Supramolecular Design Institute

Oak Ridge, TN, United States

Supramolecular Design Institute

Oak Ridge, TN, United States
SEARCH FILTERS
Time filter
Source Type

Collins M.S.,University of Oregon | Choi R.Y.,University of Oregon | Zakharov L.N.,University of Oregon | Watson L.A.,Earlham College | And 2 more authors.
Chemical Science | Year: 2015

The synthesis of six trinuclear Pn3L2 macrobicycles (Pn = As, Sb) was achieved by self-assembly of a pnictogen trichloride and a 2,4,6-trisubstituted-1,3,5-benzenetrimethanethiol ligand. 1H-NMR spectroscopy reveals self-assembly in 1,1,2,2-tetrachloroethane is dynamic in solution producing two structural isomers. The symmetric and the asymmetric isomers (in which a single chloride ligand is cast in an opposing direction from other chlorides) of the As3L2 complexes exist in a ca. 2:1 distribution, whereas only the symmetric isomer is observed in solution for Sb3L2. Solvent effects appear to influence conformational isomerism and conversion to the final products. Macrobicycles were confirmed by 1H-NMR spectroscopy and X-ray crystallography and further studied by MP2/LANL2DZ optimizations. This journal is © The Royal Society of Chemistry.


Tresca B.W.,University of Oregon | Hansen R.J.,University of Oregon | Chau C.V.,University of Oregon | Hay B.P.,Supramolecular Design Institute | And 3 more authors.
Journal of the American Chemical Society | Year: 2015

Aryl CH hydrogen bonds (HBs) are now commonly recognized as important factors in a number of fields, including molecular biology, stereoselective catalysis, and anion supramolecular chemistry. As the utility of CH HBs has grown, so to has the need to understand the structure-activity relationship for tuning both their strength and selectivity. Although there has been significant computational effort in this area, an experimental study of the substituent effects on CH HBs has not been previously undertaken. Herein we disclose a systematic study of a single CH HB by using traditional urea donors as directing groups in a supramolecular binding cavity. Experimentally determined association constants are examined by a combination of computational (electrostatic potential) and empirical (σm and σp) values for substituent effects. The dominance of electrostatic parameters, as observed in a computational DFT study, is consistent with current CH HB theory; however, a novel anion dependence of the substituent effects is revealed in solution. © 2015 American Chemical Society.


PubMed | University of Oregon and Supramolecular Design Institute
Type: Journal Article | Journal: Journal of the American Chemical Society | Year: 2015

Aryl CH hydrogen bonds (HBs) are now commonly recognized as important factors in a number of fields, including molecular biology, stereoselective catalysis, and anion supramolecular chemistry. As the utility of CH HBs has grown, so to has the need to understand the structure-activity relationship for tuning both their strength and selectivity. Although there has been significant computational effort in this area, an experimental study of the substituent effects on CH HBs has not been previously undertaken. Herein we disclose a systematic study of a single CH HB by using traditional urea donors as directing groups in a supramolecular binding cavity. Experimentally determined association constants are examined by a combination of computational (electrostatic potential) and empirical (m and p) values for substituent effects. The dominance of electrostatic parameters, as observed in a computational DFT study, is consistent with current CH HB theory; however, a novel anion dependence of the substituent effects is revealed in solution.


Kim S.K.,University of Texas at Austin | Lee J.,University of Texas at Austin | Williams N.J.,University of Tennessee at Knoxville | Williams N.J.,Oak Ridge National Laboratory | And 4 more authors.
Journal of the American Chemical Society | Year: 2014

Cage-type calix[4]pyrroles 2 and 3 bearing two additional pyrrole groups on the strap have been synthesized. Compared with the parent calix[4]pyrrole (1), they were found to exhibit remarkably enhanced affinities for anions, including the sulfate anion (TBA+ salts), in organic media (CD2Cl2). This increase is ascribed to participation of the bipyrrole units in anion binding. Receptors 2 and 3 extract the hydrophilic sulfate anion (as the methyltrialkyl(C8-10)ammonium (A336+) salt) from aqueous media into a chloroform phase with significantly improved efficiency (>10-fold relative to calix[4]pyrrole 1). These two receptors also solubilize into chloroform the otherwise insoluble sulfate salt, (TMA)2SO4 (tetramethylammonium sulfate). © 2014 American Chemical Society.


