Joseph S. Francisco

University of Nebraska at Lincoln, Lincoln, Nebraska, United States

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Publications (473)1697.43 Total impact

  • Heather A Rypkema, Amitabha Sinha, Joseph S Francisco
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    ABSTRACT: Electronic structure calculations of the pertinent stationary points on the potential energy surface show that carboxylic acids can act effectively as catalysts in the hydration of acetaldehyde. Barriers to this catalyzed process correlate strongly with pKa of the acid, providing the potential to provide predictive capacity of the effectiveness of carboxylic acid catalysts. Transition states for the acid-catalyzed systems take the form of pseudo-6-membered rings through the linear nature of their hydrogen bonds, which accounts for their relative stability compared to the more strained direct and water-catalyzed systems. When considered as a stepwise reaction of a dimerization followed by reaction/complexation, it is likely that collisional stabilization of the pre-reactive complex is more likely than reaction in the free gas phase, although the catalyzed hydration does retain the potential to proceed on water surfaces or in droplets. Lastly, it is observed that post-reactive diol-acid complexes are significantly stable (~12-17 kcal/mol) relative to isolated products, suggesting the possibility of long-lived hygroscopic species that could act as a seed molecule for condensation of secondary organic aerosols.
    The Journal of Physical Chemistry A 03/2015; 119(19). DOI:10.1021/jp510704j · 2.78 Impact Factor
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    ABSTRACT: Employing first-principles density functional theory (DFT), the structures and electronic and mechanical properties of Al(111)/ZrB2(0001) heterojunctions are investigated. It is found that both B-terminated ZrB2(0001) and Zr-terminated ZrB2(0001) can form heterojunction interfaces with Al(111) surface. The heterojunction with B-terminated ZrB2(0001) is demonstrated to be most stable by comparing the surface adhesion energies of six different heterojunction models. In the stable configurations, the Al atom is found projecting to the hexagonal hollow site of neighbouring boron layer for the B-terminated ZrB2(001), and locating at the top site of the boron atoms for Zr-terminated ZrB2(001) interface. The mechanisms of interface interaction are investigated by density of states, charge density difference and band structure calculations. It is found that covalent bonds between surface Al atoms and B atoms are formed in the B-terminated heterojunction, whereas the Al atoms and Zr atoms are stabilised by interface metallic bonds for the Zr-terminated case. Mechanical properties of Al/ZrB2 heterojunctions are also predicted in the current work. The values of moduli of Al/ZrB2 heterojunctions are determined to be between those of single crystal Al and ZrB2, which exhibit the transition of mechanical strength between two bulk phases. DFT calculations with the current models provide the mechanical properties for each heterojunction and the corresponding contributions by each type of interface in the composite materials. This work paves the way for industrial applications of Al(111)/ZrB2(0001) heterojunctions.
    Molecular Physics 02/2015; DOI:10.1080/00268976.2015.1014441 · 1.64 Impact Factor
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    ABSTRACT: Conspectus Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in the environment, but they can also originate endogenously, initiated by electron reduction of molecular oxygen. These molecules have important biological signaling activities, but they cause oxidative stress when dysfunction within the antioxidant system occurs. Excess ROS in living organisms can lead to problems, such as protein oxidation-through either cleavage of the polypeptide chain or modification of amino acid side chains-and lipid oxidation.
    Accounts of Chemical Research 02/2015; 48(3). DOI:10.1021/ar500412p · 24.35 Impact Factor
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    ABSTRACT: Surface level ozone destruction in polar environments may be initiated by oxidation of bromide ions by ozone, ultimately leading to Br2 production. While ab initio calculations are used to support development of atmospheric chemistry models, errors can occur in study of the bromide-ozone reaction due to inappropriate treatment of the many-electron species and the charge nature of the reaction. In this work, a high level ab initio study is used to take into account the electronic correlation and the polarization effects. Our results show three possible pathways for the reaction. In particular, we find that this process, while endothermic on a singlet spin state surface, can be energetically feasible on the triplet surface. The triplet surface can be reached through photo-excitation of ozone or by the spin crossing of the potential energy surface. Since this process is known to occur in the dark, it may be that it occurs after intersystem crossing to a triplet surface. This paper also provides a starting point calibration for any future ab initio calculation studies of the bromide-ozone reaction, from the gas to the condensed phase.
