The work described in this dissertation focuses on the optical characterization of micron-sized structures with mesoscale (100-1000 nm) features to investigate of the optical analog to the quantum corral. Lithographically patterned arrays of metallic rings and ellipses were used to study how light can be manipulated and confined within these...
This thesis attempts a combined theoretical/experimental investigation of two fundamental scaling laws in charge transfer reactions: how the rate of those reactions varies as a function of distance between an electron donor and an electron acceptor and how the rate varies as a function of the number of distinct pathways...
This thesis investigates singlet exciton fission, a physical process that converts one singlet exciton to a pair of triplet excitons. Singlet fission was discovered nearly forty years ago, but the mechanism for this process is still not well understood. Recent work has suggested that singlet fission may be capable of...
Metallic nanostructures are able to confine and manipulate electromagnetic fields because light can couple to free electron oscillations called surface plasmons (SPs). These plasmons exist on metal surfaces as localized (short-range) or as propagating (long-range) modes depending upon the size and geometry of the nanostructure. This dichotomy is primarily an...
This thesis summarizes our research efforts on the application of the nano-structured anodic aluminum oxide (AAO) membrane in heterogeneous catalysis. Procedures for growing the AAO membrane in the center of an aluminum disc have been developed by appropriately masking the disk's perimeter during the anodization and etching steps. The remaining...
Chemical vapor deposition (CVD) is a well-developed technique for growing thin films of a wide variety of materials, which relies on the development of new and better performing metal-organic precursors. To this end, three studies have been conducted into the compatibility of sulfur and phosphine containing ligands with low- and...
Conjugated organic molecules and polymers hold significant promise for use as active materials in electronic devices. Employing such "soft" materials can decrease cost of device fabrication, while enabling unique properties such as mechanical flexibility, large-area coverage, and highly tunable materials properties. A primary roadblock to the realization of this dream...
Metal nanoprisms are a novel class of anisotropic nanomaterials with unique optical properties dependent on their size, shape, and composition. Silver nanoprisms are of particular interest because their surface plasmon resonance bands are readily tunable in the visible and near-IR region. The objectives of this thesis research focus on photochemical...
Chapter 1 describes the homopolymerization of styrene and the copolymerization of ethylene and styrenic comonomers mediated by the single-site bimetallic "constrained geometry catalysts" (CGCs), (µ-CH2CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](TiMe2)}2 [EBICGC(TiMe2)2; Ti2], (µ-CH2CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](ZrMe2)}2 [EBICGC(ZrMe2)2; Zr2], (µ-CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](TiMe2)}2 [MBICGC(TiMe2)2; C1-Ti2], and (µ-CH2-3,3'){(η5-indenyl)[1-Me2Si(tBuN)](ZrMe2)}2 [MBICGC(ZrMe2)2; C1-Zr2], in combination with the borate activator/cocatalyst Ph3C+B(C6F5)4- (B1). Under identical styrene homopolymerization conditions,...
N-Heterocyclic carbene catalysis has recently emerged as an important field in organic chemistry. Two new strategies have been developed to advance the use of N-heterocyclic carbenes (NHCs) as Lewis-base organic catalysts. The first approach utilizes NHCs to catalyze the generation of homoenolates and the conjugated Breslow intermediate is added to...
Magnetic resonance imaging (MRI) is a technique widely used in both clinical and experimental settings to produce high-resolution images of opaque living organisms without utilizing ionizing radiation. Currently, MR imaging is augmented by contrast agents; however, these small molecule Gd(III) chelates are confined to extracellular and vascular regions of the...
The electronic properties of various transparent conducting oxide (TCO) surfaces are probed electrochemically via self-assembled monolayers (SAMs). A novel graftable probe molecule having a tethered trichlorosilyl group and a redox-active ferrocenyl functionality (Fc(CH2)4SiCl3) is synthesized for this purpose. On as-received ITO, saturation coverage by a close-packed monolayer having of 6.6...
