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Pullen, Sonja
Publications (10 of 19) Show all publications
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
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
Roy, S., Pascanu, V., Pullen, S., Gonzalez Miera, G., Martin-Matute, B. & Ott, S. (2017). Catalyst accessibility to chemical reductants in metal–organic frameworks. Chemical Communications, 53(22), 3257-3260
Open this publication in new window or tab >>Catalyst accessibility to chemical reductants in metal–organic frameworks
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2017 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 22, p. 3257-3260Article in journal (Refereed) Published
Abstract [en]

A molecular H2-evolving catalyst, [Fe2(cbdt)(CO)6] ([FeFe], cbdt = 3-carboxybenzene-1,2-dithiolate), has been attached covalently to an amino-functionalized MIL-101(Cr) through an amide bond. Chemical reduction experiments reveal that the MOF channels can be clogged by ion pairs that are formed between the oxidized reductant and the reduced catalyst. This effect is lessened in MIL-101-NH-[FeFe] with lower [FeFe] loadings. On longer timescales, it is shown that large proportions of the [FeFe] catalysts within the MOF engage in photochemical hydrogen production and the amount of produced hydrogen is proportional to the catalyst loading.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-318972 (URN)10.1039/c7cc00022g (DOI)000398998500023 ()28261731 (PubMedID)
Available from: 2017-03-29 Created: 2017-03-29 Last updated: 2017-12-28Bibliographically approved
Mijangos, E., Roy, S., Pullen, S., Lomoth, R. & Ott, S. (2017). Evaluation of two- and three-dimensional electrode platforms for the electrochemical characterization of organometallic catalysts incorporated in non-conducting metal-organic frameworks. Dalton Transactions, 46(15), 4907-4911
Open this publication in new window or tab >>Evaluation of two- and three-dimensional electrode platforms for the electrochemical characterization of organometallic catalysts incorporated in non-conducting metal-organic frameworks
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2017 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, no 15, p. 4907-4911Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Inorganic Chemistry Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-321800 (URN)10.1039/c7dt00578d (DOI)000398888700006 ()28345708 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyKnut and Alice Wallenberg FoundationWenner-Gren FoundationsEU, European Research Council, ERC-CoG2015-681895_MOFcat
Available from: 2017-05-11 Created: 2017-05-11 Last updated: 2017-05-11Bibliographically approved
Pullen, S., Roy, S. & Ott, S. (2017). [FeFe] Hydrogenase active site model chemistry in a UiO-66metal-organic framework. Chemical Communications, 53(37), 5227-5230
Open this publication in new window or tab >>[FeFe] Hydrogenase active site model chemistry in a UiO-66metal-organic framework
2017 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 37, p. 5227-5230Article in journal (Refereed) Published
Abstract [en]

The reactivity of [Fe-2(dcbdt)(CO)(6)] (1) confined in a UiO-66(Zr) metal-organic framework towards CO ligand substitutions with phosphines of different sizes was investigated. The reaction with smaller phosphines (PX3, X = Me, Et) is more selective compared to analogous reactions in homogenous solution phase, and two CO ligands at up to 80% of all [FeFe] sites in UiO-66-1 are replaced. The produced [Fe-2(dcbdt)(CO)(4)(PX3)(2)] complexes in the UiO-66 matrix behave like typical [FeFe] hydrogenase active site model complexes, are reduced at more cathodic potentials than their hexacarbonyl analogues, and form bridging hydrides under acidic conditions.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-325338 (URN)10.1039/c7cc01620d (DOI)000400858400038 ()28443863 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyWenner-Gren FoundationsEU, European Research Council, ERC-CoG2015-681895_MOFcat
Available from: 2017-06-29 Created: 2017-06-29 Last updated: 2017-06-29Bibliographically approved
Morales Salazar, D., Mijangos, E., Pullen, S., Gao, M. & Orthaber, A. (2017). Functional small-molecules & polymers containing P[double bond, length as m-dash]C and As[double bond, length as m-dash]C bonds as hybrid π-conjugated materials. Chemical Communications, 53(6), 1120-1123
Open this publication in new window or tab >>Functional small-molecules & polymers containing P[double bond, length as m-dash]C and As[double bond, length as m-dash]C bonds as hybrid π-conjugated materials
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2017 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 6, p. 1120-1123Article in journal (Refereed) Published
Abstract [en]