    The Journal of Physical Chemistry A 02/2015; 119(19). DOI:10.1021/jp5101279 · 2.78 Impact Factor
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    ABSTRACT: We report molecular dynamics (MD) simulation evidence of a new family of two-dimensional (2D) clathrate hydrates. Particular attention is placed on the effect of size and hydrophilicity of guest-molecule on the formation of 2D clathrate hydrates. Among MD simulations undertaken, spontaneous formation of bilayer (BL) clathrate hydrates in nanoslits are found with five different hydrophobic guest molecules, namely, ethane (C2H6), ethene (C2H4), allene (C3H4), carbon dioxide (CO2) and hydrogen (H2) molecules, respectively. Our simulations suggest that the host cages in water framework are likely BL-hexagonal cages with single occupancy for H2, or BL-heptagonal cages for CO2. With further increase of guest size, the host cages for C2H6, C2H4, and C3H4 are BL-octagonal cages with single occupancy, and their long molecular axis tends to be normal to the surface of clathrate hydrates. In addition, for hydrophilic guest molecules such as NH3 and H2S which can form strong hydrogen bonds with water, we find that most guest molecules can preferentially displace water molecules from lattice sites of water framework, instead of being separately trapped within water cages. Structural analogy between the 2D and 3D clathrates enlightens us to predict stability of several bulk gas hydrates, namely, “ethane clathrate III”, “CH4 ice-i” and “H2 ice-i”. Our findings not only can enrich clathrate structures in the hydrate family but also may improve understanding of the hydrate formation in microporous media.
    01/2015; 3(10). DOI:10.1039/C4TA06857B
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    ABSTRACT: The hydrolysis of ketene (H2C=C=O) to form acetic acid involving two water molecules and also separately in the presence of one to two water molecules plus formic acid (FA) has been investigated. Our results show that while the currently accepted indirect mechanism, involving addition of water across the carbonyl C=O bond of ketene to form an ene-diol followed by tautomerization of the ene-diol to form acetic acid is the preferred pathway when water alone is present, with formic acid as catalyst, addition of water across the ketene C=C double bond to directly produce acetic acid, becomes the kinetically favored pathway for temperatures below 400K.We find that the overall barrier for ketene hydrolysis involving one water molecule plus formic acid (H2C2O + H2O + FA) is not only significantly lower than that involving two water molecules (H2C2O + 2H2O), but that FA is able to reduce the barrier height for the direct path, involving addition of water across the C=C double bond, so that it is essentially identical with(6.4 kcal/mol) that for the indirect ene-diol formation path involving addition of water across the C=O bond. For the case of ketene hydrolysis involving two water molecules plus formic acid (H2C2O + 2H2O + FA), the barrier for the direct addition of water across the C=C double bond is reduced even further, and is 2.5 kcal/mol lower relative to the ene-diol path involving addition of water across the C=O bond. In fact, the hydrolysis barrier for the H2C2O + 2H2O + FA reaction through the direct path is sufficiently low (2.5 kcal/mol) for it to be an energetically accessible pathway for acetic acid formation under atmospheric conditions. Given the structural similarity between acetic and formic acid, our results also have potential implications for aqueous phase chemistry. Thus in an aqueous environment, even in the absence of formic acid, though the initial mechanism for ketene hydrolysis is expected to involve addition of water across the carbonyl bond as is currently accepted, the production and accumulation of acetic acid will likely alter the preferred pathway to one involving addition of water across the ketene C=C double bond as the reaction proceeds.
    The Journal of Physical Chemistry A 01/2015; 119(19). DOI:10.1021/jp5076725 · 2.78 Impact Factor
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    ABSTRACT: One route to break down halomethanes is through reactions with radical species. The capability of the artificial force-induced reaction algorithm to efficiently explore a large number of radical reaction pathways has been illustrated for reactions between haloalkanes (CX3Y; X=H, F; Y=Cl, Br) and ground-state (2Σ+) cyano radicals (CN). For CH3Cl+CN, 71 stationary points in eight different pathways have been located and, in agreement with experiment, the highest rate constant (108 s−1 M−1 at 298 K) is obtained for hydrogen abstraction. For CH3Br, the rate constants for hydrogen and halogen abstraction are similar (109 s−1 M−1), whereas replacing hydrogen with fluorine eliminates the hydrogen-abstraction route and decreases the rate constants for halogen abstraction by 2–3 orders of magnitude. The detailed mapping of stationary points allows accurate calculations of product distributions, and the encouraging rate constants should motivate future studies with other radicals.
