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  • 1.
    Anderlund, Magnus F.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Högblom, Joakim
    Shi, Wei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Huang, Ping
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Eriksson, Lars
    Weihe, Högni
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Åkermark, Björn
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Magnuson, Ann
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Redox chemistry of a dimanganese(II,III) complex with an unsymmetric ligand: Water binding, deprotonation and accumulative light-induced oxidation2006Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 24, s. 5033-5047Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dinuclear manganese complex {[(Mn2L)-L-II,IIII(mu-OAc)(2)]-ClO4} has been synthesised, where L is the dianion of 2-{[bis-(pyrid-2-ylmethyl)amino]methyl}-6-{[(3,5-di-tert-butyl-2- hydroxybenzyl)(pyrid-2-ylmethyl)amino]methyl)-4-methylphenol, an unsymmetric binucleating ligand with two coordinating phenol groups. The two manganese ions, with a Mn-Mn distance of 3.498 angstrom, are bridged by the two bidentate acetate ligands and the 4-methylphenolate group of the ligand, resulting in a N3O3 and N2O4 donor set of Mn-II and Mn-II, respectively. Electrochemically [Mn2(II,III)L(mu-OAc)(2)](+) is reduced to [(Mn2L)-L-II,II(mu-OAc)(2)] at E-1/2(1)=-0.53 V versus Fc(+/0) and oxidised to [(Mn2L)-L-III,III(mu-OAC)(2)](2+) at E-1/2(2)=0.38 V versus Fc(+/0). All three redox states have been characterised by EPR, IR and UV/Vis spectroscopy. Subsequent oxidation of [(Mn2L)-L-II,III(mu-OAc)(2)](2+) [E-1/2(3)=0.75 V vs. Fc(+/0)] in dry acetonitrile results in an unstable primary product with a lifetime of about 100 ins. At high scan rates quasireversible voltammetric behaviour is found for all three electrode processes, with particularly slow electron transfer for the II,III/II,II [k(o)(1) = 0.002 cms(-1) and III,III/II,III [k(o)(2) = 0.005 cms(-1)] couples, which can be rationalised in terms of major distortions of the Mn-II centres. In aqueous media the bridging acetates are replaced by water-derived ligands. Deprotonation of these stabilises higher valence states, and photo-induced oxidation of the manganese complex results in a (Mn2L)-L-IlI,IV complex with oxo or hydroxo bridging ligands, which is further oxidised to an EPR-silent product. These results demonstrate that a larger number of metal-centred oxidations can be compressed in a narrow potential range if build up of charge is avoided by charge-compensating reactions.

  • 2.
    Arkhypchuk, Anna I.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Mijangos, Edgar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Redox Switching in Ethenyl- Bridged Bisphospholes2014Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 49, s. 16083-16087Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 2e(-)/2H(+) redox platform has been implemented in the ethenyl-bridged bisphosphol-3-ol 1 to afford the first phospholes that feature chemically reversible oxidations. Oxidation of the title compounds to the corresponding bisphosphol-3-one 2 leads to a change in conjugation topology and a concomitant hypsochromic shift of the lowest-energy absorption maximum by 100nm. Electrochemical oxidation proceeds without any detectable intermediates, whereas the deprotonated form of 1 can be observed in an aprotic medium during the reduction of 2. This dianionic intermediate 3 is characterized by end absorptions that are bathochromically shifted by circa 200nm compared to those of 2.

  • 3.
    Aster, Alexander
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström. Univ Geneva, Dept Phys Chem, 30 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland.
    Wang, Shihuai
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Mirmohades, Mohammad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Esmieu, Charlène
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik. CNRS, LCC, 205 Route Narbonne,BP 44099, F-31077 Toulouse 4, France.
    Berggren, Gustav
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Metal vs. ligand protonation and the alleged proton-shuttling role of the azadithiolate ligand in catalytic H-2 formation with FeFe hydrogenase model complexes2019Inngår i: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 10, nr 21, s. 5582-5588Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electron and proton transfer reactions of diiron complexes [Fe(2)adt(CO)(6)] (1) and [Fe(2)adt(CO)(4)(PMe3)(2)] (4), with the biomimetic azadithiolate (adt) bridging ligand, have been investigated by real-time IR- and UV-vis-spectroscopic observation to elucidate the role of the adt-N as a potential proton shuttle in catalytic H-2 formation. Protonation of the one-electron reduced complex, 1(-), occurs on the adt-N yielding 1H and the same species is obtained by one-electron reduction of 1H(+). The preference for ligand vs. metal protonation in the Fe-2(i,0) state is presumably kinetic but no evidence for tautomerization of 1H to the hydride 1Hy was observed. This shows that the adt ligand does not work as a proton relay in the formation of hydride intermediates in the reduced catalyst. A hydride intermediate 1HHy(+) is formed only by protonation of 1H with stronger acid. Adt protonation results in reduction of the catalyst at much less negative potential, but subsequent protonation of the metal centers is not slowed down, as would be expected according to the decrease in basicity. Thus, the adtH(+) complex retains a high turnover frequency at the lowered overpotential. Instead of proton shuttling, we propose that this gain in catalytic performance compared to the propyldithiolate analogue might be rationalized in terms of lower reorganization energy for hydride formation with bulk acid upon adt protonation.

  • 4.
    Beyler, Maryline
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Ezzaher, Salah
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Karnahl, Michael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Santoni, Marie-Pierre
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Pentacoordinate iron complexes as functional models of the distal iron in [FeFe] hydrogenases2011Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 47, nr 42, s. 11662-11664Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mononuclear pentacoordinate iron complexes with a free coordination site were prepared as mimics of the distal Fe (Fe(d)) in the active site of [FeFe] hydrogenases. The complexes catalyze the electrochemical reduction of protons at mild overpotential.

