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Tureček F, Yao C, Fung YME, Hayakawa S, Hashimoto M, Matsubara H. Histidine-Containing Radicals in the Gas Phase. J Phys Chem B 2009; 113:7347-66. [DOI: 10.1021/jp900719n] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- František Tureček
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, Washington, 98195, and Department of Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Chunxiang Yao
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, Washington, 98195, and Department of Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Y. M. Eva Fung
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, Washington, 98195, and Department of Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Shigeo Hayakawa
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, Washington, 98195, and Department of Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Mami Hashimoto
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, Washington, 98195, and Department of Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
| | - Hiroshi Matsubara
- Department of Chemistry, University of Washington, Bagley Hall, Box 351700, Seattle, Washington, 98195, and Department of Chemistry, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan
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Chen X, Syrstad EA, Nguyen MT, Gerbaux P, Turecek F. Adenine radicals in the gas phase: an experimental and computational study of hydrogen atom adducts to adenine. J Phys Chem A 2007; 109:8121-32. [PMID: 16834198 DOI: 10.1021/jp0529725] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The elusive hydrogen atom adduct to the N-1 position in adenine, which is thought to be the initial intermediate of chemical damage, was specifically generated in the gas phase and characterized by neutralization-reionization mass spectrometry. The N-1 adduct, 1,2-dihydroaden-2-yl radical (1), was generated by femtosecond electron transfer to N-1-protonated adenine that was selectively produced by electrospray ionization of adenine in aqueous-methanol solution. Radical 1 is an intrinsically stable species in the gas phase that undergoes specific loss of the N-1-hydrogen atom to form adenine, but does not isomerize to the more stable C-2 adduct, 1,2-dihydroaden-1-yl radical (5). Radicals 1 that are formed in the fifth and higher electronically excited states of DeltaE > or = 2.5 eV can also undergo ring-cleavage dissociations resulting in expulsion of HCN. The relative stabilities, dissociation, and transition state energies for several hydrogen atom adducts to adenine have been established computationally at highly correlated levels of theory. Transition state theory calculations of 298 K rate constants in the gas phase, including quantum tunnel corrections, indicate the branching ratios for H-atom additions to C-8, C-2, N-3, N-1, and N-7 positions in adenine as 0.68, 0.20, 0.08, 0.03, and 0.01, respectively. The relative free energies of adenine radicals in aqueous solution point to the C-8 adduct as the most stable tautomer, which is predicted to be the predominating (>99.9%) product at thermal equilibrium in solution at 298 K.
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Affiliation(s)
- Xiaohong Chen
- Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, WA 98195-1700, USA
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O'Hair RAJ, Waters T, Cao B. Sixty Years after Wittig: Gas-Phase Synthesis of Lithium Trimethylammonium Methylide, [(CH3)3NCH2Li]+. Angew Chem Int Ed Engl 2007; 46:7048-51. [PMID: 17691087 DOI: 10.1002/anie.200701972] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Richard A J O'Hair
- School of Chemistry, The University of Melbourne, Melbourne, Victoria 3010, Australia.
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O'Hair R, Waters T, Cao B. Sixty Years after Wittig: Gas-Phase Synthesis of Lithium Trimethylammonium Methylide, [(CH3)3NCH2Li]+. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200701972] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Ramesh V, Nagi Reddy P, Srinivas R, Bhanuprakash K, Vivekananda S. Ionic and neutral mercaptothiocarbonyl: A tandem mass spectrometry and computational study. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.06.095] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yao C, Syrstad EA, Turecek F. Electron transfer to protonated beta-alanine N-methylamide in the gas phase: an experimental and computational study of dissociation energetics and mechanisms. J Phys Chem A 2007; 111:4167-80. [PMID: 17455922 DOI: 10.1021/jp0705020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ammonium radicals derived from protonated beta-alanine N-methyl amide (BANMA) were generated by femtosecond collisional electron transfer to gas-phase cations prepared by chemical ionization and electrospray. Regardless of the mode of precursor ion preparation, the radicals underwent complete dissociation on the time scale of 5.15 micros. Deuterium isotope labeling and product analysis pointed out several competitive and convergent dissociation pathways that were not completely resolved by experiment. Ab initio calculations, which were extrapolated up to the CCSD(T)/6-311++G(3df,2p) level of theory, provided the proton affinity and gas-phase basicity of BANMA as PA = 971 kJ mol-1 and GB = 932 kJ mol-1 to form the most stable ion structure 1c+ in which the protonated ammonium group was internally solvated by hydrogen bonding to the amide carbonyl. Ion 1c+ was calculated to have an adiabatic recombination energy of 3.33 eV to form ammonium radical 1c*. The potential energy surface for competitive and consecutive isomerizations and dissociations of 1c* was investigated at correlated levels of theory and used for Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. RRKM unimolecular rate constants suggested that dissociations starting from the ground electronic state of radical 1c* were dominated by loss of an ammonium hydrogen atom. In contrast, dissociations starting from the B excited state were predicted to proceed by reversible isomerization to an aminoketyl radical (1f*). The latter can in part dissociate by N-Calpha bond cleavage leading to the loss of the amide methyl group. This indicates that apparently competitive dissociations observed for larger amide and peptide radicals, such as backbone cleavages and losses of side-chain groups, may originate from different electronic states and proceed on different potential energy surfaces.
