Digital Commons Network^™

The Design And Characterization Of Gold Nanoclusters As Elementary Building Blocks, Heather Gaebler

Theses and Dissertations (Comprehensive)

Gold nanoclusters with diameters in the quantum size regime (< ~2 nm) are promising building blocks for the design of novel nanomaterials as they exhibit unique size-dependent properties that can be altered and fine-tuned. The research outlined in this PhD thesis employs density functional theory to construct and analyze small ligand-protected cage and rod-shaped nanoclusters. Chapter 2 reports stable halide-protected gold nanocages that were engineered to have a closed-shell valence electron count of 18. This study finds that nanocages comprised of 19 and 20 gold atoms can be converted into stable magic number species containing 18 valence electrons by modifying their charged states via adsorption of halide ligands to the cage’s surface. Chapter 3 reports stable ligand-protected gold nanoclusters with a tetrahedral Au₄ core that were engineered to have a closed-shell valence electron count of 2. This study investigates the structural and electronic effects of halide and alkoxy ligands on the tetrahedral nanocluster and concludes that the results support the broader conclusion that it’s possible to fine-tune the stability and electronic properties of small gold nanoclusters using appropriate ligands. Chapter 4 reports stable gold nanorods that have diameters in the quantum regime that were constructed from elementary building blocks that contain “halide-staples”. This study presents different orientations of the “halide-staple” motifs on …

Spectroscopic Study Of The Br−+Ch3i→I−+Ch3br Sn2 Reaction, Hayden T. Robinson, Timothy R. Corkish, Christian T. Haakansson, Peter D. Watson, Allan J. Mckinley, Duncan A. Wild

Research outputs 2022 to 2026

Mass spectrometry and anion photoelectron spectroscopy have been used to study the gas-phase S_N2 reaction involving Br^- and CH₃I. The anion photoelectron spectra associated with the reaction intermediates of this S_N2 reaction are presented. High-level CCSD(T) calculations have been utilised to investigate the reaction intermediates that may form as a result of the S_N2 reaction along various different reaction pathways, including back-side attack and front-side attack. In addition, simulated vertical detachment energies of each reaction intermediate have been calculated to rationalise the photoelectron spectra.

Solid Electrolytes And Interface Design For High-Performance All-Solid-State Batteries, Shumin Zhang

Electronic Thesis and Dissertation Repository

All-solid-state batteries (ASSBs), in which solid superionic conductors are used as electrolytes to transport ions between cathode and anode, have been regarded as one of the most promising candidates for the next-generation energy storage technologies in electric vehicles (EVs), grid applications, etc. The advances of ASSBs over conventional lithium-ion batteries (LIBs) come from their inherent safety and high energy density, which benefits from the use of nonflammable solid electrolytes (SEs) to potentially enable metal anodes (such as Li metal or Na metal) and high-voltage cathode active materials (CAM) in ASSBs. Since that, the research and design of SEs have been …

A Theoretical Study Of Synchronous Proton Transfer In (Hf)N, (H2O) N, And (Hcl) N Where N = 3, 4, 5, Johnny Yang

Honors Theses

For (HF)_n, (H₂O)_n, and (HCl)_n (n = 3 − 5), we have rigorously characterized the structures for the minima and transition states for synchronous proton transfer (SPT) with the CCSD(T) method and aug-cc-pVTZ basis set. The electronic barrier heights (∆E^†) associated with these transition states have also been computed with the explicitly correlated CCSD(T)-F12 method and the aug-cc-pVQZ-F12 basis set (abbreviated aQZ-F12). (HCl)_n (n = 3 − 5) SPT transition states have not been previously identified to the best of our knowledge, and they have been found …

The Atomic And Electronic Structure And Tunability Of Ruddlesden-Popper Phases For Photovoltaic Applications, Britt A. Tyler

WWU Graduate School Collection

There is an increasing need for alternative energy sources that reduce the global reliance on fossil fuels. Since their demonstration in 2009, perovskite solar cells (based on compounds with the formula ABX₃, such as CH₃NH₃PbI₃) have become an extremely promising and active research area. Still, there are obstacles to the widespread use of these technologies, including their instability and the environmental impacts of lead. It is therefore important to find ways to modify and tune the structure and properties of perovskites to optimize their stability and photovoltaic performance. This research explores a …

Microsolvation Of Anions By Molecules Forming Ch∙∙X- Hydrogen Bonds, Steve Scheiner, Binod Nepal

Chemistry and Biochemistry Faculty Publications

Various anions were surrounded by n molecules of CF₃H, which was used as a prototype CH donor solvent, and the structures and energies studied by M06-2X calculations with a 6-31+G∗∗ basis set. Anions considered included the halides F^-, Cl^-, Br^- and I^-, as well as those with multiple proton acceptor sites: CN^-, NO₃ ^-, HCOO^-, CH₃COO^-, HSO₄ ^-, H₂PO₄ ^-, and anions with higher charges SO₄ ^2-, HPO₄ ^2- and PO_{4 …}

Hydrothermal Routes To Technetium Cluster Compounds, William M. Kerlin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Transition metals of groups six through nine exhibit unique direct multiple metal-metal bonding cores. Technetium is a group seven transition metal and is the lightest radioelement in the periodic table. Technetium exhibits nine oxidation states (from -I to VII) and an extensive set of mixed oxidation states due to bi- or poly- nuclear complex formation. Technetium has no stable isotopes and thirty four technetium isotopes have been discovered. Two main isotopes are of great importance ⁹⁹Tc and its metastable nuclear isomer ^99mTc. The isotope ^99mTc (T_1/2 = 6.01 hours, γ = 140.5 keV) is used in …

