Cyclodextrin-based polymers (CDPs) are adsorbents based on supramolecular receptor chemistry and have emerged as a promising technology for organic micropollutant remediation. Micropollutants are small organic molecules which contaminate water systems from human related activities. The occurrence of micropollutants in water sources is associated with many negative health, economic, and ecological...
Surface-enhanced Raman scattering (SERS) spectroscopy has been demonstrated to be a powerful analytical tool. Its chemical specificity, rapidity, and portability make it an attractive technique for biosensing, but its application to this field has been limited by the fundamental distance dependence of the surface-enhancement effect. Many biological molecules of interest...
This dissertation describes the study of photoinduced charge transfer between QDs and molecular acceptors as a probe of the defects within ligand shells of QDs and as means to photocatalyze redox reactions. For charge transfer reactions to occur between QDs and molecules in bulk solution, the molecules must interact with...
Hybrid Organic-inorganic halide perovskites are emerging semiconducting materials that have shown over 23% in power conversion efficiency (PCE) for solar cells. The most prominent materials, three-dimensional (3D) perovskites, have limited scope for structural engineering and exhibit instability when encounter with moisture and heat. Here, we focus on studying the structure-property...
Triplet excited state chemistry has enabled a range of important organic transformations by accessing reaction pathways inaccessible to photoredox chemistry. Such photoreactions are triggered by triplet photosensitizers, which absorb visible-light photons and transfer the energy to the substrate or to a co-catalyst through triplet-triplet energy transfer (TT EnT). The most...
Molecules are highly social: they recognize one another and form bonds with those they are attracted to and repel those they are not. Some molecules establish strong bonds, while others form weak, transient associations. These interactions are ubiquitous in Nature and are integral to life. For at the basis of...
Crystalline and Framework materials make up a broad class of structures which are known for their precise and regular nature. Because these materials have predictable structures and compositions to their networks, they are widely used for several applications including electronics, optics, and catalysis. While these materials are of particular interest,...
Many transcription factors (TFs) regulate oncogenic processes and are therefore desirable targets for drug intervention. However, few TF inhibitors have been developed to date due to a lack of specificity and few TF binding pockets. The Meade Lab has overcome these challenges by using cobalt-based complexes that disrupt Cys2His2 zinc...
A fundamental understanding of the photophysics involved in solar energy capture and conversion is crucial to the development of carbon-neutral energy technologies. Taking inspiration from nature, the photosynthetic reaction center (PSRC) is often modeled by simpler versions of its elements to allow for better control over the system and for...
Soft materials are inherently fluxional, with morphologies and behaviors that are dictated by their solvation state. Thus, many organic systems cannot be reliably imaged by static dry state or cryogenic-transmission electron microscopy (TEM). This motivated us to pursue liquid cell (LC) TEM method development to study our own materials and...
Oxidation is an important process in synthesizing a broad range of useful products such as polymers, pharmaceuticals, and fine chemicals. While H2O2 is a highly attractive oxidant for oxidative chemistry due to its high percentage of oxygen and environmentally friendly water byproduct, it is often used in excess due to...
Part I:Current approaches to synthesize π-conjugated polymers are dominated by thermally driven, transition-metal-mediated reactions. Herein we7 show that electron-deficient Grignard monomers readily polymerize under visible-light irradiation at room temperature in the absence of a catalyst. The product distribution can be tuned by the wavelength of irradiation based on the absorption...
Atomic layer deposition (ALD) is a gas-phase synthesis technique employed to manufacture thin films and metallic nanoparticles of various compositions and sizes, as well as individual, isolated species on various supports. An understanding of the dynamic surface chemistry that takes place during various ALD processes is vitally important for achieving...
Cobalt(III) Schiff-base complexes (Co(III)-sb) have been utilized in the literature as antibacterial, antiviral, and inhibitory agents. Recent work has utilized their ability to displace endogenous metals from metalloproteins that exhibit aberrant gain of function pathologies in human disease. Specifically, in this dissertation Co(III)-sb has been applied as inhibitors of pathogenic...
Uranium is a unique, multifaceted element that possesses rich chemistry and promise for challenging reactions. Pressing demands within nuclear stockpile stewardship and the nuclear energy sector call for development of this relatively understudied element. Uranium metal–organic frameworks (U-MOFs), a class of nanoscale hybrid materials, harness the exceptional attributes of uranium...
Self-Assembled Monolayers for MALDI-TOF Mass Spectrometry (SAMDI-MS) is a technique that combines self-assembling molecules of alkane disulfides on gold and MALDI-TOF mass spectrometry. By using well-defined monolayers with functionalizations that both prevent non-specific adsorption onto the surface and presents immobilization handles, it is possible to pull out analytes of interest,...
