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...
The work described here includes both fundamental and application based studies centered around the use of plasmonic sensors. Fundamental studies focus on probing the optical properties of nanosphere lithography (NSL) fabricated Ag nanoparticles, while surface-enhanced Raman spectroscopy (SERS) sensors are applied to identify and characterize artists' red dye and red...
The [(salen)CrCl + LB] catalyst system was found to be a highly active catalyst system for the [aziridine + CO<sub>2</sub>] coupling reaction, and exhibited a marked preference for the formation of 5-substituted oxazolidinone product, especially in the absence of cocatalyst. The activity of this catalyst system is optimized by modifying...
A catalytic, multi-component coupling reaction for the synthesis of nitrogen-containing heterocycles has been developed, via the reaction of an imine, &#945;-diazoester and unsaturated coupling partner in the presence of a copper(I) or rhodium(II) transition metal catalyst with excellent diastereo-selectivities and high yields. The transition metal-catalyzed decomposition of a diazo compound...
High relaxivity contrast agents are of great importance in the advancement of magnetic resonance imaging diagnostics for use in biomaterials. Biomaterials that are implanted into the body, with the goal of repairing or regenerating lost or damaged tissue, need to be tracked noninvasively, over time. I have completed work using...
Two new strategies have been developed to accomplish direct nucleophilic acylation reactions. In the first approach, acylsilanes are added to various electrophiles using N-heterocyclic carbenes as catalysts. The second method utilizes O-silyl thiazolium carbinols as stoichiometric acyl anion precursors to afford acylated products under mild reaction conditions.
N-heterocyclic carbenes generated...
Local structure determination in amorphous and disordered systems, which are crystallographically intractable, is critical for gaining an understanding of their properties. X-ray absorption spectroscopy (XAS) is an excellent tool for local structure determination in amorphous and disordered environmental materials. Amorphous manganese oxides produced by the freshwater bacterium Leptothrix discophora SP6...
Counteranion effects on the rate and stereochemistry of propylene polymerization mediated by ion-pair complexes derived from dimethylzirconocene precatalysts activated with strongly Lewis-acidic perfluoroarylmetalloid cocatalyst/activators are shown to arise from the strength of the cation-anion interaction. This is quantified using CS-symmetric Me2C(Cp)(Flu)ZrMe2 (Cp = C5H4, &#951;5 cyclopentadienyl; Flu = C13H8, &#951;5...
Four series of doped CdO thin films have been grown on both amorphous glass and single-crystal MgO(100) substrates by metal-organic chemical vapor deposition (MOCVD), and their phase structure, microstructure, electrical, and optical properties investigated. Epitaxial films grown on single-crystal MgO(100) exhibit biaxial, highly textured microstructures. These as-deposited doped CdO thin...
In Chapter 1, a series of "constrained geometry" organoactinide complexes, (CGC)An(NMe)2 (CGC = Me2Si(h5-Me4C5)(tBuN); An = Th, 1; U, 2), prepared via efficient in situ, two-step protodeamination routes in good yields and high purity, is presented. Both 1 and 2 are quantitatively converted to the neutrally charged, solvent-free dihalides (1-Cl2,...
Understanding the nature of quantum effects in dense biological systems is of great interestto many scientists today. It seems that the question is not does quantum mechanics dictatebiological processes, but rather by how much and to what extent. A big challenge though in thisfield is how to properly test and...
This dissertation describes the relationship between the surface chemistry of colloidal semiconductor nanocrystals (quantum dots, QDs) and their optoelectronic properties, such as photoluminescence and degree of quantum confinement. We primarily focus our efforts on one particular subset of ligands known to couple strongly to the inorganic core of the QD...
Climate change may be one of the most important puzzles the world has attempted to solve and one of the greatest challenges in this area is to improve our understanding of how atmospheric aerosol particles impact climate processes. We seek to overcome this challenge by focusing on the chemistry and...
Ultrafast spectroscopy offers an unprecedented view on the dynamic nature of chemical reactions. From charge transfer in semiconductors to folding and isomerization of proteins, these all important processes can now be monitored and in some instances even controlled on real, physical timescales. One of the biggest challenges of ultrafast science...
