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Fluch, U., McCarthy, B. D. & Ott, S. (2019). Post synthetic exchange enables orthogonal click chemistry in a metal organic framework. Dalton Transactions, 48(1), 45-49
Open this publication in new window or tab >>Post synthetic exchange enables orthogonal click chemistry in a metal organic framework
2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 1, p. 45-49Article in journal (Refereed) Published
Abstract [en]

Biphenyl-4,4'-dicarboxylic acid derivatives containing either azide or acetylene functional groups were inserted into UiO-67 metal organic frameworks (MOFs) via post synthetic linker exchange. Sequential and orthogonal click reactions could be performed on these modified MOFs by incubating the crystals with small molecule substrates bearing azide or acetylene groups in the presence of a copper catalyst. H-1 NMR of digested MOF samples showed that up to 50% of the incorporated linkers could be converted to their "clicked" triazole products. Powder X-ray diffraction confirmed that the UiO-67 structure was maintained throughout all transformations. The click reaction efficiency is discussed in context of MOF crystallite size and pore size. As the incorporation of clicked linkers could be controlled by post synthetic exchange, this work introduces a powerful method of quickly introducing orthogonal modifications into known MOF architectures.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-372868 (URN)10.1039/c8dt04563a (DOI)000453681400006 ()30516766 (PubMedID)
Funder
EU, European Research Council, ERC-CoG2015-681895_MOFcatSwedish Energy Agency
Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-01-10Bibliographically approved
Pullen, S., Maji, S., Stein, M. & Ott, S. (2019). Restricted rotation of an Fe(CO)(2)(PL3)-subunit in [FeFe]-hydrogenase active site mimics by intramolecular ligation. Dalton Transactions, 48(18), 5933-5939
Open this publication in new window or tab >>Restricted rotation of an Fe(CO)(2)(PL3)-subunit in [FeFe]-hydrogenase active site mimics by intramolecular ligation
2019 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 48, no 18, p. 5933-5939Article in journal (Refereed) Published
Abstract [en]

A new series of homodinuclear iron complexes as models of the [FeFe]-hydrogenase active site was prepared and characterized. The complexes of the general formula [Fe-2(mcbdt)(CO)(5)PPh2R] (mcbdt = benzene-1,2-dithiol-3-carboxylic acid) feature covalent tethers that link the mcbdt ligand with the phosphine ligands which are terminally coordinated to one of the Fe centres. The synthetic feasability of the concept is demonstrated with the preparation of three novel complexes. A detailed theoretical investigation showes that by introducing a rigid covalent link between the phosphine and the bridging dithiolate ligands, the rotation of the Fe(CO)(2)P unit is hindered and higher rotation barriers were calculated compared to non-linked reference complexes. The concept of restricting Fe(L)(3) rotation is an approach to kinetically stabilize terminal hydrides which are reactive intermediates in catalytic proton reduction cycles of the enzymes.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-390519 (URN)10.1039/c8dt05148h (DOI)000472449300009 ()30839992 (PubMedID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationSwedish Energy Agency
Available from: 2019-08-14 Created: 2019-08-14 Last updated: 2019-08-14Bibliographically approved
Bedin, M., Agarwala, H., Marx, J., Schünemann, V., Ott, S. & Thapper, A. (2019). Synthesis and properties of a heterobimetallic iron-manganese complex and its comparison with homobimetallic analogues. Inorganica Chimica Acta, 490, 254-260
Open this publication in new window or tab >>Synthesis and properties of a heterobimetallic iron-manganese complex and its comparison with homobimetallic analogues
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2019 (English)In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 490, p. 254-260Article in journal (Refereed) Published
Abstract [en]

