David A. Atwood

University of Kentucky, Lexington, Kentucky, United States

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Publications (217)843.69 Total impact

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    ABSTRACT: The five-coordinate compound, Salen(tBu)Al(Ac), prepared in situ from Salen(tBu)AlBr and NH4Ac, forms Lewis acid-base adducts in aqueous solution with the G-type nerve agents, sarin(GB), soman (GD), and the VX hydrolysis product EMPA. The resulting compounds, [Salen(tBu)Al(NA)]+[Ac]- (with NA = sarin, soman, and EMPA) are sufficiently stable to be identified by ESI-MS. Molecular ion peaks were detected for every compound with little or no fragmentation. The distinctive MS signatures for the [Salen(tBu)Al(NA)]+ compounds provide a new technique for identifying nerve agents in aqueous solution. The energetics of the displacement of Ac- in [Salen(tBu)Al(NA)]+[Ac]- by the nerve agent was determined computationally.
    Preview · Article · Mar 2015 · Chemical Communications
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    ABSTRACT: Combination of the dithiol N,N'-bis(2-mercaptoethyl)isophthalamide, abbreviated as BDTH2 and as 1, with excess H2SeO3 in aqueous acidic (pH ≈ 1) conditions resulted in precipitation of BDT(S-Se-S) (6), with a (77)Se NMR chemical shift of δ = 675 ppm, and oxidized BDT. When the reaction is conducted under basic conditions Se(IV) is reduced to red Se(0) and oxidized 1. No reaction takes place between 1 and selenate (Se(VI)) under acidic or basic conditions. Compound 6 is stable in air but decomposes to red Se(0) and the disulfide BDT(S-S) (9) with heating and in basic solutions. Mechanisms and energetics of the reactions leading to 6 in aqueous solution were unraveled by extensive calculations at the ωB97X-D/aug-cc-pVTZ-PP level of theory. NMR chemical shift calculations with the gauge-independent atomic orbital (GIAO) method for dimethyl sulfoxide as solvent confirm the generation of 6 (calculated δ value = 677 ppm). These results define the conditions and limitations of using 1 for the removal of selenite from wastewaters. Compound 6 is a rare example of a bidentate selenium dithiolate and provides insight into biological selenium toxicity.
    No preview · Article · Apr 2014 · Inorganic Chemistry
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    ABSTRACT: Crystals of 2-chloro-benzo-1,3,2-dithiarsole have a strongly modulated structure that can be solved and refined with relative ease in a P\overline 1, Z' = 17 approximate supercell but that is better described as incommensurate. Two conventional refinements (different superstructure approximations that differ in the placement of their crystallographic inversion centers) and a (3 + 1)-dimensional superspace refinement are all nearly equally successful, at least as measured by the usual agreement factors; the data integration, however, shows that the incommensurate description is preferable. The overall packing is determined by the stacking of the aromatic rings and probably by the segregation of As and Cl atoms to give short As...Cl contacts. A refinement of the average (Z' = 1) structure shows that there are two basic orientations of the C6S2 plane, but that those orientations must be correlated in several directions to avoid impossibly short intermolecular contacts. Along the modulation vector q the orientation of the C6S2 plane varies smoothly, but q is not a direction in which the molecules are in contact. Along the directions in which the molecules are in contact the orientation of the C6S2 plane alternates; there are also positional shifts. The single modulation q relieves packing problems in several different directions well enough that crystals that diffract well can be grown.
    Full-text · Article · Oct 2013 · Acta Crystallographica Section B: Structural Science
  • Wenli Zou · Michael Filatov · David Atwood · Dieter Cremer
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    ABSTRACT: 1,3-Benzenediamidoethanethiolatemercury [BDT-Hg or BD(S)-Hg] and its derivatives are investigated utilizing the Dirac exact relativistic normalized elimination of the small component method in connection with B3LYP, CCSD(T), and polarizable continuum calculations. It is shown that the chelating energy of BDT-Hg can be significantly increased by replacing sulfur with selenium or tellurium, thus leading to BD(Se)-Hg or BD(Te)-Hg. In this particular case, the chalcogenophilicity of mercury increases from S to Te because increasing the E-Hg bond lengths leads to a reduction of ring strain. Various possibilities of increasing the metal (M) chelating strength in BDT-M complexes are investigated, and suggestions for new chelating agents based on the BDT-M template are made.
    No preview · Article · Mar 2013 · Inorganic Chemistry
  • Mohan S. Bharara · David A. Atwood

