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...
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 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...
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...
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...
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,...
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...
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...
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 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...
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 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...
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...
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...
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,...
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...
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...
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...
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...
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 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...
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...
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...
The contents of this dissertation are divided into two sections: (1) the preparation and characterization of quaternary rare-earth chalcogenides and oxychalcogenides and (2) the localized surface plasmon resonance (LSPR) spectroscopy of metallic nanoparticles fabricated by nanosphere lithography (NSL).
Single crystals of CsTmCoS3, CsYbCoS3, CsHoCoSe3, CsYbCoSe3, and CsYbZnSe3 have been prepared...
Theoretical analysis of DNA bridge-mediated electron transfer (ET) led to the proposal that photoinduced ET might occur via either superexchange or hopping mechanisms. Electron transfer has been proposed to occur via a superexchange mechanism at short distances and via a hopping mechanism at longer distances. However, a crossover in mechanism...
This dissertation describes the use of alkanethiols and polymers for the development of lithographic affinity and resist array templates that can be utilized for directing the assembly of biological molecules, for building up multilayered polyelectrolyte thin films, and for fabricating metal solid-state nanostructures. The first two chapters of the work...
The work presented in this thesis describes investigations into linear and nonlinear optical properties of two-dimensional silver nanoparticle arrays. The linear optical measurements - extinction measurements were performed on two-dimensional square arrays of L-shaped silver nanoparticles fabricated by electron beam lithography in order to study the effect of dipole coupling...
Two new methods have been developed employing silicon-containing molecules in novel organic transformations. The first strategy utilizes Lewis base-activation of triethoxysilylalkynes to deliver mild acetylide nucleophile equivalents. The second approach involves the use of enolate additions to acylsilanes to generate β-silyloxy homoenolate intermediates.
Lewis base-catalyzed activation of triethoxysilylalkynes promotes the...
This dissertation focuses on the utilization of two coordination chemistry-based synthetic approaches, which provide the ability to rapidly and quantitatively assemble sophisticated supramolecular cofacial porphyrin complexes. Significantly, by adopting a coordination chemistry-based approach, the porphyrin-porphyrin interactions can be regulated in situ via the addition or removal of chemical effector molecules....
The first section of this thesis focuses on applications of DNA-modified gold nanoparticles (AuNPs) while the second part addresses the fundamental properties that arise from conjugating DNA to inorganic AuNPs. Two types of applications are discussed. The first application utilizes the colorimetric properties of AuNPs to screen duplex and triplex...
Interfaces and surfaces are ubiquitous in the environment. Heterogeneous binding events and reactions control the transport and speciation of dissolved pollutants in groundwater. Many heterogeneous processes occur at mineral oxide/water interfaces, and can be controlled either by the mineral oxide, or organic molecules bound to the surface. The prevalent natural...
Preventing the build-up of indoor pollutants represents an emerging goal in environmental chemistry. Heterogeneous catalysis provides an attractive method of remediating indoor air pollution, but optimization through rational catalyst design requires a detailed understanding of the catalytic surface and surface-pollutant interactions. In this work, a chemical ionization mass spectrometry (CIMS)...
The overarching theme of this thesis is the development of non-natural oligomers for use in biological applications. Chapter I details the synthesis and studies of modified peptide nucleic acid (PNA) oligomers. PNA is a synthetic oligonucleotide mimic that binds to natural nucleic acids with extremely high affinity and specificity, making...
This dissertation describes the invention and development of a new nanolithographic method: On-Wire Lithography (OWL). OWL is a simple, reproducible, and high-throughput procedure for the synthesis and lithographic processing of metal nanowires (i.e. Au, Ag, Pt, Ni, and Cu) that allows researchers to control the morphology and feature size of...
Surfaces and interfaces, which are ubiquitous in the environment, control the mobility,speciation, and ultimate fate of groundwater species. The presented work provides insight into the interfacial behavior of three environmental pollutants: hexavalent chromium, oxytetracycline, and morantel. Model surfaces are employed for these studies, including (1-102) α-Al<sub>2</sub>O<sub>3</sub> and a carboxylic acid-terminated...
Okilactomycin and chrolactomycin are antitumor antibiotics isolated in 1987 and 2001, respectively. These tetracyclic natural products possess a unique 6-5 fused tetrahydropyrone-butyrolactone. The spirocenter is part of a highly functionalized cyclohexene ring, which together with the aforementioned 6-5 system compose the core of these molecules. A six carbon, 1,3-dialkyl-substituted carbon...
