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Experimental Evidence for Heavy-Atom Tunneling in the Ring-Opening of Cyclopropylcarbinyl Radical from Intramolecular 12C/13C Kinetic Isotope Effects

Description: Article on experimental evidence for heavy-atom tunneling in the ring-opening of cyclopropylcarbinyl radical from intramolecular 12C/13C kinetic isotope effects.
Date: August 19, 2010
Creator: Gonzalez-James, Ollie M.; Zhang, Xue; Datta, Ayan; Hrovat, David A.; Singleton, Daniel A. & Borden, Weston T.
Partner: UNT College of Arts and Sciences

Periodic and Molecular Modeling Study of Donor - Acceptor Interactions in (dbbpy)Pt(tdt) • TENF and [Pt(dbbpy)(tdt)]₂ • TENF

Description: This article discusses a periodic and molecular modeling study. Supramolecular stacked materials (dbbpy)Pt(tdt)•TENF and [Pt(dbbpy)(tdt)]₂•TENF are built from (dbbpy)Pt(tdt) donors (D) with TENF acceptors (A) (TENF = 2,4,5,7-tetranitro-9-fluorenone; dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine; tdt = 3,4-toluenedithiolate).
Date: January 15, 2010
Creator: Cundari, Thomas R., 1964-; Chilukuri, Bhaskar; Hudson, Joshua M.; Minot, Christian; Omary, Mohammad A. & Rabaâ, Hassan
Partner: UNT College of Arts and Sciences

Calculations of the Relative Energies of the 2B1g and 2A2u States of Cyclobutanetetraone Radical Cation and Radical Anion Provide Further Evidence of a 3B2u Ground State for the Neutral Molecule: A Proposed Experimental Test of the Prediction of a Triplet Ground State for (CO)4

Description: Article on a proposed experimental test of the prediction of a triplet ground state for (CO)4.
Date: 2010
Creator: Zhou, Xin; Hrovat, David A. & Borden, Weston T.
Partner: UNT College of Arts and Sciences

Cyclooctatetraenes Tetrakis-Annelated with α-Dithio- or α-Diselenocarbonyl Groups: Diradicals Predicted To Have Ground States with 10 π Electrons in the Eight-Membered Ring and Two-Center, Three-Electron, σ Bonds between Two Pairs of Chalcogen Atoms

Description: Article on cyclooctatetraenes tetrakis-annelated with α-dithio- or α-diselenocarbonyl groups.
Date: February 12, 2010
Creator: Zhou, Xin; Hrovat, David A. & Borden, Weston T.
Partner: UNT College of Arts and Sciences

University of North Texas Research Strategic Plan: 2011-2020

Description: Ten-year strategic plan for the University of North Texas (UNT) research funding and programs spanning 2011-2020. It breaks down the plan into eight chapters: I. Vision Statement, II. Plan to Increase Research and External Funding, III. Plan to Improve Undergraduate Education, IV. Plan for Doctoral Programs, V. Plan for Faculty and Student Development, VI., Other Resources, VII. National Visibility, VIII. UNT as One of the Nation's Great Universities.
Date: 2010
Creator: University of North Texas
Partner: UNT Libraries Special Collections

University of North Texas Requests for Legislative Appropriations For Fiscal Years 2012 and 2013

Description: Report submitted by the University of North Texas to the Texas 81st regular legislature requesting appropriations to fund university programming and activities. It includes an overview of the university's goals, summaries of appropriations requests for fiscal years 2012 and 2013, and supporting documentation.
Date: October 18, 2010
Creator: University of North Texas
Partner: UNT Libraries Special Collections

University of North Texas Requests for Legislative Appropriations For Fiscal Years 2012 and 2013

Description: Report submitted by the University of North Texas to the Texas 81st regular legislature requesting appropriations to fund university programming and activities. It includes an overview of the university's goals, summaries of appropriations requests for fiscal years 2012 and 2013, and supporting documentation.
Date: October 18, 2010
Creator: University of North Texas
Partner: UNT Libraries Special Collections