Heterobimetallic cofactors containing one manganese and one iron ion have recently been found within the di-metal carboxylate protein family. Herein we report the synthesis and characterization of three binuclear metal complexes with Fe-Fe, Mn-Mn, and Fe-Mn metal composition. All three complexes use the same ligand framework, the BPMP ligand (HBPMP=2,6-bis[(bis (-2-pyridylmethyl)amine) methyl]-4-methylphenol)) with two additional acetate ligands bridging the two metals. In terms of stability towards metal exchange, the Fe-Mn is more stable than the Mn-Mn complex but less stable than the Fe-Fe complex. Cyclic voltammetry shows that the Fe-Mn complex behaves markedly different than the homobimetallic complexes. The Fe-Mn complex also shows higher reactivity with O-2 than both the Fe-Fe and the Mn-Mn counterparts.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2019
Keywords
Iron, Manganese, Heterobimetallic, Oxygen reactivity
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-382375 (URN)10.1016/j.ica.2019.03.029 (DOI)000463348300032 ()
Funder
Swedish Research Council
Available from: 2019-04-25 Created: 2019-04-25 Last updated: 2019-04-25Bibliographically approved
Arkhypchuk, A. I., D'Imperio, N. & Ott, S. (2019). Triarylalkenes from the site-selective reductive cross-coupling of benzophenones and aldehydes. Chemical Communications, 55(43), 6030-6033
Open this publication in new window or tab >>Triarylalkenes from the site-selective reductive cross-coupling of benzophenones and aldehydes
2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 43, p. 6030-6033Article in journal (Refereed) Published
Abstract [en]

PhP(Li)TMS converts benzophenones to phosphaalkenes which upon activation under oxidizing, basic conditions react with aromatic aldehydes under the formation of triarylalkenes. The one-pot reaction omits transition metals, proceeds at room temperature and precludes the formation of any homo-coupling products. Systematic substrate variations reveal reactivity patterns that are useful for the identification of ketone/aldehyde combinations that can be coupled in yields up to 80%.

National Category
Physical Chemistry Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-387587 (URN)10.1039/c9cc02972a (DOI)000468832200007 ()31062780 (PubMedID)
Available from: 2019-06-26 Created: 2019-06-26 Last updated: 2019-06-26Bibliographically approved
D'Imperio, N., Arkhypchuk, A. I., Mai, J. & Ott, S. (2019). Triphenylphosphaalkenes in Chemical Equilibria. European Journal of Inorganic Chemistry (11-12), 1562-1566
Open this publication in new window or tab >>Triphenylphosphaalkenes in Chemical Equilibria
2019 (English)In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 11-12, p. 1562-1566Article in journal (Refereed) Published
Abstract [en]

Triphenylphosphaalkenes 1a-c were prepared in good to excellent yields in a modified phospha-Peterson reaction between PhP(Li)TMS and benzophenones with different para-substituents at the C-phenyl groups (a: R = H, b: R = O-octyl, c: R = F). Owing to the low kinetic stabilization that is provided by the P-phenyl group, compounds 1a-c engage in reversible dimerization and oligomerization reactions, some of which are not detectable by 31P NMR monitoring. The dimers and oligomers are in chemical equilibria with monomeric 1a-c, and can be converted quantitatively to phosphinites 4a-c by the irreversible addition of methanol across the P=C double bond.

National Category
Inorganic Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:uu:diva-368871 (URN)10.1002/ejic.201801322 (DOI)000462351000016 ()
Funder
Swedish Research Council
Available from: 2018-12-09 Created: 2018-12-09 Last updated: 2019-04-12Bibliographically approved
Liu, T., Guo, M., Orthaber, A., Lomoth, R., Lundberg, M., Ott, S. & Hammarström, L. (2018). Accelerating proton-coupled electron transfer of metal hydrides in catalyst model reactions. Nature Chemistry, 10(8), 881-887
Open this publication in new window or tab >>Accelerating proton-coupled electron transfer of metal hydrides in catalyst model reactions
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2018 (English)In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 10, no 8, p. 881-887Article in journal (Refereed) Published
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.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-357209 (URN)10.1038/s41557-018-0076-x (DOI)000439420400015 ()30013192 (PubMedID)
Funder
Swedish Research Council, 2016-04271Knut and Alice Wallenberg Foundation, 2011.0067
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2019-01-04Bibliographically approved
Johnson, B. A., Bhunia, A., Fei, H., Cohen, S. M. & Ott, S. (2018). Development of a UiO-Type Thin Film Electrocatalysis Platform with Redox-Active Linkers. Journal of the American Chemical Society, 140(8), 2985-2994
Open this publication in new window or tab >>Development of a UiO-Type Thin Film Electrocatalysis Platform with Redox-Active Linkers
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2018 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 8, p. 2985-2994Article in journal (Refereed) Published
Abstract [en]

