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Liu S, Li Y, Lin J, Ke Z, Grützmacher H, Su CY, Li Z. Sequential radical and cationic reactivity at separated sites within one molecule in solution. Chem Sci 2024; 15:5376-5384. [PMID: 38577367 PMCID: PMC10988588 DOI: 10.1039/d4sc00201f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 02/29/2024] [Indexed: 04/06/2024] Open
Abstract
Distonic radical cations (DRCs) with spatially separated charge and radical sites are expected to show both radical and cationic reactivity at different sites within one molecule. However, such "dual" reactivity has rarely been observed in the condensed phase. Herein we report the isolation of crystalline 1λ2,3λ2-1-phosphonia-3-phosphinyl-cyclohex-4-enes 2a,b˙+, which can be considered delocalized DRCs and were completely characterized by crystallographic, spectroscopic, and computational methods. These DRCs contain a radical and cationic site with seven and six valence electrons, respectively, which are both stabilized via conjugation, yet remain spatially separated. They exhibit reactivity that differs from that of conventional radical cations (CRCs); specifically they show sequential radical and cationic reactivity at separated sites within one molecule in solution.
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Affiliation(s)
- Shihua Liu
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
| | - Yinwu Li
- School of Materials Science and Engineering, Sun Yat-Sen University 510006 Guangzhou China
| | - Jieli Lin
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
| | - Zhuofeng Ke
- School of Materials Science and Engineering, Sun Yat-Sen University 510006 Guangzhou China
| | - Hansjörg Grützmacher
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
- Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir-Prelog-Weg 1 Zürich 8093 Switzerland
| | - Cheng-Yong Su
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
| | - Zhongshu Li
- LIFM, IGCME, School of Chemistry, Sun Yat-Sen University Guangzhou 510006 China
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2
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Gutowski Ł, Liszewska M, Bartosewicz B, Budner B, Weyher JL, Jankiewicz BJ. Investigation of organic monoradicals reactivity using surface-enhanced Raman spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2022; 278:121312. [PMID: 35537259 DOI: 10.1016/j.saa.2022.121312] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/28/2022] [Accepted: 04/23/2022] [Indexed: 06/14/2023]
Abstract
Surface-enhanced Raman spectroscopy (SERS) and self-assembled monolayer (SAM) approaches were used to investigate the reactions of organic monoradicals with methanol. An attempt was made to generate monoradicals from thiophenols and phenylmethanethiols substituted with bromine, iodine, and nitro groups by irradiation with UV light. Monolayers of radical precursors were deposited on SERS substrates, which were then immersed in methanol and irradiated for 1 and/or 3, 6, 12 and 24 h in a UV photochemical reactor. Pre- and postreaction SERS spectra were obtained by using a confocal Raman microscope and compared with the spectra of expected products of the radical reaction with methanol. Our studies have shown that the efficiency of monoradical generation is highly dependent on the chemical structure of the precursor. In addition, it is shown that both the SERS substrate and experimental conditions used strongly influence the obtained results.
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Affiliation(s)
- Łukasz Gutowski
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Malwina Liszewska
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Bartosz Bartosewicz
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Bogusław Budner
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
| | - Jan L Weyher
- Institute of High-Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland.
