Physical Sciences and Mathematics Commons^™

Ligand-Directed Molecular Architectures: Self-Assembly Of Two-Dimensional Rectangular Metallocycles And Three-Dimensional Trigonal Or Tetragonal Prisms, Cheng-Yong Su, Yue-Ping Cai, Chun-Long Chen, Mark Smith, Wolfgang Kaim, Hans Conrad Zur Loye

Hans Conrad zur Loye

Three angular ditopic ligands (1,3-bis(benzimidazol-1-ylmethyl)-4,6-dimethylbenzene L1, 1,3-bis(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene L2, and 1,4-bis(benzimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene L3) and one tripodal ligand 1,3,5-tris(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene L4 have been prepared. Reaction of these shape-specific designed ligands with different metal salts affords a series of discrete molecular architectures: [Ag2L12](BF4)2 1, [Ag2L22](CF3SO3)2 2, [CF3SO3- Ag2L32]CF3SO3 3, [CF3SO3- Ag2L33]CF3SO3 4, [ClO4- Cu2L24](ClO4)3 5, [4H2O Ni2L24Cl4]·6H2O 6, [BF4- Ag3L42](BF4)2 7, [ClO4- Ag3L42](ClO4)2 8, and [CuI32- Cu3L42]2[Cu2I4] 9. The compounds were characterized by elemental analysis, ESI-MS, IR, and NMR spectroscopy, and X-ray crystallography. 1 is a dinuclear metallacycle with 2-fold rotational symmetry in which two syn-conformational L1ligands are connected by two linearly coordinated Ag+ ions. …

Exceptionally Stable, Hollow Tubular Metal-Organic Architectures: Synthesis, Characterization And Solid-State Transformation Study, Cheng-Yong Su, Andrea Goforth, Mark Smith, P. Pellechia, Hans Conrad Zur Loye

Hans Conrad zur Loye

An effective solvothermal procedure has been developed to synthesize the new three-dimensional metal−organic framework, [ZnF(AmTAZ)]·solvents, using either 3-amino-1,2,4-triazole (AmTAZ) or 3-amino-1,2,4-triazole-5-carboxylic acid (AmTAZAc) and a choice of several Zn(II) salts as starting materials. The three-dimensional structure displays open-ended, hollow nanotubular channels that are formed by hexanuclear metallamacrocyclic Zn₆F₆(AmTAZ)₆ rings. The framework integrity is maintained to 350 °C, at which point most of the guest solvent molecules have been removed, as evidenced by single-crystal X-ray analyses, ¹H solid-state NMR, and TGA measurements. At higher temperatures, the framework is converted either to zinc oxide (ZnO) when …

Self-Assembled Nanotubes That Reversibly Bind Acetic Acid Guests, Linda Shimizu, Andrew Hughes, Mark Smith, Matthew Davis, B. Zhang, Hans Conrad Zur Loye

Hans Conrad zur Loye

A large bis-urea macrocycle was synthesized and assembled into columnar nanotubes containing a sizable cavity. This purely organic nanotube is held together primarily by hydrogen bonding and yet shows remarkable thermal stability up to 180 °C in the presence and absence of acetic acid guest. This enables the nanotube to be used as reusable organic zeolite.

Tris(1,10-Phenanthroline)Cobalt(Ii) Triiodide, Meredith Tershany, Andrea Goforth, Mark Smith, Leroy Peterson, Hans Conrad Zur Loye

Hans Conrad zur Loye

The asymmetric unit of the title compound, [Co(C₁₂H₈N₂)₃](I₃)₂, contains one [Co(1,10-phenanthroline)₃]²⁺ cation, half each of two centrosymmetric triiodide anions, and one complete triiodide anion. The title compound was synthesized solvothermally from Co(NO₃)₂, 1,10-phenanthroline, and SnI₂, where the SnI₂ reagent serves only as a source of I atoms.

Tris(Ethylenediamine)Cobalt(Iii) Nonaiododibismuthate, Andrea Goforth, Rachael Hipp, Mark Smith, Leroy Peterson, Hans Conrad Zur Loye

Hans Conrad zur Loye

The asymmetric unit of the title compound, [Co(C₂H₈N₂)₃][Bi₂I₉], crystallizes in the orthorhombic space group Cmc2₁. The asymmetric unit contains half of a [Co(en)₃]³⁺ cation (en is ethylenediamine) and half of a [Bi₂I₉]^3- anion. Both species are located on mirror planes, requiring the [Co(en)₃]³⁺ cation to be present as a statistically disordered mixture of both enantiomeric forms. Crystals were grown solvothermally from an ethanol-water solvent mixture using rac-[Co(en)₃]I₃ and bismuth triiodide …

