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Izadi F, Szczyrba A, Datta M, Ciupak O, Demkowicz S, Rak J, Denifl S. Electron-Induced Decomposition of 5-Bromo-4-thiouracil and 5-Bromo-4-thio-2'-deoxyuridine: The Effect of the Deoxyribose Moiety on Dissociative Electron Attachment. Int J Mol Sci 2023; 24:ijms24108706. [PMID: 37240053 DOI: 10.3390/ijms24108706] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/28/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
When modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-2'-deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry was used to detect the anionic products of dissociative electron attachment (DEA), and the experimental results were supported by quantum chemical calculations performed at the M062X/aug-cc-pVTZ level of theory. Experimentally, we found that BrSU predominantly captures low-energy electrons with kinetic energies near 0 eV, though the abundance of bromine anions was rather low compared to a similar experiment with bromouracil. We suggest that, for this reaction channel, proton-transfer reactions in the transient negative ions limit the release of bromine anions.
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Affiliation(s)
- Farhad Izadi
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Adrian Szczyrba
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Magdalena Datta
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Olga Ciupak
- Department of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Sebastian Demkowicz
- Department of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Janusz Rak
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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Clothier GKK, Guimarães TR, Strover LT, Zetterlund PB, Moad G. Electrochemically-Initiated RAFT Synthesis of Low Dispersity Multiblock Copolymers by Seeded Emulsion Polymerization. ACS Macro Lett 2023; 12:331-337. [PMID: 36802531 PMCID: PMC10035029 DOI: 10.1021/acsmacrolett.3c00021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
We describe electrochemically initiated emulsion polymerization with reversible addition-fragmentation chain transfer (eRAFT) to form well-defined multiblock copolymers with low molar mass dispersity. We demonstrate the utility of our emulsion eRAFT process with the synthesis of low dispersity multiblock copolymers by seeded RAFT emulsion polymerization at ambient temperature (∼30 °C). Thus, a triblock, poly(butyl methacrylate)-block-polystyrene-block-poly(4-methylstyrene) [PBMA-b-PSt-b-PMS], and a tetrablock, poly(butyl methacrylate)-block-polystyrene-block-poly(styrene-stat-butyl acrylate)-block-polystyrene [PBMA-b-PSt-b-P(BA-stat-St)-b-PSt], were synthesized as free-flowing, colloidally stable latexes commencing with a surfactant-free poly(butyl methacrylate) macroRAFT agent seed latex. A straightforward sequential addition strategy with no intermediate purification steps was able to be employed due to the high monomer conversions achieved in each step. The method takes full advantage of compartmentalization phenomena and the nanoreactor concept described in previous work to achieve the predicted molar mass, low molar mass dispersity (Đ ∼ 1.1-1.2), incrementing particle size (Zav = 100-115 nm), and low particle size dispersity (PDI ∼ 0.02) for each generation of the multiblocks.
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Affiliation(s)
- Glenn K K Clothier
- Cluster for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Thiago R Guimarães
- Cluster for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | | | - Per B Zetterlund
- Cluster for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Graeme Moad
- CSIRO Manufacturing, Clayton, VIC 3168, Australia
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3
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Bagheri A. Application of RAFT in 3D Printing: Where Are the Future Opportunities? Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c02585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Ali Bagheri
- School of Science and Technology, University of New England, Armidale, NSW 2351, Australia
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Boyer C, Kamigaito M, Satoh K, Moad G. Radical-Promoted Single-unit Monomer Insertion (SUMI) [aka. Reversible-Deactivation Radical Addition (RDRA)]. Prog Polym Sci 2023. [DOI: 10.1016/j.progpolymsci.2023.101648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Wang Q, Bai FY, Wang Y, Niu F, Zhang Y, Mi Q, Hu K, Pan X. Photoinduced Ion-Pair Inner-Sphere Electron Transfer-Reversible Addition-Fragmentation Chain Transfer Polymerization. J Am Chem Soc 2022; 144:19942-19952. [PMID: 36266241 DOI: 10.1021/jacs.2c08173] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Photoredox-mediated reversible deactivation radical polymerization (RDRP) is a promising method of precise synthesis of polymers with diverse structures and properties. However, its mechanism mainly based on the outer-sphere electron transfer (OSET) leads to stringent requirements for an efficient photocatalyst. In this paper, the zwitterionic organoboranes [L2B]+X- are prepared and applied in reversible addition-fragmentation chain transfer (RAFT) polymerization with the photoinduced ion-pair inner-sphere electron transfer (IP-ISET) mechanism. The ion-pair electron transfer mechanism and the formation of the radical [L2B]• are supported by electron paramagnetic resonance (EPR) radical capture experiments, 1H/11B NMR spectroscopy, spectroelectrochemical spectroscopy, transient absorption spectroscopy, theoretical calculation, and photoluminescence quenching experiments. Photoluminescence quenching experiments show that when [CTA]/[[L2B]+] ≥ 0.6, it is static quenching because of the in situ formation of [L2B]+[ZCS2]-, the real catalytic species. [L2B]+[C3H7SCS2]- is synthesized, and its photoluminescence lifetime is the same as the lifetime in the static quenching experiment, indicating the formation of [L2B]+[ZCS2]- in polymerization and the IP-ISET mechanism. The matrix-assisted laser desorption ionization time-of-flight mass (MALDI-TOF MS) spectra show that the structure of [C3H7SCS2] was incorporated into the polymer, indicating that ion-pair electron transfer occurs in catalytic species. The polymerization shows high catalytic activity at ppb catalyst loading, a wide range of monomers, excellent tolerance in the presence of 5 mol % phenolic inhibitors, and the synthesis of ultrahigh-molecular-weight polymers. This protocol with the IP-ISET mechanism exhibits a value in the development of new organic transformations and polymerization methods.
