26 results on '"Stacey J. Smith"'
Search Results
2. Structural investigations of the Bi2–xSbxTe3–ySey topological insulator
- Author
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Husain F. Alnaser, Stacey J. Smith, and Taylor D. Sparks
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Inorganic Chemistry ,Materials Chemistry ,Ceramics and Composites ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2023
3. Selective N Functionalization of Methane and Ethane to Aminated Derivatives by Main-Group-Directed C–H Activation
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Niles Jensen Gunsalus, Daniel H. Ess, Roy A. Periana, Anjaneyulu Koppaka, Brian G. Hashiguchi, Stacey J. Smith, and Sae Hume Park
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Alkane ,chemistry.chemical_classification ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Molecular systems ,010402 general chemistry ,01 natural sciences ,Methane ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Group (periodic table) ,Surface modification ,Organic chemistry ,Physical and Theoretical Chemistry ,Amination - Abstract
To our knowledge, there is no precedent for the direct conversion of light alkanes to aminated products by CH activation. Previous molecular systems reported for alkane amination operate by radical...
- Published
- 2019
4. Heat capacities and thermodynamic functions of the ZIF organic linkers imidazole, 2-methylimidazole, and 2-ethylimidazole
- Author
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Peter F. Rosen, Brian F. Woodfield, Stacey J. Smith, and Jason J. Calvin
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Phase transition ,Chemistry ,Thermodynamics ,02 engineering and technology ,2-Methylimidazole ,010402 general chemistry ,01 natural sciences ,Heat capacity ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Metal ,symbols.namesake ,chemistry.chemical_compound ,020401 chemical engineering ,visual_art ,visual_art.visual_art_medium ,symbols ,Imidazole ,General Materials Science ,Metal-organic framework ,0204 chemical engineering ,Physical and Theoretical Chemistry ,Debye ,Zeolitic imidazolate framework - Abstract
Metal organic frameworks (MOFs) are a novel class of materials that consist of a lattice of metal centers linked by organic molecules. Previously, heat capacities and thermodynamic functions have been reported for a series of crystalline polymorphs of Zn(EtIm)2, a zeolitic imidazolate framework family of MOFs that have potential applications in CO2 sequestration. In those studies, an anomalous trend in the heat capacity and thermodynamic functions was observed that was not predicted. To further investigate these materials and their thermodynamic data, the low-temperature heat capacities of imidazole, 2-methylimidazole, and 2-ethylimidazole, organic linkers that are present in Zn(EtIm)2 and similar materials, were measured by a Quantum Design Physical Property Measurement System (PPMS) from 1.8–300 K. The data collected was fit to theoretical functions below 10 K, orthogonal polynomials from 5–60 K, and a sum of Debye and Einstein functions above 50 K. These functions were used to generate Cp,m°, Δ0TSm°, Δ0THm°, and Φm° values at smoothed temperatures from 0–300 K. This investigation revealed the presence of a second-order phase transition in 2-ethylimidazole that may yield insight into the anomalous heat capacity behavior present in Zn(EtIm)2.
- Published
- 2019
5. Novel chiral aryltetraline lactone core and furo[3,4-c]pyranone structure for the synthesis of bioactive lignans and furopyranones
- Author
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Peter Mpaata, Dickson Bonsrah, Alexander Camp, Chandler Miller, Karson Ballard, Zach Johnson, Liahona Angelie, Stacey J. Smith, and Merritt B. Andrus
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Inorganic Chemistry ,Structural Biology ,General Materials Science ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Biochemistry - Published
- 2022
6. Terahertz generation of two methoxy stilbazolium crystals: MBST and MBSC
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Sin-Hang Ho, Erika W. Jackson, Claire Rader, Karissa C. Kenney, Stacey J. Smith, Isaac C. Tangen, David J. Michaelis, Zacharias Zaccardi, Gabriel A. Valdivia-Berroeta, Jeremy A. Johnson, and Charles B. Bahr
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Materials science ,Terahertz radiation ,Crystal growth ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,Inorganic Chemistry ,Optical rectification ,law ,Electric field ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Absorption (electromagnetic radiation) ,Spectroscopy ,business.industry ,Organic Chemistry ,021001 nanoscience & nanotechnology ,Laser ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Wavelength ,Sapphire ,Optoelectronics ,0210 nano-technology ,business - Abstract
Optical rectification of nonlinear optical organic crystals has been widely employed to obtain terahertz (THz) frequencies with simple laser setups. Red organic crystals like DAST, DSTMS, and OH1 have generated intense THz pulses with peak electric fields up to a few megavolts per cm. Other newer organic crystals such as HMQ-TMS and EHPSI-4NBS have shown similar performance.Recently, the yellow organic crystals BNA and HMI-TMS have drawn attention due to improved phase matching conditions compared with red crystals in the technologically important 800 nm wavelength. This light is usually obtained with widely available Ti:Sapphire lasers and therefore, the development of materials that can efficiently generate THz with these sources is of high scientific interest. In this article, we introduce the THz generation capabilities of two yellow crystals, namely, MBST and MBSC. Electric fields of similar magnitude compared to the organic generator HMQ-TMS were obtained when MBST and MBSC crystals were pumped with 800-nm light. The THz absorption profile and crystal growth are also discussed to introduce new insights in how to improve the THz output of MBST and MBSC.
