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Blachucki, W., Czapla-Masztafiak, J., Sá, J. & Szlachetko, J. (2019). A laboratory-based double X-ray spectrometer for simultaneous X-ray emission and X-ray absorption studies. Journal of Analytical Atomic Spectrometry, 34(7), 1409-1415
Open this publication in new window or tab >>A laboratory-based double X-ray spectrometer for simultaneous X-ray emission and X-ray absorption studies
2019 (English)In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 34, no 7, p. 1409-1415Article in journal (Refereed) Published
Abstract [en]

X-ray spectroscopy studies are usually performed using synchrotron radiation sources, which offer bright, coherent, energy-tuneable and monochromatic light. However, the application of synchrotron-based Xray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) is directly constrained by the limited, infrequent access to central facilities. With the advent of new technological solutions in the field of X-ray sources, optics and detectors, the development of efficient and compact laboratory X-ray spectroscopy systems is possible. A permanent laboratory-based setup offers the advantages of low cost and easy accessibility and, therefore, more flexibility in the preparation and scheduling of measurements. Herein, we report a laboratory X-ray setup allowing simultaneous XES and XAS measurements. The double von Hamos spectrometer performances are demonstrated by concurrent K beta XES and K-edge XAS measurements done for 3d elements.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-390902 (URN)10.1039/c9ja00159j (DOI)000474289100021 ()
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2019-08-19Bibliographically approved
Goncalves, L. C. P., Mansouri, H. R., PourMehdi, S., Abdellah, M., Fadiga, B. S., Bastos, E. L., . . . Rudroffe, F. (2019). Boosting photobioredox catalysis by morpholine electron donors under aerobic conditions. Catalysis Science & Technology, 9(10), 2682-2688
Open this publication in new window or tab >>Boosting photobioredox catalysis by morpholine electron donors under aerobic conditions
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2019 (English)In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 10, p. 2682-2688Article in journal (Refereed) Published
Abstract [en]

Light-driven reduction of flavins, e.g. FAD or FMN, by sacrificial electron donors emerged as a convenient method to promote biocatalytic transformations. However, flavin activation has been restricted to oxygen-free conditions to prevent enzyme deactivation caused by reactive oxygen species (ROS). Herein, we show that the photoreduction of FMN by morpholines, including 3-(N-morpholino)propanesulfonic acid (MOPS), lessens the deactivation of the enoate reductase XenB from Pseudomonas sp. during the stereoselective asymmetric enzymatic reduction of a model ,-unsaturated diketone under aerobic conditions, leading to a 91% GC-yield and a stereoselectivity greater than 94%. The kinetic stability of the thermolabile XenB was increased by more than 20-fold in MOPS buffer compared to that in Tris-HCl buffer, and a pronounced positive effect on the transition midpoint temperature was observed. The reactive form of the FMN photocatalyst is stabilized by the formation of a (3)[FMN--MOPS+] ensemble, which reduces the formation of hydrogen peroxide and other ROS in the presence of oxygen. These results contribute to broaden the application of photobiocatalytic transformations using flavin-dependent reductases.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-390605 (URN)10.1039/c9cy00496c (DOI)000472455800023 ()
Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-13Bibliographically approved
Shylin, S. I., Pavliuk, M. V., D'Amario, L., Mamedov, F., Sá, J., Berggren, G. & Fritsky, I. O. (2019). Efficient visible light-driven water oxidation catalysed by an iron(IV) clathrochelate complex. Chemical Communications, 55(23), 3335-3338
Open this publication in new window or tab >>Efficient visible light-driven water oxidation catalysed by an iron(IV) clathrochelate complex
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2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 23, p. 3335-3338Article in journal (Refereed) Published
Abstract [en]

A water-stable FeIV clathrochelate complex catalyzes fast and homogeneous photochemical oxidation of water to dioxygen with a turnover frequency of 2.27 s−1 and a maximum turnover number of 365. An FeV intermediate generated under catalytic conditions is trapped and characterised using EPR and Mössbauer spectroscopy.

Keywords
Artificial photosynthesis, water oxidation, iron catalyst, photochemical water oxidation, electrochemical water oxidation
National Category
Physical Chemistry
Research subject
Chemistry with specialization in Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-379606 (URN)10.1039/C9CC00229D (DOI)000461397500002 ()30801592 (PubMedID)
Funder
EU, Horizon 2020, 778245Swedish Institute
Available from: 2019-03-18 Created: 2019-03-18 Last updated: 2019-04-12Bibliographically approved
Pavliuk, M. V., Alvarez, S. G., Hattori, Y., Messing, M. E., Czapla-Masztafiak, J., Szlachetko, J., . . . Sá, J. (2019). Hydrated Electron Generation by Excitation of Copper Localized Surface Plasmon Resonance. Journal of Physical Chemistry Letters, 10(8), 1743-1749
Open this publication in new window or tab >>Hydrated Electron Generation by Excitation of Copper Localized Surface Plasmon Resonance
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 8, p. 1743-1749Article in journal (Refereed) Published
Abstract [en]

