Rapid Communications in Mass SpectrometryVolume 32, Issue 7 p. 604-606 LETTER TO THE EDITOR Electron affinities of substituted nitrobenzenes from negative ion mass spectrometry lifetimes and literature electron affinities Edward S. Chen, Corresponding Author Edward S. Chen eschen@bcm.edu orcid.org/0000-0003-3040-7816 Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030 USA Correspondence E.S. Chen, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. Email: eschen@bcm.eduSearch for more papers by this authorEdward C.M. Chen, Edward C.M. Chen University of Houston Clear Lake, 2700 Bay Area Blvd, Houston, TX, 77059 USASearch for more papers by this author Edward S. Chen, Corresponding Author Edward S. Chen eschen@bcm.edu orcid.org/0000-0003-3040-7816 Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030 USA Correspondence E.S. Chen, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. Email: eschen@bcm.eduSearch for more papers by this authorEdward C.M. Chen, Edward C.M. Chen University of Houston Clear Lake, 2700 Bay Area Blvd, Houston, TX, 77059 USASearch for more papers by this author First published: 03 February 2018 https://doi.org/10.1002/rcm.8072Citations: 10Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume32, Issue715 April 2018Pages 604-606 RelatedInformation

Essentials The rs773902 SNP results in differences in platelet protease-activated receptor (PAR4) function. The functional consequences of rs773902 were analyzed in human platelets and stroke patients. rs773902 affects thrombin-induced platelet function, PAR4 desensitization, stroke association. Enhanced PAR4 Thr120 effects on platelet function are blocked by ticagrelor. SUMMARY: Background F2RL3 encodes protease-activated receptor (PAR) 4 and harbors an A/G single-nucleotide polymorphism (SNP) (rs773902) with racially dimorphic allelic frequencies. This SNP mediates an alanine to threonine substitution at residue 120 that alters platelet PAR4 activation by the artificial PAR4-activation peptide (PAR4-AP) AYPGKF. Objectives To determine the functional effects of rs773902 on stimulation by a physiological agonist, thrombin, and on antiplatelet antagonist activity. Methods Healthy human donors were screened and genotyped for rs773902. Platelet function in response to thrombin was assessed without and with antiplatelet antagonists. The association of rs773902 alleles with stroke was assessed in the Stroke Genetics Network study. Results As compared with rs773902 GG donors, platelets from rs773902 AA donors had increased aggregation in response to subnanomolar concentrations of thrombin, increased granule secretion, and decreased sensitivity to PAR4 desensitization. In the presence of PAR1 blockade, this genotype effect was abolished by higher concentrations of or longer exposure to thrombin. We were unable to detect a genotype effect on thrombin-induced PAR4 cleavage, dimerization, and lipid raft localization; however, rs773902 AA platelets required a three-fold higher level of PAR4-AP for receptor desensitization. Ticagrelor, but not vorapaxar, abolished the PAR4 variant effect on thrombin-induced platelet aggregation. A significant association of modest effect was detected between the rs773902 A allele and stroke. Conclusion The F2RL3 rs773902 SNP alters platelet reactivity to thrombin; the allelic effect requires P2Y12 , and is not affected by gender. Ticagrelor blocks the enhanced reactivity of rs773902 A platelets. PAR4 encoded by the rs773902 A allele is relatively resistant to desensitization and may contribute to stroke risk.

RATIONALE The anion mass spectral lifetimes for several aromatic hydrocarbons reported in the subject article were related to significantly different electron affinities. The different values are rationalized using negative ion mass spectral data. METHODS Electron affinities for polycyclic aromatic hydrocarbons are reported from the temperature dependence of unpublished electron capture detector data. These are compared with published values and the largest values are assigned to the ground state. RESULTS The ground state adiabatic electron affinities: (eV) pentacene, 1.41 (3); tetracene, 1.058 (5); benz(a)pyrene, 0.82 (4); benz(a) anthracene, 0.69 (2) anthracene, 0.68 (2); and pyrene, 0.59 (1) are used to assign excited state adiabatic electron affinities: (eV) tetracene: 0.88 (4); anthracene 0.53 (1); pyrene, 0.41 (1); benz(a)anthracene, 0.39 (10); chrysene, 0.32 (1); and phenanthrene, 0.12 (2) and ground state adiabatic electron affinities: (eV) dibenz(a,j)anthracene, 0.69 (3); dibenz(a,h)anthracene, 0.68 (3); benz(e)pyrene, 0.60 (3); and picene, 0.59 (3) from experimental data. The lifetime of benz(a)pyrene is predicted to be larger than 150 μs and for benzo(c)phenanthrene and picene about 40 μs, from ground state adiabatic electron affinities. CONCLUSIONS The assignments of adiabatic electron affinities of aromatic hydrocarbons determined from electron capture detector and mass spectrometric data to ground and excited states are supported by constant electronegativities. A set of consistent ground state adiabatic electron affinities for 15 polycyclic aromatic hydrocarbons is related to lifetimes from the subject article.