- Published
- 2021
7. La-Dopant Location in La-Doped γ-Al2O3 Nanoparticles Synthesized Using a Novel One-Pot Process
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Juliana Boerio-Goates, Branton J. Campbell, Calvin H. Bartholomew, Stacey J. Smith, Baiyu Huang, and Brian F. Woodfield
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Materials science ,Dopant ,Extended X-ray absorption fine structure ,Catalyst support ,Doping ,Nanoparticle ,chemistry.chemical_element ,Nanotechnology ,Oxygen ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,General Energy ,Chemical engineering ,chemistry ,law ,Lanthanum ,Calcination ,Physical and Theoretical Chemistry - Abstract
We have recently developed a “solvent-deficient” method of synthesizing high surface area γ-Al2O3 nanoparticles that show promise for catalyst support applications. Here, we investigate doping the alumina with La3+ to stabilize the γ phase to higher temperatures. The one-pot method for synthesizing La-doped γ-Al2O3 nanoparticles developed here has several advantages over conventional methods including requiring only 3 h instead of 3 days and wasting no lanthanum. TEM, X-ray PDF, and BET analyses as a function of calcination temperature show that the La stabilizes the γ phase by 100 °C. In order to begin understanding the mechanism of stabilization, the location of the La3+ atoms in our doped γ-Al2O3 nanoparticles is investigated via X-ray PDF and EXAFS analyses which indicate that the La dopant adsorbs as single, isolated atoms on the γ-Al2O3 surface. As calcination temperature increases, the immediate oxygen coordination shell of the La becomes increasingly like La2O3 though an extended La2O3 lattice is ...
- Published
- 2015
8. Heat capacity and thermodynamic functions of nano-TiO2 anatase in relation to bulk-TiO2 anatase
- Author
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Thomas Parry, Brian F. Woodfield, Stacey J. Smith, Guangshi Li, Liping Li, Trent F. Walker, Jacob Schliesser, and Juliana Boerio-Goates
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Anatase ,Chemistry ,Phase (matter) ,Anhydrous ,Thermodynamics ,General Materials Science ,Calorimetry ,Physical and Theoretical Chemistry ,Atmospheric temperature range ,Material properties ,Heat capacity ,Atomic and Molecular Physics, and Optics ,Degree (temperature) - Abstract
Several conflicting reports have suggested that heat capacities and the thermodynamic properties of materials change as their particle size decreases into the nanoscale. To further investigate this, we have measured the constant pressure heat capacities of three 7 nm TiO2 anatase samples containing varying amounts of surface-adsorbed water using a combination of adiabatic and semi-adiabatic calorimetric methods. These samples have a high degree of chemical, phase, and size purity determined by rigorous characterization. Molar heat capacities were measured from T = (0.5 to 320) K, and data were fit to a sum of theoretical functions in the low temperature (T T > 75 K), and a combination of Debye and Einstein functions in the high temperature range (T > 35 K). These fits were used to generate C p ,m ° , Δ 0 T S m ° , Δ 0 T H m ° , and φ m ° values at smoothed temperatures between (0.5 and 300) K for all hydrated samples. Standard molar entropies at T = 298.15 K were calculated to be 73.868, 66.072, and 63.845 J · K−1 · mol−1 all with a standard uncertainty of 0.002· Δ 0 T S m ° for samples TiO2 · 0.677H2O, TiO2 · 0.532H2O, and TiO2 · 0.379H2O, respectively. These and other thermodynamic values were then corrected for water content to yield bare nano-TiO2 thermodynamic properties at T = 298.15 K, and we show that the resultant thermodynamic properties of anhydrous TiO2 anatase nanoparticles equal those of bulk TiO2 anatase within experimental uncertainty. Thus we show quantitatively that the difference in thermodynamic properties between bulk and nano-TiO2 must be attributed to surface adsorbed water.