Metal–organic frameworks (MOFs) as electrocatalysis scaffolds are appealing due to the large concentration of catalytic units that can be assembled in three dimensions. To harness the full potential of these materials, charge transport to the redox catalysts within the MOF has to be ensured. Herein, we report the first electroactive MOF with the UiO/PIZOF topology (Zr(dcphOH-NDI)), i.e., one of the most widely used MOFs for catalyst incorporation, by using redox-active naphthalene diimide-based linkers (dcphOH-NDI). Hydroxyl groups were included on the dcphOH-NDI linker to facilitate proton transport through the material. Potentiometric titrations of Zr(dcphOH-NDI) show the proton-responsive behavior via the −OH groups on the linkers and the bridging Zr-μ3-OH of the secondary building units with pKa values of 6.10 and 3.45, respectively. When grown directly onto transparent conductive fluorine-doped tin oxide (FTO), 1 μm thin films of Zr(dcphOH-NDI)@FTO could be achieved. Zr(dcphOH-NDI)@FTO displays reversible electrochromic behavior as a result of the sequential one-electron reductions of the redox-active NDI linkers. Importantly, 97% of the NDI sites are electrochemically active at applied potentials. Charge propagation through the thin film proceeds through a linker-to-linker hopping mechanism that is charge-balanced by electrolyte transport, giving rise to cyclic voltammograms of the thin films that show characteristics of a diffusion-controlled process. The equivalent diffusion coefficient, De, that contains contributions from both phenomena was measured directly by UV/vis spectroelectrochemistry. Using KPF6 as electrolyte, De was determined to be De(KPF6) = (5.4 ± 1.1) × 10–11 cm2 s–1, while an increase in countercation size to n-Bu4N+ led to a significant decrease of De by about 1 order of magnitude (De(n-Bu4NPF6) = (4.0 ± 2.5) × 10–12 cm2 s–1).

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-351270 (URN)10.1021/jacs.7b13077 (DOI)000426617700044 ()29421875 (PubMedID)
Funder
Swedish Research Council
Available from: 2018-06-04 Created: 2018-06-04 Last updated: 2018-06-04Bibliographically approved
Gilbert Gatty, M., Pullen, S., Sheibani, E., Tian, H., Ott, S. & Hammarström, L. (2018). Direct evidence of catalyst reduction on dye and catalyst co-sensitized NiO photocathodes by mid-infrared transient absorption spectroscopy. Chemical Science, 9(22), 4983-4991
Open this publication in new window or tab >>Direct evidence of catalyst reduction on dye and catalyst co-sensitized NiO photocathodes by mid-infrared transient absorption spectroscopy
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2018 (English)In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 9, no 22, p. 4983-4991Article in journal (Refereed) Published
Abstract [en]