Computational Study of Small Molecule Activation via Low-Coordinate Late First-Row Transition Metal Complexes

Description: Methane and dinitrogen are abundant precursors to numerous valuable chemicals such as methanol and ammonia, respectively. However, given the robustness of these substrates, catalytically circumventing the high temperatures and pressures required for such transformations has been a challenging task for chemists. In this work, computational studies of various transition metal catalysts for methane C-H activation and N2 activation have been carried out. For methane C-H activation, catalysts of the form LnM=E are studied, where Ln is the supporting ligand (dihydrophosphinoethane or β-diketiminate), E the activating ligand (O, NCH3, NCF3) at which C-H activation takes place, and M the late transition metal (Fe,Co,Ni,Cu). A hydrogen atom abstraction (HAA) / radical rebound (RR) mechanism is assumed for methane functionalization (CH4 à CH3EH). Since the best energetics are found for (β-diket)Ni=O and (β-diket)Cu=O catalysts, with or without CF3 substituents around the supporting ligand periphery, complete methane-to-methanol cycles were studied for such systems, for which N2O was used as oxygen atom transfer (OAT) reagent. Both monometallic and bimetallic OAT pathways are addressed. Monometallic Fe-N2 complexes of various supporting ligands (LnFe-N2) are studied at the beginning of the N2 activation chapter, where the effect of ligand on N2 activation in end-on vs. side-on N2 isomers is discussed. For (β-diket)Fe-N2 complexes, the additional influence of diketiminate donor atom (N(H) vs. S) is briefly addressed. The remainder of the chapter expands upon the treatment of β-diketiminate complexes. First, the activation and relative stabilities of side-bound and end-bound N2 isomers in monometallic ((β-diket)M-N2) and bimetallic ((β-diket)M-N2-M(β-diket)) first row transition metal complexes are addressed. Second, the thermodynamics of H/H+/H- addition to (β-diket)Fe-bound N2, followed by subsequent H additions up to release of ammonia, is discussed, for which two mechanisms (distal and alternating) are considered. Finally, the chapter concludes with partial distal and alternating mechanisms for H addition to N2 ...
Date: May 2010
Creator: Pierpont, Aaron
Partner: UNT Libraries

Sensitization of Lanthanides and Organic-Based Phosphorescence via Energy Transfer and Heavy-Atom Effects

Description: The major topics discussed are the phosphorescence sensitization in the lanthanides via energy transfer and in the organics by heavy atom effects. The f-f transitions in lanthanides are parity forbidden and have weak molar extinction coefficients. Upon complexation with the ligand, ttrpy (4'-p-Tolyl-[2,2':6',2"]-terpyridine) the absorption takes place through the ligand and the excitation is transferred to the lanthanides, which in turn emit. This process is known as "sensitized luminescence." Bright red emission from europium and bright green emission from terbium complexes were observed. There is ongoing work on the making of OLEDs with neutral complexes of lanthanide hexafluoroacetyl acetonate/ttrpy, studied in this dissertation. Attempts to observe analogous energy transfer from the inorganic donor complexes of Au(I) thiocyanates were unsuccessful due to poor overlap of the emissions of these systems with the absorptions of Eu(III) and Tb(III). Photophysics of silver-aromatic complexes deals with the enhancement of phosphorescence in the aromatics. The heavy atom effect of the silver is responsible for this enhancement in phosphorescence. Aromatics such as naphthalene, perylene, anthracene and pyrene were involved in this study. Stern Volmer plots were studied by performing the quenching studies. The quenchers employed were both heavy metals such as silver and thallium and lighter metal like potassium. Dynamic quenching as the predominant phenomenon was noticed.
Date: May 2010
Creator: Arvapally, Ravi K.
Partner: UNT Libraries