- Published
- 2015
9. Heat capacity and thermodynamic functions of nano-TiO2 rutile in relation to bulk-TiO2 rutile
- Author
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Jacob Schliesser, Brian F. Woodfield, Juliana Boerio-Goates, Guangshi Li, Trent F. Walker, Stacey J. Smith, Thomas Parry, and Liping Li
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Chemistry ,Rutile ,Yield (chemistry) ,Phase (matter) ,Thermodynamics ,General Materials Science ,Calorimetry ,Physical and Theoretical Chemistry ,Atmospheric temperature range ,Adiabatic process ,Material properties ,Heat capacity ,Atomic and Molecular Physics, and Optics - Abstract
Several conflicting reports have suggested that the thermodynamic properties of materials change with respect to particle size. To investigate this, we have measured the constant pressure heat capacities of three 7 nm TiO2 rutile samples containing varying amounts of surface-adsorbed water using a combination of adiabatic and semi-adiabatic calorimetric methods. These samples have a high degree of chemical, phase, and size purity determined by rigorous characterization. Molar heat capacities were measured from T = (0.5 to 320) K, and data were fitted to a sum of theoretical functions in the low temperature (T T/K > 75), and a combination of Debye and Einstein functions in the high temperature range (T > 35 K). These fits were used to generate Cp , m ∘ , Δ 0 T S m ∘ , Δ 0 T H m ∘ , and φ m ∘ values at selected temperatures between (0.5 and 300) K for all samples. Standard molar entropies at T = 298.15 K were calculated to be (62.066, 59.422, and 58.035) J · K−1 · mol−1 all with a standard uncertainty of 0.002· Δ 0 T S m ∘ for samples TiO2·0.361H2O, TiO2·0.296H2O, and TiO2·0.244H2O, respectively. These and other thermodynamic values were then corrected for water content to yield bare nano-TiO2 thermodynamic properties at T = 298.15 K, and we show that the resultant thermodynamic properties of anhydrous TiO2 rutile nanoparticles equal those of bulk TiO2 rutile within experimental uncertainty. Thus we show quantitatively that the difference in thermodynamic properties between bulk and nano-TiO2 must be attributed to surface adsorbed water.
- Published
- 2015
10. A Broadly Applicable Strategy for Entry into Homogeneous Nickel(0) Catalysts from Air-Stable Nickel(II) Complexes
- Author
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Peter Müller, Timothy F. Jamison, Eric A. Standley, and Stacey J. Smith
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Denticity ,010405 organic chemistry ,Chemistry ,Ligand ,Aryl ,Organic Chemistry ,chemistry.chemical_element ,Nanotechnology ,010402 general chemistry ,01 natural sciences ,Article ,0104 chemical sciences ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,Nickel ,Glovebox ,Polymer chemistry ,Reactivity (chemistry) ,Physical and Theoretical Chemistry ,Phosphine - Abstract
A series of air-stable nickel complexes of the form L2Ni(aryl) X (L = monodentate phosphine, X = Cl, Br) and LNi(aryl)X (L = bis-phosphine) have been synthesized and are presented as a library of precatalysts suitable for a wide variety of nickel-catalyzed transformations. These complexes are easily synthesized from low-cost NiCl2·6H2O or NiBr2·3H2O and the desired ligand followed by addition of 1 equiv of Grignard reagent. A selection of these complexes were characterized by single-crystal X-ray diffraction, and an analysis of their structural features is provided. A case study of their use as precatalysts for the nickel-catalyzed carbonyl-ene reaction is presented, showing superior reactivity in comparison to reactions using Ni(cod)2. Furthermore, as the precatalysts are all stable to air, no glovebox or inert-atmosphere techniques are required to make use of these complexes for nickel-catalyzed reactions.