Halide perovskites, AMX3 (A = monocation, B = Ge, Sn, or Pb, and X = halogen), present a versatile class of solution-processable semiconductors made from earth abundant materials with outstanding electrical and optical properties. Their solar cell efficiencies have dramatically increased from ~9% to ~22% in less than five years...
With the dual challenges of meeting global energy demand and mitigating anthropogenic climate change, significant effort is being applied to generating power from renewable sources. The dye-sensitized solar cell (DSC) is a photovoltaic technology capable of generating electricity from sunlight, but suffers losses in efficiency due to deleterious electron transfer...
Organic photovoltaics (OPVs) are an attractive solar energy technology for low-current applications. Herein is described the supramolecular design and methodology to manipulate intermolecular interactions in order to create an active layer in OPVs devices composed of crystalline and amorphous donor-acceptor domains, which has been proposed as the ideal morphology for...
Raman spectroscopy is an established and versatile molecular sensing technique, but it is limited by its modest chemical sensitivity. Surface-enhanced Raman spectroscopy (SERS) can amplify otherwise weak normal Raman signals up to nine to ten orders of magnitude, giving rise to its application in many molecular sensing problems, including those...
Interprotein electron transfer (ET) occupies a central role in both chemistry and biology, as it is important in a variety of functions including cellular respiration, metabolism, and energy transduction during photosynthesis. Consequently, understanding the protein-protein recognition and docking that controls interprotein ET is an important field of scientific research.
One...
Surface-enhanced Raman spectroscopy (SERS) is a powerful technique for characterizing molecular systems. It combines the chemical selectivity of vibrational spectroscopy with plasmonic signal enhancement to achieve the ultimate limit of detection--a single molecule. By overcoming the effects of ensemble averaging, single molecule SERS (SMSERS) probes distributions in molecular interactions and...
Metalloporphyrins fulfill incredibly diverse chemical roles in biology and photocatalysis, where they act as photosensitizers, redox sites, substrate binding sites, and facilitators of long range electron transfer. Metalloporphyrin chemistry is uniquely tuneable through conformation and functionalization of the porphyrin ring, choice of metal, and interaction with the environment as these...
The FDA approvals of afatinib and ibrutinib in 2013 led to a heightened interest in cysteine-reactive covalent inhibitors. However, there are few methods to discover new cysteine-reactive inhibitors for enzymes for which reversible binding scaffolds are not known. To this end, we rationally designed a chemical system to attach a...
The properties of crystalline materials are controlled by their composition and by their structure, however, the structure of a crystal is only partly controlled by its composition. Development of specifically directed inorganic syntheses will require an understanding of the dynamics of crystal phase forming processes, especially those processes involved in...
Human skin oils are significant scavengers of atmospheric oxidants in occupied indoor environments. Many techniques used to study gas-phase transformations of surface films indoors have been limited to off-line bulk analysis, although more surface-selective methodologies are emerging. Here, we present a multi-prong analytical approach to characterizing skin oil ozonolysis. Skin...
Natural gas is likely to become one of the main sources of carbon-based chemicals in the next century due to rapidly increasing natural gas production levels. This has created new incentives to find materials that are active and selective towards alkane partial oxidation reactions that are relevant for natural gas...
A fundamental materials science question is “why and how will this material form?” The experimental,computation, and time resources necessary to answer this question consume significant resources due to the
predominantly trial-and-error based approaches common in materials research. This dissertation reintroduces
a number of fundamental thermodynamics-based tools for the study of...
Raman spectroscopy is an analytical technique that utilizes inelastic scattering of light to obtain structural information of analyte molecules. The weak intrinsic process of Raman scattering, however, can be greatly enhanced when molecules are placed on or near a surface of noble metal with nanostructures. Discovered over 40 years, surface-enhanced...
Extensive study of nanomaterial chemical and optical properties has enabled their integration into a variety of applications. However, less thoroughly investigated are the heat generation and dissipation processes of nanomaterials following optical excitation. These phenomena are of immense importance as thermal energy can distort a material’s structure, which has profound...
Metal-organic frameworks (MOFs) are porous, crystalline materials synthesized by combining metal nodes and organic linkers through self-assembly. The diverse range of building blocks available allows for extensive tunability of MOFs, enabling the optimization of these materials for various applications, such as gas storage, separations, and catalysis. This study aimed to...