•Electron Affinities from gas chromatography electron capture detectors are reviewed.•New electron affinities from complementary methods are reported.•The accuracy and precision of electron affinities from three methods are established.•Optimized procedures for analytical and physical measurements are presented.

RATIONALE:Superoxide is the most significant homonuclear diatomic anion in biochemistry. Theory predicts 12 doublet (X, A-K) and 12 quartet (a-l) electronic states split by spin orbital coupling into 54 states dissociating to the (3) P(O) + (2) P(O(-) ) limit. Dissociation energies for the 27 bonding states with positive electron affinities have been determined from mass spectrometric data. However, the 27 antibonding states with negative electron affinities have not been experimentally characterized.METHODS:The electron affinity of the hydrogen atom per electron, the Hylleraas, is the fundamental measure of electron correlation. It has been used to assign and evaluate experimental electron affinities of atoms and diatomic molecules. The 27 negative electron affinities of oxygen are estimated from the 27 positive values and the Hylleraas. These values are used to determine frequencies and internuclear separations by fitting theoretical electron impact distributions to the gas-phase mass spectrometric atomic oxygen anion distribution peaking at about 6.5 eV.RESULTS:The dissociation energies, internuclear distances and frequencies giving the first complete set of Morse potential energy curves for the 54 superoxide states dissociating to the lowest limit are reported from mass spectrometric data. The potentials are compared to theoretical and empirical literature curves.CONCLUSIONS:The existence of the 27 bonding and 27 antibonding spin orbital coupling superoxide states dissociating to (3) P(O) + (2) P(O(-) ) is established from mass analyzed thermal, photon, and electron ionization data. There are electron affinities from 0 to 0.15 eV, and onsets and peaks for dissociative electron attachment that cannot be explained by the 54 states. These support the existence of the 36 superoxide spin states dissociating to [(1) D(O) + (2) P(O(-) )] and [(1) S(O) + (2) P(O(-) )] predicted by quantum mechanics. Copyright © 2016 John Wiley & Sons, Ltd.

RATIONALEPerfluorocarbons such as perfluoromethylcyclohexane (c-C6 F11 -CF3 ) are important man-made chemicals that have many uses including plasma processing, blood substitutes and atmospheric tracers. It is important to know the kinetics and thermodynamics of the reactions of thermal electrons with these molecules since they are potentially harmful greenhouse gases that can accumulate in the atmosphere.METHODSThe least-squares fits of the temperature dependence of electron-capture detection and atmospheric pressure negative ion mass spectrometry to a kinetic model are used to determine the electron affinities of c-C6 F11 -CF3 , activation energies for the formation of c-C6 F10 -CF3 , and c-C6 F11 anions and single bond dissociation energies. These are supported by semi-empirical quantum mechanical calculations. These techniques were previously used to characterize superoxide, NO and SF6 anions.RESULTSThe literature electron affinities: (eV) c-C6 F11 -CF3 , 1.06, c-C6 F10 -CF3 , 3.9, c-C6 F11 , 3.5 and D(R1-CF3 ), 3.8; D(R-F), 4.3 are supported. Additional electron affinities for c-C6 F11 -CF3 , from 0.5 to 1.5 eV are assigned to excited states. The ground state electron affinity is 3.0(2) eV from the photodetachment threshold. Pseudo one-dimensional anionic Morse potentials illustrating the mechanism for the reaction of thermal electrons with c-C6 F11 -CF3 are presented. The major anion peaks in perfluorokerosene-L are identified. An experimental setup for studying thermal electron capture reactions at variable temperatures, pressures and concentrations proposed by Herder in 2004 is presented.CONCLUSIONSThere are multiple anions of c-C6 F11 -CF3 more stable than the neutral. Electron-capture detection and atmospheric pressure negative ion mass spectrometry are effective general methods for determining multiple electron affinities similar to the photodetachment, flowing afterglow, magnetron, negative surface ionization, swarm and beam procedures. Semi-empirical theoretical calculations support experimental results. Additional mass analysis studies of reactions of c-C6 F11 -CF3 with electrons over a wide range of temperatures, pressures and electron energies are desirable.