  • 5.
    Borgström, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Johansson, Olof
    Lomoth, Reiner
    Berglund-Baudin, Helena
    Wallin, Staffan
    Sun, Licheng
    Åkermark, Björn
    Hammarström, Leif
    Electron Donor-Acceptor Dyads and Triads Based on Tris(bipyridine) Ruthenium(II) and Benzoquinone: Synthesis, Characterization, and Photoinduced Electron Transfer Reactions2003Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, s. 5173-5184Artikkel i tidsskrift (Fagfellevurdert)
  • 6.
    Borgström, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Ott, Sascha
    Lomoth, Reiner
    Bergquist, Jonas
    Hammarström, Leif
    Johansson, Olof
    Femtosecond Pump-Pump-Probe Investigation of a Ru(II)-Ru(II)-Acceptor Triad: Attempts at Achieving High Energy Charge-Separated StatesManuskript (Annet vitenskapelig)
  • 7.
    Borgström, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi. Fysikalisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Bergquist, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi. Analytisk kemi.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Johansson, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Photoinduced energy transfer coupled to charge separation in a Ru(II)-Ru(II)-acceptor triad.2006Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 45, nr 12, s. 4820-4829Artikkel i tidsskrift (Fagfellevurdert)
  • 8. Canton, Sophie E.
    et al.
    Zhang, Xiaoyi
    Zhang, Jianxin
    van Driel, Tim B.
    Kjaer, Kasper S.
    Haldrup, Kristoffer
    Chabera, Pavel
    Harlang, Tobias
    Suarez-Alcantara, Karina
    Liu, Yizhu
    Perez, Jorge
    Bordage, Amelie
    Papai, Matyas
    Vanko, Gyoergy
    Jennings, Guy
    Kurtz, Charles A.
    Rovezzi, Mauro
    Glatzel, Pieter
    Smolentsev, Grigory
    Uhlig, Jens
    Dohn, Asmus O.
    Christensen, Morten
    Galler, Andreas
    Gawelda, Wojciech
    Bressler, Christian
    Lemke, Henrik T.
    Moller, Klaus B.
    Nielsen, Martin M.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Warnmark, Kenneth
    Sundstrom, Villy
    Toward Highlighting the Ultrafast Electron Transfer Dynamics at the Optically Dark Sites of Photocatalysts2013Inngår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 4, nr 11, s. 1972-1976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Building a detailed understanding of the structure function relationship is a crucial step in the optimization of molecular photocatalysts employed in water splitting schemes. The optically dark nature of their active sites usually prevents a complete mapping of the photoinduced dynamics. In this work, transient X-ray absorption spectroscopy highlights the electronic and geometric changes that affect such a center in a bimetallic model complex. Upon selective excitation of the ruthenium chromophore, the cobalt moiety is reduced through intramolecular electron transfer and undergoes a spin flip accompanied by an average bond elongation of 0.20 +/- 0.03 angstrom. The analysis is supported by simulations based on density functional theory structures (B3LYP*/TZVP) and FEFF 9.0 multiple scattering calculations. More generally, these results exemplify the large potential of the technique for tracking elusive intermediates that impart unique functionalities in photochemical devices.

  • 9.
    Chabera, Pavel
    et al.
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Kjaer, Kasper S.
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden.;Stanford Univ, SLAC Natl Accelerator Lab, PULSE Inst, Menlo Pk, CA 94025 USA..
    Prakash, Om
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Honarfar, Alireza
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Liu, Yizhu
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Fredin, Lisa A.
    Lund Univ, Dept Chem, Div Theoret Chem, Box 124, SE-22100 Lund, Sweden..
    Harlang, Tobias C. B.
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Lidin, Sven
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Uhlig, Jens
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Sundstrom, Villy
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Persson, Petter
    Lund Univ, Dept Chem, Div Theoret Chem, Box 124, SE-22100 Lund, Sweden..
    Warnmark, Kenneth
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Fe-II Hexa N-Heterocyclic Carbene Complex with a 528 ps Metal-to-Ligand Charge-Transfer Excited-State Lifetime2018Inngår i: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 9, nr 3, s. 459-463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The iron carbene complex [Fe-II(btz)(3)](PF6)(2) (where btz = 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene)) has been synthesized, isolated, and characterized as a low-spin ferrous complex. It exhibits strong metal-to-ligand charge transfer (MLCT) absorption bands throughout the visible spectrum, and excitation of these bands gives rise to a (MLCT)-M-3 state with a 528 ps excited-state lifetime in CH3CN solution that is more than one order of magnitude longer compared with the MLCT lifetime of any previously reported Fe-II complex. The low potential of the [Fe(btz)(3)](3+)/[Fe(btz)(3)](2+) redox couple makes the (MLCT)-M-3 state of [Fe-II(btz)(3)](2+) a potent photo-reductant that can be generated by light absorption throughout the visible spectrum. Taken together with our recent results on the [Fe-III(btz)(3)](3+) form of this complex, these results show that the Fe-II and Fe-III oxidation states of the same Fe(btz)(3) complex feature long-lived MLCT and LMCT states, respectively, demonstrating the versatility of iron N-heterocyclic carbene complexes as promising light-harvesters for a broad range of oxidizing and reducing conditions.

