Synthetic organic chemistry continues to be a driver in the discovery and development of new molecules for applications in biology, medicine, crop science, polymer science, and materials science. Central to the continued development of this field is the pursuit of new strategies and methods for the efficient construction of molecules...
Nonlinear optical (NLO) effects are used universally in modern day telecommunication and form the foundation of emergent photonic technologies. Twisted intramolecular charge transfer (TICT) chromophores, composed of a donor and acceptor fragment connected by a twisted bi-aryl bridge, combine large molecular NLO response with properties such as transparency in the...
Bimetallic polymerization catalysis represents a small, though active, area of research due largely to the interesting properties observed in the resulting product polymers, including higher molecular weight, increased comonomer incorporation, and enhanced tacticity. Current work is focused on furthering an understanding of the active catalytic species that give rise to...
The thermodynamics and kinetics of electron transfer reactions in catalysis, energy conversion and storage, and plasmon-driven chemistry depend strongly on nanoscale electrode surface structure. To elucidate the structure-function relationships that determine nanoscale electrochemical reactivity, it is necessary to observe electron transfer reactions one molecule at a time. Over the past...
Ultrafast, multi-dimensional coherent spectroscopy (MD-CS) has enabled scientists to probe fundamental aspects of chemical and photo-physical reactions on the nanosecond to femtosecond timescales. Using MD-CS, scientific contributions ranging from increased understanding of energy transfer in photosynthetic biological proteins to correlating the motion of electrons in semiconductors have been achieved. Concurrent...
The objective of this work has been the design of new lubricant additives to target friction in the boundary lubrication regime and the hydrodynamic lubrication regime. Modern automotive engines operate at higher temperatures and speeds than ever before, and therefore require new and more effective lubricant additives to meet higher...
Spherical nucleic acids (SNAs) are a class of structures composed of spherical nanoparticle cores that are densely functionalized with radially oriented, linear DNA. SNAs exhibit properties that are distinct from those of their linear counterparts. These constructs can readily enter cells, evade nuclease degradation, and bind complementary DNA targets with...
Self-assembled monolayers as tunable chemical platforms broadly enable the study of the interaction between biological species and synthetic surfaces. Unlike small molecule chemistry where the freely diffusible product can interact with biological targets as an inhibitor or probe, interfacial chemistry allows for the controlled and multi-valent presentation of ligands to...
Fused polycyclic scaffolds with three-dimensional complexity from an array of stereocenters compose the core structures of countless natural product families with a variety of desirable biological activity. The development of synthetic methods and strategies to afford rapid access to these structures is essential to expose a wealth of untapped biological...
Organic Photovoltaic (OPV) materials are of great interest as a low-cost material the purposes of achieving wide spread, solar energy adoption. However, a limiting factor in materials development is the ability to proactively determine the active layer thin film morphology that largely informs device performance. Thus, understanding how materials design...
Organic Photovoltaic (OPV) materials are of great interest as a low-cost material the purposes of achieving wide spread, solar energy adoption. However, a limiting factor in materials development is the ability to proactively determine the active layer thin film morphology that largely informs device performance. Thus, understanding how materials design...
The projected increase in the use of nanomaterials raises concerns about adverse impacts new technologies utilizing these materials may have on the environment. These concerns can be addressed from a chemical perspective by studying how emerging nanomaterials interact with biological systems. Fundamentally, the key interactions for nanomaterial uptake into a...
Noncentrosymmetry (NCS) is a requirement for many properties such as piezoelectricity, pyroelectricity, and nonlinear optical activity like second harmonic generation which are desirable for a variety of commercial applications. One method which has been employed to successfully synthesize NCS compounds utilizes acentric anionic groups, such as oxyfluoride metal complexes, as...
High-pressure and -temperature synthesis is a powerful tool for synthesizing new intermetallic compounds that cannot be formed using traditional solid-state syntheses. Such metastable compounds can exhibit unrivaled structural complexity, unique bonding, and unusual properties. In the simplest case, there are many binary systems in which no intermetallic compounds are known....
The diverse reactivity patterns, unique structural features imparted by the cumulated double bonds, and possibility of axial chirality have garnered allenes considerable attention in organic synthesis. Numerous methods have been described in the literature to afford optically active allenes starting from chiral starting materials, yet catalytic and asymmetric methods to...
The discovery and tailoring of new useful organic molecules for applications such as medicine and materials science is highly driven by meaningful developments in chemical methodology, and some of the most impactful advances have invoked catalysis to increase efficiency and specificity. N-heterocyclic carbenes (NHCs) have continuously occupied a prominent space...
The expanding use of nanomaterials in consumer products challenges scientists to understand the impact of these materials before their inevitable release into the environment. In the same way that the widespread use of DDT and asbestos has caused unforeseen negative impacts on both the environment and on human health, the...
Photovoltaic technology can help meet the exploding world energy demand in a sustainable and environmentally friendly way. Organic photovoltaics (OPVs) are especially attractive because they can be constructed with low-cost organic content and are amenable to high-throughput large-scale fabrication techniques. Synthetic modification of organic semiconductors has paved way for the...
My research interests, which span organic, inorganic, physical and biochemistry, have focused broadly on photo-, magneto- and redox-active molecules, especially those with potential applications in organic photovoltaics, spintronics and electronics. My research under the joint supervision of Professor Wasielewski and Professor Fraser Stoddart has concentrated upon understanding electronic and magnetic...
Starting materials for natural products, ideally synthesized using low-cost, highly active and selective catalysts, are of great interest to the pharmaceutical industry. Relevant reactions include the synthesis of 1,2-dihydropyridines, reduction of ketones/aldehydes, cleavage of esters, and reduction of amides to amines. Hydroelementation is an important catalytic process that involves H-E...
The electronic spin state (S) of metal ions is fundamental to the performance of magnets, protein cofactors, and magnetic resonance imaging (MRI) contrast agents. The ability to manipulate the spin state of transition metals allows for the development of advanced materials with emergent properties. This following chapters will introduce two...
Small hydrocarbons and their oxygenated derivatives are critical to atmospheric organic aerosol formation and growth. Secondary organic aerosols (SOAs) constitute a significant portion of total atmospheric organic aerosols, and are often generated through the oxidation of biogenic volatile organic compounds (VOCs) such as isoprene, -pinene, and -caryophyllene. Interfaces of SOA...
Contained in the following dissertation are detailed investigations regarding the thermodynamics of small molecule activation by metalloporphyrin complexes isolated within metal-organic frameworks (MOFs). Chapter 1 provides a description of the role metalloporphyrin complexes play in biological systems and the challenges associated with studying small molecule activation by metalloporphryin sites in...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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 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...
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 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...
<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>...
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...
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...
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...
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...
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...
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 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...
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...
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 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...
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...
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;...