    No preview · Chapter · Dec 2011
  • Mohan S. Bharara · David A. Atwood
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    ABSTRACT: This article covers basic chemistry of lead(II) including coordination geometries of halides, pseudohalides, oxides, carboxylates, thiolates, and nitrogen and/or phosphorus-containing ligands. Coordination number around lead(II) ranges from 1 to 12 but is by no means comprehensive. Tetrahedral four-coordination is observed only for lead(IV) compounds with bulky ligands. Lead forms halide complexes with both oxidation states but lead(IV) halides are much less stable then monomeric lead(II) halides. Like lead(II) halides, lead pseudohalides also form complexes with donor molecules and these complexes are irregular with high coordination number. Binary and ternary oxides of lead have found importance in electronic and technological applications, while polymeric lead(II) alkoxides [Pb(OR2)] are insoluble and poorly characterized. Ternary and mixed oxides of lead with perovskite structure are electroactive and are characterized by large dielectric constants. Lead(II) chalcogenides especially PbS, are photoconductors and widely used in photoelectric cells and IR detectors. Lead derivatives of oxyacids and organic acid, containing bivalent lead are extensively used in organic synthesis as oxidizing agents. The variable structure of highly coordinate lead(II) carboxylates and their complexes are characterized by intermolecular association. 207Pb NMR and potentiometry have been widely employed for study of lead compounds in solution. Reduction of lead in liquid ammonia or direct fusion of various metals at 700°C results in the formation of anionic clusters. Such species have been identified with 207Pb NMR in solution or recently by laser ablation in gaseous state.Keywords:lead halides;R3Pb·radicals;perovskite structure;ferromagnetic;mixed oxides and alkoxides;photoconductors;207Pb NMR;Pb – S interactions;amidoplumbylenes;nonorganometallic lead complexes;lead clusters
    No preview · Chapter · Dec 2011
  • David A. Atwood · M. Kamruz Zaman

