A5065920626- Radioactive contamination and transfer
- Radioactive element chemistry and processing
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Radioactivity and Radon Measurements
- Nuclear Physics and Applications
- Organic Light-Emitting Diodes Research
- Nuclear reactor physics and engineering
- Ionic liquids properties and applications
- Nuclear Materials and Properties
- Organic Electronics and Photovoltaics
- Molecular Junctions and Nanostructures
- Organometallic Complex Synthesis and Catalysis
- Synthesis and Properties of Aromatic Compounds
- Conducting polymers and applications
- Radiopharmaceutical Chemistry and Applications
- Luminescence and Fluorescent Materials
- Electrochemical Analysis and Applications
- Nuclear and radioactivity studies
- Chemical Synthesis and Characterization
- Coordination Chemistry and Organometallics
- Molten salt chemistry and electrochemical processes
- Molecular spectroscopy and chirality
- Lichen and fungal ecology
- Crystallography and molecular interactions
Los Alamos National Laboratory
2010-2023
University of Cincinnati
2003
University of Rochester
1998-2001
University of Washington
1996-2000
University of California, Santa Barbara
1998-2000
National Iranian Oil Company (Iran)
1947
A novel topological strategy is described for designing amorphous molecular solids suitable optoelectronic applications. In this approach, chromophores are attached to a tetrahdral point of convergence. Stilbenoid units were covalently linked tetraphenylmethane, tetraphenyladamantane, or tetraphenylsilane cores using palladium catalyzed coupling methodology. Thus, reaction E(C6H5X)4 (E = C and adamantane, X I; E Si, Br) with styrene 4,4'-tert-butylvinylstilbene under Heck conditions yields...
A series of paracyclophane derivatives that hold chromophores varying conjugation lengths has been synthesized using palladium-mediated coupling reactions. These molecules mimic solid-state interactions in main-chain polychromophores and conjugated emissive polymers such as poly(p-phenylenevinylene) (PPV). Their optical properties give insight into the energetics photoexcitations localized a discrete chromophore relative to state containing through-space delocalized core. Thus,...
Protonation of TpM(PR3)H2 (M = Rh, Ir) complexes with HBF4·Et2O or [H(Et2O)2][B(Ar)4] (Ar 3,5-(CF3)2C6H3) affords cationic which exhibit a single hydride resonance at all accessible temperatures in the 1H NMR spectrum. Formulation as fluxional dihydrogen/hydride is indicated by short T1(min) values ca. 22 ms (Ir) and 7 (Rh). The relaxation times are consistent H−H bond lengths 0.88−1.11 Å iridium 0.73−0.92 rhodium depending on relative rate dihydrogen rotational motion. In case complexes,...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSynthesis, Spectroscopy, and Morphology of TetrastilbenoidmethanesWarren J. Oldham, Jr.†, Rene Lachicotte, Guillermo C. Bazan*View Author Information Department Chemistry, University Rochester Rochester, New York 14627 † Current address: FED Corporation, Hopewell Junction, NY 12533. In papers with more than one author, the asterisk indicates name author to whom inquiries about paper should be addressed.Cite this: Am. Chem. Soc. 1998, 120, 12,...
Treatment of UO2Cl2(thf)3 in THF with two equivalents 1,3-dimesitylimidazole-2-ylidene (IMes) or 1,3-dimesityl-4,5-dichloroimidazole-2-ylidene (IMesCl2) yields novel monomeric uranyl N-heterocyclic carbene complexes, representing the first examples actinyl carbon bonds.
This paper describes an approach to measuring extinct fission products that would allow for the characterization of a nuclear test at any time. The isotopic composition molybdenum in five samples glassy debris from 1945 Trinity has been measured. Nonnatural compositions were observed, reflecting input decay short-lived (95)Zr and (97)Zr. By both perturbation (95)Mo/(96)Mo (97)Mo/(96)Mo ratios total amount samples, it is possible calculate original concentrations (97)Zr isotopes formed...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and Properties of [TpIr(PMe3)(H2)H]BF4: observation Novel Isotopic PerturbationD. M. Heinekey Warren J. Oldham Jr.Cite this: Am. Chem. Soc. 1994, 116, 7, 3137–3138Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https://pubs.acs.org/doi/10.1021/ja00086a059https://doi.org/10.1021/ja00086a059research-articleACS PublicationsRequest reuse permissionsArticle...
Room temperature ionic liquids composed of bis(trifluoromethylsulfonyl)imide anions and 1,3-ethylmethylimidazolium (EMI) cations are shown to stabilize monomeric ligand deficient transition metal complexes via four distinct binding modes: monodentate nitrogen or oxygen coordination and/or bidentate oxygen-oxygen' nitrogen-oxygen (eta1-N, eta1-O, eta2-O,O' eta2-N,O).