High Temperature Superconductivity In Y-Ba-Cu-O: Identification Of A Copper-Rich Superconducting Phase, Angelica Stacy, John Badding, Margret Gesselbracht, William Ham, Gary Holland, Renata Hoskins, Steven Keller, Clark Millikan, Hans Conrad Zur Loye

Hans Conrad zur Loye

For the past 15 years, advances in superconductivity have come about only slowly and even a 0.5 K increase in transition temperature was noteworthy. Until April 1986, the highest transition temperatures were near 23 K. At that time, Bednorz and Muller reported superconductivity in La-Ba-Cu-0 compounds above 30K. Following this breakthrough, there were further studies of these phases and superconductivity was found also in similar solids containing Sr and Ca instead of Ba. The superconducting phase was identified as a layered perovskite A2-xBxCu04 with tetragonal symmetry, where A = La3+ and B = Ca2+, Sr2+, or Ba2+. The Sr compounds …

Tetrakis(N-Ethyl-9-Oxo-4-Azonia-5-Aza-9h-Fluorene) Tetra-Μ3-Iodo-Hexa-Μ2-Iodo-Dodecaiodohexabismuthate, Meredith Tershany, Andrea Goforth, Mark Smith, Leroy Peterson, Hans Conrad Zur Loye

Hans Conrad zur Loye

The new iodobismuthate compound (C13H11N2O)4[Bi6I22] has been synthesized solvothermally by reacting BiI3, Zn(NO3)2·6H2O and 4,5-diazafluoren-9-one in a water/ethanol solvent mixture. The asymmetric unit of the compound contains two independent [N-ethyl-4,5-dafo]+ cations and one-half of a centrosymmetric [Bi6I22]4- anion. The average terminal Bi-I, Bi-2-I and Bi-3-I bond lengths in the anion are 2.8923 (2), 3.1403 (2) and 3.3022 (2) Å, respectively.

Alkyne Metathesis With Simple Catalyst Systems: Efficient Synthesis Of Conjugated Polymers Containing Vinyl Groups In Main Or Side Chain, Glen Brizius, Neil Pschirer, Winfried Steffen, Katherine Stitzer, Hans Conrad Zur Loye, Uwe Bunz

Hans Conrad zur Loye

The synthesis of novel conjugated polymers by acyclic diyne metathesis (ADIMET) is reported. These polymers are hybrids between poly(p-phenylenevinylene) and poly(p-phenyleneneethynylene) (PPE). They contain phenylene, ethynylene, and vinylene groups (PhPh, PPVE). Simple in situ catalysts formed from Mo(CO)6 and 4-chlorophenol were used to metathesize the dipropynyl(tetraalkyl)stilbene monomers. The monomers are made by a combination of Horner reactions and Heck-type couplings. The PPVEs form in high yields and are structurally defined. They show degrees of polymerization (Pn) of 30−220 repeating units (i.e. 60−450 benzene rings), demonstrating that the presence of the double bonds does not interfere with alkyne metathesis. The PPVEs …

Euknatao5: Crystal Growth, Structure And Photoluminescence Property, Irina Roof, Mark Smith, Sangmoon Park, Hans Conrad Zur Loye

Hans Conrad zur Loye

The synthesis, structure determination, and intrinsic luminescent properties of a new tantalate, EuKNaTaO5, are reported. Single crystals of the title compound were grown out of a reactive KOH/NaOH eutectic melt. Luminescence in many materials is activated by doping a rare earth cation into the solid matrix; we report undoped, all-rare earth EuKNaTaO5, which exhibits bright orange room temperature photoluminescence.

Tetraquabis(5-Fluorosaccharinato)Nickel(Ii), Larnelle Peterson, Jennifer Kelley, Leroy Peterson, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

In the centrosymmetric title complex, [Ni(C7H3FNO3S)2(H2O)4], the NiII atom exhibits a slightly distorted trans-NiN2O4 octahedral coordination. The nitrogen donors are provided by two 5-fluorosaccharinate ligands and the oxygen donors are provided by four water molecules. The crystal structure features O-HO and bifurcated O-H(F,O) hydrogen bonds, the latter involving the F atom of the 5-fluorosaccharinate ligand.