  • 10.
    Chabera, Pavel
    et al.
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Liu, Yizhu
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Prakash, Om
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Thyrhaug, Erling
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    El Nahhas, Amal
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Honarfar, Alireza
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Essen, Sofia
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Fredin, Lisa A.
    Lund Univ, Dept Chem, Div Theoret Chem, Box 124, SE-22100 Lund, Sweden..
    Harlang, Tobias C. B.
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden.;Tech Univ Denmark, Dept Phys, DK-2800 Lyngby, Denmark..
    Kjaer, Kasper S.
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden.;Tech Univ Denmark, Dept Phys, DK-2800 Lyngby, Denmark..
    Handrup, Karsten
    Lund Univ, Dept Phys, Div Synchrotron Radiat Res, Box 118, SE-22100 Lund, Sweden..
    Ericson, Fredric
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrosystemteknik.
    Tatsuno, Hideyuki
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Morgan, Kelsey
    NIST, Boulder, CO 80305 USA..
    Schnadt, Joachim
    Lund Univ, Dept Phys, Div Synchrotron Radiat Res, Box 118, SE-22100 Lund, Sweden..
    Häggström, Lennart
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Ericsson, Tore
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Sobkowiak, Adam
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Strukturkemi.
    Lidin, Sven
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    Huang, Ping
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Uhlig, Jens
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Bendix, Jesper
    Univ Copenhagen, Dept Chem, Univ Pk 5, DK-2100 Copenhagen, Denmark..
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sundström, Villy
    Lund Univ, Dept Chem, Div Phys Chem, Box 124, SE-22100 Lund, Sweden..
    Persson, Petter
    Lund Univ, Dept Chem, Div Theoret Chem, Box 124, SE-22100 Lund, Sweden..
    Warnmark, Kenneth
    Lund Univ, Dept Chem, CAS, Box 124, SE-22100 Lund, Sweden..
    A low-spin Fe(III) complex with 100-ps ligand-to-metal charge transfer photoluminescence2017Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 543, nr 7647, s. 695-+Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transition-metal complexes are used as photosensitizers(1), in light-emitting diodes, for biosensing and in photocatalysis(2). A key feature in these applications is excitation from the ground state to a charge-transfer state(3,4); the long charge-transfer-state lifetimes typical for complexes of ruthenium(5) and other precious metals are often essential to ensure high performance. There is much interest in replacing these scarce elements with Earth-abundant metals, with iron(6) and copper(7) being particularly attractive owing to their low cost and non-toxicity. But despite the exploration of innovative molecular designs(6,8-10), it remains a formidable scientific challenge(11) to access Earth-abundant transition-metal complexes with long-lived charge-transfer excited states. No known iron complexes are considered(12) photoluminescent at room temperature, and their rapid excited-state deactivation precludes their use as photosensitizers(13-15). Here we present the iron complex [Fe(btz)(3)](3+) (where btz is 3,3'-dimethyl-1,1'-bis(p-tolyl)-4,4'-bis(1,2,3-triazol-5-ylidene)), and show that the superior sigma-donor and pi-acceptor electron properties of the ligand stabilize the excited state sufficiently to realize a long charge-transfer lifetime of 100 picoseconds (ps) and room-temperature photoluminescence. This species is a low-spin Fe(III) d(5) complex, and emission occurs from a long-lived doublet ligand-to-metal charge-transfer ((LMCT)-L-2) state that is rarely seen for transition-metal complexes(4,16,17). The absence of intersystem crossing, which often gives rise to large excited-state energy losses in transition-metal complexes, enables the observation of spin-allowed emission directly to the ground state and could be exploited as an increased driving force in photochemical reactions on surfaces. These findings suggest that appropriate design strategies can deliver new iron-based materials for use as light emitters and photosensitizers.

  • 11.
    Eilers, Gerriet
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Schwartz, Lennart
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Stein, Matthias
    Zampella, Giuseppe
    de Gioia, Luca
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Ligand versus metal protonation of an iron hydrogenase active site mimic2007Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, nr 25, s. 7075-7084Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The protonation behavior of the iron hydrogenase active-site mimic [Fe2(u-adt)(CO)4(PMe3)2] (1; adt=N-benzyl-azadithiolate) has been investigated by spectroscopic, electrochemical, and computational methods. The combination of an adt bridge and electron-donating phosphine ligands allows protonation of either the adt nitrogen to give [Fe2(μ-Hadt)(CO)4(PMe3)2]+ ([1H]+), the Fe-Fe bond to give [Fe2-(μ-adt)(μ-H)(CO)4(PMe3)2]+ ([1Hy]+), or both sites simultaneously to give [Fe2(μ-Hadt)(μ-H)(CO)4(PMe3)2]2+ ([1HHy]2+). Complex 1 and its protonation products have been characterized in acetonitrile solution by IR, 1H, and 31PNMR spectroscopy. The solution structures of all protonation states feature a basal/basal orientation of the phosphine ligands, which contrasts with the basal/apical structure of 1 in the solid state. Density functional calculations have been performed on all protonation states and a comparison between calculated and experimental spectra confirms the structural assignments. The ligand protonated complex [1H]+ (pKa =12) is the initial, metastable protonation product while the hydride [1Hy]+ (pKa=15) is the thermodynamically stable singly protonated form. Tautomerization of cation [1H]+ to [1Hy]+ does not occur spontaneously. However, it can be catalyzed by HCl (k=2.2M-1s-1), which results in the selective formation of cation [1Hy]+. The protonations of the two basic sites have strong mutual effects on their basicities such that the hydride (pKa=8) and the ammonium proton (pKa=5) of the doubly protonated cationic complex [1HHy]2+ are considerably more acidic than in the singly protonated analogues. The formation of dication [1HHy]2+ from cation [1H]+ is exceptionally slow with perchloric or trifluoromethanesulfonic acid (k= 0.15 M-1s-1), while the dication is formed substantially faster (k > 102 M-1 s-1) with hydrobromic acid. Electrochemically, 1 undergoes irreversible reduction at -2.2V versus ferrocene, and this potential shifts to -1.6, - 1.1, and -1.0 V for the cationic complexes [1H]+, [1Hy]+, and [1HHy]2+, respectively, upon protonation. The doubly protonated form [1HHy]2+ is reduced at less negative potential than all previously reported hydrogenase models, although catalytic proton reduction at this potential is characterized by slow turnover.