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Affiliation(s)
- Qianyi Wang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200438, China
| | - Feng-Yang Bai
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang, Liaoning 110034, China
| | - Yinling Wang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200438, China
| | - Fushuang Niu
- Department of Chemistry, Fudan University, Shanghai 200438, China
| | - Yifei Zhang
- Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang, Liaoning 110034, China
| | - Qixi Mi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ke Hu
- Department of Chemistry, Fudan University, Shanghai 200438, China
| | - Xiangcheng Pan
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200438, China
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Arthur-Baidoo E, Ončák M, Denifl S. Electron attachment to fluorodeoxyglucose: Dissociation dynamics in a molecule of near-zero electron affinity. J Chem Phys 2022; 157:074301. [PMID: 35987575 DOI: 10.1063/5.0101726] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Fluorodeoxyglucose (FDG) is a glucose derivative with fluorine at the C2 position. The molecule containing the radioactive F-18 isotope is well known from its application in positron emission tomography as a radiotracer in tumor examination. In the stable form with the F-19 isotope, FDG was proposed as a potential radiosensitizer. Since reduction processes may be relevant in radiosensitization, we investigated low-energy electron attachment to FDG with a crossed electron-molecule beam experiment and with quantum chemical calculations as well as molecular dynamics at elevated temperatures to reveal statistical dissociation. We experimentally find that the susceptibility of FDG to low-energy electrons is relatively low. The calculations indicate that upon attachment of an electron with a kinetic energy of ∼0 eV, only dipole-bound states are accessible, which agrees with the weak ion yields observed in the experiment. The temporary negative ions formed upon electron attachment to FDG may decay by a large variety of dissociation reactions. The major fragmentation channels include H2O, HF, and H2 dissociation, accompanied by ring opening.
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Affiliation(s)
- Eugene Arthur-Baidoo
- Institut fücr Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Milan Ončák
- Institut fücr Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut fücr Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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Electron Attachment to 5-Fluorouracil: The Role of Hydrogen Fluoride in Dissociation Chemistry. Int J Mol Sci 2022; 23:ijms23158325. [PMID: 35955461 PMCID: PMC9369043 DOI: 10.3390/ijms23158325] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 12/03/2022] Open
Abstract
We investigate dissociative electron attachment to 5-fluorouracil (5-FU) employing a crossed electron-molecular beam experiment and quantum chemical calculations. Upon the formation of the 5-FU- anion, 12 different fragmentation products are observed, the most probable dissociation channel being H loss. The parent anion, 5-FU-, is not stable on the experimental timescale (~140 µs), most probably due to the low electron affinity of FU; simple HF loss and F- formation are seen only with a rather weak abundance. The initial dynamics upon electron attachment seems to be governed by hydrogen atom pre-dissociation followed by either its full dissociation or roaming in the vicinity of the molecule, recombining eventually into the HF molecule. When the HF molecule is formed, the released energy might be used for various ring cleavage reactions. Our results show that higher yields of the fluorine anion are most probably prevented through both faster dissociation of an H atom and recombination of F- with a proton to form HF. Resonance calculations indicate that F- is formed upon shape as well as core-excited resonances.
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Sensing the ortho Positions in C6Cl6 and C6H4Cl2 from Cl2− Formation upon Molecular Reduction. Molecules 2022; 27:molecules27154820. [PMID: 35956769 PMCID: PMC9369944 DOI: 10.3390/molecules27154820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 11/17/2022] Open
Abstract
The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl2−. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using ortho-, meta- and para-dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations. We also observed that Cl2− formation can only occur in 1,2-C6H4Cl2, where the two closest C–Cl bonds are cleaved while the chlorine atoms are brought together within the ring framework due to excess energy dissipation. These results show that a strong coupling between electronic and C–Cl bending motion is responsible for a positional isomeric effect, where molecular recognition is a determining factor in chlorine anion formation.
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Ziegler P, Pelc A, Arthur-Baidoo E, Ameixa J, Ončák M, Denifl S. Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule. RSC Adv 2021; 11:32425-32434. [PMID: 35495526 PMCID: PMC9041917 DOI: 10.1039/d1ra06083j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/13/2021] [Indexed: 12/20/2022] Open
Abstract
Nicotinamide (C6H6N2O) is a biologically relevant molecule. This compound has several important roles related to the anabolic and metabolic processes that take place in living organisms. It is also used as a radiosensitizer in tumor therapy. As a result of the interaction of high-energy radiation with matter, low-energy electrons are also released, which can also interact with other molecules, forming several types of ions. In the present investigation, dissociative electron attachment to C6H6N2O has been studied in a crossed electron-molecular beams experiment in the electron energy range of about 0-15 eV. In the experiment, six anionic species were detected: C6H5N2O-, C5H4N-, NCO-, O-/NH2 -, and CN-, with NCO- being the most prominent anion. We also provide detailed computational results regarding the energetic thresholds and pathways of the respective dissociative electron attachment (DEA) channels. The experimental results are compared with the theoretical ones and on this basis, the possible DEA reactions for the formation of anions at a given resonance energy were assigned as well as the generation of neutrals fragments such as pyridine and its several derivatives and radicals are predicted. The pyridine ring seems to stay intact during the DEA process.
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Affiliation(s)
- Patrick Ziegler
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Andrzej Pelc
- Maria Curie-Skłodowska University, Department of Biophysics, Mass Spectrometry Laboratory Pl. M. C.-Skłodowskiej 1 20-031 Lublin Poland
| | - Eugene Arthur-Baidoo
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Joao Ameixa
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria .,Centre of Physics and Technological Research, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa 2829-516 Caparica Portugal
| | - Milan Ončák
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Stephan Denifl
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
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