and the high-spin (HS) states of the iron centers. This LS-to-HS transition induced an increase of the unit cell volume by 10.6%. Meanwhile, a modulation of multiple [C–Hδ+···Hδ−–B] dihydrogen bonds stimulates a contraction in direction c (2.2%). The simplicity of the synthesis, mild temperatures of transition, a pronounced thermochromism, stability upon thermal cycling, a striking volume expansion upon SCO, and an easy processability to composite films make this new complex an attractive material for switchable components of diverse applications.

  • 43.
    Blomberg, Margareta R. A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Role of the Two Metals in the Active Sites of Heme Copper Oxidases-A Study of NO Reduction in cbb(3) Cytochrome c Oxidase2020In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 59, no 16, p. 11542-11553Article in journal (Refereed)
    Abstract [en]

    The superfamily of heme copper oxidases reduces molecular oxygen or nitric oxide, and the active sites comprise a high-spin heme group (a(3) or b(3)) and a non-heme metal (Cu-B or Fe-B). The cbb(3) C family of cytochrome c oxidases, with the highspin heme b(3) and CUB in the active site, is a subfamily of the heme copper oxidases that can reduce both molecular oxygen, which is the main substrate, and nitric oxide. The mechanism for NO reduction in cbb(3) oxidase is studied here using hybrid density functional theory and compared to other cytochrome c oxidases (A and B families), with a high-spin heme a(3) and Cu-B in the active site, and to cytochrome c dependent NO reductase, with a high-spin heme b(3) and a nonheme Fe-B in the active site. It is found that the reaction mechanism and the detailed reaction energetics of the cbb(3) oxidases are not similar to those of cytochrome c dependent NO reductase, which has the same type of high-spin heme group but a different nonheme metal. This is in contrast to earlier expectations. Instead, the NO reduction mechanism in cbb(3) oxidases is very similar to that in the other cytochrome c oxidases, with the same non-heme metal, CUB, and is independent of the type of high-spin heme group. The conclusion is that the type of non-heme metal (CUB or Fe-B) in the active site of the heme copper oxidases is more important for the reaction mechanisms than the type of high-spin heme, at least for the NO reduction reaction. The reason is that the protoncoupled reduction potentials of the active site cofactors determine the energetics for the NO reduction reaction, and they depend to a larger extent on the non-heme metal. Observed differences in NO reduction reactivity among the various cytochrome c oxidases may be explained by differences outside the BNC, affecting the rate of proton transfer, rather than in the BNC itself.

  • 44. Blomberg, Margareta R. A.
    et al.
    Johansson, Adam Johannes
    Stockholm University.
    Siegbahn, Per E. M.
    O-O bond cleavage in dinuclear peroxo complexes of iron porphyrins: a quantum chemical study2007In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, no 19, p. 7992-7997Article in journal (Refereed)
    Abstract [en]

    To gain insight into the mechanisms of O-2 activation and cleavage in metalloenzymes, biomimetic metal complexes have been constructed and experimentally characterized. One such model complex is the dinuclear peroxo complex of iron porphyrins observed at low temperature in a noncoordinating solvent. The present theoretical study examines the O-O bond cleavage in these complexes, experimentally observed to occur either at increased temperature or when a strongly coordinating base is added. Using hybrid density functional theory, it is shown that the O-O bond cleavage always occurs in a state where two low-spin irons (S = +/- 1/2) are antiferromagnetically coupled to a diamagnetic state. This state is the ground state when the strong base is present and forms an axial ligand to the free iron positions. In contrast, without the axial ligands, the ground state of the clinuclear peroxo complex has two high-spin irons (S = +/- 5/2) coupled antiferromagnetically. Thus, the activation barrier for O-O bond cleavage is higher without the base because it includes also the promotion energy from the ground state to the reacting state. It is further found that this excitation energy, going from 10 unpaired electrons in the high-spin case to 2 in the low-spin case, is unusually difficult to determine accurately from density functional theory because it is extremely sensitive to the amount of exact exchange included in the functional.