Organic light emitting diodes (OLEDs) are fabricated and characterized on anodes modified by a variety of surface treatments. OLED performance response is correlated to the treatment conditions with current-voltage (I-V) measurements and impedance spectroscopy. Small-scale OLED arrays are fabricated using a novel shadow mask approach and are characterized with electrical...
The work of this dissertation was aimed at synthesizing new types of nanoparticle-DNA conjugates, investigating their chemical and physical properties, and exploring their biodiagnostic applications. Chapters Two and Three describe the synthesis of new types of nanoparticle-DNA conjugates: (1) silver nanoparticle-DNA conjugates (DNA-Ag NPs) and (2) 2-nm gold nanoparticle-DNA conjugates...
Copper serves as a cofactor for many proteins and enzymes involved in important biological processes, but at the same time, excessive copper is toxic to cell. Thus, the intracellular copper concentration must be tightly controlled such that copper is provided to essential enzymes but does not accumulate to toxic levels....
The early transition metal oxide fluoride molecular anions with the general formula [MOxF6-x]n- with x = 1 for M = V5+, Nb5+, Ta5+ (n = 2) and x = 2 for M = Mo6+, W6+ (n = 2) feature distorted octahedral coordinations, that arise from electronic dπ pπ metal oxide...
The work presented here describes investigations into the interaction of resonant molecules with metallic nanoparticles by localized surface plasmon resonance (LSPR) spectroscopy. The contents of this thesis include the study of the coupling mechanism between molecular resonance and plasmon resonance from experimental and theoretical perspectives and applications of this mechanism...
Particulate methane monooxygenase (pMMO) is a membrane-bound metalloenzyme that oxidizes methane to methanol in methanotrophic bacteria. The nature of the pMMO active site and the overall metal content are controversial, with spectroscopic and crystallographic data suggesting the presence of a mononuclear copper center, a dinuclear copper center, a trinuclear center,...
Nanoscale materials are demonstrating new properties and promising applications with each passing day. The fabrication of ever more complex and precise nanomaterials represents a continuing drive in the fields of physics, chemistry, and biology. Template-based approaches provide an attractive method of producing new inaccessible materials by modifying and confining older...
My thesis focuses on the design and synthesis of lanthanide coordination complexes as Zn(II)-responsive magnetic resonance imaging (MRI) contrast agents. These agents produce an increase in MR intensity upon binding of Zn(II) through water modulation to Gd(III) chelates. To this end, several Zn(II)-responsive contrast agents have been synthesized and studied...
The need for readily synthesized scaffold architectures to build monodisperse, high molar mass mobility modifiers or "drag-tags" in end-labeled free solution electrophoresis (ELFSE) led to the development of a novel class of multivalent molecular tools. Poly-N-substituted glycines (peptoids) were created with evenly spaced amino groups as branching points along the...
The biological antagonism between copper and molybdenum, first observed when cattle developed copper deficiencies after ingesting high levels of plant-born molybdenum, is currently being used in humans to treat two conditions: Wilson's Disease as well as several forms of metastatic cancer. There is surprisingly little known about the interaction of...
The promise of a clean, renewable, and abundant energy supply make the efficient conversion of solar energy to electricity a compelling scientific and societal goal. In the following chapters, I will describe my efforts to advance one class of photovoltaic technology, dye-sensitized solar cells, by demonstration and characterization of unexplored...
Magnetic resonance imaging (MRI) is an advanced imaging modality that is experiencing increasing popularity in clinical and experimental settings. MRI enjoys the benefit of high-resolution, the use of non-ionizing radiation, and the ability to distinguish between soft tissues. MR imaging is enhanced with the use of Gd3+ chelated contrast agents;...
Au nanoprisms are a new type of inorganic nanoparticle that is particularly interesting because these particles can be made in high yield, are composed of a metal with well known surface chemistry, exhibit strong, architecture and environment-sensitive optical features, and have well-defined crystallographic facets. All of these features make Au...