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Affiliation(s)
- Chunxiang Yao
- Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, WA 98195-1700, USA
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Gerbaux P, Dechamps N, Flammang R, Nagi Reddy P, Srinivas R. New experiments on HNCSe and HCNSe radical cations. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2006; 20:151-6. [PMID: 16331727 DOI: 10.1002/rcm.2276] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Dissociative ionization of the selenourea Se=C(NH(2))(2) (2) conveniently generates beams of pure isocyanoselenic acid radical cations. The HNCSe(.+) connectivity is established by collisional activation and by associative ion-molecule reactions with dimethyl sulfide or nitric oxide using a large-scale hybrid mass spectrometer.
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Affiliation(s)
- P Gerbaux
- Laboratory of Organic Chemistry and Center of Mass Spectrometry, University of Mons-Hainaut, Avenue Maistriau 19, B-7000 Mons, Belgium
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Roithová J, Schröder D, Schwarz H. Unimolecular Fragmentation of CH3NH2: Towards a Mechanistic Description of HCN Formation. European J Org Chem 2005. [DOI: 10.1002/ejoc.200500029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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HAYAKAWA S, KABUKI N, KAWAMURA Y, KITAGUCHI A. The Basis of Charge Inversion Mass Spectrometry: I: Historical Introduction and Differences between Four Types of Charge Inversion. ACTA ACUST UNITED AC 2005. [DOI: 10.5702/massspec.53.33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Tureček F. Transient Intermediates of Chemical Reactions by Neutralization-Reionization Mass Spectrometry. Top Curr Chem (Cham) 2003. [DOI: 10.1007/3-540-36113-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Gerbaux P, Haverbeke YV, Flammang R. Experimental and theoretical study of the gas-phase interaction between ionized nitrile sulfides and pyridine. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2003; 14:241-252. [PMID: 12648931 DOI: 10.1016/s1044-0305(02)00912-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The gas-phase reactivity of ionized nitrile sulfides, R-C[triple bond]N(+)-S*, towards neutral pyridine was studied both experimentally (six sector hybrid mass spectrometer) and theoretically (density functional theory and Møller-Plesset ab initio calculations). An ionized sulfur atom transfer and a cycloaddition process respectively yielding ionized pyridine N-thioxide and a thiazolopyridinium cation were observed. Whereas the very efficient S*+ transfer reaction probably involves the intermediacy of several ion-molecule complexes, the thiazolopyridinium ion formation is likely to be initiated by an electrophilic attack of the R-C[triple bond]N(+)-S* ion on the nitrogen atom of pyridine; the resulting intermediate then undergo an intramolecular substitution of an alpha-hydrogen atom by the sulfur atom.
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Affiliation(s)
- Pascal Gerbaux
- Organic Chemistry Laboratory, University of Mons-Hainaut, Mons, Belgium.
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del Carmen Sicilia M, Mó O, Yáñez M, Guillemin JC, Gal JF, Maria PC. Is allylphosphine a carbon or a phosphorus base in the gas phase? EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2003; 9:245-255. [PMID: 12939477 DOI: 10.1255/ejms.558] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The gas-phase basicity of allylphosphine (2-propenylphosphine) was measured by means of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry techniques. A complete survey of the allylphosphine-H(+) potential energy surface, carried out through the use of high-level G2(MP2) and B3LYP/6-311+G(3df,2p) calculations, allows us to conclude that, under low-pressure, low-energy ICR conditions, the interaction between the protonated reference base, B(ref)H(+), and allylphosphine leads to a complex in which B(ref)H(+) attaches to the phosphorus atom of allylphosphine, where the electrostatic potential is strongly attractive. Hence, in the first step only the phosphorus protonated species should be formed. Its isomerization to yield the C(beta)-protonated form, which is the global minimum of the potential energy surface, implies a very high activation barrier that cannot be overtaken under normal experimental ICR conditions. Therefore, the main conclusion of our study is that allylphosphine behaves as a phosphorus base in the gas phase, even though the C(beta)-protonated structure is the most stable protonated species. We have also shown that both C(beta)- and C(gamma)-protonation triggers a cyclization of the system. An analysis of the bonding of the different protonated species as compared with that of the neutral system is presented.
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2001; 36:976-987. [PMID: 11523099 DOI: 10.1002/jms.95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Alcamí M, Mó O, Yáñez M. Computational chemistry: a useful (sometimes mandatory) tool in mass spectrometry studies. MASS SPECTROMETRY REVIEWS 2001; 20:195-245. [PMID: 11835306 DOI: 10.1002/mas.10005] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this review, we present a brief summary of the theoretical methods most frequently used in gas-phase ion chemistry. In subsequent sections, the performance of these methods is analyzed, paying attention to the reliability of geometries, vibrational frequencies, energies, and entropies. The possible pathologies of the different methods, in the form of instabilities of the wave function or spin contamination problems, are discussed. Several examples are presented to illustrate the usefulness of ab initio or density functional theory (DFT) methods to predict the existence of elusive molecules and/or to characterize non-conventional structures, and to rationalize the charge redistributions normally associated with ion-molecule interactions and which result in bond-weakening or bond-reinforcement effects. Finally, the role of non-classical structures in ion-molecule interactions is also illustrated with different examples.
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Affiliation(s)
- M Alcamí
- Departamento de Química, C-9, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain
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Yranzo G, Elguero J, Flammang R, Wentrup C. Formation of Cumulenes, Triple-Bonded, and Related Compounds by Flash Vacuum Thermolysis of Five-Membered Heterocycles. European J Org Chem 2001. [DOI: 10.1002/1099-0690(200106)2001:12<2209::aid-ejoc2209>3.0.co;2-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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