| | - Bartłomiej J Jankiewicz
- Institute of Optoelectronics, Military University of Technology, gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
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Andrikopoulos B, Sidhu PK, Taggert BI, Nathanael JG, O'Hair RAJ, Wille U. Reaction of Distonic Aryl and Alkyl Radical Cations with Amines: The Role of Charge and Spin Revealed by Mass Spectrometry, Kinetic Studies, and DFT Calculations. Chempluschem 2020. [DOI: 10.1002/cplu.201900706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Benjamin Andrikopoulos
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Parvinder K. Sidhu
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Bethany I. Taggert
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Joses G. Nathanael
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Richard A. J. O'Hair
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
| | - Uta Wille
- School of Chemistry Bio21 Institute The University of Melbourne 30 Flemington Road, Parkville Victoria 3010 Australia
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4
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Cinar ME, Lal M, Deiseroth HJ, Schlirf J, Schmittel M. Detection and follow-up reactions of distonic β
, β
-dimesityl enol radical cations containing nitrogen heterocyclic bases. J PHYS ORG CHEM 2018. [DOI: 10.1002/poc.3865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- M. Emin Cinar
- Department Chemie-Biologie; Universität Siegen; Siegen Germany
| | - Mukul Lal
- Department Chemie-Biologie; Universität Siegen; Siegen Germany
| | | | - Jens Schlirf
- Department Chemie-Biologie; Universität Siegen; Siegen Germany
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5
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Bright CC, Prendergast MB, Kelly PD, Bezzina JP, Blanksby SJ, da Silva G, Trevitt AJ. Highly efficient gas-phase reactivity of protonated pyridine radicals with propene. Phys Chem Chem Phys 2018; 19:31072-31084. [PMID: 29152628 DOI: 10.1039/c7cp06644a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Small nitrogen containing heteroaromatics are fundamental building blocks for many biological molecules, including the DNA nucleotides. Pyridine, as a prototypical N-heteroaromatic, has been implicated in the chemical evolution of many extraterrestrial environments, including the atmosphere of Titan. This paper reports on the gas-phase ion-molecule reactions of the three dehydro-N-pyridinium radical cation isomers with propene. Photodissociation ion-trap mass spectrometry experiments are used to measure product branching ratios and reaction kinetics. Reaction efficiencies for 2-dehydro-N-pyridinium, 3-dehydro-N-pyridinium and 4-dehydro-N-pyridinium with propene are 70%, 47% and 41%, respectively. The m/z 106 channel is the major product channel across all cases and assigned 2-, 3-, and 4-vinylpyridinium for each reaction. The m/z 93 channel is also significant and assigned the 2-, 3-, and 4-N-protonated-picolyl radical cation for each case. H-Abstraction from propene is not competitive under experimental conditions. Potential energy schemes, at the M06-2X/6-31(2df,p) level of theory and basis set, are described to assist in rationalising observed product branching ratios and elucidating possible reaction mechanisms. Reaction barriers to the production of vinylpyridinium (m/z 106) + CH3 are the lowest identified for the 3- and 4-dehydro-N-pyridinium reactions, in support of the observed dominance of the m/z 106 ion signal. Ethylene loss via ring-mediated H-transfer along the propyl group is found to be the lowest energy pathway for the 2-dehydro-N-pyridinium reaction, suggesting a preference toward m/z 93 (N-protonated-picolyl radical cation) over the experimentally observed products. Entropic bottle-necks along the m/z 93 pathway however, associated with ring-mediated H-atom transfer, are responsible for the dominance of m/z 106 in the 2-dehydro-N-pyridinium + propene reaction. For all three isomers, computed barriers for all observed reaction channels were below the entrance channel, suggesting these reactions can contribute to molecular weight growth in extraterrestrial environments with accelerated reaction rates in low temperature regions of space.
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Affiliation(s)
- Cameron C Bright
- School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia.
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6
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Bezzina JP, Prendergast MB, Blanksby SJ, Trevitt AJ. Gas-Phase Oxidation of the Protonated Uracil-5-yl Radical Cation. J Phys Chem A 2018; 122:890-896. [PMID: 29295616 DOI: 10.1021/acs.jpca.7b09411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study targets the kinetics and product detection of the gas-phase oxidation reaction of the protonated 5-dehydrouracil (uracil-5-yl) distonic radical cation using ion-trap mass spectrometry. Protonated 5-dehydrouracil radical ions (5-dehydrouracilH+ radical ion, m/z 112) are produced within an ion trap by laser photolysis of protonated 5-iodouracil. Storage of the 5-dehydrouracilH+ radical ion in the presence of controlled concentration of O2 reveals two main products. The major reaction product pathway is assigned as the formation of protonated 2-hydroxypyrimidine-4,5-dione (m/z 127) + •OH. A second product ion (m/z 99), putatively assigned as a five-member-ring ketone structure, is tentatively explained as arising from the decarbonylation (-CO) of protonated 2-hydroxypyrimidine-4,5-dione. Because protonation of the 5-dehydrouracil radical likely forms a dienol structure, the O2 reaction at the 5 position is ortho to an -OH group. Following this addition of O2, the peroxyl-radical intermediate isomerizes by H atom transfer from the -OH group. The ensuing hydroperoxide then decomposes to eliminate •OH radical. It is shown that this elimination of •OH radical (-17 Da) is evidence for the presence of an -OH group ortho to the initial phenyl radical site, in good accord with calculations. The subsequent CO loss mechanism, to form the aforementioned five-member-ring structure, is unclear, but some pathways are discussed. By following the kinetics of the reaction, the room temperature second-order rate coefficient of the 5-dehydrouracilH+ distonic radical cation with molecular oxygen is measured at 7.2 × 10-11 cm3 molecule-1 s-1, Φ = 12% (with ±50% total accuracy). For aryl radical reactions with O2, the presence of the •OH elimination product pathway, following the peroxyl-radical formation, is an indicator of an -OH group ortho to the radical site.