Stable phospha- and arsaalkenes were used to synthesize polymers containing unsaturated P[double bond, length as m-dash]C and As[double bond, length as m-dash]C moieties. The composition, chemical environment, structure, optical, and electronic properties of the monomers and polymers were elucidated. The incorporation of the heteroatom-carbon double bonded units efficiently perturbs the optoelectronics and solid state features of both monomeric and polymeric scaffolds. Proof-of principle work supports their responsive character through post-functionalisation and electrochromic behaviour. To the best of our knowledge, this is the first example of a polymer containing arsenic-carbon double bonds.

National Category
Organic Chemistry Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-312610 (URN)10.1039/c6cc08736a (DOI)000393978300026 ()28054056 (PubMedID)
Funder
Lars Hierta Memorial FoundationStiftelsen Olle Engkvist ByggmästareSwedish Research Council, 2013-4763
Available from: 2017-01-12 Created: 2017-01-12 Last updated: 2017-11-29Bibliographically approved
Pavliuk, M. V., Cieślak,, A. M., Abdellah, M., Budinská, A., Pullen, S., Sokolowski, K., . . . Sá, J. (2017). Hydrogen evolution with nanoengineered ZnO interfaces decorated using a beetroot extract and a hydrogenase mimic. Sustainable Energy & Fuels, 1, 69-73
Open this publication in new window or tab >>Hydrogen evolution with nanoengineered ZnO interfaces decorated using a beetroot extract and a hydrogenase mimic
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2017 (English)In: Sustainable Energy & Fuels, ISSN 2398-4902, Vol. 1, p. 69-73Article in journal (Refereed) Published
Abstract [en]

Herein, we report a nano-hybrid photo-system based on abundant elements for H2 production with visible light. The photo-system's proficiency relates to the novel ZnO nanocrystals employed. The ZnO carboxylate oligoethylene glycol shell enhances charge separation and accumulates reactive electrons for the photocatalytic process. 

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
Keywords
H2 evolution
National Category
Physical Chemistry Engineering and Technology
Research subject
Chemistry with specialization in Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-335979 (URN)10.1039/c6se00066e (DOI)000422769100006 ()
Available from: 2017-12-11 Created: 2017-12-11 Last updated: 2018-12-17Bibliographically approved
Pullen, S. (2017). Mimicking the Outer Coordination Sphere in [FeFe]-Hydrogenase Active Site Models: From Extended Ligand Design to Metal-Organic Frameworks. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Mimicking the Outer Coordination Sphere in [FeFe]-Hydrogenase Active Site Models: From Extended Ligand Design to Metal-Organic Frameworks
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Biomimetic catalysis is an important research field, as a better understanding of nature´s powerful toolbox for the conversion of molecules can lead to technological progress. [FeFe]-hydrogenases are very efficient catalysts for hydrogen production. These enzymes play a crucial role in the metabolism of green algae and certain cyanobacteria. Their active site consists of a diiron complex that is embedded in an interactive protein matrix.

In this thesis, two pathways for mimicking the outer coordination sphere effects resulting from the protein matrix are explored.

The first is the construction of model complexes containing phosphine ligands that are coordinated to the iron center as well as covalently linked to the bridging ligand of the complex. The effect of such linkers is an increased energy barrier for the rotation of the Fe(CO2)(PL3)-subunit, which potentially could stabilize a terminal hydride that is an important intermediate in the proton reduction cycle.

The second pathway follows the incorporation of [FeFe]-hydrogenase active site model complexes into metal-organic frameworks (MOFs). Resulting MOF-catalysts exhibit increased photocatalytic activity compared to homogenous references due to a stabilizing effect on catalytic intermediates by the surrounding framework. Catalyst accessibility within the MOF and the influence of the framework on chemical reactivity are examined in the work presented. Furthermore, an initial step towards application of MOF-catalysts in a device was made by interfacing them with electrodes.

The work of this thesis highlights strategies for the improvement of biomimetic model catalysts and the knowledge gained can be transferred to other systems mimicking the function of enzymes. 