    ChemPhysChem 01/2015; 16(1). DOI:10.1002/cphc.201402601 · 3.36 Impact Factor
  • Lei Tan, Frantisek Turecek, Joseph S Francisco, Yu Xia
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    ABSTRACT: Heteroatom-centered radicals are known to play critical roles in atmospheric chemistry, organic synthesis, and biology. While most studies have focused on the radical reactivity such as hydrogen abstraction, the base properties of heteroatom-centered radicals have long been overlooked, despite the profound consequences, such as their ability to participate in hydrogen-bonding networks. In this study, we use the sulfinyl radical (-SO•) as a model to show that the dual properties of heteroatom-centered radicals, i.e., their ability to function as a radical and a base, can coexist in peptides and be differentiated by examining the loss of hydrosulfinyl radical (SOH) upon unimolecular dissociation of the peptide sulfinyl radical ions in the gas phase. The loss of SOH can result from two channels: one involves hydrogen atom abstraction, which reflects the radical property; the other is initiated by proton transfer to the sulfinyl radical, manifesting its base property. Tuning of the two properties of peptide sulfinyl radicals can be achieved by varying the chemical properties of the neighboring functional groups, which demonstrates the influence of the local chemical environment on the behavior of the radical species. The experimental approach established in this study to probe the dual chemical property of peptide sulfinyl radical can be potentially applied to studying other types of heteroatom-centered radical species of biological significance.
    The Journal of Physical Chemistry A 11/2014; 118(50). DOI:10.1021/jp510362p · 2.78 Impact Factor
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    ABSTRACT: Post-translational mechanisms of protein oxidation as a result of reactive oxygen species (ROS) can occur under physiological conditions to yield selective side-chain and backbone modifications including abstractions, donations, additions, substitutions, and fragmentation. In order to characterize the selectivity of radical-mediated fragmentation, quantum mechanical investigations using ab initio and density functional methods were employed to evaluate site, conformation, and pathway trends of small trialanine peptides resembling a β-strand and a β-turn. Comparisons of reaction enthalpies show that the diamide pathway is more energetically favorable than the α-amidation pathway and that both pathways are site and conformationally selective. These findings readily contribute to the understanding of oxidative stress in biochemical processes.
    The Journal of Physical Chemistry A 11/2014; DOI:10.1021/jp508877m · 2.78 Impact Factor
  • Alexander Cory Davis, Joseph S Francisco
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    ABSTRACT: During both the atmospheric oxidation and combustion of volatile organic compounds, sequential addition of oxygen can lead to compounds that contain multiple hydrogen bonding sites. The presence of two or more of these sites on a hydrocarbon introduces the possibility of intramolecular H-bonding, which can have a stabilizing effect on the reactants, products, and transition states of subsequent reactions. The present work compares the absolute energies of two sets of conformations, those that contain intramolecular H-bonds and those that lack intramolecular H-bonds, for each reactant, product, and transition state species in the 1,2 through 1,7 H-migrations and Cα-Cβ, Cα-H and Cα-OH bond scission reactions in the n-hydroxyeth-1-oxy through n-hydroxyhex-1-oxy radicals, for n ranging from 1 to 6. The difference in energy between the two conformations represents the balance between the stabilizing effects of H-bonds, and the steric cost of bringing the two H-bonding sites together. The effect of intramolecular H-bonding and the OH group is assessed by comparing the net intramolecular H-bond stabilization energies, the reaction enthalpies and barrier heights of the n-hydroxyalkoxy radical reactions with the corresponding alkoxy radicals values. The results suggest that there is a complex dependence on the location of the two H-bonding groups, the location of the abstraction or bond scission and the shape of the transition state that dictates the extent to which intramolecular H-bonding effects the relative importance of H-migration and bond scission reactions for each n-hydroxyalkoxy radical. These findings have important implications for future studies on hydrocarbons with multiple H-bonding sites.