Kim S.K.,University of Texas at Austin | Lynch V.M.,University of Texas at Austin | Hay B.P.,Supramolecular Design Institute | Kim J.S.,Korea University | Sessler J.L.,University of Texas at Austin
Chemical Science | Year: 2015

In order to understand the still-poorly understood interplay between calix[4]arene conformations and cation and anion recognition in multicomponent systems, the ion pair receptors 1 and 2 were synthesized. In solution and in the solid state, the calix[4]arene subunit of receptor 1 adopts a cone conformation, while that of 2 interconverts between the cone and the partial cone conformation. These geometric features differ from previous systems where the calix[4]arene moiety was locked in the 1,3-alternate conformation. A combination of 1H NMR spectroscopic analyses and single crystal X-ray diffraction studies reveal that receptor 1 binds the fluoride and the chloride anion via significantly different binding modes, displaying, for instance, 1:1 and 2:3 binding stoichiometries with CsF and CsCl, respectively. In the case of 2, the conformation of the calix[4]arene constituent of 2 is highly dependent on the size and quantity of anions present. For example, upon treatment of 2 with the fluoride anion (as both the TBA+ and Cs+ salts), the calix[4]arene unit coexists as cone and partial cone conformers that are inter-convertible. In the presence of excess CsF, the aromatic rings of the calix[4]arene subunit becomes locked in the pinched cone conformation with the result that an ion pair-mediated coordination polymer is formed. In the presence of excess CsCl, the calix[4]arene unit of 2 adopts only the partial cone conformation stabilized by aryl CH-anion hydrogen bonding interactions. The present systems constitute a rare set of related receptors wherein the effects of conformational changes are so tightly coupled with ion recognition. © The Royal Society of Chemistry 2015.


Ouizem S.,University of New Mexico | Rosario-Amorin D.,University of New Mexico | Dickie D.A.,University of New Mexico | Hay B.P.,Supramolecular Design Institute | Paine R.T.,University of New Mexico
Polyhedron | Year: 2015

Abstract Syntheses for new potentially chelating ligands, 2,6-bis((1H-pyrazol-1-yl)methyl)pyridine 1-oxide (2), ((6-((1H-pyrazol-1-yl)methyl)pyridin-2-yl)methyl)diphenylphosphine oxide (4) and 2-((1H-pyrazol-1-yl)methyl)-6-((diphenylphosphoryl)methyl)pyridine 1-oxide (5), that are based upon pyridine or pyridine N-oxide platforms functionalized with pyrazol-1-ylmethyl and diphenylphosphinoylmethyl substituents, are reported along with results from molecular modeling analyses that assess the strain energy encountered by the ligands in tridentate chelate interactions for gas phase [Eu(L)3+]complexes. Coordination chemistry with selected lanthanide nitrates is described along with X-ray crystal structure determinations for the three ligands and three representative coordination complexes. © 2015 Elsevier Ltd.


Vukovic S.,Oak Ridge National Laboratory | Vukovic S.,University of Cambridge | Hay B.P.,Oak Ridge National Laboratory | Hay B.P.,Supramolecular Design Institute | Bryantsev V.S.,Oak Ridge National Laboratory
Inorganic Chemistry | Year: 2015

The ability to predict the equilibrium constants for the formation of 1:1 uranyl/ligand complexes (log K1 values) provides the essential foundation for the rational design of ligands with enhanced uranyl affinity and selectivity. We use density functional theory (B3LYP) and the integral equation formalism polarizable continuum model (IEF-PCM) to compute aqueous stability constants for UO22+ complexes with 18 donor ligands. Theoretical calculations permit reasonably good estimates of relative binding strengths, while the absolute log K1 values are significantly overestimated. Accurate predictions of the absolute log K1 values (root-mean-square deviation from experiment <1.0 for log K1 values ranging from 0 to 16.8) can be obtained by fitting the experimental data for two groups of mono- and divalent negative oxygen donor ligands. The utility of correlations is demonstrated for amidoxime and imide dioxime ligands, providing a useful means of screening for new ligands with strong chelating capability to uranyl. © 2015 American Chemical Society.


Bryantsev V.S.,Oak Ridge National Laboratory | Hay B.P.,Oak Ridge National Laboratory | Hay B.P.,Supramolecular Design Institute
Dalton Transactions | Year: 2015

Selective extraction of minor actinides from lanthanides is a critical step in the reduction of radiotoxicity of spent nuclear fuels. However, the design of suitable ligands for separating chemically similar 4f- and 5f-block trivalent metal ions poses a significant challenge. First-principles calculations should play an important role in the design of new separation agents, but their ability to predict metal ion selectivity has not been systematically evaluated. In this work, we examine the ability of several density functional theory methods to predict selectivity of Am(iii) and Eu(iii) with oxygen, mixed oxygen-nitrogen, and sulfur donor ligands. The results establish a computational method capable of predicting the correct order of selectivities obtained from liquid-liquid extraction and aqueous phase complexation studies. To allow reasonably accurate predictions, it was critical to employ sufficiently flexible basis sets and provide proper account of solvation effects. The approach is utilized to estimate the selectivity of novel amide-functionalized diazine and 1,2,3-triazole ligands. © The Royal Society of Chemistry 2015.


McCann B.W.,Oak Ridge National Laboratory | Silva N.D.,Iowa State University | Windus T.L.,Iowa State University | Gordon M.S.,Iowa State University | And 3 more authors.
Inorganic Chemistry | Year: 2016

Computer-aided molecular design and high-throughput screening of viable host architectures can significantly reduce the efforts in the design of novel ligands for efficient extraction of rare earth elements. This paper presents a computational approach to the deliberate design of bis-phosphine oxide host architectures that are structurally organized for complexation of trivalent lanthanides. Molecule building software, HostDesigner, was interfaced with molecular mechanics software, PCModel, providing a tool for generating and screening millions of potential R2(O)P-link-P(O)R2 ligand geometries. The molecular mechanics ranking of ligand structures is consistent with both the solution-phase free energies of complexation obtained with density functional theory and the performance of known bis-phosphine oxide extractants. For the case where the link is -CH2-, evaluation of the ligand geometry provides the first characterization of a steric origin for the "anomalous aryl strengthening" effect. The design approach has identified a number of novel bis-phosphine oxide ligands that are better organized for lanthanide complexation than previously studied examples. © 2016 American Chemical Society.


PubMed | Oak Ridge National Laboratory, Iowa State University and Supramolecular Design Institute
Type: Journal Article | Journal: Inorganic chemistry | Year: 2016

Computer-aided molecular design and high-throughput screening of viable host architectures can significantly reduce the efforts in the design of novel ligands for efficient extraction of rare earth elements. This paper presents a computational approach to the deliberate design of bis-phosphine oxide host architectures that are structurally organized for complexation of trivalent lanthanides. Molecule building software, HostDesigner, was interfaced with molecular mechanics software, PCModel, providing a tool for generating and screening millions of potential R2(O)P-link-P(O)R2 ligand geometries. The molecular mechanics ranking of ligand structures is consistent with both the solution-phase free energies of complexation obtained with density functional theory and the performance of known bis-phosphine oxide extractants. For the case where the link is -CH2-, evaluation of the ligand geometry provides the first characterization of a steric origin for the anomalous aryl strengthening effect. The design approach has identified a number of novel bis-phosphine oxide ligands that are better organized for lanthanide complexation than previously studied examples.

Loading Supramolecular Design Institute collaborators
Loading Supramolecular Design Institute collaborators