Co-sensitization of molecular dyes and catalysts on semiconductor surfaces is a promising strategy to build photoelectrodes for solar fuel production. In such a photoelectrode, understanding the charge transfer reactions between the molecular dye, catalyst and semiconductor material is key to guide further improvement of their photocatalytic performance. Herein, femtosecond mid-infrared transient absorption spectroscopy is used, for the first time, to probe charge transfer reactions leading to catalyst reduction on co-sensitized nickel oxide (NiO) photocathodes. The NiO films were co-sensitized with a molecular dye and a proton reducing catalyst from the family of [FeFe](bdt)(CO)(6) (bdt = benzene-1,2-dithiolate) complexes. Two dyes were used: an organic push-pull dye denoted E2 with a triarylamine-oligothiophene-dicyanovinyl structure and a coumarin 343 dye. Upon photo-excitation of the dye, a clear spectroscopic signature of the reduced catalyst is observed a few picoseconds after excitation in all co-sensitized NiO films. However, kinetic analysis of the transient absorption signals of the dye and reduced catalyst reveal important mechanistic differences in the first reduction of the catalyst depending on the co-sensitized molecular dye (E2 or C343). While catalyst reduction is preceded by hole injection in NiO in C343-sensitized NiO films, the singly reduced catalyst is formed by direct electron transfer from the excited dye E2* to the catalyst in E2-sensitized NiO films. This change in mechanism also impacts the lifetime of the reduced catalyst, which is only ca. 50 ps in E2-sensitized NiO films but is >5 ns in C343-sensitized NiO films. Finally, the implication of this mechanistic study for the development of better co-sensitized photocathodes is discussed.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-358380 (URN)10.1039/c8sc00990b (DOI)000434693300008 ()
Funder
Swedish Energy Agency, 11645-5
Available from: 2018-08-29 Created: 2018-08-29 Last updated: 2018-08-29Bibliographically approved
Bhunia, A., Johnson, B. A., Czapla-Masztafiak, J., Sá, J. & Ott, S. (2018). Formal water oxidation turnover frequencies from MIL-101(Cr) anchored Ru(bda) depend on oxidant concentration. Chemical Communications, 54, 7770-7773
Open this publication in new window or tab >>Formal water oxidation turnover frequencies from MIL-101(Cr) anchored Ru(bda) depend on oxidant concentration
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, p. 7770-7773Article in journal (Refereed) Published
Abstract [en]

The molecular water oxidation catalyst [Ru(bda)(L)(2)] has been incorporated into pyridine-decorated MIL-101(Cr) metal-organic frameworks. The resulting MIL-101@Ru materials exhibit turnover frequencies (TOFs) up to ten times higher compared to the homogenous reference. An unusual dependence of the formal TOFs on oxidant concentration is observed that ultimately arises from differing amounts of catalysts in the MOF crystals being active.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Inorganic Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-361265 (URN)10.1039/c8cc02300j (DOI)000438237700009 ()29926035 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyKnut and Alice Wallenberg FoundationEU, European Research Council, ERC-CoG2015-681895_MOFcat
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2018-10-11 Created: 2018-10-11 Last updated: 2018-10-11Bibliographically approved
Roy, S., Bhunia, A., Schuth, N., Haumann, M. & Ott, S. (2018). Light-driven hydrogen evolution catalyzed by a cobaloxime catalyst incorporated in a MIL-101(Cr) metal-organic framework. SUSTAINABLE ENERGY & FUELS, 2(6), 1148-1152
Open this publication in new window or tab >>Light-driven hydrogen evolution catalyzed by a cobaloxime catalyst incorporated in a MIL-101(Cr) metal-organic framework
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2018 (English)In: SUSTAINABLE ENERGY & FUELS, ISSN 2398-4902, Vol. 2, no 6, p. 1148-1152Article in journal (Refereed) Published
Abstract [en]

A cobaloxime H-2 evolution catalyst with a hydroxo-functionalized pyridine ligand, Co(dmgH)(2)(4-HEP)Cl [dmgH = dimethylglyoxime, 4-HEP = 4-(2-hydroxyethyl)pyridine] was immobilized on a chromium terephthalate metal-organic framework (MOF), MIL-101(Cr), to construct a MOF-catalyst hybrid which displays good photocatalytic H-2 evolution activity. The longevity of the cobaloxime catalyst is increased by MOF incorporation, but limited by the stability of the cobalt-pyridine bond under turnover conditions.

National Category
Physical Chemistry Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-357705 (URN)10.1039/c8se00072g (DOI)000434241200003 ()
Funder
Swedish Research CouncilSwedish Energy AgencyEU, European Research Council, ERC-CoG2015-681895_MOFcatWenner-Gren Foundations
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-21Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-1691-729X

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