David A. Atwood

University of Kentucky, Lexington, Kentucky, United States

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Publications (204)780.46 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.
    Chemical Communications 03/2015; 51(45). DOI:10.1039/C5CC00466G · 6.83 Impact Factor
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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.
    Inorganic Chemistry 04/2014; 53(8). DOI:10.1021/ic402909t · 4.79 Impact Factor
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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.
    10/2013; 69(Pt 5):496-508. DOI:10.1107/S205251921301782X
  • 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.
    Inorganic Chemistry 03/2013; 52(5):2497-504. DOI:10.1021/ic302444b · 4.79 Impact Factor
  • 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
    Encyclopedia of Inorganic and Bioinorganic Chemistry, 12/2011; , ISBN: 9781119951438
  • Amitabha Mitra · David A. Atwood
    Encyclopedia of Inorganic and Bioinorganic Chemistry, 12/2011; , ISBN: 9781119951438
  • 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.
    Chemical Reviews 06/2011; 111(9):5345-403. DOI:10.1021/cr100193y · 45.66 Impact Factor
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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.
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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.
    ChemInform 11/2010; 22(44). DOI:10.1002/chin.199144250
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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.
    Journal of Toxicology and Environmental Health Part A 08/2010; 73(19):1298-313. DOI:10.1080/15287394.2010.484709 · 1.83 Impact Factor
  • 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.
    ChemInform 08/2010; 23(32). DOI:10.1002/chin.199232198
  • 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.
    Fuel 06/2010; 89(6-89):1326-1330. DOI:10.1016/j.fuel.2009.10.031 · 3.41 Impact Factor
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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.
    ChemInform 05/2010; 24(20). DOI:10.1002/chin.199320254
  • 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.
    ChemInform 03/2010; 30(12). DOI:10.1002/chin.199912269
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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.
    ChemInform 02/2010; 32(7). DOI:10.1002/chin.200107233
  • 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.
    ChemInform 02/2010; 24(6). DOI:10.1002/chin.199306242
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    ABSTRACT: The Atwood group has designed and synthesized a new class of sulfur-containing compounds, one of which is “BDTH2” (based on the common name, 1,3-Benzene Diamidoethane Thiol) that covalently and irreversibly precipitates mercury and other soft heavy metals and metalloids (Cu, Cd, Pb, As, Se) from water (see: Inorg. Chem. 46 (2007) 1975). BDTH2 reduces aqueous heavy metal concentrations in the ppm and ppb range to below instrumental detection limits. Furthermore, the BDT-metal compounds are stable over a wide pH range and in oxidative and reductive conditions. This has made BDTH2 of utility for soft metal removal in applications such as gold mining, acid mine drainage and lead battery recycling. BDTH2 reduces metal leaching from sulfide minerals and coal through surface covalent bonding. The presentation will describe the fundamental chemistry underlying the unique bonding ability of BDTH2 to soft metals as well as selected remediation applications. BDTH2 is now being marketed under the name "B9" by Merloc, LLC (Inquiries@MerlocLLC.com)
    64th American Chemical Society Southwest Regional Meeting; 11/2009
  • David Atwood · Daniel J. Williams · Amitabha Mitra
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    ABSTRACT: Binuclear boron halide compounds of the type L[BX2]2 (L= Salen(tBu) ligands, X= Cl, Br) can dealkylate a wide range of organophosphate compounds with high conversion at room temperature. Mononuclear boron Schiff base compounds of the type LBX (L= Salen ligands, X=Br, Cl) (Inorg. Chem. 45 (2006) 9213) and aluminum Schiff base compounds of the type Salen(tBu)AlBr (J. Am. Chem. Soc. 128 (2006) 1147) can also dealkylate organophosphates. In these reactions the resulting product is a compound where the dealkylated phosphate ester is covalently bonded to the group 13 element through a hydrolytically stable M-O-P linkage. Recently, the U.S. Army Edgewood Chemical and Biological Center has demonstrated the dealkylation of actual nerve agents and pesticides with these compounds (New J. Chem. 32 (2008) 783). Thus, the dealkylation reaction may be used to deactivate nerve agents in bulk or decontaminate objects exposed to such agents in the field. The resulting byproducts would be non-toxic, stable solids that could be left in situ or disposed of through routine handing. Studies are in progress to determine whether the dealkylation of phosphate esters can be conducted in the gas phase, opening the possibility of using the group 13 reagents in gas mask filters and airborne nerve agent sensors.
    64th American Chemical Society Southwest Regional Meeting; 11/2009
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    ABSTRACT: This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
    NeuroToxicology 10/2009; DOI:10.1016/j.neuro.2009.09.008 · 3.05 Impact Factor
  • David A. Atwood
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    ABSTRACT: There are 1,100 coal-fired electricity generating utilities in the U.S. emitting 48 tons of mercury, a potent neurotoxin, each year. Twenty or more eastern states have either begun, or will begin, regulating Hg emissions from these utilities. A nationwide federal rule is expected by 2013. Thus, there is an immediate need for effective clean-coal technologies that can mitigate mercury release from coal-fired utilities. For several years now the Atwood group has been working with a set of sulfur-containing compounds designed to bind soft heavy metals through strong, covalent M-S bonds. The best of this group is benzene-1,3-diamidoethanethiol (BDTH2 which is particularly effective for removing the mercuric ion from water. It has been shown to irreversibly bind Hg under a wide range of laboratory conditions, in gold mining effluent, acid mine drainage, for soil-borne mercury, and works for low ppb levels in surface water near former chlor-alkali facilities. Importantly, the resulting BDT-Hg precipitate does not release mercury under either strongly acidic or basic conditions. This presentation will describe the recent developments in the use of BDTH2 in mercury capture.
    2009 AIChE Spring National Meeting; 04/2009

Publication Stats

4k Citations
780.46 Total Impact Points

Institutions

  • 1998–2014
    • 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
  • 1996
    • Technische Universität München
      München, Bavaria, Germany
  • 1995–1996
    • Dakota State University
      Fargo, North Dakota, United States
  • 1987–1992
    • University of Alabama
      • Department of Chemistry
      Tuscaloosa, AL, United States