  • 12.
    Eilers, Gerriet
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Zettersten, Camilla
    Nyholm, Leif
    Hammarström, Leif
    Lomoth, Reiner
    Ligand exchange upon oxidation of a dinuclear Mn complex - Detection of structural changes by FT-IR spectroscopy and ESI-MS.2005Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, nr 6, s. 1033-1041Artikkel i tidsskrift (Fagfellevurdert)
  • 13.
    Fredin, Lisa
    et al.
    NIST, Mat Measurement Lab, Chem Sci, Rockville, MD USA..
    Chabera, Pavel
    Lund Univ, Dept Chem, Chem Phys, Lund, Sweden..
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Sundstrom, Villy
    Lund Univ, Lund, Sweden..
    Warnmark, Kenneth
    Lund Univ, Lund, Sweden..
    Persson, Petter
    Lund Univ, Theoret Chem, Lund, Sweden..
    Photochemistry of iron(III) carbenes2017Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Artikkel i tidsskrift (Annet vitenskapelig)
  • 14. Fryxelius, Jacob
    et al.
    Eilers, Gerriet
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen.
    Feyziyev, Yashar
    Magnuson, Ann
    Sun, Licheng
    Lomoth, Reiner
    Synthesis and redox properties of a [meso-tris(4-nitrophenyl) corrolato]Mn(III) complex.2005Inngår i: Journal of Porphyrins and Phthalocyanines, ISSN 1088-4246, E-ISSN 1099-1409, nr 9(6), s. 379-386Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Hammarström, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Brown, Allison
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Mirmohades, Mohammad
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pullen, Sonja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Mechanistic investigations and detection of intermediates of molecular proton reduction catalysts2014Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 247, artikkel-id 95-INORArtikkel i tidsskrift (Annet vitenskapelig)
  • 16.
    Hammarström, Leif
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Capturing intermediates of molecular solar fuels catalysts by time-resolved mid-IR spectroscopy2017Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Artikkel i tidsskrift (Annet vitenskapelig)
  • 17.
    Harlang, Tobias C. B.
    et al.
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden..
    Liu, Yizhu
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden.;Lund Univ, Dept Chem, Ctr Anal & Synth, SE-22100 Lund, Sweden..
    Gordivska, Olga
    Lund Univ, Dept Chem, Ctr Anal & Synth, SE-22100 Lund, Sweden..
    Fredin, Lisa A.
    Lund Univ, Dept Chem, Theoret Chem Div, SE-22100 Lund, Sweden..
    Ponseca, Carlito S., Jr.
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden..
    Huang, Ping
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Chabera, Pavel
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden..
    Kjaer, Kasper S.
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden.;Tech Univ Denmark, Dept Phys, DK-2800 Lyngby, Denmark..
    Mateos, Helena
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden..
    Uhlig, Jens
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden..
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Wallenberg, Reine
    Lund Univ, nCHREM, SE-22100 Lund, Sweden..
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Persson, Petter
    Lund Univ, Dept Chem, Theoret Chem Div, SE-22100 Lund, Sweden..
    Sundstroem, Villy
    Lund Univ, Dept Chem Phys, SE-22100 Lund, Sweden..
    Waernmark, Kenneth
    Lund Univ, Dept Chem, Ctr Anal & Synth, SE-22100 Lund, Sweden..
    Iron sensitizer converts light to electrons with 92% yield2015Inngår i: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 7, nr 11, s. 883-889Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solar energy conversion in photovoltaics or photocatalysis involves light harvesting, or sensitization, of a semiconductor or catalyst as a first step. Rare elements are frequently used for this purpose, but they are obviously not ideal for large-scale implementation. Great efforts have been made to replace the widely used ruthenium with more abundant analogues like iron, but without much success due to the very short-lived excited states of the resulting iron complexes. Here, we describe the development of an iron-nitrogen-heterocyclic-carbene sensitizer with an excited-state lifetime that is nearly a thousand-fold longer than that of traditional iron polypyridyl complexes. By the use of electron paramagnetic resonance, transient absorption spectroscopy, transient terahertz spectroscopy and quantum chemical calculations, we show that the iron complex generates photoelectrons in the conduction band of titanium dioxide with a quantum yield of 92% from the 3MLCT (metal-to-ligand charge transfer) state. These results open up possibilities to develop solar energy-converting materials based on abundant elements.

  • 18.
    He, Jianjun
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Benkö, Gábor
    Korodi, Ferenc
    Polívka, Tomás
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Åkermark, Björn
    Sun, Licheng
    Hagfeldt, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Sundström, Villy
    Modified Phtalocyanines for Efficient Near-IR Sensitization of Nanostructured TiO2 Electrode2002Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Journal of American Chemical Society, Vol. 124, s. 4922-4932Artikkel i tidsskrift (Fagfellevurdert)
  • 19.
    Huang, P.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Magnusson, A.
    Lomoth, R.
    Abrahamsson, M.
    Tamm, M.
    Sun, L.
    van Rotterdam, B.
    Park, J.
    Hammarström, L.
    Åkermark, B.
    Styring, S.
    Photo-induced oxidation of a dinuclear Mn2II,II complex to the Mn2III, IV state by inter- and intramolecular electron transfer to RuIIItris-bipyridine2002Inngår i: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 91, s. 159-172Artikkel i tidsskrift (Fagfellevurdert)
  • 20.
    Häupl, Tilmann
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Lomoth, Reiner
    Hammarström, Leif
    Femtosecund Dynamics of the Photoexcited Methyl Viologen Radical Cation2003Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 107, nr 4, s. 435-438Artikkel i tidsskrift (Fagfellevurdert)
  • 21.
    Jane, R. T.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Gaudemer, E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Surface modification of carbon and metal electrodes with bistable molecular redox switches by click and amide coupling2015Inngår i: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, nr 38, s. 10023-10030Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ruthenium complexes [Ru(R-Ph-tpy)(bpyMeOHpy)] (Ph-tpy = 4'-(4-R-phenyl)-2,2':6',2 ''-terpyridine, R = NH2, COOH, CRCH, bpyMeOHpy = 1-[6-(2,2'-bipyridyl)]-1-(2-pyridyl)-ethanol) were covalently attached to carbon and metal electrodes by amide and click coupling reactions. Coupling agents were covalently grafted onto the electrodes by electrochemical reduction of p-functionalized diazonium tethers X-Ph-N-2(+) (X = COOH, NO2, N-3) followed by electrochemical reduction of the nitro tether. The modification of the electrode surfaces with the Ru complexes results in a hysteretic current-voltage response based on the redox-induced N-6/N5O linkage isomerism of the ambidentate pyridyl/alkoxy unit in the bpyMeOHpy chelate ligand. The immobilized complexes can be exhaustively addressed electrochemically with scan rates <= 10000 V s(-1) and can switch uniformly with kinetic and thermodynamic parameters similar to the properties of reference complexes in homogeneous solution.

  • 22.
    Jane, Reuben T.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Redox hysteresis on carbon electrodes covalently modified with a bistable ruthenium complex2015Inngår i: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 3, nr 24, s. 6260-6265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A ruthenium complex bearing an ambidentate ligand was covalently attached to glassy carbon and carbon fiber electrodes by reduction of an aryldiazonium anchoring group placed on the terpyridine spectator ligand. The diazonium grafting method results in robust attachment and yields high surface concentrations of 2.4 x 10(-10) mol cm(-2). The attached complexes can be addressed electrochemically and the electrodes were characterized with scan rates of up to 2000 V s(-1). The redox-induced N/O linkage isomerism of the pyridyl/alkoxy ambidentate ligand results in a hysteretic current-voltage response (E-1 degrees = 0.83, E-2 degrees = 0.34 V) of the modified electrodes. The immobilization has no deleterious effects on the isomerization reactions of the molecular material that proceed with thermodynamic (2.4 < pK(1) < 3.7 (Ru(III) O -> N), -6.0 < pK(2) < -4.8 (Ru(II) O -> N)) and kinetic parameters (k(b1) = 2.5 x 10(2) s(-1) (Ru(III) N -> O), k(f2) = 2.5 x 10(2) s(-1) (Ru(II) O -> N)) comparable to analogous complexes in homogeneous solution.