- Published
- 2014
11. Misbehaving twins: how messy is too messy
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Stacey J. Smith and Gabriel Valdivia
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Inorganic Chemistry ,Structural Biology ,General Materials Science ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Biochemistry - Published
- 2019
12. Designing molecular terahertz generation crystals: optimal packing could be just one carbon away
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Erika W. Jackson, Jeremy A. Johnson, Adam X. Wayment, Karissa C. Kenney, Gabriel A. Valdivia-Berroeta, Isaac C. Tangen, Stacey J. Smith, Charles B. Bahr, and David J. Michaelis
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Materials science ,Terahertz radiation ,business.industry ,chemistry.chemical_element ,Condensed Matter Physics ,Biochemistry ,Inorganic Chemistry ,chemistry ,Structural Biology ,Optoelectronics ,General Materials Science ,Physical and Theoretical Chemistry ,business ,Carbon - Published
- 2019
13. B(C6F5)3 Activation of Oxo Tungsten Complexes That Are Relevant to Olefin Metathesis
- Author
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Peter Müller, Stacey J. Smith, Dmitry V. Peryshkov, William P. Forrest, and Richard R. Schrock
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Inorganic Chemistry ,Steric effects ,chemistry.chemical_compound ,Ethylene ,Olefin metathesis ,Chemistry ,Ligand ,Stereochemistry ,Organic Chemistry ,chemistry.chemical_element ,Physical and Theoretical Chemistry ,Tungsten ,Single isomer - Abstract
We have found that coordination of B(C6F5)3 to an oxo ligand in tungsten oxo alkylidene bis(aryloxide) complexes, where the aryloxide is O-2,6-(mesityl)2C6H3 (HMTO) or 2,6-diadamantyl-4-methylphenoxide (dAdPO), accelerates the formation of metallacyclobutane complexes from alkylidenes as well as the rearrangement of metallacyclobutane complexes. In contrast, a tungstacyclopentane complex, W(O)(C4H8)(OHMT)2, is relatively stable toward rearrangement in the presence of B(C6F5)3. A careful balance of steric factors allows a single isomer of W(O)(trans-4,4-dimethylpent-2-ene)(dAdPO)2 to be formed from W(O)(CH-t-Bu)(dAdPO)2 in the presence of both ethylene and B(C6F5)3.
- Published
- 2013
14. Z-Selective Ring-Opening Metathesis Polymerization of 3-Substituted Cyclooctenes by Monoaryloxide Pyrrolide Imido Alkylidene (MAP) Catalysts of Molybdenum and Tungsten
- Author
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Jihua Zhang, Daniel J. Kozera, Hyangsoo Jeong, Ning Ren, Marc A. Hillmyer, Richard R. Schrock, and Stacey J. Smith
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chemistry.chemical_classification ,Steric effects ,Chemistry ,Stereochemistry ,Organic Chemistry ,chemistry.chemical_element ,ROMP ,Polymer ,Metathesis ,Medicinal chemistry ,Catalysis ,Inorganic Chemistry ,Polymerization ,Molybdenum ,Ring-opening metathesis polymerisation ,Physical and Theoretical Chemistry - Abstract
Ring-opening metathesis polymerization of a series of 3-substituted cyclooctenes (3-MeCOE, 3-HexCOE, and 3-PhCOE) initiated by various Mo and W MAP complexes leads to cis,HT-poly(3-RCOE) polymers. The apparent rate of polymerization of 3-HexCOE by W(N-t-Bu)(CH-t-Bu)(Pyr)(OHMT) (1c; Pyr = pyrrolide; OHMT = O-2,6-Mesityl2C6H3) is greater than the rate of polymerization by Mo(N-t-Bu)(CH-t-Bu)(Pyr)(OHMT) (1b), but both gave the same cis,HT polymer structures. Formation of HT-poly(3-RCOE) employing 1c takes place via propagating species in which the R group (methyl, hexyl, or phenyl) is on C2 of the propagating alkylidene chain, a type of intermediate that has been modeled through the preparation of W(N-t-Bu)(CHCHMeEt)(Pyr)(OHMT). The rate of ROMP is exceedingly sensitive to steric factors: e.g., W(N-t-Bu)(CH-t-Bu)(Me2Pyr)(OHMT), the dimethylpyrrolide analogue of 1c, essentially did not polymerize 3-HexCOE at 22 °C. When a sample of W(N-t-Bu)(CHCHMeEt)(Pyr)(OHMT) and 3-methyl-1-pentene in CDCl3 is cooled to −2...