Two pseudo-para substituted bis-diimino[2.2]paracyclophane ligands (4,16-bis(picolinaldimine)-[2.2]paracyclophane (BPPc) and 4,16-bis(methyl-picolinaldimine)-[2.2]paracyclophane (BmPPc)) were prepared by the condensation reaction of appropriate picolinaldimine with 4,16-diamino-[2.2]paracyclophane (2). An improved synthesis 2 from [2.2]paracyclophane also is reported. BPPc (3a): monoclinic, P2(1)/c, a = 8.2238(11) A, b 15.336(2) c 8.4532(11) beta 98.578(3) degrees, V 1054.2(2) A(3), Z 2. To...
As part of a nuclear forensics capability, rapid and effective methods to analyze for plutonium other actinide metals are needed. A key requirement these is that they afford high chemical yield while still providing isotopic information necessary forensic evaluation. Toward this objective, new method binding analysis by alpha spectrometry has been developed. Thin films Kläui-type tripodal oxygen donor ligands were prepared spin-casting solutions onto glass substrates. Three different...
Solutions of TpM(C2H4)2 (M = Rh (1a) and Ir (1b)) react with 1 equiv PPh3 to yield TpM(PPh3)(C2H4) (2a,b). The new complexes adopt trigonal-bipyramidal structures in solution triphenylphosphine coordinated the axial site ethylene positioned equatorial plane. For 2a pyrazolyl arms Tp ligand exchange positions on NMR time scale (ΔG⧧ 14.3 kcal mol-1, 279 K); however, no is observed case 2b, even at 353 K > 18.4 mol-1). Complexes 2a,b molecular hydrogen TpM(PPh3)H2 (3a,b) free ethylene. Kinetic...
New measurement and assessment techniques have been applied to the radiochemical reevaluation of Trinity Event. Thirteen trinitite samples were dissolved analyzed using a combination traditional decay counting methods mass spectrometry techniques. The resulting data assessed advanced simulation tools afford final yield determination 24.8 ± 2 kt TNT equivalent, substantially higher than previous U.S. Department Energy released value 21 kt.
S. F. Birch, W. J. Oldham and E. A. Johnson, Chem. Soc., 1947, 818 DOI: 10.1039/JR9470000818
In nuclear forensic analyses, measurements of actinide elements in a sample can assist with identifying interdicted or unknown materials. While these radiochemical signatures have been extensively investigated uranium materials, less is known about bulk neptunium samples. This paper describes the measurement trace concentrations and isotopic profiles 237Np oxide sample. Uranium, plutonium, americium, curium were determined deemed potentially useful for distinguishing different sources 237Np....
Abstract The N‐heterocyclic carbene, 1,3‐dimesityl‐imidazol‐2‐ylidene (IMes) reacts with tetrahydrofuran (THF) in the presence of an oxidizing uranyl triflate complex, UO 2 (OTf) (thf) 3 ( − OTf = OSO CF ), to give 1,4‐bis(1,3‐dimesityl‐2‐imidazolium)‐1,3‐butadiene bis(trifluoromethanesulfonate), formally understood as coupling product two equivalents IMes [CHCHCHCH](OTf) . Copyright © 2005 John Wiley & Sons, Ltd.
On July 16, 1945, the Trinity nuclear test exploded in desert near Alamogordo, New Mexico. A variety of new diagnostic experiments were fielded an effort to understand detailed performance device. This paper describes a series radiochemical that designed measure efficiency and neutron fluence test. These experiments, scientists who led them, laid foundation weapons radiochemistry for decades come.
Nanosecond electroluminescence (EL) overshoots observed when multilayer blue 4,4′-bis(2,2′-diphenyl vinyl)-1,1′-biphenyl (DPVBi)-based organic light-emitting devices (OLEDs) are excited by rectangular voltage pulses described. The occur at the turn-off and exceed cw brightness up to an order of magnitude. Time-resolved images OLEDs demonstrate that emission from most sample surface decays with a single time constant τ1=13±3 ns. This decay is attributed recombination charges which accumulate...
Methylene chloride solutions of the tris(1-pyrazolyl)borate (Tp) complexes TpIr(PPh3)(C2H4) or TpIr(C2H4)2 react with excess PPh3 via activation a pyrazole C−H bond to form equilibrium mixtures TpIr(PPh3)(C2H4), (N,C5,N-Tp-H)Ir(PPh3)2H (1), and free ethylene upon standing at room temperature. Complete conversion 1 was accomplished by removing displaced ethylene. The hydride complex purified protonation unbound nitrogen ring afford cationic 2 as BF4 salt. Deprotonation affords in good yield...