    The Journal of Physical Chemistry A 10/2014; DOI:10.1021/jp506436g · 2.78 Impact Factor
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    ABSTRACT: The present theoretical calculations on CP X2Σ+, A2Π, 14Σ+, 14Δ, 14Π, 16Π and 16Σ+ electronic states use standard and explicitly correlated coupled cluster approaches, multi-reference configuration interaction (MRCI) techniques in connection with a large panel of basis sets. We also examined core–valence (CV) and scalar relativistic (SR) effects. For the ground electronic state, our calculations reveal that the MRCI+CV+SR method and the coupled cluster technique with perturbative treatment of triple excitations including scalar relativistic effects computed with the Douglas-Kroll approach (RCCSD[T]-DK) in connection with a large basis set lead to an accurate description of CP(X2Σ+). We computed the evolution along the internuclear distance of the diagonal and the off-diagonal spin–orbit integrals between the X2Σ+ and A2Π states. These integrals are then incorporated together with the corresponding potentials into variational treatment of the nuclear motion. We deduced hence the energy positions of the low and high vibronic levels of X2Σ+ and A2Π states. Finally, it is shown the necessity of considering the spin–orbit coupling for accurate prediction of the energy position of these levels.
    Molecular Physics 10/2014; 112(20). DOI:10.1080/00268976.2014.901567 · 1.64 Impact Factor
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    ABSTRACT: Equation of motion coupled cluster calculations were performed on various structures of OH in clusters with one, two, three, and four water molecules to determine the energies of valence and charge transfer states. Motivation for these calculations is to understand the absorption spectrum of OH in water. Previous calculations on these species have confirmed that the longer wavelength transition observed is due to the A((2)∑) ← X((2)∏) valence transition, while the shorter wavelength transition is due to a charge-transfer from H2O to OH. While these previous calculations identified the lowest energy charge-transfer state, our calculations have included sufficient states to identify additional solvent-to-solute charge transfer states. The minimum energy structures of the clusters were determined by application of the Monte Carlo technique to identify candidate cluster structures, followed by optimization at the level of second-order Møller-Plesset perturbation theory. Calculations were performed on two structures of OH-H2O, three structures of OH-(H2O)2, four structures of OH-(H2O)3, and seven structures of OH-(H2O)4. Confirming previous calculations, as the number of water molecules increases, the energies of the excited valence and charge-transfer states decrease; however, the total number of charge-transfer states increases with the number of water molecules, suggesting that in the limit of OH in liquid water, the charge-transfer states form a band.
    The Journal of Chemical Physics 09/2014; 141(10):104315. DOI:10.1063/1.4894772 · 3.12 Impact Factor
  • Mariano Méndez, Joseph S. Francisco, David A. Dixon
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    ABSTRACT: Simple hydrides of compounds containing N, S, and O are of significant interest due to the role that they play in atmospheric chemistry and in biological pathways. There is a lack of quantitative thermodynamic data on these compounds. We have used a reliable computational chemistry approach based on valence CCSD(T) calculations extrapolated to the complete basis set limit with additional corrections to predict the heats of formation and bond dissociation energies of such compounds. The results show that compounds with the ability of the central S atom to effectively expand its valency leads to more stable isomers and, as a consequence, that those with the NSO structural motif are thermochemically more stable than those with the SNO motif. In addition, SO bonds are preferred over NO bonds.
    Chemistry - A European Journal 08/2014; 20(33). DOI:10.1002/chem.201404076 · 5.70 Impact Factor
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    ABSTRACT: First-principles simulations suggest that additional OH formation in the troposphere can result from ozone interactions with the surface of cloud droplets. Ozone exhibits an affinity for the air-water interface, which modifies its UV and visible light spectroscopic signatures and photolytic rate constant in the troposphere. Ozone cross sections on the red side of the Hartley band (290- to 350-nm region) and in the Chappuis band (450-700 nm) are increased due to electronic ozone-water interactions. This effect, combined with the potential contribution of the O3 + hν → O((3)P) + O2(X(3)Σg (-)) photolytic channel at the interface, leads to an enhancement of the OH radical formation rate by four orders of magnitude. This finding suggests that clouds can influence the overall oxidizing capacity of the troposphere on a global scale by stimulating the production of OH radicals through ozone photolysis by UV and visible light at the air-water interface.
    Proceedings of the National Academy of Sciences 07/2014; 111(32). DOI:10.1073/pnas.1411727111 · 9.81 Impact Factor
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    ABSTRACT: Neon hydrate was synthesized and studied by in situ neutron diffraction at 480 MPa and temperatures ranging from 260 to 70 K. For the first time to our knowledge, we demonstrate that neon atoms can be enclathrated in water molecules to form ice II-structured hydrates. The guest Ne atoms occupy the centers of D2O channels and have substantial freedom of movement owing to the lack of direct bonding between guest molecules and host lattices. Molecular dynamics simulation confirms that the resolved structure where Ne dissolved in ice II is thermodynamically stable at 480 MPa and 260 K. The density distributions indicate that the vibration of Ne atoms is mainly in planes perpendicular to D2O channels, whereas their distributions along the channels are further constrained by interactions between adjacent Ne atoms.