The safe and efficient storage of hydrogen is possibly the chief obstacle to its use as a fuel on a large scale. Metal-organic frameworks (MOFs) are well poised to provide unique solutions to hydrogen storage, and gas storage in general, a result of their crystalline, porous networks that present the...
The new binuclear organo-zirconium and -titanium metal complexes {2,7-di-[(2,6diisopropylphenyl)imino]-1,8-naphthalenediolato group 4 metal complexes {1,8-(O)2C10H4-2,7[CH=N(2,6-iPr2C6H3)]2}Zr2Cl6(THF)2 (FI2-Zr2) and {1,8-(O)2C10H4-2,7-[CH=N(2,6-
i 2 t
Pr2C6H3)]2}Ti2Cl6(THF)2 (FI -Ti2) are compared to the mononuclear analogues {3- Bu-2(O)C6H3CH=N(2,6-iPr2C6H3)}ZrCl3(THF) (FI-Zr1) and {3-tBu-2-(O)C6H3CH=N(2,6-
i
Pr2C6H3)}TiCl3(THF) (FI-Ti1), respectively, in ethylene polymerization and ethylene + olefin copolymerization processes. The comonomers studied...
The utilization of hydrofluoric acid for the preparation of silver vanadium oxide fluorides has been advanced for the synthesis of Ag<sub>4</sub>V<sub>2</sub>O<sub>6</sub>F<sub>2</sub> and Ag<sub>3</sub>VO<sub>2</sub>F<sub>4</sub>. Silver-rich metal oxide fluorides are important battery cathode materials due to the high reduction potential of silver vs. Li, which is made even higher by the incorporation...
This work is a research effort aimed at understanding the mechanisms of single-molecule surface-enhanced Raman spectroscopy (SMSERS). In the decade since its discovery in 1997, the role of resonance Raman (RR) enhancement, the origin of blinking, and the properties of the hot spot formed at the junction of two nanoparticles...
π-Conjugated oligomeric and polymeric semiconductors have been the focus of intense research over the past few decades as alternatives to inorganic semiconductors for low-cost electronic applications such as organic field-effect transistors (OFETs). These materials enable vapor- or solution-phase fabrication of large-area, light-weight electronic devices, and are compatible with plastic substrates...
This thesis focuses on the design of hybrid organic materials comprising polymers and small molecules for biodiagnostic and electronic applications. Specifically, the electrochemical and fluorescent signaling properties of terthiophene-functionalized polymers are combined with the enhanced recognition properties of DNA hybrid materials, culminating in the development of a "loaded" probe for...
The overarching goal of this work is to understand nanometer scale junctions and electron transport through molecules in these junctions. Calculations detailing quantum interference in the electron transport through molecules, and the control of these features, show great potential for use as discrete electronic elements. Concurrent work on the fabrication...
Polyvalent oligonucleotide functionalized gold nanoparticle conjugates (DNA-AuNPs) possess unusual properties, which derive from their particle and oligonucleotide subunits as well as their three-dimensional architectures. This dissertation explores the role each chemical component plays in the conjugate's architecture and assembly and recognition capabilities. It also describes their application as probes in...
In this work several self-assembling PA systems containing covalent-linking functionalities have been investigated. These covalently linkable PAs were designed to probe the supramolecular structure by covalent capture of the nanofibers and also improve the mechanical stiffness of the gel-material. The diacetylene motif was the main functional group investigated because of...
Magnetic Resonance Imaging is a non-invasive modality that allows for deep-tissue imaging. Contrast agents decrease image acquisition time and increase the intrinsic contrast between different types of tissue. A new family of enzyme-activated contrast agents is emerging that has the ability to report on enzymatic processes in vivo. Towards this...
<span style="font-family: Calibri;">BaNa-Y is a catalyst for reduction of nitrogen oxides (NO and NO<sub>2</sub>) with added reductants at temperatures of ~200 °C. Studies were performed over BaNa-Y and related catalysts to unravel the roles that nitrates and nitrites play in determining the processes and pathways involved in NOx reduction. <o:p></o:p></span></p>...