- Published
- 2013
15. High Oxidation State Molybdenum Imido Heteroatom-Substituted Alkylidene Complexes
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Amir H. Hoveyda, Peter Müller, Richard R. Schrock, Stefan M. Kilyanek, Erik M. Townsend, and Stacey J. Smith
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Steric effects ,Organic Chemistry ,Heteroatom ,chemistry.chemical_element ,Photochemistry ,Medicinal chemistry ,Catalysis ,Adduct ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Molybdenum ,Oxidation state ,Salt metathesis reaction ,Physical and Theoretical Chemistry ,Acetonitrile - Abstract
Reactions between Mo(NAr)(CHR)(Me2Pyr)-(OTPP) (Ar = 2,6-i-Pr2C6H3, R = H or CHCMe2Ph, Me2Pyr = 2,5-dimethylpyrrolide, OTPP = O-2,3,5,6-Ph4C6H) and CH2=CHX where X = B(pin), SiMe3, N-carbazolyl, N-pyrrolidinonyl, PPh2, OPr, or SPh lead to Mo(NAr)(CHX)-(Me2Pyr)(OTPP) complexes in good yield. All have been characterized through X-ray studies (as an acetonitrile adduct in the case of X = PPh2). The efficiencies of metathesis reactions initiated by Mo(NAr)(CHX)(Me2Pyr)(OTPP) complexes can be rationalized on the basis of steric factors; electronic differences imposed as a consequence of X being bound to the alkylidene carbon do not seem to play a major role. Side reactions that promote catalyst decomposition do not appear to be a serious limitation for Mo=CHX species.
- Published
- 2013
16. Synthesis and ROMP Chemistry of Decafluoroterphenoxide Molybdenum Imido Alkylidene and Ethylene Complexes
- Author
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Richard R. Schrock, Peter Müller, Jian Yuan, Stacey J. Smith, and Laura C. H. Gerber
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chemistry.chemical_classification ,Ethylene ,Organic Chemistry ,chemistry.chemical_element ,Polymer ,ROMP ,Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Polymerization ,Molybdenum ,Tacticity ,Polymer chemistry ,Physical and Theoretical Chemistry ,Norbornene - Abstract
The bisDFTO alkylidene complexes of molybdenum Mo(NR)(CHCMe2Ph)(DFTO)2 (R = 2,6-i-Pr2C6H3, 2,6-Me2C6H3, C6F5, 1-adamantyl; DFTO = 2,6-(C6F5)2C6H3O) and monoaryloxide monopyrrolide (MAP) complexes Mo(NR)(CHCMe2Ph)(Me2Pyr)(OAr) (Me2Pyr = 2,5-dimethylpyrrolide; R = C6F5, OAr = DFTO, 2,6-dimesitylphenoxide (HMTO); R = 2,6-Me2C6H3, OAr = DFTO) have been prepared in good yields. Addition of dicarbomethoxynorbornadiene (DCMNBD) to bisDFTO complexes yielded polymers that have a cis,isotactic structure. Polymerization of DCMNBD by Mo(NC6F5)(CHCMe2Ph)(Me2Pyr)(HMTO) gives a polymer that contains the expected cis,syndiotactic structure, but polymerization of DCMNBD by Mo(NR)(CHCMe2Ph)(Me2Pyr)(DFTO) (R = C6F5, 2,6-Me2C6H3) generates a polymer that has a cis,isotactic structure, the first observation of a cis,isotactic polymer prepared employing a MAP initiator. Norbornene is polymerized to give what is proposed to be highly tactic cis-polyNBE. Addition of ethylene to Mo(NC6F5)(CHCMe2Ph)(DFTO)2 leads to formation of Mo...