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Affiliation(s)
- James P Bezzina
- School of Chemistry, University of Wollongong , Wollongong, Australia 2522
| | | | - Stephen J Blanksby
- Central Analytical Research Facility, Institute for Future Environments, Queensland University of Technology , Brisbane, Australia 4001
| | - Adam J Trevitt
- School of Chemistry, University of Wollongong , Wollongong, Australia 2522
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Cai Y, Wang J, Zhang Y, Li Z, Hu D, Zheng N, Chen H. Detection of Fleeting Amine Radical Cations and Elucidation of Chain Processes in Visible-Light-Mediated [3 + 2] Annulation by Online Mass Spectrometric Techniques. J Am Chem Soc 2017; 139:12259-12266. [PMID: 28786686 DOI: 10.1021/jacs.7b06319] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Visible-light-mediated photoredox reactions have recently emerged as a powerful means for organic synthesis and thus have generated significant interest from the organic chemistry community. Although the mechanisms of these reactions have been probed by a number of techniques such as NMR, fluorescence quenching, and laser flash photolysis and various degrees of success has been achieved, mechanistic ambiguity still exists (for instance, the involvement of the chain mechanism is still under debate) because of the lack of structural information about the proposed and short-lived intermediates. Herein, we present the detection of transient amine radical cations involved in the intermolecular [3 + 2] annulation reaction of N-cyclopropylaniline (CPA, 1) and styrene 2 by electrospray ionization mass spectrometry (ESI-MS) in combination with online laser irradiation of the reaction mixture. In particular, the reactive CPA radical cation 1+•, the reduced photocatalyst Ru(I)(bpz)3+, and the [3 + 2] annulation product radical cation 3+• are all successfully detected and confirmed by high-resolution MS. More importantly, the post-irradiation reaction with an additional substrate, isotope-labeled CPA, following photolysis of 1, 2, and Ru catalyst provides strong evidence to support the chain mechanism in the [3 + 2] annulation reaction. Furthermore, the key step of the proposed chain reaction, the oxidation of CPA 1 to amine radical cation 1+• by product radical cation 3+• (generated using online electrochemical oxidation of 3), is successfully established. Additionally, the coupling of ESI-MS with online laser irradiation has been successfully applied to probe the photostability of photocatalysts.
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Affiliation(s)
- Yi Cai
- Department of Chemistry and Biochemistry, Center of Intelligent Chemical Instrumentation, Edison Biotechnology Institute, Ohio University , Athens, Ohio 45701, United States
| | - Jiang Wang
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Yuexiang Zhang
- Department of Chemistry and Biochemistry, Center of Intelligent Chemical Instrumentation, Edison Biotechnology Institute, Ohio University , Athens, Ohio 45701, United States
| | - Zhi Li
- Department of Chemistry and Biochemistry, Center of Intelligent Chemical Instrumentation, Edison Biotechnology Institute, Ohio University , Athens, Ohio 45701, United States
| | - David Hu
- Department of Chemistry and Biochemistry, Center of Intelligent Chemical Instrumentation, Edison Biotechnology Institute, Ohio University , Athens, Ohio 45701, United States
| | - Nan Zheng
- Department of Chemistry and Biochemistry, University of Arkansas , Fayetteville, Arkansas 72701, United States
| | - Hao Chen
- Department of Chemistry and Biochemistry, Center of Intelligent Chemical Instrumentation, Edison Biotechnology Institute, Ohio University , Athens, Ohio 45701, United States
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8
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Widjaja F, Max JP, Jin Z, Nash JJ, Kenttämaa HI. Gas-phase Reactivity of meta-Benzyne Analogs Toward Small Oligonucleotides of Differing Lengths. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1392-1405. [PMID: 28456883 DOI: 10.1007/s13361-017-1655-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/05/2017] [Accepted: 03/06/2017] [Indexed: 06/07/2023]
Abstract