Metal-organic frameworks (MOFs) are a class of highly modular materials with welldefined three-dimensional architectures, permanent porosity, and diverse chemical functionalities, which show promise for a wide range of applications, including gas storage and separation, drug delivery, chemical sensing, and catalysis. Nanoparticle forms of MOFs have similar properties but are dispersible...
Photovoltaic devices containing organic semiconducting chromophores are a promising technology for the conversion of solar energy into electricity. Research into the molecular design and processing of these materials has propelled the power conversion efficiency of laboratory-fabricated organic polymer solar cells (PSCs) to over 17%, which exceeds the 10% threshold deemed...
Proteins are the nanoscale building blocks of life. Their sophisticated but well-defined architectures result in complex biological functions, including ones involved in metabolism, photosynthesis, transcription, translation, and immunity. To study and improve upon the natural functions of proteins, it is desirable to develop methodology for organizing proteins into targeted architectures....
Per- and polyfluoroalkyl substances (PFAS) are man-made compounds containing multiple carbon–fluorine bonds. The unique properties of this strong bond simultaneously make PFAS useful for a number of industrial and consumer applications, toxic to living organisms, and difficult to remediate. Because the pervasive pollution of water sources with PFAS occurs at...
The opposing activities of phosphatases and kinases determine the phosphorylation status of proteins, yet kinases have received disproportionate attention in studies of cellular processes, with the roles of phosphatases remaining less understood. This dissertation describes the use of self-assembled monolayer laser desorption/ionization mass spectrometry (SAMDI-MS) together with peptide arrays to...
Two-dimensional (2D) covalent organic frameworks (COFs) are a class of crystalline polymer networks that polymerize and crystallize into layered structures, characterized by their atomically precise structure, permanent porosity and high modularity. Imine-linked COFs are one of the most important and promising classes of macromolecular sheets, which form by the condensation...
Organic photovoltaics offer an opportunity to make solar cells more affordable and widely accessible using cheap, solution-processable light-absorbing layers. In order to realize new technologies, a fundamental understanding of organic chromophore photophysics is required to overcome efficiency limitations. Throughout this doctoral work, I investigated the kinetic and physical characteristics of...
Molecular-oriented single-site heterogeneous catalysis is a powerful approach to address the long-lasting challenge of the structure-activity relationship in catalysis, as it allows molecular level control of the catalytic centers and thus the elucidation of reaction mechanisms. In this dissertation, single-site molybdenum-dioxo species have been immobilized on carbon supports, i.e. activated...
Over the past 15 years, there have been significant developments in expanding the singlet fission (SF) library and understanding the SF mechanism. SF has been a topic of interest in recent years due to its potential applications in organic photovoltaics. During SF, a singlet exciton energetically down-converts into two triplet...
Part I: Design of Photo-Responsive Molecules towards Biomedical ApplicationsThe use of light to control systems provides numerous advantages such as spatiotemporal precision, non-invasive penetration, and precise energy input. Specifically, molecules that undergo photoinduced cleavage, photoremovable protecting groups (PPGs) have emerged as an active area of research due to their broad...
The idea that structure determines the properties of a material is a powerful concept in chemistry and in all fields in which chemistry is important, including engineering, medicine, and materials science. My research aims to better understand the structure-property relationships of a class of materials known as metal–organic frameworks (MOFs)....
This work examines important heterogeneous processes of organic molecules on surfaces, in the contexts of atmospheric and indoor environments. In large forest ecosystems, biogenic secondary organic aerosols (SOAs) constitute a dominant fraction of organic particulate matter in the atmosphere. The formation of SOAs starts from the emission of volatile organic...
The effective capture and detoxification of chemical warfare agents (CWAs) is a pressing need in the modern world. Materials are needed for both the destruction of weapon stockpiles and personal protection via fabric coatings or respirators. Attractive candidates for these applications include metal–organic frameworks (MOFs) – highly crystalline materials composed...
Molecular self-assembly is a process in which molecules spontaneously form ordered aggregates, the process of which is important in the natural world, considering those ordered systems and complex architectures contained in a living cell. The goal of chemists is to design simple molecules or chemical systems that can undergo molecular...
Formed through self-assembly of polynuclear node clusters and multitopic organic linkers, metal–organic frameworks (MOFs) are a class of three-dimensional crystalline materials. Due to their exceptional porosity, high surface areas, amenability to construction, chemical diversity, uniformly arrayed metal-containing nodes, and highly modular nature, MOFs are an ideal class of materials for...
Understanding the photophysical processes of organic materials is important for utilizing them as functional photonic materials. Typical photophysical processes include intersystem crossing, charge transfer (CT), symmetry-breaking charge separation (SB-CS), singlet fission (SF), etc. There are serval factors that can lead to different photophysical processes, such as the molecular energy levels,...