- Published
- 2013
17. Heat capacity and thermodynamics of a synthetic two-line ferrihydrite, FeOOH·0.027H2O
- Author
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Quan Shi, Kristina Lilova, A.V. Radha, Juliana Boerio-Goates, Claine L. Snow, Stacey J. Smith, Brian F. Woodfield, and Alexandra Navrotsky
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Standard molar entropy ,Iron oxide ,Thermodynamics ,Environmental pollution ,Calorimetry ,Heat capacity ,Atomic and Molecular Physics, and Optics ,Standard enthalpy of formation ,Gibbs free energy ,chemistry.chemical_compound ,symbols.namesake ,Ferrihydrite ,chemistry ,symbols ,General Materials Science ,Physical and Theoretical Chemistry - Abstract
Ferrihydrite is a fine-grained and variable, in terms of structure and water content, iron oxyhydroxide found in many geologic environments, in living organisms, and in environmental pollution. The thermodynamic study of ferrihydrite is important for understanding geochemical transformations involving iron as well as in the study of iron in chemical synthesis and biological systems. In this study, the heat capacity of a synthetic two-line ferrihydrite, which showed typically broad X-ray diffraction peaks due to small particle size and/or disorder but had a rather low excess water content, FeOOH·0.027H2O, was measured over the temperature range of (2 to 300) K. Using these data, the standard molar entropy, S m o , of this two-line ferrihydrite was calculated to be (71.7 ± 0.2) J · K−1 · mol−1, while that of the stoichiometric (no excess water) material, FeOOH was estimated to be (69.8 ± 0.2) J · K−1 · mol−1. These measured entropies are in moderate agreement with, though slightly higher, than those estimated much more indirectly by Majzlan et al. (2004) [15] The heat capacity data below T = 12 K were fit to theoretical models to study the underlying contributions to the heat capacity. The fit required an anisotropic ferrimagnetic spin wave component, which agrees with studies that characterize two-line ferrihydrite as a ferrimagnet. The fit also required a linear term, which most likely stems from defects in the ferrihydrite particles. Using enthalpy of formation from the elements −(542.3 ± 0.8 kJ · mol−1 for FeOOH·0.027H2O or −(534.6 ± 1.0) kJ · mol−1 for FeOOH obtained from acid solution calorimetry of the same sample, the standard Gibbs energy of formation from the elements for this ferrihydrite sample was calculated to be −(473.0 ± 1.0) kJ · mol−1 for FeOOH·0.027H2O and −(465.3 ± 1.0) kJ · mol−1 for FeOOH.
- Published
- 2013
18. Characterization of Surface Defect Sites on Bulk and Nanophase Anatase and Rutile TiO2 by Low-Temperature Specific Heat
- Author
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Guangshe Li, Stacey J. Smith, Juliana Boerio-Goates, Brian F. Woodfield, Alexandra Navrotsky, B. E. Lang, and Shengfeng Liu
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Anatase ,General Energy ,Materials science ,Excess heat ,Chemical engineering ,Specific heat ,Rutile ,Inorganic chemistry ,Nanoparticle ,Physical and Theoretical Chemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Characterization (materials science) - Abstract
The specific heats of highly hydrated 7 nm nanoparticles and lightly hydrated 200 nm particles of rutile and anatase show a small, broad maximum below 5 K. The excess heat capacity can be modeled w...
- Published
- 2013
19. Heat capacity studies of the iron oxyhydroxides akaganéite (β-FeOOH) and lepidocrocite (γ-FeOOH)
- Author
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Claine L. Snow, Brian F. Woodfield, Alexandra Navrotsky, Stacey J. Smith, Quan Shi, Juliana Boerio-Goates, and B. E. Lang
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Goethite ,Standard molar entropy ,Akaganéite ,Chemistry ,Inorganic chemistry ,engineering.material ,Atmospheric temperature range ,Heat capacity ,Atomic and Molecular Physics, and Optics ,Adsorption ,visual_art ,engineering ,visual_art.visual_art_medium ,Antiferromagnetism ,Physical chemistry ,General Materials Science ,Physical and Theoretical Chemistry ,Lepidocrocite - Abstract
The iron oxides and iron oxyhydroxides exist as several different polymorphs, and a thermodynamic understanding of these polymorphs can provide us with an understanding of their relative stability and chemical reactivity. This study provides heat capacity measurements for lepidocrocite (γ-FeOOH) over the temperature range (0.8 to 38) K and akaganeite (β-FeOOH) over the range (0.7 to 302) K. Fits of the heat capacity of the two samples below T = 15 K showed similar behavior to previously published fits of goethite (α-FeOOH), which required a linear term and an anisotropic gap parameter to model accurately the antiferromagnetic spin–wave contributions. The akaganeite measurements were compared to previously reported measurements all of which showed significant disagreement. It is believed that the measurements reported here are the most reliable. Also, the presence of adsorbed water contributes significantly to the heat capacity of akaganeite, and the standard molar entropy at T = 298.15 K of the hydrated form was calculated to be (81.8 ± 2) J · mol−1 · K−1.