This thesis describes a novel demonstration of quantum teleportation, a protocol within the broader field of quantum information science, carried out by an electron transfer reaction within a molecular system. As described in Chapter 1, quantum information science has potential impacts in computation, communication, and cryptography. This field relies on...
Theoretical investigation of photochemical processes in molecules is a nontrivial task. Ab initio calculations that completely describe such processes are often intractable to perform given today’s hardware. Thus, to gain insight into common areas of interest, such as in transition metal photochemistry and organic photovoltaics, less accurate but more feasible...
The demand for low cost, unconventional electronics requires new materials with unique characteristics that the traditionally used silicon-based technologies cannot provide. Metal oxide semiconductors, such has amorphous indium gallium zinc oxide (a-IGZO), have made impressive strides as alternatives to amorphous silicon for electronics applications. However, to achieve the full potential...
Metal–Organic Frameworks (MOFs) is a class of material comprising organic linkers and inorganic, metal-ion-containing nodes, with diverse functionalities and wide-range of applications. Because of their porous nature and functional nodes and linkers, they are competent candidates for gas storage, separation, catalysis, and so on. Most MOFs, however, are intrinsically insulating,...
Quantum dots (QDs) are promising photocatalysts due to their large extinction coefficient, large surface area-to-volume ratio, and stability upon irradiation. QDs have been studied in photocatalytic hydrogen production, CO2 reduction, and reduction of small organic molecules such as nitrobenzene. This dissertation describes the application of QDs in two photocatalytic cross-coupling...
Secondary organic aerosol (SOA) particles are a class of highly abundant atmospheric constituents that represent a substantial fraction of carbon within the climate system. A subset of naturally-occurring SOA particles are formed through atmospheric oxidation of biogenic volatile organic compounds (BVOCs), forming oxygenated products of lower volatility that can partition...
Mixed-dimensional heterojunctions between two-dimensional (2D) materials and organic semiconductors is a rapidly growing field. This is motivated by the promise of leveraging the extraordinary properties of 2D materials with the synthetic tunability and reconfigurability of organic electronics, allowing the realization of new physics or devices that are not possible in...
Understanding the characteristics of interfaces between materials and solvent media such as structure, chemistry, and charge remains crucial to determining the properties and performance of numerous systems and technologies. This thesis focuses specifically on characterizing the interactions of water at oxide interfaces. A large collection of questions remains unanswered about...
This thesis document is comprised of three research projects. The first investigates the active vibrational modes involved in twisted intramolecular charge transfer in a Julolidine-BODIPY dyad using two-dimensional electronic spectroscopy along with DFT calculations. We identified two types of vibrations, compression and torsional motion, as playing an important role in...
High-throughput methods enable rapid experimentation and/or screening of thousands of samples simultaneously. Mass-spectrometry based methods are of particular interest since they provide a label-free way to detect all species present in a given reaction mixture. To circumvent sample preparation and purification—which is typically a slow process—the Mrksich group developed a...
Soft functional materials are fundamentally interesting from a chemistry standpoint and have exciting applications in robotics, chemical and biomolecule sensing, and biomedical engineering. In addition, soft materials are also useful in lithography, particularly cantilever-free scanning probe lithography (CFSPL). Because of their low modulus, biocompatibility, stimuli responsiveness, malleability, and other characteristics,...
In the first two decades of the 21st century, metal organic frameworks (MOFs) have attracted much attention in both fundamental-research and-industrial application areas. Derived from a vast library of both inorganic metal nodes and organic linker bridges, MOFs are crystalline materials whose structures and chemical environments can both be tuned...
DNA is extremely versatile and powerful, both as a construct in biological applications and as a ligand in materials design due to the fact that its recognition properties can be programmed through sequence and length. Spherical nucleic acids (SNAs), nanoparticles surrounded by a dense shell of DNA or RNA, are...
Renewable energy technology, more so than ever before, is critical to the survival of humanity. For decades, concentrated efforts into designing and developing such novel devices resulted in the innovation of solar-driven photovoltaics that were competitive with nonrenewable alternatives. This thesis explores the dynamic behavior of alternative material candidates that...