Publications by authors named "Tiffany Kinnibrugh"

Metal fluorides (e.g., FeF and FeF) have received attention as conversion-type cathode materials for Li-ion batteries due to their higher theoretical capacity compared to that of common intercalation materials.

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Article Synopsis
  • - Nonstoichiometric lead oxides are crucial for the performance and lifespan of lead-acid batteries, as they enhance the positive electrode's effectiveness and adhesion properties.
  • - Research identified at least two intermediate phases of lead oxide through various analysis techniques, confirming their structural changes and oxidation states during battery cycling.
  • - Using advanced computational methods, the stability of these lead oxide phases was examined, offering insights into their formation and variations seen in past studies.
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Iridium nanoparticles are important catalysts for several chemical and energy conversion reactions. Studies of iridium nanoparticles have also been a key for the development of kinetic models of nanomaterial formation. However, compared to other metals such as gold or platinum, knowledge on the nature of prenucleation species and structural insights into the resultant nanoparticles are missing, especially for nanoparticles obtained from IrCl precursors investigated here.

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Solvation and mesoscale ordering of sulfuric acid and other strong acid solutions leads to suppressed freezing points and strong rheological changes with varying concentration. While the solid-state structures are well-understood, studies focused on the evolving solvation structure in the solution phase have probed a limited concentration range (∼1-6 M). This study applies a total scattering approach in both the wide-angle X-ray scattering (WAXS) and pair distribution function (PDF) regimes to elucidate the evolving solvation structure over its full range of acid concentration (0-18 M).

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A surfactant-free synthesis of precious metal nanoparticles (NPs) performed in alkaline low-boiling-point solvents has been recently reported. Monoalcohols are here investigated as solvents and reducing agents to obtain colloidal Os nanoparticles by using low-temperature (<100 °C) surfactant-free syntheses. The effect of the precursor (OsCl or HOsCl), precursor concentration (up to 100 mM), solvent (methanol or ethanol), presence or absence of a base (NaOH), and addition of water (0 to 100 vol %) on the resulting nanomaterials is discussed.

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The development of nanomaterials often relies on wet-chemical synthesis performed in reflux setups using round-bottom flasks. Here, an alternative approach to synthesize nanomaterials is presented that uses glass tubes designed for NMR analysis as reactors. This approach uses less solvent and energy, generates less waste, provides safer conditions, is less prone to contamination, and is compatible with high-throughput screening.

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Using N-(phosphonomethyl) iminodiacetic acid (H4PMIDA), as a complexing agent, two new complexes, (NH4)La(PMIDA)(H2O)•H2O, 1 and (NH4)Yb(PMIDA), 2 have been synthesized hydrothermally. In both compounds, the metal ions are trapped by a three five-membered chelate rings by the chelating PMIDA anions giving a tricapped trigonal prismatic LaO8N and monocapped trigonal prismatic YbO6N geometries for 1 and 2, respectively. The structure of 1 consists of La(PMIDA)(H2O) chelating units, linked together by the phosphonate oxygen atoms O1 and O3 to form a chain along the c-axis.

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Potentiostatic intermittent titration technique (PITT) was applied to FeF2, FeF3, and FeO0.67F1.33 to gain insight into the transport-related aspects of the conversion reaction by quantitative analysis of Li(+) diffusion and hysteresis.

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Metal-organic frameworks (MOFs) can provide a matrix for the assembly of organic chromophores into well-defined geometries, allowing for tuning of the material properties and study of structure-property relationships. Here, we report on the effect of the coordinated metal ion on the luminescence properties of eight isostructural MOFs having the formula M(1)2M(2)L3(DMF)2 (M(1) = M(2) = Zn (1), Cd (2), Mn (3), Co (4); M(1) = Zn, M(2) = Cd (5), Mn (6), Co (7); M(1) = Co, M(2) = Mn (8); L = trans-4,4'-stilbene dicarboxylate), synthesized by reaction of the appropriate metal nitrate or mixtures of metal nitrates with LH2 in DMF. The crystal structures of 2, 3 and 5-8 were determined by X-ray diffraction to be composed of trinuclear metal clusters linked by stilbene dicarboxylate linkers in a paddlewheel geometry, extending to form a 2-D layered structure.

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The target complexes, bis{(E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-oxopiperidinium} butanedioate, 2C27H36N3O(+)·C4H4O4(2-), (II), and bis{(E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-oxopiperidinium} decanedioate, 2C27H36N3O(+)·C10H16O4(2-), (III), were obtained by solvent-mediated crystallization of the active pharmaceutical ingredient (API) (E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-piperidone and pharmaceutically acceptable dicarboxylic (succinic and sebacic) acids from ethanol solution. They have been characterized by melting point, IR spectroscopy and single-crystal X-ray diffraction. For the sake of comparison, the structure of the starting API, (E,E)-3,5-bis[4-(diethylamino)benzylidene]-4-piperidone methanol monosolvate, C27H35N3O·CH4O, (I), has also been studied.

