David A. Atwood

University of Kentucky, Lexington, KY, United States

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Publications (193)401.19 Total impact

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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.
    Acta crystallographica Section B, Structural science, crystal engineering and materials. 10/2013; 69(Pt 5):496-508.
  • Amitabha Mitra, David A. Atwood
    Encyclopedia of Inorganic and Bioinorganic Chemistry, 12/2011; , ISBN: 9781119951438
  • 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. 01/2010;
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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 01/2010; 73(19):1298-313. · 1.73 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 01/2010; 32(7).
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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
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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; · 2.65 Impact Factor
  • Kevin R. Henke, David A. Atwood
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    ABSTRACT: Chapter 5 contains a section titled: Arsenic in coal and oil shale utilization and their by-products.
    Arsenic: Environmental Chemistry, Health Threats and Waste Treatment, 03/2009: pages 277 - 302; , ISBN: 9780470741122
  • David Atwood
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    ABSTRACT: Organophosphate esters are active components of chemical warfare agents and pesticides. The cleavage of the P-O-C linkage in these molecules provides a first step for their destruction. Our group has shown that 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 . The reactions are catalytic in the presence of excess BBr3 and are thought to proceed through the formation of a phosphate coordinated boron cation. Mononuclear boron Schiff base compounds of the type LBX (L= Salen ligands, X=Br, Cl) and aluminum Schiff base compounds of the type Salen(tBu)AlBr can also dealkylate organophosphates (J. Am. Chem. Soc. 128 (2006) 1147). Recently, the deactivation of actual nerve agents and pesticides with these compounds has recently been reported (New J. Chem. 32 (2008) 783). These reactions demonstrate the complete deactivation of nerve agents and pesticides in a single step resulting in non-hazardous, covalently-bonded group 13 phosphate products. Studies are in progress to fully characterize the dealkylated product, elucidate the mechanism of the reaction and determine the optimum reaction conditions for utilization of this reaction in actual applications.
    60th American Chemical Society Southeast Regional Meeting; 11/2008
  • Source
    Samuel Dagorne, David A Atwood
    Chemical Reviews 10/2008; 108(10):4037-71. · 41.30 Impact Factor
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    ABSTRACT: Mercury pollution is a serious challenge faced by environmental chemists over the world. For several years now, our group has been developing new compounds to precipitate and thereby remove mercury from water. In this paper, we present a new family of alkyl thiol mercury chelates to add to the aromatic ligands we have previously reported. These new compounds are effective at precipitating mercury from water and with an excess of the best compound, removal is quantitative. Furthermore, the precipitates are stable and released little to no mercury back into solution during leaching studies.
    Journal of Hazardous Materials 09/2008; 156(1-3):458-65. · 3.93 Impact Factor
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    ABSTRACT: Background: Macaques are commonly used in pre-clinical vaccine safety testing, but the combined childhood vaccine regimen, rather than individual vaccines, has not been studied. Childhood vaccines are a possible causal factor in autism, and abnormal behaviors and anomalous amygdala growth are potentially inter-related features of this condition. Objectives: The objective of this study was to compare early infant cognition and behavior with amygdala size and opioid binding in rhesus macaques receiving the recommended childhood vaccines (1994-1999), the majority of which contained the bactericidal preservative ethylmercurithiosalicylic acid (thimerosal). Methods: Macaques were administered the recommended infant vaccines, adjusted for age and thimerosal dose (exposed; N=13), or saline (unexposed; N=3). Primate development, cognition and social behavior were assessed for both vaccinated and unvaccinated infants using standardized tests developed at the Washington National Primate Research Center. Amygdala growth and binding were measured serially by MRI and by the binding of the non-selective opioid antagonist [11C]diprenorphine, measured by PET, respectively, before (T1) and after (T2) the administration of the measles-mumps-rubella vaccine (MMR). Results: Compared with unexposed animals, significant neurodevelopmental deficits were evident for exposed animals in survival reflexes, tests of color discrimination and reversal, and learning sets. Differences in behaviors were observed between exposed and unexposed animals and within the exposed group before and after MMR vaccination. Compared with unexposed animals, exposed animals showed attenuation of amygdala growth and differences in the amygdala binding of [11C]diprenorphine. Interaction models identified significant associations between specific aberrant social and non-social behaviors, isotope binding, and vaccine exposure. Conclusions: This animal model, which examines for the first time, behavioral, functional, and neuromorphometric consequences of the childhood vaccine regimen, mimics certain neurological abnormalities of autism. The findings raise important safety issues while providing a potential model for examining aspects of causation and disease pathogenesis in acquired disorders of behavior and development.
    International Meeting for Autism Research 2008; 05/2008