    No preview · Chapter · Dec 2011
  • Ronald C. Bakus · David A. Atwood

    No preview · Chapter · Dec 2011
  • Amitabha Mitra · David A. Atwood

    No preview · Chapter · Dec 2011
  • Amitabha Mitra · David Atwood

    No preview · Chapter · Oct 2011
  • Kibong Kim · Olga G Tsay · David A Atwood · David G Churchill
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    ABSTRACT: The destruction and detection methods for the chemical warfare agents are examined. Acetyl-cholinesterase (AChE) inhibition is the most well-known mode of action of nerve agents. When nerve impulses reach a nerve ending, acetylcholine is released from the terminals of presynaptic nerves into the synaptic or neuromuscular junction and binds to the ACh receptor site on the postsynaptic membrane, thereby causing stimulation of the nerve fibers or muscles. Enzymatic hydrolysis involves nucleophilic addition and acid-based reactions at the catalytic site of the enzyme that involves a catalytic triad. Neutralization with aqueous NaOH at ambient temperature allows for the destruction of significant quantities of sarin (GB). VX and R-VX are completely hydrolyzed within 1-2 months at room temperature to nontoxic compounds in the presence of a stoichiometric amount of water. Peroxides are attractive reactants for decontamination because they are nontoxic and noncorrosive.
    No preview · Article · Jun 2011 · Chemical Reviews
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    ABSTRACT: Group 13 chelates incorporating boron and aluminum deactivated the chemical warfare agents (CWAs) VX, sarin (GB), soman (GD), and the pesticide, diazinon, under mild conditions. The deactivation occured through elimination of alkyl bromide resulting in solid products containing a robust Al-O-P or B-O-P linkage. The Group 13 chelate deactivation methodology produces non-toxic, easily disposable solid proudcts after combination with CWAs. In previous studies the group 13 chelates were found to be active for a wide range of organophosphates, organophosphonates, and organophosphinates (OPs). Thus, the compounds could be used as a deactivating agent for a wide range of problematic compounds possessing P-O-C linkages, including, CWAs, pesticides, and plasticizers. The majority of the chelate compounds are of the general formula: LBX , L(BX2)2 and LAlX where L = an inexpensive, easily prepared Schiff base chelate and X = Cl and Br. This article will describe the range of compounds that can be used in the dealkylation reaction. The primary focus will be on chelates of the Salen class (Salen = N, N ′-alkylene(or arylene)bis(salicylideneimine)), but a wider of range of chelates could be used for the reaction as this review will demonstrate.
    Full-text · Article · Dec 2010 · Main Group Chemistry
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · Nov 2010 · ChemInform
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    ABSTRACT: This study examined whether acquisition of neonatal reflexes in newborn rhesus macaques was influenced by receipt of a single neonatal dose of hepatitis B vaccine containing the preservative thimerosal (Th). Hepatitis B vaccine containing a weight-adjusted Th dose was administered to male macaques within 24 h of birth (n = 13). Unexposed animals received saline placebo (n = 4) or no injection (n = 3). Infants were tested daily for acquisition of nine survival, motor, and sensorimotor reflexes. In exposed animals there was a significant delay in the acquisition of root, snout, and suck reflexes, compared with unexposed animals. No neonatal responses were significantly delayed in unexposed animals. Gestational age (GA) and birth weight (BW) were not significantly correlated. Cox regression models were used to evaluate main effects and interactions of exposure with BW and GA as independent predictors and time-invariant covariates. Significant main effects remained for exposure on root and suck when controlling for GA and BW, such that exposed animals were relatively delayed in time-to-criterion. Interaction models indicated there were various interactions between exposure, GA, and BW and that inclusion of the relevant interaction terms significantly improved model fit. This, in turn, indicated that lower BW and/or lower GA exacerbated the adverse effects following vaccine exposure. This primate model provides a possible means of assessing adverse neurodevelopmental outcomes from neonatal Th-containing hepatitis B vaccine exposure, particularly in infants of lower GA or BW. The mechanisms underlying these effects and the requirements for Th requires further study.
    Full-text · Article · Aug 2010 · Journal of Toxicology and Environmental Health Part A
  • A. H. COWLEY · F. GABBAI · R. SCHLUTER · D. ATWOOD
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · Aug 2010 · ChemInform
  • Lisa Y. Blue · Partha Jana · David A. Atwood
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    ABSTRACT: BDTH2, 1,3-benzenediamidoethanethiol (common name) and closely related derivatives were specifically designed to become insoluble after the formation of linear, covalent bonds to aqueous mercury(II). BDTH2 (IUPAC nomenclature, N,N′-bis(2-mercaptoethyl)isophthalamide) emerged as the preeminent reagent for the complete precipitation of mercury from water after several years of studies with a wide range of compounds having one, two, three, and four thiol groups. BDTH2 does not become inactive through oxidation to disulfide and can be applied to mercury-containing water as acidic, basic, and ethanolic solutions. The BDT–Hg precipitate is extremely stable and leaches low-ppm levels of mercury only under extremely acidic and basic conditions. BDTH2 is also effective in the aqueous precipitation of other soft, divalent metals, such as copper, cadmium, lead, and the main group elements, arsenic and selenium. The insolubility of the BDT–M compounds can be attributed to the presence of strong, non-polar, covalent M–S bonding within a water-insoluble organic framework. BDTH2 has no known biological toxicity and is being sold as a nutritional supplement under the trade name OSR-1. This review describes the chemistry, precipitation, and leaching studies of BDTH2 with mercury.
    No preview · Article · Jun 2010 · Fuel
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · May 2010 · ChemInform
  • David A. Atwood
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · Mar 2010 · ChemInform
  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · Feb 2010 · ChemInform
  • D. A. ATWOOD · A. H. COWLEY · R. A. JONES · M. A. MARDONES
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    No preview · Article · Feb 2010 · ChemInform

Publication Stats

5k Citations
843.69 Total Impact Points

Institutions

  • 1998-2015
    • University of Kentucky
      • Department of Chemistry
      Lexington, Kentucky, United States
    • University of North Dakota
      Grand Forks, North Dakota, United States
  • 2006-2010
    • University of Northern Iowa
      • Department of Chemistry and Biochemistry
      سدار فالز، آیووا, Iowa, United States
  • 1991-2010
    • University of Texas at Austin
      • Department of Chemistry and Biochemistry
      Austin, Texas, United States
  • 2008
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France
  • 1994-2006
    • North Dakota State University
      • Department of Chemistry and Biochemistry
      Fargo, North Dakota, United States
  • 2000
    • Universidad Autónoma del Estado de Morelos
      • Center of Chemical Research (CIQ)
      Cuernavaca, Morelos, Mexico
  • 1995-1996
    • Dakota State University
      Fargo, North Dakota, United States
  • 1987
    • University of Alabama
      • Department of Chemistry
      Tuscaloosa, Alabama, United States