- Published
- 2011
20. The missing link: first successful structural analysis of 2-ethylimidazole, a ZIF linker
- Author
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Brian F. Woodfield, Jason J. Calvin, and Stacey J. Smith
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Inorganic Chemistry ,Structural Biology ,Chemistry ,General Materials Science ,Link (geometry) ,2-ethylimidazole ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Biochemistry ,Linker ,Combinatorial chemistry - Published
- 2018
21. Heat capacities and thermodynamic functions of hexagonal ice from T=0.5K to T=38K
- Author
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Stacey J. Smith, Juliana Boerio-Goates, Brian F. Woodfield, B. E. Lang, and Shengfeng Liu
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Hexagonal crystal system ,Chemistry ,Enthalpy ,Thermodynamics ,General Materials Science ,Physical and Theoretical Chemistry ,Heat capacity ,Atomic and Molecular Physics, and Optics - Abstract
The heat capacity of water in the form of hexagonal ice was measured between T = 0.5 K and T = 38 K using a semi-adiabatic calorimetric method. Since heat capacity data below T = 2 K have never been measured for water, this study presents the lowest measured values of the specific heat of water to date. Fits of the data were used to generate thermodynamic functions of water at smoothed temperatures between 0.5 K and 38 K. Both our experimental heat capacities and calculated enthalpy increments agree well with previously published values and thus supplement other studies well.
- Published
- 2007
22. Allylic aminations with hindered secondary amine nucleophiles catalyzed by heterobimetallic Pd-Ti complexes
- Author
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Ryjul W. Stokes, Whitney K. Walker, David J. Michaelis, Diana L. Anderson, and Stacey J. Smith
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Steric effects ,Allylic rearrangement ,Organic Chemistry ,Biochemistry ,Combinatorial chemistry ,Pyrrolidine ,Catalysis ,chemistry.chemical_compound ,chemistry ,Nucleophile ,Intramolecular force ,Amine gas treating ,Piperidine ,Physical and Theoretical Chemistry - Abstract
Phosphinoamide-scaffolded heterobimetallic palladium–titanium complexes are highly effective catalysts for allylic aminations of allylic chlorides with hindered secondary amine nucleophiles. Three titanium-containing ligands are shown to assemble active catalysts in situ and enable catalysis at room temperature. A variety of sterically bulky secondary amines are efficiently allylated in high yields with as little as 1 mol % palladium catalyst. Piperidine and pyrrolidine products are also efficiently generated via intramolecular aminations with hindered amine nucleophiles.
- Published
- 2015
23. Investigating the local structure and phase evolution of mesoporous gamma alumina using pair distribution function (PDF) analysis
- Author
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Stacey J. Smith, Ying Zhang, Brian F. Woodfield, and Daniel H. Ess
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Inorganic Chemistry ,Materials science ,Structural Biology ,Chemical physics ,Pair distribution function ,General Materials Science ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Mesoporous material ,Biochemistry ,Phase evolution ,Local structure - Published
- 2017
24. Synthesis of Tungsten Imido Alkylidene Complexes that Contain an Electron-Withdrawing Imido Ligand
- Author
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Peter Müller, Stacey J. Smith, Jonathan C. Axtell, Richard R. Schrock, and Amir H. Hoveyda
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010405 organic chemistry ,Ligand ,Organic Chemistry ,chemistry.chemical_element ,Tungsten ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Article ,0104 chemical sciences ,3. Good health ,Inorganic Chemistry ,chemistry ,Polymerization ,Polar effect ,Organic chemistry ,Physical and Theoretical Chemistry ,Other Chemical Sciences - Abstract
Tungsten NArR alkylidene complexes have been prepared that contain the electron-withdrawing ArR groups 2,4,6-X3C6H2 (ArX3, X = Cl, Br), 2,6-Cl2-4-CF3C6H2 (ArCl2CF3), and 3,5-(CF3)2C6H3 (Ar(CF3)2). Reported complexes include W(NArR)2Cl2(dme) (dme = 1,2-dimethoxyethane), W(NArR)2(CH2CMe3)2, W(NArR)(CHCMe3)(OTf)2(dme), and W(NArR)(CHCMe3)(ODBMP)2 (DBMP = 4-Me-2,6-(CHPh2)C6H2). The W(NArR)(CHCMe3)(ODBMP)2 complexes were explored as initiators for the polymerization of 2,3-dicarbomethoxynorbornadiene (DCMNBD).