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. p. 115
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1498
Keywords
[FeFe]-hydrogenases, outer coordination sphere, model complexes, biomimetic catalysis, artificial photosynthesis, metal-organic frameworks
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-318975 (URN)978-91-554-9878-8 (ISBN)
Public defence
2017-05-19, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2017-04-28 Created: 2017-03-30 Last updated: 2017-05-05
Pavliuk, M. V., Mijangos, E., Makhankova, V. G., Kokozay, V. N., Pullen, S., Liu, J., . . . Thapper, A. (2016). Homogeneous Cobalt/Vanadium Complexes as Precursors for Functionalized Mixed Oxides in Visible-Light-Driven Water Oxidation. ChemSusChem, 9(20), 2957-2966
Open this publication in new window or tab >>Homogeneous Cobalt/Vanadium Complexes as Precursors for Functionalized Mixed Oxides in Visible-Light-Driven Water Oxidation
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2016 (English)In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 20, p. 2957-2966Article in journal (Refereed) Published
Abstract [en]

The heterometallic complexes (NH4)2[Co(H2O)6]2[V10O28]·4H2O (1) and (NH4)2[Co(H2O)5(β-HAla)]2[V10O28]·4H2O (2) have been synthesized and used for the preparation of mixed oxides as catalysts for water oxidation. Thermal decomposition of 1 and 2 at relatively low temperatures (<500 °C) leads to the formation of the solid mixed oxides CoV2O6/V2O5 (3) and Co2V2O7/V2O5 (4). The complexes (1, 2) and heterogeneous materials (3, 4) act as catalysts for photoinduced water oxidation. A modification of the thermal decomposition procedure allowed the deposition of mixed metal oxides (MMO) on a mesoporous TiO2 film. The electrodes containing Co/V MMOs in TiO2 films were used for electrocatalytic water oxidation and showed good stability and sustained anodic currents of about 5 mA cm−2 at 1.72 V versus relative hydrogen electrode (RHE). This method of functionalizing TiO2 films with MMOs at relatively low temperatures (<500 °C) can be used to produce other oxides with different functionality for applications in, for example, artificial photosynthesis.

Keywords
cobalt, heterogeneous catalysis, mixed oxides, synthesis design, water oxidation
National Category
Inorganic Chemistry
Research subject
Chemistry with specialization in Molecular Biomimetics
Identifiers
urn:nbn:se:uu:diva-306375 (URN)10.1002/cssc.201600769 (DOI)000386953500011 ()
Funder
Swedish Energy Agency, 11674-5Knut and Alice Wallenberg Foundation, 2011.0067Swedish Institute, 00284/2013
Available from: 2016-10-27 Created: 2016-10-27 Last updated: 2017-11-29Bibliographically approved
Pullen, S. & Ott, S. (2016). Photochemical Hydrogen Production with Metal-Organic Frameworks. Paper presented at 17th International Symposium on Relations Between Homogeneous and Heterogeneous Catalysis (ISSHC), JUL 12-15, 2015, Utrecht, NETHERLANDS. Topics in catalysis, 59(19-20), 1712-1721
Open this publication in new window or tab >>Photochemical Hydrogen Production with Metal-Organic Frameworks
2016 (English)In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 59, no 19-20, p. 1712-1721Article in journal, Meeting abstract (Refereed) Published
Abstract [en]

Metal-Organic Frameworks (MOFs) have attracted increasing attention for the creation of solid-state platforms for catalysis applications. In this review article, we present strategies to employ MOF-based materials in photochemical hydrogen production. The scope ranges from the incorporation of single functions (catalyst or photosensitizer) to multifunctional MOFs that combine both light-harvesting and catalysis in one scaffold.

Keywords
Metal-organic Framework, Light-harvesting, Photocatalysis, Hydrogen
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-312064 (URN)10.1007/s11244-016-0690-z (DOI)000388825800005 ()
Conference
17th International Symposium on Relations Between Homogeneous and Heterogeneous Catalysis (ISSHC), JUL 12-15, 2015, Utrecht, NETHERLANDS
Available from: 2017-01-04 Created: 2017-01-04 Last updated: 2017-11-29Bibliographically approved
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