Industrial processes heavily rely on catalysts to control product selectivity and lower energy barriers required for chemical transformations. Catalysts are most commonly solid heterogeneous catalysts that facilitate separations from reaction mixtures and enhance recyclability. Heterogeneous catalysts used in industrial processes exhibit efficacious results, but in certain instances drawing structure-function relationships...
The invention of GdIII-based magnetic resonance imaging (MRI) probes substantially expanded the capability of MRI in visualizing details in tissue. Building upon the achievement of GdIII-based complexes, more ideal probes should feature contrast that is responsive to biomarkers, such as redox status and ion concentrations. The abnormality of these biomarkers...
In the design of efficient adsorbents for the sequestration of toxic molecules and the separation of volatile organic compounds, two important criteria are: high porosity and high density of sorptive sites. The work in this thesis showcases how metal-organic frameworks (MOFs) can be used as porous adsorbent templates where many...
The study of solid-state organic chromophores has been soaring in the last decade owing to their wide applications in organic photovoltaics. These organic chromophores can absorb light in the visible region and form free charge carriers with proper design in molecular structure and device fabrication. In solid state, chromophores are...
The translation of proteins as effective intracellular drug candidates is limited by the challenge of cellular entry and their vulnerability to degradation. To advance their therapeutic potential, cell-impermeable proteins can be readily transformed into protein spherical nucleic acids (ProSNAs) or encapsulated into liposomal spherical nucleic acids (L-SNAs), structures defined by...
Continuous and coordinated materials discovery efforts have amassed a wealth of knowledge concerning many general classes of materials. The number of known phases of all structure-types, however, is far less than number of possible materials dictated by the elements on the periodic table. Recently, with improved computational abilities and well-developed...
The discovery of abundant reserves of shale gas over this past decade has reshaped the world’s energy landscape. It has renewed interests in the activation and conversion of methane as well as other light alkanes. While the oxidative coupling of methane (OCM) and oxidative dehydrogenation (ODH) of ethane and propane...
Proteins are a class of nanoscale building block with remarkable chemical complexity and sophistication: their diverse functions, shapes and symmetry, and atomically monodisperse structures far surpass the range of nanoparticles that can be accessed synthetically. The chemical topology of proteins that drive their assembly into higher order materials are central...
Peptides consists of a series of amino acids connected via an amide type of covalent chemical bond. A diverse field of applications such as biosensors,2 catalysis,4 and biomedicine6 include the oligomeric forms of peptides due to their genuine features comparing to other biomacromolecules. Particularly, peptides in the field of biomedical...
Chemical modifications of oligonucleotides (ONs) have advanced these molecules towards clinical approvals. On their own, native ONs have poor pharmacokinetic properties, such as rapid degradation by nucleases and poor cell uptake, which limit their potential therapeutic applications. Chemical modifications of ONs can increase their stability, alter their interactions with cells,...
Despite the increasing interest in biogenic secondary organic aerosols (SOAs), their role in the climate system remains the greatest source of uncertainty in global models. Cloud formation, critical for the net cooling effect provided by cloud cover, is dependent on the abundance of SOA particles and their ability to activate...
The development of new catalytic methodologies for the precision synthesis of carbon-carbon bonds is central to the advancement of synthetic organic chemistry. Significant focuses of these efforts are made on the enantio- and diastereoselective synthesis of carbon frameworks, especially as chemists and biologists become more aware of the impact of...
Synthesis opens the pathway to examine a plethora of complex structures. Whether the target is a naturally occurring compound or a proposed molecule never observed before, synthetic routes can be developed to help understand a variety of properties that the molecule can contain. Synthetic efforts have helped elucidate the absolute...
As the interest in rational synthesis for solid-state materials accelerates, there is an urgent need to understand the design principles concealed within these reactions. In situ material synthesis provides such an avenue to not only uncover these assembling rules, but also for finding new materials even in seemingly familiar phase...
Recent advances in combinatorial chemistry, synthetic biology, and ‘omics’ research require high-throughput methods for performing and analyzing thousands to millions of reactions in one day. However, it is a challenge to engineer high-throughput systems that can autonomously conduct and analyze such a large number of reactions in a generalizable and...
The use of light to understand detailed electronic structure and chemical properties of a molecule through light-matter interaction is fundamentally essential to design and analyze any chemical system. Over the past decades, rapid developments on optics and laser techniques improved the detection efficiency of multiphoton processes with more detailed chemical...
Metalloenzymes catalyze remarkable reactions in Nature using transition metal ions. Common earth-abundant metals like copper, iron, zinc, and magnesium catalyze reactions that are the basis of life. These metal sites lend their chemistries to facilitate these reactions, making studying the structure and properties important in understanding the enzymes' abilities and...
This thesis presents results on photophysics and spin dynamics of photoactive organic molecules that possess one unpaired electron spin in the ground state and two or three unpaired spins upon photoexcitation. The excited state dynamics of the systems were studied using transient optical absorption spectroscopies and non-Boltzmann population on the...