  • 23. Johansson, Olof
    et al.
    Borgström, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Lomoth, Reiner
    Palmblad, Magnus
    Bergquist, Jonas
    Hammarström, Leif
    Sun, Licheng
    Åkermark, Björn
    Electron Donor-Acceptor Dyads Based on Ruthenium(II) Bipyridine and Terpyridine Complexes Bound to Naphtalenediimide2003Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 42, s. 2908-2918Artikkel i tidsskrift (Fagfellevurdert)
  • 24.
    Johansson, Olof
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Eriksson, Lars
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Pd-catalyzed diarylation of aniline: a way to a non-linear bis(terpyridyl) ligand providing increased electronic communication2008Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, nr 28, s. 3649-3651Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An amine-linked bis(terpyridyl) ligand, prepared via Pd-catalyzed diarylation of aniline, mediates unusually strong metal-metal interaction in its Ru-2 polypyridyl complex.

  • 25.
    Johansson, Olof
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Johannissen, Linus O.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Bistable Molecular Switches Based on Linkage Isomerization in Ruthenium Polypyridyl Complexes with a Ligand-Bound Ambidentate Motif2009Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, nr 5, s. 1195-1204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electron-transfer-induced linkage isomerization was investigated in a series of bis-tridentate Ru polypyridyl complexes [Ru(L-X-OH)(Y-tpy)](2+) with ambidentate ligand L-X-OH bpy-C(R)(OH)-py (bpy-2,2'-bipyridine py-pyridine; R-H, Me, Ph, or tBu) and spectator ligand Y-tpy (tpy 2.2':6',2 ''-terpyridine, Y-p-tolyl, p-PhCO2Me, Cl, OEt, N-pyrrolidine). The ligand-bound ambidentate motif switches reversibly between N and O coordination in the Ru-II and Ru-III state,respectively. The potentials of the Ru-III/II couple differ by about 0.5 V between the isomers, and this results in a bistable electrochemical response of the molecular switches. The effects of structural modifications in form of substituents on the linking carbon atom of the ambidentate ligand and on the central pyridine moiety of the spectator ligand were investigated by electrochemical and computational methods. Differences in isomerization behavior span six orders of magnitude in rate constants and two orders of magnitude in equilibrium constants. The results can be interpreted in terms of steric and electronic substituent effects and their influence on rotational barriers, ligation geometry, and electron deficiency of the metal center.

  • 26.
    Johansson, Olof
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Molecular hysteresis in a rigid dinuclear ruthenium polypyridyl complex incorporating a ligand-bound ambidentate motif2008Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, nr 13, s. 5531-5533Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 27.
    Johansson, Olof
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik. Avdelningen för molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Rapid electrochemically induced linkage isomerism in a ruthenium(II) polypyridyl complex2005Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 12, s. 1578-80Artikkel i tidsskrift (Fagfellevurdert)
  • 28. Johansson, Olof
    et al.
    Wolpher, Henriette
    Borgström, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Lomoth, Reiner
    Hammarström, Leif
    Bergquist, Jonas
    Sun, Licheng
    Åkermark, Björn
    Intramolecular Charge Separation in a Hydrogen Bonded Tyrosine-Ruthenium(II)-Naphtalene Diimide Triad2004Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, s. 194-195Artikkel i tidsskrift (Fagfellevurdert)
  • 29.
    Kaur-Ghumaan, Sandeep
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Schwartz, Lennart
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik.
    Stein, Matthias
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Catalytic Hydrogen Evolution from Mononuclear Iron(II) Carbonyl Complexes as Minimal Functional Models of the [FeFe] Hydrogenase Active Site2010Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, nr 43, s. 8033-8036Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    How much iron does it take? Mononuclear complexes [FeII(3,6-R2bdt)(CO)2(PMe3)2] (bdt=1,2-C6H4(S)2; R=H, Cl) can be reversibly protonated at the sulfur ligands, can catalyze the electrochemical reduction of protons, and are thus minimal functional models of the [FeFe] hydrogenases (see scheme). DFT calculations show that cleavage of an FeS bond leads to the generation of a free coordination site, which is crucial for the formation of hydrides that are key intermediates in the generation of hydrogen.

  • 30.
    Kjmer, Kasper Skov
    et al.
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Kaul, Nidhi
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Prakash, Om
    Lund Univ, CAS, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Chabera, Pavel
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Rosemann, Nils W.
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Honarfar, Alireza
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Gordivska, Olga
    Lund Univ, CAS, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Fredin, Lisa A.
    Lund Univ, Div Theoret Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden;Lehigh Univ, Dept Chem, 6 E Packer Ave, Bethlehem, PA 18015 USA.
    Bergquist, Karl-Erik
    Lund Univ, CAS, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Häggström, Lennart
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Ericsson, Tore
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Fysiska sektionen, Institutionen för fysik och astronomi, Materialfysik.
    Lindh, Linnea
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Yartsev, Arkady
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Huang, Ping
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Uhlug, Jens
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Bendix, Jesper
    Univ Copenhagen, Dept Chem, Univ Pk 5, DK-2100 Copenhagen, Denmark.
    Strand, Daniel
    Lund Univ, CAS, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Sundström, Villy
    Lund Univ, Div Phys Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Persson, Petter
    Lund Univ, Div Theoret Chem, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Wärnmark, Kenneth
    Lund Univ, CAS, Dept Chem, Box 124, SE-22100 Lund, Sweden.
    Luminescence and reactivity of a charge-transfer excited iron complex with nanosecond lifetime2019Inngår i: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 363, nr 6424, s. 249-253Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Iron's abundance and rich coordination chemistry are potentially appealing features for photochemical applications. However, the photoexcitable charge-transfer states of most iron complexes are limited by picosecond or subpicosecond deactivation through low-lying metal-centered states, resulting in inefficient electron-transfer reactivity and complete lack of photoluminescence. In this study, we show that octahedral coordination of iron(Ill) by two mono-anionic facial tris-carbene ligands can markedly suppress such deactivation. The resulting complex [Fe(phtmeimb)(2)](+), where phtmeimb is {phenyl[tris(3-methylimidazol-1-ylidene)]borate}(-), exhibits strong, visible, room temperature photoluminescence with a 2.0-nanosecond lifetime and 2% quantum yield via spin-allowed transition from a doublet ligand-to-metal charge-transfer ((LMCT)-L-2) state to the doublet ground state. Reductive and oxidative electron-transfer reactions were observed for the (2)LMCTstate of [Fe(phtmeimb)(2)](+) in bimolecular quenching studies with methylviologen and diphenylamine.