  • 45. Bodor, A.
    et al.
    Toth, I.
    Banyai, I.
    Szabo, Zoltan
    KTH, Superseded Departments (pre-2005), Chemistry.
    Hefter, G. T.
    F-19 NMR study of the equilibria and dynamics of the Al3+/F- system2000In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 39, no 12, p. 2530-2537Article in journal (Refereed)
    Abstract [en]

    A careful reinvestigation by high-field F-19 NMR (470 MHz) spectroscopy has been made of the Al3+/F- system in aqueous solution under carefully controlled conditions of pH, concentration, ionic strength (I), and temperature. The F-19 NMR spectra show five distinct signals at 278 K and I = 0.6 M (TMACl) which have been attributed to the complexes AlFi(3-i)+(aq) with i less than or equal to 5. There was no need to invoke AlFi(OH)(j)((3-i-j)+) mixed complexes in the model under our experimental conditions (pH less than or equal to 6.5), nor was any evidence obtained for the formation of AlF63-(aq) at very high ratios of F-/Al3+. The stepwise equilibrium constants obtained for the complexes by integration of the F-19 signals are in good agreement with literature data given the differences in medium and temperature. In I = 0.6 M TMACl at 278 K and in I = 3 M KCl at 298 K the log K-i values are 6.42, 5.31, 3.99, 2.50, and 0.84 (for species i = 1-5) and 6.35, 5.25, and 4.11 (for species i = 1-3), respectively. Disappearance of the F-19 NMR signals under certain conditions was shown to be due to precipitation. Certain 19F NMR signals exhibit temperature- and concentration-dependent exchange broadening. Detailed line shape analysis of the spectra and magnetization transfer measurements indicate that the kinetics are dominated by F- exchange rather than complex formation. The detected reactions and their rate constants are AlF22+ + *F- reversible arrow AIF*F2+ + F- (k(02) = (1.8 +/- 0.3) x 10(6) M-1 s(-1)), AlF30 + *F- reversible arrow (AlF2F0)-F-* + F- (k(03) = (3.9 +/- 0.9) x 10(6) M-1 s(-1)), and AlF30 + H*F reversible arrow AlF2*F-0 + HF (k(03)(H) = (6.6 +/- 0.5) x 10(4) M-1 s(-1)). The rates of these exchange reactions increase markedly with increasing F- substitution. Thus, the reactions of AlF2+(aq) were too inert to be detected even on the T-1 NMR time scale, while some of the reactions of AlF30(aq) were fast, causing large line broadening. The ligand exchange appears to follow an associative interchange mechanism. The cis-trans isomerization of AlF2+(aq), consistent with octahedral geometry for that complex, is slowed sufficiently to be observed at temperatures around 270 R. Difference between the Al3+/F- system and the much studied Al3+/OH- system are briefly commented on.

  • 46.
    Boniolo, Manuel
    et al.
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Hossain, Md Kamal
    Synthetic Molecular Chemistry, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Chernev, Petko
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Suremann, Nina F.
    Synthetic Molecular Chemistry, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Heizmann, Philipp A.
    Synthetic Molecular Chemistry, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Lyvik, Amanda S.L.
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Beyer, Paul
    Physics Department, Freie Universität Berlin, Berlin, Germany.
    Haumann, Michael
    Physics Department, Freie Universität Berlin, Berlin, Germany.
    Huang, Ping
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Salhi, Nessima
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Cheah, Mun Hon
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Shylin, Sergii I.
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Lundberg, Marcus
    Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Thapper, Anders
    Synthetic Molecular Chemistry, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Molecular Biomimetics, Department of Chemistry, Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Water Oxidation by Pentapyridyl Base Metal Complexes? A Case Study2022In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 61, no 24, p. 9104-9118Article in journal (Refereed)
    Abstract [en]