The gas-phase reactivity of two aromatic carbon-centered σ,σ-biradicals (meta-benzyne analogs) and a related monoradical towards small oligonucleotides of differing lengths was investigated in a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer coupled with laser-induced acoustic desorption (LIAD). The mono- and biradicals were positively charged to allow for manipulation in the mass spectrometer. The oligonucleotides were evaporated into the gas phase as intact neutral molecules by using LIAD. One of the biradicals was found to be unreactive. The reactive biradical reacts with dinucleoside phosphates and trinucleoside diphosphates mainly by addition to a nucleobase moiety followed by cleavage of the glycosidic bond, leading to a nucleobase radical (e.g., base-H) abstraction. In some instances, after the initial cleavage, the unquenched radical site of the biradical abstracts a hydrogen atom from the neutral fragment, which results in a net nucleobase abstraction. In sharp contrast, the related monoradical mainly undergoes facile hydrogen atom abstraction from the sugar moiety. As the size of the oligonucleotides increases, the rate of hydrogen atom abstraction from the sugar moiety by the monoradical was found to increase due to the presence of more hydrogen atom donor sites, and it is the only reaction observed for tetranucleoside triphosphates. Hence, the monoradical only attacks sugar moieties in these substrates. The biradical also shows significant attack at the sugar moiety for tetranucleoside triphosphates. This drastic change in reactivity indicates that the size of the oligonucleotides plays a key role in the outcome of these reactions. This finding is attributed to more compact conformations in the gas phase for the tetranucleoside triphosphates than for the smaller oligonucleotides, which result from stronger stabilizing interactions between the nucleobases. Graphical Abstract ᅟ.
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Affiliation(s)
- Fanny Widjaja
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
- , 1 Makeway Ave #15-03, Singapore, 228598, Singapore
| | - Joann P Max
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
| | - Zhicheng Jin
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
- Northeast Ohio Medical University, 4209 OH-44, Rootstown, OH, 44272, USA
| | - John J Nash
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA.
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9
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Kim MS, Park SK. Photoreaction of 3-Allyloxy-2-pentamethyldisilanylpyridine. B KOREAN CHEM SOC 2014. [DOI: 10.5012/bkcs.2014.35.11.3373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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10
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Williams PE, Jankiewicz BJ, Yang L, Kenttämaa HI. Properties and reactivity of gaseous distonic radical ions with aryl radical sites. Chem Rev 2013; 113:6949-85. [PMID: 23987564 PMCID: PMC3889672 DOI: 10.1021/cr400121w] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Peggy E. Williams
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906
| | | | - Linan Yang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906
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Widjaja F, Jin Z, Nash JJ, Kenttämaa HI. Comparison of the reactivity of the three distonic isomers of the pyridine radical cation toward tetrahydrofuran in solution and in the gas phase. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:469-480. [PMID: 23345033 PMCID: PMC3624042 DOI: 10.1007/s13361-012-0543-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/08/2012] [Accepted: 11/09/2012] [Indexed: 06/01/2023]
Abstract
The reactivity of the three distonic isomers of the pyridine radical cation toward tetrahydrofuran is compared in solution and in the gas phase. In solution, the distonic ions were generated by UV photolysis at 300 nm from iodo-precursors in acidic 50:50 tetrahydrofuran/water solutions. In the gas phase, the ions were generated by collisionally activated dissociation (CAD) of protonated iodo-precursors in an FT-ICR mass spectrometer, as described in the literature. The same major reaction, hydrogen atom abstraction, was observed in solution and in the gas phase. Attempts to cleave the iodine atom from the 2-iodopyridinium cation in the gas phase and in solution yielded the 2-pyridyl cation in addition to the desired 2-dehydropyridinium cation. In the gas phase, this ion was ejected prior to the examination of the desired ion's chemical properties. This was not possible in solution. This study suggests that solvation effects are not significant for radical reactions of charged radicals. On the other hand, the even-electron ion studied, the 2-pyridyl cation, shows substantial solvation effects. For example, in solution, the 2-pyridyl cation forms a stable adduct with tetrahydrofuran, whereas in the gas phase, only addition/elimination reactions were observed.
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