Observation Of An Oxygen Isotope Effect In Yba2Cu3O7, Kevin Leary, Hans Conrad Zur Loye, Steven Keller, Tanya Faltens, William Ham, James Michaels, Angelica Stacy

Hans Conrad zur Loye

A small decrease in Tc of 0.3 K to 0.5 K is observed when as much as 90% of the 16O in YBa2Cu3O7 is substituted with18O. This result is consistent with our observation that there is an oxygen isotope effect in La1.85Sr0.15CuO4, but in contrast with previous reports that there is no isotope effect for YBa2Cu3O7. This new result suggests that phonons play an important role in the electron-pairing mechanism in YBa2Cu3O7.

Observation Of An Isotope Shift In The Superconducting Transition Temperature Of La1.85Sr0.15Cuo4, Tanya Faltens, William Ham, Steven Keller, Kevin Leary, James Michaels, Angelica Stacy, Hans Conrad Zur Loye, Donald Morris, T Barbee, Marvin Cohen, Cohen Hoen, A Zettl

Hans Conrad zur Loye

An oxygen isotope shift is observed in superconducting La1.85Sr0.15CuO4 when 18O is substituted partially for 16O; the superconducting transition temperature Tc is lowered by 0.3 to 1.0 K in different samples. We examine these results using conventioanl phonon-mediated BCS theory and conclude that, for La1.85Sr0.15CuO4, phonons play an important role in the pairing mechanism.

Bis[Μ-1,2-Bis(2-Pyridyl)Ethyne-K2N:N']Bis[Aquadinitratocadmium(Ii)], Badruz Zaman, Matthew Davis, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

Two twisted 1,2-bis(2-pyridyl)ethyne ligands bridge two Cd²⁺ centers in the C₂-symmetric title complex, [Cd₂(NO₃)₄(-C₁₂H₈N₂)₂(H₂O)₂]. The bridging ligands arch across one another creating a `zigzag loop' molecular geometry. Two nitrate ions and a water molecule complete the irregular seven-coordinate Cd-atom environment. The dihedral angles between the equivalent pyridyl ring planes of the two independent ligands are 67.2 (1)°. O_water-HO_nitrate hydrogen bonding creates two-dimensional layers parallel to the ab plane.

Formula: [Cd₂(NO₃)₄(C …

Crystal Growth And Structure Determination Of Novel Barium Rhodates: Stepping Stones Towards 2h-Barho3, Katherine Stitzer, Ahmed Abed, Jacques Darriet, Hans Conrad Zur Loye

Hans Conrad zur Loye

Single crystals of two new barium rhodates were grown from a molten potassium carbonate flux. The new rhodates, Ba₁₁Rh₁₀O₃₀ and Ba₃₂Rh₂₉O₈₇, are structurally related to the 2H-hexagonal perovskite structure and are characterized by pseudo one-dimensional chains of alternating face-sharing trigonal prisms and octahedra. The structures of Ba₁₁Rh₁₀O₃₀ and Ba₃₂Rh₂₉O₈₇ were solved using the 4D superspace group approach in Jana2000. Ba₁₁Rh₁₀O₃₀, with a repeat of nine RhO₆ octahedra followed by one RhO_{6 …}

Trisodium Dicalcium Bismuth Hexaoxide, Irina Puzdrjakova, Rene Macquart, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

Single crystals of the title compound, Na3Ca2BiO6, were grown from a high-temperature reactive flux solution of Na2CO3. Na3Ca2BiO6 crystallizes as an ordered rock-salt structure (space group Fddd), in which the octahedral holes in the oxide array are filled by an ordered 3:2:1 arrangement of Na+, Ca2+ and Bi5+ cations. All atoms except for one O atom lie on special positions; site symmetries are as follows: Bi 222, Ca 2, Na 222 and 2, O 2.

Tetraaquabis(3-Fluoropyridine-4-Carboxylato-Κn)Zinc(Ii) Dihydrate, Jonetha Fleming, Jennifer Kelley, Leroy Peterson, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

In the title compound, [Zn(C₆H₃FNO₂)₂(H₂O)₄]·2H₂O, the Zn^II atom is octahedrally coordinated in a ZnO₄N₂ environment by two 3-fluoropyridine-4-carboxylate (3-fpy4-cbx) ligands and four water molecules. The [Zn(3-fpy4-cbx)₂(H₂O)₄] molecules form a three-dimensional network through strong O-HO and weak O-HF hydrogen bonds between 3-fpy4-cbx and water molecules. The crystal used for data collection was a twin, with the twin law corresponding to a 180° rotation about the real-space [001] axis. The major twin fraction refined to 0.795 (1).