Metal oxide surfaces are generally recognized as active substrates for many catalytic reactions. Density Functional Theory (DFT) has been found as a useful computational tool to investigate the geometry, energy, electronic structure of reactive oxide surfaces and their interaction with small molecules and fragments. In this thesis, primary efforts have...
Small molecule organic materials based on perylene- and naphthalene- diimide are synthesized and characterized for use as semiconductor thin films in organic field-effect transistors. The orbital energetics of the materials are investigated via electrochemical, spectroscopic, and computational techniques. The thin film solids are characterized by x-ray diffraction techniques and surface...
Direct dynamics quasiclassical trajectory (QCT) calculations are performed to study the dynamics of model atom + polyatom reactions. In the first part of this thesis, we examine adiabatic dynamics of H/O reaction with simple alkanes, CD4 and C2H6. Overall good agreement with state-of-the-art experiments shows that the molecular motion is...
This dissertation covers the synthesis and study of peptide nucleic acids (PNAs), specifically, derivatives of PNA containing amine-bearing sidechains or cyclopentane portions. PNAs are non-natural nucleic acids that have far reaching potential in therapeutics and nucleic acid detection. Despite immense potential and widespread application, improving on the design and applications...
Alkenylsilanes of varying chain lengths are investigated as simultaneous chain transfer agents + comonomers in organotitanium-mediated olefin polymerization processes. Ethylene + alkenylsilane polymerizations were carried out with activated Me2Si(Me4C5)(NtBu)TiMe2 and (-CH2CH2-3,3'){(5-indenyl )[1-Me2Si(tBuN)]}2Ti2Me4 precatalysts. Alkenylsilane incorporation levels follow the trend C8H15SiH3 < C6H11SiH3 ≈ C4H7SiH3 < C3H5SiH3. Long-chain branching levels versus...
Nanoplasmonics is an emerging branch of photonics that studies the optical properties of noble metals. Nanostructured noble metal materials, which can strongly interact with light and support various plasmon modes, are exceptional candidates for nanophotonic devices. This work describes the latest advances in the fabrication of ordered silver nanoparticles or...
The work presented here describes investigations into the optical properties of single silver nanoparticles. The contents of this thesis are divided into two parts: (1) single nanoparticle localized surface plasmon resonance (LSPR) spectroscopy and sensing and (2) approaches to combining LSPR spectroscopy with atomic force and transmission electron microscopies. Part...
The work presented in this dissertation is centered on experimental efforts to maximize the sensitivity of surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) toward their application in ultrasensitive nanoscale chemical analysis. The work focuses on fundamental studies of the plasmonic properties of silver nanostructures, and how those properties...
Theoretical studies on electronic structure governing charge transport properties are investigated to understand and improve the prediction of electron charge carrier organic semiconductors used in field-effect transistors. Perfluorinated oligothiophene semiconductors have shown experimental n-type behavior, but placement of fluorinated aryl groups changes charge polarities. Models were developed to investigate how...
This thesis consists of the synthesis and photophysical characterization of chlorophyll- and porphyrin- based multichromophore arrays designed for the purpose of studying energy and charge transfer therein. The first series of arrays consists of donor-acceptor dyads in which various arylene diimide electron acceptors are attached through a phenyl group to...
Part 1. The complex folded structures associated with RNA allow for specific protein-RNA interactions and also create binding sites for small molecules. Developing organic molecules that can bind RNA with high affinity and specificity is a challenge that must be overcome for RNA to be considered a viable drug target....
The porphyrazines (pzs), a class of porphyrin derivatives, have shown potential as therapeutic and imaging agents due to a combination of their near-IR absorbance/fluorescence and their enhanced chemical flexibility. Cell viability/proliferation assays and fluorescence microscopy were carried out in both tumor and normal cells to characterize the biological activity of...
This dissertation describes the development and use of novel chemical affinity templates to direct the assembly and preserve the activity of biological molecules in surface- and solution-based biomolecular assays. The majority of work described herein focuses on advancing biological nanoarray technology to enable the study of fundamentally important biological processes...
UV Raman spectroscopy is a powerful tool to investigate hydrocarbons-zeolite systems, including the coke formation mechanism during MTH reactions, the sorbet-framework interactions and the quantitative analysis of catalytic reactions.
First, methanol, dimethyl ether and ethylene reactions were carried out on H-MFI with different Si/Al atomic ratios to study the coke...