  • 31.
    Lei, Pengxiang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Hedlund, Maria
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Rensmo, Håkan
    Johansson, Olof
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    The role of colloid formation in the photoinduced H2 production with a RuII-PdII supramolecular complex: A study by GC, XPS, and TEM2008Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 130, nr 1, s. 26-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dinuclear Run(II)-Pd-II complex shows efficient H-2 production in the presence of triethylamine as a sacrificial electron and proton donor under visible light irradiation. XPS and TEM analyses reveal that photoreduction of Pd-II to Pd-0 causes dissociation of Pd from the complex to form colloids that are suggested to be the actual catalyst for H-2 production.

  • 32.
    Liu, Tianfei
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Guo, Meiyuan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Teoretisk kemi.
    Orthaber, Andreas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lundberg, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Teoretisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Accelerating proton-coupled electron transfer of metal hydrides in catalyst model reactions2018Inngår i: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 10, nr 8, s. 881-887Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal hydrides are key intermediates in catalytic proton reduction and dihydrogen oxidation. There is currently much interest in appending proton relays near the metal centre to accelerate catalysis by proton-coupled electron transfer (PCET). However, the elementary PCET steps and the role of the proton relays are still poorly understood, and direct kinetic studies of these processes are scarce. Here, we report a series of tungsten hydride complexes as proxy catalysts, with covalently attached pyridyl groups as proton acceptors. The rate of their PCET reaction with external oxidants is increased by several orders of magnitude compared to that of the analogous systems with external pyridine on account of facilitated proton transfer. Moreover, the mechanism of the PCET reaction is altered by the appended bases. A unique feature is that the reaction can be tuned to follow three distinct PCET mechanisms-electron-first, proton-first or a concerted reaction-with very different sensitivities to oxidant and base strength. Such knowledge is crucial for rational improvements of solar fuel catalysts.

  • 33. Liu, Yizhu
    et al.
    Harlang, Tobias
    Canton, Sophie E.
    Chabera, Pavel
    Suarez-Alcantara, Karina
    Fleckhaus, Andre
    Vithanage, Dimali A.
    Göransson, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Corani, Alice
    Lomoth, Reiner
    Sundstrom, Villy
    Warnmark, Kenneth
    Towards longer-lived metal-to-ligand charge transfer states of iron(II) complexes: an N-heterocyclic carbene approach2013Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, nr 57, s. 6412-6414Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 9 ps (MLCT)-M-3 lifetime was achieved by a Fe-II complex based on C(NHC)<^>N(py)<^>C(NHC) pincer ligands. This is the longest known so far for any kind of complexes of this abundant metal, and increased by almost two orders of magnitude compared to the reference Fe-II bis-terpyridine complex.

  • 34. Liu, Yizhu
    et al.
    Kjær, Kasper S.
    Fredin, Lisa A.
    Chábera, Pavel
    Harlang, Tobias
    Canton, Sophie E.
    Lidin, Sven
    Zhang, Jianxin
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Bergquist, Karl-Erik
    Persson, Petter
    Wärnmark, Kenneth
    Sundström, Villy
    A Heteroleptic Ferrous Complex with Mesoionic Bis(1,2,3-triazol-5-ylidene) Ligands: Taming the MLCT Excited State of Iron(II)2015Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, nr 9, s. 3628-3639Artikkel i tidsskrift (Fagfellevurdert)
  • 35.
    Lomoth, R
    et al.
    University of Leipzig.
    Brede, O
    Spectral and kinetic identification of radical cations of pyrimidine bases by stepwise electron transfer1998Inngår i: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 288, nr 1, s. 47-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radical cations of methylated derivatives of uracil and thymine were generated by electron transfer to the parent radical cation, generated in acetone by nanosecond pulse radiolysis. The resulting transient absorption peaking around 400 and 550 nm is assigned to the radical cations of the pyrimidine bases. Direct kinetic and spectroscopic evidence for this assignment has been given by a subsequent electron transfer from triphenylamine to the pyrimidine radical cations yielding the characteristic absorption spectrum of the triphenylamine radical cation. (C) 1998 Elsevier Science B.V. All rights reserved.

  • 36.
    Lomoth, R
    et al.
    University of Leipzig.
    Naumov, S
    Brede, O
    Genuine pyrimidine radical cations generated by radiation-induced electron transfer to butyl chloride or acetone parent ions1999Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 103, nr 15, s. 2641-2648Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Radical cations of multiple methylated uracils and thymines were generated by electron transfer to parent ions of solvents of low polarity such as n-butyl chloride and acetone. Pulse radiolysis resulted in the transient optical absorption spectra of the pyrimidine radical cations (Py.+) which exhibit bands generally peaking around lambda = 400 nm and in acetone showing an additional band in the range of lambda(max) = 500-560 nm. The identification of the solute radical cations is based on the direct observation of the formation of Py.+ by electron transfer (k = (1-2) x 10(10) M(-1)s(-1)), the nucleophilic reaction with the counterion (e.g., Cl-), the relatively low reactivity with oxygen even for the fully methylated nitrogen groups (k < 2 x 10(8) M(-1)s(-1)), and the observation of a subsequent electron transfer from triphenylamine to the pyrimidine radical cations proceeding in a diffusion-controlled manner. The solvent dependence of the spectral shape of Py.+ was also studied in acetone/n-butyl chloride mixtures and was found to depend on the polarity of the surroundings. This phenomenon is explained in terms of a lactam-lactim-like tautomerism of the transient involving the whole plane molecule. Quantum chemical calculations support the experimental findings by explaining the spectral structure and enable the formulation of the lactims as either 1,4- or 3,4-localized.