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    ABSTRACT: Mercury is present in many industrial processes at low concentrations and is a cause for concern due to the propensity for mercury to bioaccumulate. As a cumulative toxin, introduction of mercury into the environment at any level has the potential to adversely affect ecologic systems. To date, no commercial precipitants are available that can irreversibly and permanently bind mercury. In the current work, selected commercial reagents were compared alongside the dianionic ligand 1,3-benzenediamidoethanethiolate (BDET(2-)) to test the feasibility of low-level (parts-per-billion, ppb) mercury treatment for groundwater near a chloralkali plant. Of all the reagents examined, only K(2)BDET was capable of reducing mercury concentrations to below instrumental detection limits of 0.05 ppb with the added benefit of producing a stable precipitate.
    Water Research 05/2008; 42(8-9):2025-8. · 4.66 Impact Factor
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    ABSTRACT: New halogen-containing tetrametallic aluminium alkoxides of formula [Al{(mu-OEt)2AlMeCl}3] ( 2-cis; 2-trans), and [Al{(mu-OEt)2AlBr2}3] ( 4), have been synthesized by combining Al(OEt)3 and Me2AlCl (for 2) or EtAlBr2 (for 4). They were fully characterized by (1H, 27Al) NMR, IR, mp, elemental analysis, and single-crystal X-ray diffractometry. The chloride analogue of 4, [Al{(mu-OEt)2AlCl2}3] ( 3), prepared previously using a different route, was also prepared here by combining Al(OEt)3 and EtAlCl2.
    Dalton Transactions 03/2008; · 3.81 Impact Factor
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    ABSTRACT: Schiff baseboron and aluminium bromides have been used to cleave organophosphate nerve agents and pesticides and their simulants: salben(tBu)[BBr2]2 was very effective in cleaving the VX simulants EMPPT and DEPPT and nerve agent VX; salen(tBu)AlBr was effective in cleaving the nerve agents VX and Soman and the pesticideDiazinon.
    New Journal of Chemistry 01/2008; 32(5). · 2.97 Impact Factor
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    ABSTRACT: Acid mine drainage (AMD) from metal sulfides that result in heavy metal leaching into the environment is a prevalent problem. Coating natural pyrite (FeS2/SiO2) and galena (PbS) mineral surfaces with benzene-1,3-diamidoethanethiol (BDET) was found to be an effective method for preventing heavy metal leaching into aqueous media. The natural pyrite examined was found to have a significant amount of quartz in its matrix that influenced its ability to bind with BDET. X-ray photoelectron spectroscopy (XPS) core level shifts of the S 2p, N1s, Fe 2p and Pb 4f orbitals upon complexation revealed that greater BDET binding to these metal sulfides correlated with ligand-to-metal (LMCT) charge transfer. Improved binding of BDET to FeS2 over PbS was observed as the concentration of metal in the supernatant dramatically decreased. Stronger BDET binding to FeS2/SiO2 was attributed to LMCT from the open shell Fe absent in the corresponding metal in galena (Pb), which had a closed shell configuration. Comparison of N 1s spectra in control experiments show that SiO2 resulted in a reduced number of N 1s oxidation states, improving anti-leaching properties. Coverage of BDET complexed to FeS2/SiO2 was markedly greater than that for PbS, in agreement with inductive coupled plasma optical emission spectrometry (ICP-OES) data. Photoelectron spectroscopy data revealed that the electronic shell structure of the sulfide metal is a contributing factor in BDET’s ability to inhibit heavy metal leaching.
    Colloids and Surfaces A Physicochemical and Engineering Aspects 01/2008; 331(3):155-161. · 2.11 Impact Factor
  • Samuel Dagorne, 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 200 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 01/2008; 39(51).
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    ABSTRACT: Benzene-1,3-diamidoethanethiol (BDETH2) is an exceptional precipitant for removing soft heavy metals from water. The present work will detail the bonding arrangement of BDETH2 to the metals Cd, Hg, and Pb, along with the full characterization data of the BDET-M compounds. It was found that the Hg compound has a linear S-M-S geometry. The characterization data consisted of Mp, EA, IR, Raman, MS, XANES, EXAFS, and solid-state multinuclear NMR.
    Inorganic Chemistry 04/2007; 46(6):1975-80. · 4.59 Impact Factor
  • K. M. Zaman, C. Chusuei, D. A. Atwood
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    ABSTRACT: The use of benzene-1,3-diamidoethanethiol as a covalent surface coating for the prevention of metal leaching was demonstrated with several sulfide minerals including cinnabar (HgS), pyrite (FeS), chalcopyrite (CuFeS), covellite (CuS), galena (PbS), realgar (AsS) and sphalerite (ZnS). The minerals were coated with sufficient H2BDT to bind the surface metals in a 1:1 ratio. Leaching at pH 1, 3 and 7 was then conducted on both treated and untreated minerals. ICP and CVAFS (for mercury) analyses revealed that the coated minerals showed a dramatic reduction in metal leaching as compared to uncoated control samples. X-ray photoelectron spectroscopy indicated the formation of covalent bonds between the sulphur of the ligand and the metals from the minerals. Results indicate that it would be possible to prevent acid mine drainage through the binding of the metals in coal. 51 refs., 4 figs., 8 tabs.
    Main Group Chemistry - MAIN GROUP CHEM. 01/2007; 6:169-184.

Publication Stats

751 Citations
401.19 Total Impact Points

Institutions

  • 1998–2011
    • University of Kentucky
      • Department of Chemistry
      Lexington, KY, United States
  • 2008
    • University of Strasbourg
      Strasburg, Alsace, France
  • 1995–2006
    • North Dakota State University
      • Department of Chemistry and Biochemistry
      Fargo, North Dakota, United States
  • 1991–2002
    • University of Texas at Austin
      • Department of Chemistry and Biochemistry
      Austin, Texas, United States
  • 2000
    • Universidad Autónoma del Estado de Morelos
      • Center of Chemical Research (CIQ)
      Cuernavaca, Morelos, Mexico
  • 1993
    • Texas State University
      • Department of Chemistry & Biochemistry
      San Marcos, TX, United States
  • 1987–1992
    • University of Alabama
      • Department of Chemistry
      Tuscaloosa, AL, United States