    The design of molecular water oxidation catalysts (WOCs) requires a rational approach that considers the intermediate steps of the catalytic cycle, including water binding, deprotonation, storage of oxidizing equivalents, O-O bond formation, and O2 release. We investigated several of these properties for a series of base metal complexes (M = Mn, Fe, Co, Ni) bearing two variants of a pentapyridyl ligand framework, of which some were reported previously to be active WOCs. We found that only [Fe(Py5OMe)Cl]+ (Py5OMe = pyridine-2,6-diylbis[di-(pyridin-2-yl)methoxymethane]) showed an appreciable catalytic activity with a turnover number (TON) = 130 in light-driven experiments using the [Ru(bpy)3]2+/S2O82- system at pH 8.0, but that activity is demonstrated to arise from the rapid degradation in the buffered solution leading to the formation of catalytically active amorphous iron oxide/hydroxide (FeOOH), which subsequently lost the catalytic activity by forming more extensive and structured FeOOH species. The detailed analysis of the redox and water-binding properties employing electrochemistry, X-ray absorption spectroscopy (XAS), UV-vis spectroscopy, and density-functional theory (DFT) showed that all complexes were able to undergo the MIII/MII oxidation, but none was able to yield a detectable amount of a MIV state in our potential window (up to +2 V vs SHE). This inability was traced to (i) the preference for binding Cl- or acetonitrile instead of water-derived species in the apical position, which excludes redox leveling via proton coupled electron transfer, and (ii) the lack of sigma donor ligands that would stabilize oxidation states beyond MIII. On that basis, design features for next-generation molecular WOCs are suggested.

    Download full text (pdf)
    fulltext
  • 47.
    Boniolo, Manuel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hossain, Md Kamal
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Chernev, Petko
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Suremann, Nina F.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Heizmann, Philipp A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Lyvik, Amanda S.L.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Beyer, Paul
    Physics Department, Freie Universität Berlin, 14195 Berlin, Germany.
    Haumann, Michael
    Physics Department, Freie Universität Berlin, 14195 Berlin, Germany.
    Huang, Ping
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Salhi-Benachenhou, Nessima
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Cheah, Mun Hon
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Shylin, Sergii I.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Lundberg, Marcus
    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, Synthetic Molecular Chemistry.
    Messinger, Johannes
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Department of Chemistry, Chemical Biological Centre, Umeå University, 90187 Umeå, Sweden.
    Water Oxidation by Pentapyridyl Base Metal Complexes?: A Case Study2022In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 61, no 24, p. 9104-9118Article in journal (Refereed)
    Abstract [en]

    The design of molecular water oxidation catalysts (WOCs) requires a rational approach that considers the intermediate steps of the catalytic cycle, including water binding, deprotonation, storage of oxidizing equivalents, O–O bond formation, and O2 release. We investigated several of these properties for a series of base metal complexes (M = Mn, Fe, Co, Ni) bearing two variants of a pentapyridyl ligand framework, of which some were reported previously to be active WOCs. We found that only [Fe(Py5OMe)Cl]+ (Py5OMe = pyridine-2,6-diylbis[di-(pyridin-2-yl)methoxymethane]) showed an appreciable catalytic activity with a turnover number (TON) = 130 in light-driven experiments using the [Ru(bpy)3]2+/S2O82– system at pH 8.0, but that activity is demonstrated to arise from the rapid degradation in the buffered solution leading to the formation of catalytically active amorphous iron oxide/hydroxide (FeOOH), which subsequently lost the catalytic activity by forming more extensive and structured FeOOH species. The detailed analysis of the redox and water-binding properties employing electrochemistry, X-ray absorption spectroscopy (XAS), UV–vis spectroscopy, and density-functional theory (DFT) showed that all complexes were able to undergo the MIII/MII oxidation, but none was able to yield a detectable amount of a MIV state in our potential window (up to +2 V vs SHE). This inability was traced to (i) the preference for binding Cl– or acetonitrile instead of water-derived species in the apical position, which excludes redox leveling via proton coupled electron transfer, and (ii) the lack of sigma donor ligands that would stabilize oxidation states beyond MIII. On that basis, design features for next-generation molecular WOCs are suggested.