    Proceedings of the National Academy of Sciences 07/2014; 111(29). DOI:10.1073/pnas.1410690111 · 9.81 Impact Factor
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    ABSTRACT: We performed accurate ab initio investigations of the geometric parameters and the vibrational structure of neutral HNS/HSN triatomics and their singly charged anions and cations. We used standard and explicitly correlated coupled cluster approaches in connection with large basis sets. At the highest levels of description, we show that results nicely approach those obtained at the complete basis set limit. Moreover, we generated the three-dimensional potential energy surfaces (3D PESs) for these molecular entities at the coupled cluster level with singles and doubles and a perturbative treatment of triple excitations, along with a basis set of augmented quintuple-zeta quality (aug-cc-pV5Z). A full set of spectroscopic constants are deduced from these potentials by applying perturbation theory. In addition, these 3D PESs are incorporated into variational treatment of the nuclear motions. The pattern of the lowest vibrational levels and corresponding wavefunctions, up to around 4000 cm(-1) above the corresponding potential energy minimum, is presented for the first time.
    The Journal of Chemical Physics 06/2014; 140(24):244309. DOI:10.1063/1.4883915 · 3.12 Impact Factor
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    ABSTRACT: Carbon monoxide clathrate hydrate is a potentially important constituent in the solar system. In contrast to the well-established relation between the size of gaseous molecule and hydrate structure, previous work showed that carbon monoxide molecules preferentially form structure-I rather than structure-II gas hydrate. Resolving this discrepancy is fundamentally important to understanding clathrate formation, structure stabilization and the role the dipole moment/molecular polarizability plays in these processes. Here we report the synthesis of structure-II carbon monoxide hydrate under moderate high-pressure/low-temperature conditions. We demonstrate that the relative stability between structure-I and structure-II hydrates is primarily determined by kinetically controlled cage filling and associated binding energies. Within hexakaidecahedral cage, molecular dynamic simulations of density distributions reveal eight low-energy wells forming a cubic geometry in favour of the occupancy of carbon monoxide molecules, suggesting that the carbon monoxide-water and carbon monoxide-carbon monoxide interactions with adjacent cages provide a significant source of stability for the structure-II clathrate framework.
    Nature Communications 06/2014; 5:4128. DOI:10.1038/ncomms5128 · 10.74 Impact Factor
  • Wenhui Zhao, Lu Wang, Jaeil Bai, Joseph S Francisco, Xiao Cheng Zeng
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    ABSTRACT: We present molecular dynamics simulation evidences of spontaneous formation of quasi-one-dimensional (Q1D) hydrogen gas hydrates within nanometer-diameter (1-1.3 nm) single-walled carbon nanotubes (SW-CNTs) near ambient temperature. Contrary to conventional 3D gas hydrates in which the guest molecules are typically contained in individual and isolated cages in the host lattice, the guest H2 molecules in the Q1D gas hydrates are contained within a 1D nanochannel in which the H2 molecules form a molecule wire. In particular, we show that in the (15,0) zigzag SW-CNT, the hexagonal H2 hydrate tends to form, with one H2 molecule per hexagonal prism, while in the (16,0) zigzag SW-CNT, the heptagonal H2 hydrate tends to form, with one H2 molecule per heptagonal prism. In contrast, in the (17,0) zigzag SW-CNT, the octagonal H2 hydrate can form, with either one H2 or two H2 molecules per pentagonal prism (single or double occupancy). Interestingly, in the hexagonal or heptagonal ice nanotube, the H2 wire is solid-like as the axial diffusion constant is very low (< 5×10-10 cm2/s), whereas in the octagonal ice nanotube, the H2 wire is liquid-like as its axial diffusion constant is comparable to 10-5 cm2/s.