Hydrated electrons are important in radiation chemistry and charge transfer reactions, with applications that include chemical damage of DNA, catalysis, and signaling. Conventionally, hydrated electrons are produced by pulsed radiolysis, sonolysis, two-ultraviolet-photon laser excitation of liquid water, or photodetachment of suitable electron donors. Here we report a method for the generation of hydrated electrons via single-visible-photon excitation of localized surface plasmon resonances (LSPRs) of supported sub-3 nm copper nanoparticles in contact with water. Only excitations at the LSPR maximum resulted in the formation of hydrated electrons, suggesting that plasmon excitation plays a crucial role in promoting electron transfer from the nanoparticle into the solution. The reactivity of the hydrated electrons was confirmed via proton reduction and concomitant H-2 evolution in the presence of a Ru/TiO2 catalyst.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-383191 (URN)10.1021/acs.jpclett.9b00792 (DOI)000465507700014 ()30920838 (PubMedID)
Funder
Swedish Research CouncilStiftelsen Olle Engkvist Byggmästare
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2019-07-24 Created: 2019-07-24 Last updated: 2019-07-24Bibliographically approved
Blachucki, W., Kayser, Y., Czapla-Masztafiak, J., Guo, M., Juranic, P., Kavcic, M., . . . Szlachetko, J. (2019). Inception of electronic damage of matter by photon-driven post-ionization mechanisms. Structural Dynamics, 6(2), Article ID 024901.
Open this publication in new window or tab >>Inception of electronic damage of matter by photon-driven post-ionization mechanisms
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2019 (English)In: Structural Dynamics, ISSN 2329-7778, Vol. 6, no 2, article id 024901Article in journal (Refereed) Published
Abstract [en]

"Probe-before-destroy" methodology permitted diffraction and imaging measurements of intact specimens using ultrabright but highly destructive X-ray free-electron laser (XFEL) pulses. The methodology takes advantage of XFEL pulses ultrashort duration to outrun the destructive nature of the X-rays. Atomic movement, generally on the order of >50 fs, regulates the maximum pulse duration for intact specimen measurements. In this contribution, we report the electronic structure damage of a molecule with ultrashort X-ray pulses under preservation of the atoms' positions. A detailed investigation of the X-ray induced processes revealed that X-ray absorption events in the solvent produce a significant number of solvated electrons within attosecond and femtosecond timescales that are capable of coulombic interactions with the probed molecules. The presented findings show a strong influence on the experimental spectra coming from ionization of the probed atoms' surroundings leading to electronic structure modification much faster than direct absorption of photons. This work calls for consideration of this phenomenon in cases focused on samples embedded in, e.g., solutions or in matrices, which in fact concerns most of the experimental studies.

National Category
Atom and Molecular Physics and Optics Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-383884 (URN)10.1063/1.5090332 (DOI)000466710000011 ()31041363 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, KAW-2013.0020
Available from: 2019-05-29 Created: 2019-05-29 Last updated: 2019-05-29Bibliographically approved
Meier de Andrade, A., Kullgren, J., Sá, J. & Broqvist, P. (2019). Insights into reactive nanoparticles. In: : . Paper presented at 2019 EMMC-eSSENCE Meeting "Multiscale modelling of materials and molecules: Physics-based and data-driven.".
Open this publication in new window or tab >>Insights into reactive nanoparticles
2019 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-394007 (URN)
Conference
2019 EMMC-eSSENCE Meeting "Multiscale modelling of materials and molecules: Physics-based and data-driven."
Available from: 2019-10-01 Created: 2019-10-01 Last updated: 2019-10-01
Goncalves, L. C. P., Mansouri, H. R., Bastos, E. L., Abdellah, M., Fadiga, B. S., Sá, J., . . . Mihovilovic, M. D. (2019). Morpholine-based buffers activate aerobic photobiocatalysis via spin correlated ion pair formation. Catalysis Science & Technology, 9(6), 1365-1371
Open this publication in new window or tab >>Morpholine-based buffers activate aerobic photobiocatalysis via spin correlated ion pair formation
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2019 (English)In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 9, no 6, p. 1365-1371Article in journal (Refereed) Published
Abstract [en]