  • 37.
    Lomoth, R
    et al.
    University of Leipzig.
    Naumov, S
    Brede, O
    Transients of the oxidation of pyrimidines with SO4•-: Structure and reactivity of the resulting radicals1999Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 103, nr 33, s. 6571-6579Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Depending on the methylation pattern, the reaction of SO4.- with various methylated pyrimidines yields radicals deprotonated at N(1) and C(5)-OH or C(6)-OH adduct radicals and probably allyl radicals by subsequent deprotonation at the C(5)-methyl group of the thymines. All of these radicals are derived from the initial SO4.- adducts on the pyrimidines that have lifetimes of several microseconds in the case of N(1)-methylated thymines. These transients could be taken for long lived pyrimidine radical cations. However, spectral and kinetic comparison with the pyrimidine radical cations generated by electron transfer in nonpolar solvents (butyl chloride, acetone) reveals the adduct nature of these transients. In the course of sulfate adduct decay, pyrimidine radical cations could be formed as nondetectable short-lived (tau < 20ns) intermediates rapidly reacting to the above-mentioned radical products. The reactivity of the SO4.- adducts, as well as that of the other pyrimidinyl radicals observed, was characterized by the subsequent oxidation of triphenylamine and di- or trimethoxybenzene, which supports the mechanistic interpretation given above. Hence there is no indication of long-lived pyrimidine radical cations under the conditions of the SO4.- oxidation of pyrimidines in aqueous solution.

  • 38.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Redox-Stimulated Motion and Bistability in Metal Complexes and Organometallic Compounds2013Inngår i: Antioxidants and Redox Signaling, ISSN 1523-0864, E-ISSN 1557-7716, Vol. 19, nr 15, s. 1803-1814Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Significance: Control over reversible changes to molecular structure forms the basis for artificial molecular machines that could eventually lead to the development of molecule-based nanotechnology. Recent Advances: Particular applications in information storage and processing could emerge where the structural rearrangements give rise to bistability and molecular hysteresis effects. Critical Issues: Oxidation-state-dependent coordination and bonding preferences in transition metal complexes and organometallic compounds provide a versatile approach to the control of molecular motions by redox input, but so far, few structural motifs have been applied in redox-actuated molecular machines. Future Directions: Further progress toward molecule-based nanoscale devices might be accomplished with molecular components derived from a wider range of structural themes and forms of molecular motion. Examples of redox-stimulated rearrangements in metal complexes and organometallic compounds are described that have been employed in molecular machines or could be considered for the design of new functional molecules.

  • 39.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Huang, Ping
    Zheng, Jiutian
    Sun, Licheng
    Hammarström, Leif
    Åkermark, Björn
    Styring, Stenbjörn
    Synthesis and Characterization of a Dinuclear Manganese(III,III) Complex with Three Phenolate Ligands2002Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, s. 2965-2974Artikkel i tidsskrift (Fagfellevurdert)
  • 40.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Häupl, Tilmann
    Johansson, Olof
    Hammarström, Leif
    Redox-Switchable Direction of Photoinduced Electron Transfer in an Ru(bpy)3+2-Viologen Dyad2002Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 8, nr 1, s. 102-110Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Liu, Tianfei
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Wang, Shihuai
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Probing the elementary steps of PCET catalysis2018Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Artikkel i tidsskrift (Annet vitenskapelig)
  • 42.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Magnuson, Ann
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Sjödin, Martin
    Huang, Ping
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Kemisk fysik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap, Molekylär biomimetik.
    Mimicking the electron donor side of Photosystem II in artificial photosynthesis.2006Inngår i: Photosynthesis Research, ISSN 0166-8595, E-ISSN 1573-5079, s. 1-16Artikkel i tidsskrift (Fagfellevurdert)
  • 43.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Magnuson, Ann
    Xu, Yunhua
    Sun, Licheng
    Mixed-Valance Properties of an Acetate-Bridged Dinuclear Ruthenium (II,II) Complex2003Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 107, s. 4373-4380Artikkel i tidsskrift (Fagfellevurdert)
  • 44.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Magnusson, Ann
    Xu, Yunhua
    Sun, Licheng
    Mixed-Valance Properties of an Acetate-Bridged Dinuclear Ruthenium (II,II) Complex2003Inngår i: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 107, s. 4373-4380Artikkel i tidsskrift (Fagfellevurdert)
  • 45.
    Lomoth, Reiner
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Introducing a dark reaction to photochemistry: photocatalytic hydrogen from [FeFe] hydrogenase active site model complexes2009Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, nr 45, s. 9952-9959Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The light-driven splitting of water into its constituting elements gives access to a valuable fuel from an abundant substrate, using sunlight as the only energy source. Synthetic diiron complexes as functional models of the [FeFe] hydrogenase H(2)ase enzyme active site have moved into the centre of focus as potentially viable catalysts for the reductive side of this process, i.e. the reduction of protons to molecular hydrogen. The active site of the enzyme, as well as its mimics in an artificial system, are required to accumulate two electrons from single electron transfer events and to combine them with two protons to form hydrogen. Whereas in biology this reaction is not coupled to photosynthesis and thus proceeds in the dark, additional aspects need to be considered when designing a functional artificial system for the light-driven reduction of protons. Suitable photosensitizers have to be chosen that not only provide sufficient driving force for the reduction of the synthetic diiron catalyst, but also allow for selective excitation to minimize photodegradation. Electron transfer efficiencies have to be optimized for all steps and the sequential nature of the catalyst reduction requires a sufficient stability of potentially labile intermediates of the catalytic cycle. In this perspective, systems for the light-driven conversion of protons to molecular hydrogen are discussed where the catalyst is based on model complexes of the [FeFe] H(2)ase active site. Covalently linked dyads, supramolecular assemblies and multi-component systems will be examined with an emphasis on mechanistic electron transfer schemes, the properties of the individual components, their scope and their potential limitations.