    Journal of the American Chemical Society 06/2014; 136(30). DOI:10.1021/ja5041539 · 11.44 Impact Factor
  • Montu K Hazra, Joseph S Francisco, Amitabha Sinha
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    ABSTRACT: The hydrolysis of glyoxal involving one to three water molecules and also in the presence of a water molecule and formic acid has been investigated. Our results show that glyoxal-diol is the major product of the hydrolysis and that formic acid, through its ability to facilitate intermolecular hydrogen atom transfer, is considerably more efficient compared to water as a catalyst in the hydrolysis process. Additionally once the glyoxal-diol is formed, the barrier for further hydrolysis to form the glyoxal-tetrol is effectively reduced to zero in the presence of a single water and formic acid molecule. There are two important implications arising from these findings. First, the results suggest that under the catalytic influence of formic acid, glyoxal hydrolysis can impact the growth of atmospheric aerosols. As a result of enhanced hydrogen bonding, mediated through their polar OH functional groups, the diol and tetrol products are expected to have significantly lower vapor pressure compared to the parent glyoxal molecule; hence they can more readily partition into the particle phase and contribute to the growth of secondary organic aerosols. In addition, our findings provide insight into how glyoxal-diol and glyoxal-tetrol might be formed under atmospheric conditions associated with water restricted environments and strongly suggest that the formation of these precursors for secondary organic aerosol growth is not likely restricted solely to the bulk aqueous phase as is currently assumed.
    The Journal of Physical Chemistry A 05/2014; 118(23). DOI:10.1021/jp502126m · 2.78 Impact Factor
  • Lei Tan, Hanfeng Hu, Joseph S Francisco, Yu Xia
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    ABSTRACT: Glycyl radicals are important bioorganic radical species involved in enzymatic catalysis. Herein, we demonstrate that the stability of glycyl-type radicals (X-(.) CH-Y) can be tuned on a molecular level by varying the X and Y substituents and experimentally probed by mass spectrometry. This approach is based on the gas-phase dissociation of cysteine sulfinyl radical (X-Cys SO .-Y) ions through homolysis of a Cα Cβ bond. This fragmentation produces a glycyl-type radical upon losing CH2 SO, and the degree of this loss is closely tied to the stability of the as-formed radical. Theoretical calculations indicate that the energy of the Cα Cβ bond homolysis is predominantly affected by the stability of the glycyl radical product through the captodative effect, rather than that of the parent sulfinyl radical. This finding suggests a novel experimental method to probe the stability of bioorganic radicals, which can potentially broaden our understanding of these important reactive intermediates.
    Angewandte Chemie International Edition 02/2014; 53(7). DOI:10.1002/anie.201310480 · 11.34 Impact Factor

Publication Stats

5k Citations
1,697.43 Total Impact Points


  • 2014–2015
    • University of Nebraska at Lincoln
      • • College of Arts and Sciences
      • • Department of Chemistry
      Lincoln, Nebraska, United States
  • 1994–2015
    • Purdue University
      • • Department of Chemistry
      • • Department of Earth and Atmospheric Sciences
      West Lafayette, Indiana, United States
    • NASA
      Вашингтон, West Virginia, United States
  • 2013
    • Laboratoire de Spectroscopie Atomique Moléculaire et Applications
      Tunis-Ville, Tūnis, Tunisia
  • 2010
    • Haverford College
      • Department of Chemistry
      Norristown, Pennsylvania, United States
  • 1990–2010
    • University of Bath
      • Department of Chemistry
      Bath, England, United Kingdom
  • 1987–2007
    • Wayne State University
      • Department of Chemistry
      Detroit, MI, United States
  • 2005
    • Bergische Universität Wuppertal
      • Inorganic Chemistry
      Wuppertal, North Rhine-Westphalia, Germany
  • 1999
    • Williams College
      • Department of Chemistry
      Williamstown, New Jersey, United States
    • California State University, Los Angeles
      • Department of Chemistry and Biochemistry
      Los Ángeles, California, United States
  • 1998
    • University of Illinois, Urbana-Champaign
      • Department of Atmospheric Sciences
      Urbana, Illinois, United States
  • 1993–1997
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
  • 1996
    • Pasadena City College
      Pasadena, Texas, United States
  • 1991
    • Griffith University
      Southport, Queensland, Australia
  • 1988
    • University of Bristol
      Bristol, England, United Kingdom
    • University of Detroit Mercy
      • Department Chemistry and Biochemistry
      Detroit, Michigan, United States
  • 1981–1987
    • Massachusetts Institute of Technology
      • Department of Chemistry
      Cambridge, Massachusetts, United States
    • University of Sydney
      Sydney, New South Wales, Australia
  • 1985
    • University of Cambridge
      Cambridge, England, United Kingdom