Binary Technetium Halides, Erik Vaughan Johnstone

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, the synthetic and coordination chemistry as well as the physico-chemical properties of binary technetium (Tc) chlorides, bromides, and iodides were investigated. Resulting from these studies was the discovery of five new binary Tc halide phases: α/β-TcCl₃, α/β-TcCl₂, and TcI₃, and the reinvestigation of the chemistries of TcBr₃ and TcX₄ (X = Cl, Br). Prior to 2009, the chemistry of binary Tc halides was poorly studied and defined by only three compounds, i.e., TcF₆, TcF₅, and TcCl₄. Today, ten phases are known (i.e., TcF …

Concentration Effects And Ion Properties Controlling The Fractionation Of Halides During Aerosol Formation, Marcelo I. Guzman, Richa R. Athalye, Jose M. Rodriguez

Chemistry Faculty Publications

During the aerosolization process at the sea surface, halides are incorporated into aerosol droplets, where they may play an important role in tropospheric ozone chemistry. Although this process may significantly contribute to the formation of reactive gas phase molecular halogens, little is known about the environmental factors that control how halides selectively accumulate at the air-water interface. In this study, the production of sea spray aerosol is simulated using electrospray ionization (ESI) of 100 nM equimolar solutions of NaCl, NaBr, NaI, NaNO(2), NaNO(3), NaClO(4), and NaIO(4). The microdroplets generated are analyzed by mass spectrometry to study the comparative enrichment of …

Chemical Modification On Gold Slides To Gain Better Control Of Patterning Techniques, Ragini Vuppalapati

Masters Theses & Specialist Projects

Nanolithography is a rapidly evolving field that requires new combinations of techniques to improve patterning and to assist in fabricating electromechanical devices. An increasing number of applications require surfaces with defined regions of different chemical functionality. In our previous project optimum conditions for lithographic patterning were determined and potential blockers were identified to reduce force on the tip.

This work is focused on identifying good chemical modifications that will allow better control of basic patterning and to investigate the minimum force of patterning required while using each chemical system. The primary aim is to gain better control of basic pattern …

Probing The Mechanisms Of Enantioselective Hydrogenation Of Simple Olefins With Chiral Rhodium Catalysts In The Presence Of Anions, Jillian M. Buriak, Jason C. Klein, Deborah Herrington, John A. Osborn

Peer Reviewed Articles

The strong influence of various anions upon the hydrogenation of 2-phenyl-1-butene, catalyzed by chiral rhodium catalysts was investigated. Both sulfonates and halides exert large increases in the enantioselectivity when [Rh{(−)-bdpp}(NBD)]ClO4 (bdpp=2,4-bis(diphenylphosphino)pentane, NBD=2,5-norbornadiene) is used as the catalyst precursor at high pressures (70 atm) of dihydrogen in nonpolar solvents. A dihydride mechanism similar to that for Wilkinson's catalyst [RhCl(PPh3)3] was shown to be operating at both high- and low-pressure conditions through a combination of catalytic studies, 31P, 1H and parahydrogen-induced polarization (PHIP) NMR experiments. With sulfonate and in neat methanol, however, a mechanistic switch takes place from a dihydride route (dihydrogen …

Synthesis And Resolution Of Enantiomeric Quaternary Ammonium Halides, Wei Lee

University of the Pacific Theses and Dissertations

The purpose of the work described in this thesis was the synthesis of a new class of surfactants containing chiral cationic end groups and the synthesis of two chiral reactant molecules which would react in the presence of these surfactants. The structures of the surfactant and substrate molecules were designed to maximize their stereochemical interactions and in this way reveal details of the nature of micellar catalysis. In order to indicate why these structures were selected, several examples of micellar catalysis and the factors influencing it will be discussed in the following pages.

Voltammetric And Electrochemical Kinetic Studies Of The Halides And Halogens At A Platinum Rotating Ring-Disk Electrode In Anhydrous Acetic Acid, Donald Harrison Cranney

Theses and Dissertations

The electrochemical behavior of the iodine-iodide couple was investigated in both basic and neutral acetic acid solutions at a platinum rotating ring-disk electrode. Voltammetric curves were obtained and discussed. Various kinetic parameters were determined and by comparing to theoretical kinetic parameters a probable reaction mechanism was deduced. The mechanism that best fit experimental results is the following I- + S = I(S) + e- I(S) + I- = I2 + S + e (slow). The electrochemical behavior of bromine, bromide, and chloride was also investigated in the same media. Voltammetric curves were recorded and discussed with emphasis on the hysteresis …

Thermodynamics Of I) Metal Cyanide Coordination, Ii) Water Formation, And Iii) Metal Halide Coordination, John Dewey Hale

Theses and Dissertations

ΔH values for the formation of Ni(CN)4(aq)= have been determined calorimetrically at 25° using a simple calorimeter and a thermometric titration procedure at high and low ionic strengths, respectively. Extrapolation of these ΔH values to infinite dilution resulted in a ΔH° value of -42.7 kcal./mole. Combination of ΔH° and ΔF° values gives a ΔS° value of -5.5 e.u. for Ni(CN)4(aq)= formation. A value of +70 e.u. is calculated for the ionic entropy of Ni(CN)4(aq)=. A preliminary investigation of the Zn(CN)4(aq)= system indicated the existence of zinc cyanide complexes other than Zn(CN)4= and allowed calculation of an approximate ΔH° value of …