Catena-Poly[[Diaquadinitratozinc(Ii)]Bis(Μ-1,4-Di-3-Pyridyl-2,3-Diaza-1,3-Butadiene)], Shakoya Paulin, Pierre Kelly, Kenneth Williams, Andrea Goforth, Mark Smith, Leroy Peterson, Hans Conrad Zur Loye

Hans Conrad zur Loye

The polymeric title complex, [Zn(NO3)2(C24H20N8)(H2O)2]n, features distorted ZnN2O4 octahedra with each ZnII atom being located on an inversion center. Adjacent Zn ions are doubly bridged by two equivalent 1,4-di-3-pyridyl-2,3-diaza-1,3-butadiene ligands to form linear chains.

Absence Of The Metal-Support Interaction For Ni/Tio2 Composites Prepared Using Ion-Exchange Techniques, Hans Conrad Zur Loye, Tanya Faltens, Angelica Stacy

Hans Conrad zur Loye

Many recent reports on the surface properties of transition-metalcatalysts dispersed on high surface area oxide supports have shown that the support can alter markedly the intrinsic activity of the metal. In particular, when group 8-10 metals are supported on reducible metal oxides, the surface chemistry and the electronic properties of the composite depend on the reduction temperature used for pretreatment. For example, the chemisorption of H2 at room temperature on metal-TiO2 composites decreases sharply as the reduction temperature used to prepare the catalyst is increased from 573 to 773 K. This change in surface chemistryhas been attributed to a strong …

Novel Mixed-Valent (V/Vi) Triple Perovskite Ruthenates: Observation Of A Complex Low Temperature Structural And Magnetic Transition, Katherine Stitzer, Mark Smith, William Gemmill, Hans Conrad Zur Loye

Hans Conrad zur Loye

Two new mixed-valent triple perovskites, Ba3MRu2O9 (M = Li, Na), were grown from reactive hydroxide fluxes. They crystallize in the hexagonal space group P63/mmc, where Ru(V) and Ru(VI) are disordered on only one crystallographic site. Upon cooling, single crystals of Ba3NaRu2O9 undergo a complex symmetry-breaking structural transition at ca. 225 K from room-temperature hexagonal symmetry to a low-temperature orthorhombic symmetry, space group Cmcm. Accompanying this structural transition is a rather abrupt decrease in the magnetic susceptibility at 210 K followed by a steady decrease in the susceptibility with decreasing temperature. Interestingly, the lithium analogue does not display any structural transition …

Structure Determination Of Two New Incommensurate Compounds, Ba1+X[(CuXRh1-X)O3], With X = 0.1605 And X = 0.1695, Using A General Method Based On The Superspacegroup Approach, Mirvat Zakhour-Nakhl, John Claridge, Jacques Darriet, Francois Weill, Hans Conrad Zur Loye, Juan Perez-Mato

Hans Conrad zur Loye

The single-crystal structures of two incommensurate compounds, Ba1+x[(CuxRh1-x)O3] with x = 0.1605 and x = 0.1695, were solved by a general method using the superspace group approach. A saw-tooth function was used to model both the occupational and displacive modulations. This approach requires very few refineable parameters and leads to low residuals, R = 0.0370 and R = 0.0330 for x = 0.1605 and x = 0.1695, respectively. The idealized structures of these two compounds consist of [(CuxRh1-x)O3]∞ chains containing groups of five face-shared (RhO6) octahedra separated by (CuO6) trigonal prisms. These chains in turn are separated from each other …

Poly[Μ2-Nitrato-(Μ4-Pyrazine-2-Carboxylato)Disilver(I)], Kathryn Seward, Joseph Ellsworth, Zeeshan Khaliq, Hans Conrad Zur Loye

Hans Conrad zur Loye

The title compound, [Ag2(C5H3N2O2)(NO3)]n, is a three-dimensional coordination polymer containing two-dimensional slabs held together by bridging nitrate groups. AgNO4 and AgNO5 silver coordination polyhedra arise. Weak argentophilic interactions [AgAg = 3.0686 (7) Å] occur in the crystal structure.

Ac Susceptibility Of Sr3CuptXIr1-XO6: A Magnetic System With Competing Interactions And Dimensionality, S Irons, T Sangrey, K Beauchamp, M Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

Sr3CuPtxIr1-xO6 has been cited as an example of a one-dimensional quantum spin chain with competing ferromagnetic and antiferromagnetic interactions. We have measured the ac susceptibility of Sr3CuPtxIr1-xO6 with x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7, in magnetic fields of 0–60 kOe, and at temperatures down to 0.275 K. Our data show that the x=endpoint Sr3CuIrO6, exhibits long-range ferromagnetic order at T=20.1 K, contrary to results from dc susceptibility studies which indicated that it remained a one-dimensional ferromagnet to below 4 K. When platinum is substituted for iridium, antiferromagnetic couplings are introduced, and the susceptibility shows a diminishing signature …

“[Cu(Pyrazine-2-Carboxylate)2]2Cd4I8: Unprecedented 1-D Serpentine Chains And Regular 2-D Regular Metal-Organic Square Grids In A 3-D Framework., Delia Ciurtin, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

A novel three-dimensional coordination polymer containingan unprecedented one-dimensional serpentine motif conjoinedwith a two-dimensional square grid motif is presented.