The use of enzymes for synthetic applications is a powerful and environmentally-benign approach to increase molecular complexity. Oxidoreductases selectively introduce oxygen and hydrogen atoms into myriad substrates, catalyzing the synthesis of chemical and pharmaceutical building blocks for chemical production. However, broader application of this class of enzymes is limited by the requirements of expensive cofactors and low operational stability. Herein, we show that morpholine-based buffers, especially 3-(N-morpholino)propanesulfonic acid (MOPS), promote photoinduced flavoenzyme-catalyzed asymmetric redox transformations by regenerating the flavin cofactor via sacrificial electron donation and by increasing the operational stability of flavin-dependent oxidoreductases. The stabilization of the active forms of flavin by MOPS via formation of the spin correlated ion pair (3)[flavin(-)-MOPS+] ensemble reduces the formation of hydrogen peroxide, circumventing the oxygen dilemma under aerobic conditions detrimental to fragile enzymes.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-381585 (URN)10.1039/c8cy02524j (DOI)000462662100003 ()
Available from: 2019-04-12 Created: 2019-04-12 Last updated: 2019-04-12Bibliographically approved
Sá, J. & Medlin, J. W. (2019). On-the-fly Catalyst Modification: Strategy to Improve Catalytic Processes Selectivity and Understanding. ChemCatChem, 11(15), 3355-3365
Open this publication in new window or tab >>On-the-fly Catalyst Modification: Strategy to Improve Catalytic Processes Selectivity and Understanding
2019 (English)In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 11, no 15, p. 3355-3365Article, review/survey (Refereed) Published
Abstract [en]

Hydrogenation is a quintessential process to the chemical industry. It is heavily involved in organic synthesis and fuel production, among other processes. Preferentially the reactions are carried out with heterogeneous catalysts and when possible in flow mode. Herein, we provide a retrospective on selective surface modification of catalysts for improved selectivity and understanding of catalytic reactivity. In addition, we provide a prospectus for an emerging strategy of carrying out surface modification on-the-fly to produce novel catalysts in a fast and reproducible way and to understand catalytic phenomena.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2019
Keywords
on-the-fly catalyst modification, structure-performance relationship, hydrogenation, flow catalysis, laboratory X-ray photon-in photon out spectroscopy
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-395362 (URN)10.1002/cctc.201900770 (DOI)000480290100003 ()
Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17Bibliographically approved
Hattori, Y., Abdellah, M., Meng, J., Zheng, K. & Sá, J. (2019). Simultaneous Hot Electron and Hole Injection upon Excitation of Gold Surface Plasmon. Journal of Physical Chemistry Letters, 10(11), 3140-3146
Open this publication in new window or tab >>Simultaneous Hot Electron and Hole Injection upon Excitation of Gold Surface Plasmon
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 11, p. 3140-3146Article in journal (Refereed) Published
Abstract [en]

We have successfully investigated the simultaneous injection of hot electrons and holes upon excitation of gold localized surface plasmon resonance (LSPR). The studies were performed on all-solid-state plasmonic system composed of titanium dioxide (TiO2)/poly(3,4-ethylenedioxythiophene) :poly(styrenesulfonic acid) (PEDOT:PSS) p-n junctions with gold nanoparticles (Au NPs). The study revealed that both charge carriers are transferred within 200 fs to the respective charge acceptors, exhibiting a free carrier transport behavior. We also confirmed that the transfer of charge carriers are accompanied by change in the initial relaxation dynamics of Au NPs.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-389600 (URN)10.1021/acs.jpclett.9b01085 (DOI)000471079400075 ()31117685 (PubMedID)
Funder
Swedish Research Council
Available from: 2019-07-24 Created: 2019-07-24 Last updated: 2019-07-24Bibliographically approved
Wojtaszek, K., Wach, A., Czapla-Masztafiak, J., Tyrala, K., Sá, J., Özer, L. Y., . . . Szlachetko, J. (2019). The influence of nitrogen doping on the electronic structure of the valence and conduction band in TiO2. Journal of Synchrotron Radiation, 26, 145-151
Open this publication in new window or tab >>The influence of nitrogen doping on the electronic structure of the valence and conduction band in TiO2
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2019 (English)In: Journal of Synchrotron Radiation, ISSN 0909-0495, E-ISSN 1600-5775, Vol. 26, p. 145-151Article in journal (Refereed) Published
Abstract [en]

X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS) provide a unique opportunity to probe both the highest occupied and the lowest unoccupied states in matter with bulk sensitivity. In this work, a combination of valence-to-core XES and pre-edge XAS techniques are used to determine changes induced in the electronic structure of titanium dioxide doped with nitrogen atoms. Based on the experimental data it is shown that N-doping leads to incorporation of the p-states on the occupied electronic site. For the conduction band, a decrease in population of the lowest unoccupied d-localized orbitals with respect to the d-delocalized orbitals is observed. As confirmed by theoretical calculations, the N p-states in TiO2 structure are characterized by higher binding energy than the O p-states which gives a smaller value of the band-gap energy for the doped material.

Place, publisher, year, edition, pages
INT UNION CRYSTALLOGRAPHY, 2019
Keywords
X-ray emission spectroscopy, X-ray absorption spectroscopy, electronic structure analysis, TiO2 doping
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-376891 (URN)10.1107/S1600577518016685 (DOI)000456025200018 ()30655479 (PubMedID)
Available from: 2019-02-12 Created: 2019-02-12 Last updated: 2019-02-12Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2124-9510

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