  • 46.
    Magnuson, Ann
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Anderlund, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Johansson, Olof
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Lindblad, Peter
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Polivka, Tomas
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Stensjö, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Styring, Stenbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Sundström, Villy
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fotokemi och molekylärvetenskap.
    Biomimetic and Microbial Approaches to Solar Fuel Generation2009Inngår i: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 42, nr 12, s. 1899-1909Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Photosynthesis is performed by a multitude of organisms, but in P nearly all cases, it is variations on a common theme: absorption of light followed by energy transfer to a reaction center where charge separation takes place, This initial form of chemical energy is stabilized by the biosynthesis of carbohydrates. To produce these energy-rich products, a substrate is needed that feeds in reductive equivalents, When photosynthetic microorganisms learned to use water as a substrate some 2 billion years ago, a fundamental barrier against unlimited use of solar energy was overcome. The possibility of solar energy use has inspired researchers to construct artificial photosynthetic systems that show analogy to parts of the intricate molecular machinery of photosynthesis. Recent years have seen a reorientation of efforts toward creating integrated light-to-fuel systems that can use solar energy for direct synthesis of energy-rich compounds, so-called solar fuels. Sustainable production of solar fuels is a long awaited development that promises extensive solar energy use combined with long-term storage. The stoichiometry of water splitting into molecular oxygen, protons, and electrons is deceptively simple; achieving it by chemical catalysis has proven remarkably difficult. The reaction center Photosystem II couples light-induced charge separation to an efficient molecular water-splitting catalyst, a Mn4Ca complex, and is thus an important template for biomimetic chemistry. In our aims to design biomimetic manganese complexes for light-driven water oxidation, we link photosensitizers and charge-separation motifs to potential catalysts in supramolecular assemblies. In photosynthesis, production of carbohydrates demands the delivery of multiple reducing equivalents to CO2. In contrast, the two-electron reduction of protons to molecular hydrogen is much less demanding. Virtually all microorganisms have enzymes called hydrogenases that convert protons to hydrogen, many of them with good catalytic efficiency. The catalytic sites of hydrogenases are now the center of attention of biomimetic efforts, providing prospects for catalytic hydrogen production with inexpensive metals. Thus, we might complete the water-to-fuel conversion: light + 2H(2)O -> 2H(2) + O-2 This reaction formula is to some extent already elegantly fulfilled by cyanobacteria and green algae, water-splitting photosynthetic microorganisms that under certain conditions also can produce hydrogen. An alternative route to hydrogen from solar energy is therefore to engineer these organisms to produce hydrogen more efficiently. This Account describes our original approach to combine research in these two fields: mimicking structural and functional principles of both Photosystem II and hydrogenases by synthetic chemistry and engineering cyanobacteria to become better hydrogen producers and ultimately developing new routes toward synthetic biology.

  • 47.
    Magnuson, Ann
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Liebisch, Peter
    Haumann, Michael
    Högblom, Joakim
    Anderlund, Magnus F
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström.
    Meyer-Klaucke, Wolfram
    Dau, Holger
    Bridging-mode changes facilitate successive oxidation steps at about 1 V in two binuclear manganese complexes - implications for photosynthetic water-oxidation.2006Inngår i: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 100, s. 1234-1243Artikkel i tidsskrift (Fagfellevurdert)
  • 48.
    Mijangos, Edgar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Roy, Souvik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Pullen, Sonja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Evaluation of two- and three-dimensional electrode platforms for the electrochemical characterization of organometallic catalysts incorporated in non-conducting metal-organic frameworks2017Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, nr 15, s. 4907-4911Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of a reliable platform for the electrochemical characterization of a redox-active molecular diiron complex, [FeFe], immobilized in a non-conducting metal organic framework (MOF), UiO-66, based on glassy-carbon electrodes is reported. Voltammetric data with appreciable current responses can be obtained by the use of multiwalled carbon nanotubes (MWCNT) or mesoporous carbon (CB) additives that function as conductive scaffolds to interface the MOF crystals in "three-dimensional" electrodes. In the investigated UiO-66-[FeFe] sample, the low abundance of [FeFe] in the MOF and the intrinsic insulating properties of UiO-66 prevent charge transport through the framework, and consequently, only [FeFe] units that are in direct physical contact with the electrode material are electrochemically addressable.

  • 49.
    Mirmohades, Mohammad
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Pullen, Sonja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Stein, Matthias
    Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg.
    Maji, Somnath
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Ott, Sascha
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Molekylär biomimetik.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Direct Observation of Key Catalytic Intermediates in a Photoinduced Proton Reduction Cycle with a Diiron Carbonyl Complex2014Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, nr 50, s. 17366-17369Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure and reactivity of intermediatesin the photocatalytic cycle of a proton reductioncatalyst, [Fe2(bdt)(CO)6] (bdt = benzenedithiolate), wereinvestigated by time-resolved spectroscopy. The singlyreduced catalyst [Fe2(bdt)(CO)6]−, a key intermediate inphotocatalytic H2 formation, was generated by reactionwith one-electron reductants in laser flash-quench experimentsand could be observed spectroscopically on thenanoseconds to microseconds time scale. From UV/visand IR spectroscopy, [Fe2(bdt)(CO)6]− is readilydistinguished from the two-electron reduced catalyst[Fe2(bdt)(CO)6]2− that is obtained inevitably in theelectrochemical reduction of [Fe2(bdt)(CO)6]. For thedisproportionation rate constant of [Fe2(bdt)(CO)6]−, anupper limit on the order of 107 M−1 s−1 was estimated,which precludes a major role of [Fe2(bdt)(CO)6]2− inphotoinduced proton reduction cycles. Structurally [Fe2-(bdt)(CO)6]− is characterized by a rather asymmetricallydistorted geometry with one broken Fe−S bond and sixterminal CO ligands. Acids with pKa ≤ 12.7 protonate[Fe2(bdt)(CO)6]− with bimolecular rate constants of 4 ×106, 7 × 106, and 2 × 108 M−1 s−1 (trichloroacetic,trifluoroacetic, and toluenesulfonic acids, respectively).The resulting hydride complex [Fe2(bdt)(CO)6H] istherefore likely to be an intermediate in photocatalyticcycles. This intermediate resembles structurally andelectronically the parent complex [Fe2(bdt)(CO)6], withvery similar carbonyl stretching frequencies.

  • 50.
    Nachtigall, Olaf
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - Ångström, Fysikalisk kemi.
    Dahlstrand, Christian
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Lundstedt, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Gogoll, Adolf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Syntetisk organisk kemi.
    Webb, Matthew J
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Grennberg, Helena
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för kemi - BMC, Fysikalisk-organisk kemi.
    Pyrene–Azobenzene Dyads and Their Photochemistry2014Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2014, nr 5, s. 966-972Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The facile synthesis of three new folding azobenzene-pyrene systems 13, connected together by a serendipitously obtained and unpredicted ester linkage, is reported. Additional characterization of the photochemistry of these systems revealed variations in azobenzene photoisomerization (trans-cis and cis-trans) and quenching of pyrene fluorescence, as a result of intra-excitation energy transfer from the pyrene chromophore to an azobenzene. Through the use of aryl substituent electronic effects to tune the absorption properties of the azobenzene relative to the pyrene, we show that efficient photo-switching can be achieved when the trans-azobenzene absorbance band is well separated from that of the pyrene (compound 1), whereas overlap of the corresponding absorbance bands in the cases of 2 and 3 significantly compromises trans-cis isomerization by enhancing cis-trans interconversion.

12 1 - 50 of 76
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