Poly[Diaqua(Μ4-3-Fluorophthalato-Κ4O:O:O':O'')Cadmium(Ii)], Diana Rishmawi, Katie Lewis, Mark Smith, Leroy Peterson, Hans Conrad Zur Loye

Hans Conrad zur Loye

The crystal structure of the title compound, [Cd(C8H3FO4)(H2O)2]n, consists of polymeric sheets formed by the bridging of octahedrally coordinated CdII by carboxylate O atoms of the 3-fluorophthalate (3-fpt2-) ligand. The layers exhibit hydrogen bonding between each of two coordinated water molecules and two O atoms of the ligand. Adjacent sheets are connected through - interactions.

Sr3Mgpto6, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

Single crystals of the mixed alkaline earth platinate, tristrontium magnesium platinum hexaoxide, Sr₃MgPtO₆, were grown from a KOH flux at 1273 K. The compound adopts the rhombohedral K₄CdCl₆ structure type, featuring chains of face-shared, distorted MgO₆ trigonal prisms (Mg site symmetry 32) and PtO₆ octahedra (Pt site symmetry ) surrounded by columns of Sr²⁺ ions (Sr site symmetry 2).

Growth Of Sr6Rh5O15 Single Crystals From High Temperature Solutions: 1. Structure Determination Using The Traditional 3d And The 4d Superspace Group Methods. 2. Magnetic Measurements On Oriented Single Crystals, Katherine Stitzer, Ahmed Abed, Jacques Darriet, Hans Conrad Zur Loye

Hans Conrad zur Loye

Single crystals of Sr₆Rh₅O₁₅ were grown from a molten potassium carbonate flux. The structure was solved by both the traditional 3-D crystallographic approach and the 4-D superspace group approach using JANA2000. Both methods produced an equivalent structure determination, thereby confirming the 4-D superspace group approach as an effective structure solution method for 3-D commensurate composite structures. Sr₆Rh₅O₁₅ corresponds to the n = 1, m = 1 member of the A_3n+3mA‘_nB_3m+nO_9m+6n family of 2H hexagonal …

Changes In The Electronic Structure Of Ni/TioX Composites As A Function Of Reduction Temperature, Hans Conrad Zur Loye, Angelica Stacy

Hans Conrad zur Loye

Transition-metal catalysts are dispersed on high surface area oxide supports in order to obtain a large catalytic activity per metal atom. Many supports, such as SiO2, and A1203, are considered to be inert; that is, these supports do not alter the intrinsic activity of the metal significantly but only serve to increase the surface area of the metal and prevent sintering. For some oxide supports, however, there is a strong interaction between the metal and the support. In particular, TiO2, can affect the activity of the supported metal depending on the conditions under which the metal-titanium dioxide composite is prepared. …

Poly[(Nitrato-KO)Tris((Μ3-1h-1,2,4-Triazolato)Dizinc(Ii)]: A Three-Dimensional Coordination Polymer, Josephy Ellsworth, Mark Smith, Hans Conrad Zur Loye

Hans Conrad zur Loye

In the title compound, [Zn2(C2H2N3)3(NO3)], there are two unique Zn atoms, both with site symmetry m. One forms a ZnN3O tetrahedron and the other a ZnN6 octahedron. One and a half 1H-1,2,4-triazolate ligands, with the half-ligand located on a mirror plane, and a disordered nitrate anion complete the asymmetric unit of the structure. The polymeric connectivity is three-dimensional.

Surface Chemistry Of Nickel Supported On TiNO2n-1, Hans Conrad Zur Loye, Tanya Faltens, Angelica Stacy

Hans Conrad zur Loye

Small metal particles dispersed on inorganic oxides are among the most important heterogeneous catalysts. While the primary function of the oxide support is to increase the metal surface area, these supports can cause pronounced changes in the catalytic and chemisorption properties of the metal. In particular, metals supported on TiO2, have attracted attention due to the observation that activity and selectivity for Fischer-Tropsch synthesis can be altered, depending on the temperature a t which the metal Ti02 composite is reduced. Furthermore, H2 and CO chemisorption are suppressed for composites reduced at higher temperatures. In this paper, we show that the …