The work described in this dissertation focuses on the development of a general approach to create nanoscale transition metal chalcogenide materials and new methods for controlling architecture of gold pyramidal structures. In the former, we used chemical nanofabrication, a combination of top-down patterning and bottom-up solid-state synthesis, to achieve control...
This thesis discusses the synthesis, self-assembly, and conductivity properties of novel oligothiophene derivatives with an emphasis on how molecular structure effects the assembly. In order to facilitate self-assembly in conjugated molecules, specific non-covenant forces were included into the molecular design of several derivatives. First, an amphiphilic oligothiophene derivative consisting of...
The focus of this thesis is the design of non-natural molecules for use in biological applications. Chapter one details a strategy to use small molecules to reactivate mutated p53, an oncoprotein that is prevalent in several types of cancer, back to its wild-type function. Wild-type p53 has the ability to...
Many metal ions are of critical importance in many cellular functions. The very properties of these metal ions that make them useful also make them toxic to the cell. In the course of evolution, many metal ion homeostasis systems have developed to provide balance between the necessity and toxicity of...
The nonlinear optical technique, second harmonic generation (SHG), is applied here for the first time to probe single and double strand DNA (ssDNA and dsDNA) chemically attached to fused quartz/water interfaces. DNA interfaces are often a critical functional component of biodetection, thus, the development of molecular biosensors requires a thorough...
The tools of computational chemistry allow researchers to gain insight into chemical systems that would be difficult or impossible to gain experimentally. This dissertation discusses the application of several of these computational tools to chemical systems of interest. First, we present several studies of plasmon resonance in Ag nanoclusters using...
Plasmonic chemistry is an emerging field of research that contains great promise for new chemical reactivity, but thus far has been improperly observed. The goals of using plasmonic chemistry typically revolve around the use of nonequilibrium charge carriers that migrate to the surface of a plasmonic substrate to perform redox...
Quantum information processing (QIP) is an emerging computational paradigm with the potential to enable a vast increase in computational power, fundamentally transforming fields from structural biology to finance. QIP employs qubits, or quantum bits, as its fundamental units of information, which can exist in not just the classical states of...
Bulk heterojunction (BHJ) organic photovoltaic (OPV) devices have been extensively studied to achieve power conversion efficiencies well above 10%. New research into alternative materials that allow for cheaper and more industrially viable fabrication of flexible solar cells has been at the forefront of the energy field for the past few...
Three-dimensional (3D) and two-dimensional (2D) hybrid halide perovskites have emerged as front-runners in solar energy conversion applications with the potential to provide low-cost renewable energy. Being at the interface of chemistry, physics, materials science, and electrical engineering, the field of perovskite solar cells has become a top area of interest...
This dissertation describes the fundamental studies of photoinduced charge-carrier transfer from colloidal metal chalcogenide quantum dots (QDs) to surface-adsorbed molecular redox partners. In addition, we also present the use of visible-light absorbing QDs in photocatalytic applications. CdS QDs are used as photocatalysts in a C-C coupling reaction, in which no...
The development of organic photovoltaic devices benefits from understanding the fundamental processes underlying charge generation in thin films of organic semiconductors. This dissertation exploits model systems of π-stacked chromophores such as perylene-3,4:9,10-bis(dicarboximide) (PDI) and 3,6-bis(aryl)diketopyrrolopyrrole (DPP) to study these processes using ultrafast electronic and vibrational spectroscopy. In particular, the characterization...
The work presented in this dissertation examines the interplay between electron transfer reactions and electron spin in photoactive organic molecules. Organic compounds that undergo electron transfer reactions after absorbing light are important in natural photosynthesis, photobiology, and synthetic photovoltaics. These electron transfer reactions depend on the spin states of the...
Chemical probes are versatile and unique tools for biomedical research. A chemical probe is simply a selective small-molecule modulator of protein function that allows the user to ask mechanistic and phenotypic questions about its molecular target in biochemical, cell-based or animal studies. Experiments involving selective inhibitors can help delineate key...