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An aluminium carboxymethylphosphonate of composition (NH(4))(2)Al(H(1/2)O(3)PCH(2)CO(2))(2) has been prepared hydrothermally. The aluminium cation is chelated by six membered rings formed from bonding by both the carboxylate and phosphonate oxygens. These chelate rings in turn form larger eight membered rings by connecting to similar chelate groups to form chains running along the a-axis.

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Structural simplification of an antimitotic natural product podophyllotoxin with mimetic heterocyclic scaffolds constructed using multicomponent reactions led to the identification of compounds exhibiting low nanomolar antiproliferative and apoptosis-inducing properties. The most potent compounds were found in the dihydropyridopyrazole, dihydropyridonaphthalene, dihydropyridoindole, and dihydropyridopyrimidine scaffold series. Biochemical mechanistic studies performed with dihydropyridopyrazole compounds showed that these heterocycles inhibit in vitro tubulin polymerization and disrupt the formation of mitotic spindles in dividing cells at low nanomolar concentrations, in a manner similar to podophyllotoxin itself.

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Crystal structures have been determined for six dipolar polyene chromophores with metallocenyl - ferrocenyl (Fc), octamethylferrocenyl (Fc″), or ruthenocenyl (Rc) - donors and strong heterocyclic acceptors based on 1,3-diethyl-2-thiobarbituric acid or 3-dicyanomethylidene-2,3-dihydrobenzothiophene-1,1-dioxide. In each case, crystals were found to belong to centrosymmetric space groups. For one example, polymer-induced heteronucleation revealed the existence of two additional polymorphs, which were inactive in second-harmonic generation, suggesting that they were also centrosymmetric.

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The electronic properties of the 2,6-diiododithieno[3,2-b:2',3'-d] thiophene molecule and crystal are investigated by means of UV-vis spectroscopy, cyclic voltammetry, X-ray crystallography, and density functional theory. The experimental and calculated properties of the compound are compared to those exhibited by the parent molecule, dithieno[3,2-b:2',3'-d]thiophene. Quantum-chemical studies of the 2,6-diiododithieno[3,2-b:2',3'-d]thiophene crystal suggest uniaxial hole-transport character with an effective mass of about 2m(0), comparable to that in the pentacene single crystal.

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The molecules of the title compounds, C(16)H(15)NOS(2), (I), and C(16)H(13)Br(2)NOS(2), (II), are E,E-isomers and consist of an extensive conjugated system, which determines their molecular geometries. Compound (I) crystallizes in the monoclinic space group P2(1)/c. It has one thiophene ring disordered over two positions, with a minor component contribution of 0.

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A novel cobalt(II)-organic framework, [Co2(OH)(3,4-PBC)3]n (I), has been acquired by the reaction of CoO with an unsymmetrical pyridylbenzoate ligand, 3-pyrid-4-ylbenzoic acid (3,4-PBC). Single-crystal X-ray diffraction studies reveal that it is comprised of [CoII4(mu3-OH)2] clusters linked by the unsymmetrical ligand 3,4-PBC, forming a novel helical double-layered metal-organic architecture. A significant overall antiferromagnetic behavior has been observed for this compound.

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Article Synopsis
  • Researchers have successfully isolated and characterized salts of dications from two diarylamine compounds after oxidizing them with two electrons, revealing new structural data for these "bipolarons."
  • Techniques like ESR, NMR, and magnetometry indicate that these dications possess singlet ground states, implying a stable configuration.
  • X-ray crystallography and (1)H NMR data show bond lengths approaching a quinoidal pattern without fully achieving it, suggesting that structures thought to be quinoidal can vary significantly in their bond length characteristics.
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The E-4,4'-bis[di(p-anisyl)amino]stilbene cation is a class-III mixed-valence species with electronic coupling comparable to that in its biphenyl-bridged analogue, whereas its tolane-bridged analogue belongs to class II.

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A complex featuring two triarylamine redox centers bridged by Pt, trans-bis(triethylphosphine)-bis{4-[bis(4-methoxyphenyl)amino]phenylethynyl} platinum(II), has been synthesized as a model system for pi-conjugated Pt-containing polymers. Analysis of the intervalence charge-transfer band displayed by its mixed-valence monocation affords a quantitative assessment of electronic delocalization through the Pt bridge; this is found to be only slightly smaller than that determined for a benzene-bridged analogue. These results are supported by density functional theory calculations, which show that the active orbitals involved in the electron-transfer process in both cases have similar delocalization through the bridging unit.

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