Theoretical adiabatic electron affinities are often considered inaccurate because they are referenced to only a single value. Ground state electron affinities for all the main group elements and homonuclear diatomics were identified recently using the normalized binding energy of the hydrogen atom: [0.75420375(3)/2 = 0.37710187(1) eV]. Here we revisit experimental values and extend the identifications to diatomics in the G2-1 set. We assign new ground state electron affinities: (eV) Cl 2 , 3.2(2); Br 2 , 2.87(14); CH, 2.1(2); H 2 , 0.6 ; NH, 1.1, SiH, 1.90. Anion Morse potentials are calculated for H 2 and N 2 from positive electron affinities and for hyperfine superoxide states for the first time.

RATIONALE Sulfur hexafluoride (SF6 ) is the most frequently used standard for anion mass spectrometry because of its large temperature-independent cross-section for electron attachment. However, the kinetic and thermodynamic properties--the products of the reactions, and the number of negative ion states of the SF(n)--are presently in dispute. METHODS The electron affinities for SF(n) (n = 1-6) are predicted by assuming dissociation energies and ground-state electron affinities based on literature values. The temperature dependence of the 2012 negative surface ionization mass spectrometer data, and other negative ionization mass spectrometry, electron capture detector, and beam and magnetron data, are analyzed using a kinetic model. RESULTS More precise and accurate activation energies for thermal electron attachment and electron affinities of SF6 , SF5 and SF4 are reported. The largest experimental electron affinities of SF, SF2 and SF3 are assigned to the ground states. Ionic Morse potentials for multiple states are calculated. A mechanism for the formation of the ionic products observed in negative surface ionization thermal electron attachment to SF6 is presented. CONCLUSIONS Negative surface ionization on a hot filament with mass spectrometry is a relatively simple and effective method for determining electron affinities similar to the electron capture detector, magnetron, swarm and beam procedures. A new method of predicting the number of negative ion states from dissociation limits establishes targets for the data analysis. Pseudo one-dimensional anionic Morse potentials illustrate the mechanism for the reaction of thermal electrons with SF6 and the consecutive dissociation pathways.

Theoretical hyperfine valence electron affinities of O-2 are identified in thermal, electron impact, photon and electrochemical data. The ranges of the 162 values are: (eV) 72-[(XII)-I-2, 1.030(2) to 1.100(2): (CII)-I-2, 0.410(2) to 0.480(2); d(4)II, 0.228 to 0.342; f(4)II, 0.128 to 0.242]; 36-[b(4)Delta, 0.685 to 0.917; A(2)Delta, 0.541 to 0.611]; 54-[a(4)Sigma, 0.920 to 0.990; e(4)Sigma, 0.215 to 0.285; b(4)Sigma, 0.710 to 0.780; B-2 Sigma, 0.495 to 0.545; D-2 Sigma, 0.395 to 0.445; E-2 Sigma, 0.335 to 0.385]. These demonstrate the existence of 162 bonding and 162 antibonding hyperfine states dissociating to the lowest limits. Multiple long range Efimov-like states with electron affinities less than 0.10 eV are also identified. (C) 2014 Elsevier B.V. All rights reserved.

Rapid Communications in Mass SpectrometryVolume 27, Issue 1 p. 281-283 Letter to the Editor Ground state electron affinities based on " Generation of negative ions from SF6 gas by means of hot surface ionization" : A. Pelc, Rapid Commun. Mass Spectrom. 2012, 26, 577–582 Edward S. Chen, Corresponding Author Edward S. Chen Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030 USA E. S. Chen, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. E-mail: eschen@bcm.eduSearch for more papers by this authorEdward C. M. Chen, Edward C. M. Chen University of Houston Clear Lake, 2700 Bay Area Blvd, Houston, TX, 77059 USASearch for more papers by this author Edward S. Chen, Corresponding Author Edward S. Chen Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030 USA E. S. Chen, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA. E-mail: eschen@bcm.eduSearch for more papers by this authorEdward C. M. Chen, Edward C. M. Chen University of Houston Clear Lake, 2700 Bay Area Blvd, Houston, TX, 77059 USASearch for more papers by this author First published: 12 December 2012 https://doi.org/10.1002/rcm.6438Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume27, Issue115 January 2013Pages 281-283 RelatedInformation

Only one electron affinity of oxygen, 43(1) kJ mol−1 is generally cited since the molecular orbital theory anion bond order [3/4] gives an electron affinity, 14 kJ mol−1. However, electron correlation rules predict 27 bonding and 27 antibonding spin orbital coupling states. The relative bond orders (RBOs), 12/13 to [1/4] and the 13 valence electrons of superoxide are used to calculate electron affinities 103 to −243 kJ mol−1 consistent with experimental and theoretical values. These are used to construct 54 ionic Morse potentials.