    Download full text (pdf)
    fulltext
  • 48.
    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.

  • 49.
    Bonneau, Charlotte
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Sanchez-Smith, Rebeca
    Guo, Bing
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Zhang, Daliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Inge, Andrew Kentaro
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Open-Framework Germanate Built from the Hexagonal Packing of Rigid Cylinders2009In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 48, no 21, p. 9962-9964Article in journal (Refereed)
    Abstract [en]

    We present a novel open-framework oxide material constructed from Ge10(O,OH)28 (Ge10) oxide clusters prepared via a nonsurfactant route. The material shows two distinct pore windows of 9.43 and 4.65 Å and a low framework density structure of 12.7 Ge atoms per 1000 Å3. The topological study leads to the recognition of a newly observed trinodal 6,7-heterocoordinated net related to the 7-coordinated swh net. The structure displays large rigid cylinders showing features indicating a growth mechanism by hard-sphere packing of the inorganic moiety similar to that observed in mesoporous materials.

  • 50. Borgstrom, M.
    et al.
    Johansson, O.
    Lomoth, R.
    Baudin, H. B.
    Wallin, S.
    Sun, Licheng C.
    Akermark, B.
    Hammarstrom, L.
    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, no 17, p. 5173-5184Article in journal (Refereed)
    Abstract [en]

    Two electron donor-acceptor triads based on a benzoquinone acceptor linked to a light absorbing [Ru(bpy)(3)](2+) complex have been synthesized. In triad 6 (denoted Ru-II-BQ-Co-III), a [Co(bpy)(3)](3+) complex, a potential secondary acceptor, was linked to the quinone. In the other triad, 8 (denoted PTZ-Ru-II-BQ), a phenothiazine donor was linked to the ruthenium moiety. The corresponding dyads Ru-II-BQ (4) and PTZ-Ru-II (9) were prepared for comparison. Upon light excitation in the visible band of the ruthenium moiety, electron transfer to the quinone occurred with a rate constant k(1) = 5 x 10(9) s(-1) (tau(1) = 200 ps) in all the quinone containing complexes. Recombination to the ground state followed, with a rate constant k(b) similar to 4.5 x 10(8) s(-1) (tau(b) similar to 2.2 ns), for both Ru-II-BQ and Ru-II-BQ-Co-III with no indication of a charge shift to generate the reduced Coll moiety. In the PTZ-Ru-II-BQ triad, however, the initial charge separation was followed by a rapid (k > 5 x 10(9) s(-1)) electron transfer from the phenothiazine moiety to give the fairly long-lived PTZ(.+)-Ru-II-BQ(.-) state (tau = 80 ns) in unusually high yield for a [Ru(bPY)(3)](2+)- based triad (> 90%), that lies at DeltaGdegrees = 1.32 eV relative to the ground state. Unfortunately, this triad turned out to be rather photolabile. Interestingly, coupling between the oxidized PTZ(.+) and the BQ(.-) moieties seemed to occur. This discouraged further extension to incorporate more redox active units. Finally, in the dyad PTZ-Ru-II a reversible, near isoergonic electron transfer was observed on excitation. Thus, a quasiequilibrium was established with an observed time constant of 7 ns, with ca. 82% of the population in the PTZ-Ru-*(II) state and 18% in the PTZ(.+)Ru(II)(bpy(.-)) state. These states decayed in parallel with an observed lifetime of 90 ns. The initial electron transfer to form the PTZ(.+)-Ru-II(bpy(.-)) state was thus faster than what would have been inferred from the Ru-*(II) emission decay (tau = 90 ns). This result suggests that reports for related PTZ-Ru-II and PTZ-Ru-II-acceptor complexes in the literature might need to be reconsidered.

1234567 1 - 50 of 421
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf