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Minneapolis, MN, United States

Daly S.R.,University of Illinois at Urbana - Champaign | Piccoli P.M.B.,Argonne National Laboratory | Schultz A.J.,Argonne National Laboratory | Todorova T.K.,University of Geneva | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2010

(Figure Presented) Playing with a full deck: Single-crystal X-ray and neutron diffraction data show that the Th center in the title complex 1 (see structure; Th orange, B beige, N purple, C black, H blue) forms bonds with 15 H atoms, thus making 1 the first crystallographically characterized example of a complex with a Werner coordination number of fifteen. DFT calculations suggest that 1 adopts the fully symmetric 16-coordinate structure in the gas phase. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. Source

Miller D.L.,207 Pleasant St SE | Lu C.C.,207 Pleasant St SE
Dalton Transactions | Year: 2012

A new macrobicyclic ligand has been prepared, and it is shown to bind Zn 2+ on the inside. The ligand consists of a triamido(amine) motif to coordinate the metal ion and a narrow, hydrophobic channel above the metal binding site. © 2012 The Royal Society of Chemistry. Source

Gurusamy-Thangavelu S.A.,207 Pleasant St SE | Emond S.J.,207 Pleasant St SE | Kulshrestha A.,207 Pleasant St SE | Hillmyer M.A.,207 Pleasant St SE | And 3 more authors.
Polymer Chemistry | Year: 2012

Ring opening transesterification polymerization of lactones derived from menthone and carvomenthone was used to synthesize polyols for polyurethane film formulations. The polyols were synthesized at 140°C using tin(ii) octoate as catalyst, diethanolamine as trifunctional initiator, and with ratios of lactone:initiator of 9:1 or 18:1. Polyol structural features were deduced by comparison of NMR spectral data with those of simple model amide/esters of the initiator. Films were formulated from the renewable polyols, diphenylmethane diisocyanate [or poly(diphenylmethane diisocyanate)], and diethylene glycol. Thermal and mechanical properties of these polyurethane films were measured, demonstrating their potential utility as biobased thermosets for rigid or flexible foams. This journal is © 2012 The Royal Society of Chemistry. Source

Tereniak S.J.,207 Pleasant St SE | Marlier E.E.,207 Pleasant St SE | Lu C.C.,207 Pleasant St SE
Dalton Transactions | Year: 2012

The three-coordinate Ni(i) complex Ni(Cl)(P 2), where P 2 is the diphosphine iPrDPDBFphos, reacts with the acids HCl·(dioxane) and 2,6-lutidinium chloride to generate Ni(H)(Cl)(P 2) and Ni(Cl) 2(P 2). Photolysis of the Ni(H)(X)(P 2) (for X = Cl, Br) results in formation of H 2 and the Ni(i) halide. This reaction also proceeds in reverse when heated. © 2012 The Royal Society of Chemistry. Source

Stemig A.M.,207 Pleasant St SE | Do T.A.,207 Pleasant St SE | Yuwono V.M.,207 Pleasant St SE | Arnold W.A.,500 Pillsbury Dr SE | Lee Penn R.,207 Pleasant St SE
Environmental Science: Nano | Year: 2014

Iron mineral systems are effective at transforming highly oxidized contaminants in natural and engineered systems. The rate at which the contaminant degrades may be influenced by the amount of available mineral surface area. This study used dynamic light scattering and cryogenic transmission electron microscopy to monitor changes in the aggregation state of goethite nanoparticles before and after reaction with 4-chloronitrobenzene (4-ClNB). The effects of buffer identity, buffer concentration, and adsorbing metal identity on the goethite nanoparticle suspension characteristics and reactivity were monitored. Results demonstrate that buffers, which serve to hold pH nearly constant over the course of a reaction, are not benign additives in batch reactors. In fact, the identity and concentration of the buffer used strongly influences the rate of 4-ClNB degradation by surface-associated ferrous ion. Increasing buffer concentration resulted in more compact goethite nanoparticle aggregates, and slower 4-ClNB degradation was observed. In addition, the rate of degradation changed dramatically with changing buffer identity, with rates of reaction changing by an order of magnitude when switching from 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) to tris(2-hydroxyethyl)amine (TEA). Finally, of the three metal ions selected (Ca(ii), Fe(ii), and Co(ii)), the addition and adsorption of the two transition metals resulted in a dramatic decrease in the average nanoparticle aggregate size. Furthermore, oxidation of the adsorbed Fe(ii), via O2 or 4-ClNB reduction, yielded decreases in zeta potential and increases in aggregate size. This work demonstrates that small changes in reaction parameters have a large effect on the rate of contaminant degradation through changes in nanoparticle aggregation state. © 2014 the Partner Organisations. Source

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