- Published
- 2014
25. Phase progression of γ-Al2O3 nanoparticles synthesized in a solvent-deficient environment
- Author
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Juliana Boerio-Goates, Samrat A. Amin, Branton J. Campbell, Stacey J. Smith, and Brian F. Woodfield
- Subjects
Diffraction ,Boehmite ,Chemistry ,Analytical chemistry ,Nanoparticle ,law.invention ,Catalysis ,Inorganic Chemistry ,Thermogravimetry ,Solvent ,Chemical engineering ,law ,Phase (matter) ,Calcination ,Physical and Theoretical Chemistry - Abstract
Our simple and uniquely cost-effective solvent-deficient synthetic method produces 3-5 nm Al2O3 nanoparticles which show promise as improved industrial catalyst-supports. While catalytic applications are sensitive to the details of the atomic structure, a diffraction analysis of alumina nanoparticles is challenging because of extreme size/microstrain-related peak broadening and the similarity of the diffraction patterns of various transitional Al2O3 phases. Here, we employ a combination of X-ray pair-distribution function (PDF) and Rietveld methods, together with solid-state NMR and thermogravimetry/differential thermal analysis-mass spectrometry (TG/DTA-MS), to characterize the alumina phase-progression in our nanoparticles as a function of calcination temperature between 300 and 1200 °C. In the solvent-deficient synthetic environment, a boehmite precursor phase forms which transitions to γ-Al2O3 at an extraordinarily low temperature (below 300 °C), but this γ-Al2O3 is initially riddled with boehmite-like stacking-fault defects that steadily disappear during calcination in the range from 300 to 950 °C. The healing of these defects accounts for many of the most interesting and widely reported properties of the γ-phase.
- Published
- 2013
26. Novel synthesis and structural analysis of ferrihydrite
- Author
-
Juliana Boerio-Goates, Brian F. Woodfield, Katharine Page, Branton J. Campbell, Stacey J. Smith, and Hyunjeong Kim
- Subjects
Inorganic Chemistry ,chemistry.chemical_classification ,Ferrihydrite ,Adsorption ,chemistry ,Agglomerate ,X-ray crystallography ,Inorganic chemistry ,Salt (chemistry) ,Particle size ,Crystallite ,Physical and Theoretical Chemistry ,Mesoporous material - Abstract
Naturally occurring ferrihydrite is both impure and difficult to isolate, so the numerous applications and interesting properties of ferrihydrite have spurred the development of various synthetic techniques. Nearly all techniques are based on the hydrolysis of an iron salt and require careful control of temperature, pH, and concentration. In this Article, we report a new synthetic method which does not require such control and is perhaps the fastest and simplest route to synthesizing ferrhydrite. XRD, TEM, BET, and chemical purity characterizations show that the chemically pure, 2-line ferrihydrite product consists of crystallites 2-6 nm in diameter which aggregate to form mesoporous, high surface area agglomerates that are attractive candidates for the many adsorption applications of ferrihydrite. X-ray PDF data were also collected for the ferrihydrite product and refined against the hexagonal structural model recently proposed by Michel et al. These analyses suggest that ferrihydrite has a consistent, repeatable structure independent of variation in the synthetic method, water content of the sample, or particle size of the crystallites, and this structure can be adequately described by the proposed hexagonal model.
- Published
- 2012
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