The need for complex and sophisticated materials continues to grow as society becomes more advanced. For many chemists, the design of these materials begins by looking towards model molecular systems for the identification of desirable properties and functions. As such, restricting oneself to C, H, N, O, and the other...
One of the greatest challenges in heterogeneous catalysis is the rational design and development of new catalytic systems, due to synthetic limitations in the design of solid catalysts and inhomogeneity of chemical sites at solid surfaces. This obfuscates understanding of catalyst behavior and slows improvements of processes. One approach to...
The continuing increase in atmospheric CO2 to concentrations exceeding 400 ppm has attracted considerable attention from both scientists and policymakers. Industrial fossil fuel consumption generates a significant amount of CO2 emissions, and in particular, energy-intensive molecular separations that require thermal processes, such as distillation, drying, or evaporation, are responsible for...
Biological systems that perform critical reactions like carbon dioxide reduction, water oxidation, or phosphonate ester hydrolysis consist of many separate components with many different degrees of
freedom. While the functionality of pieces of these systems can be replicated synthetically to some
degree, the integration of synthetic catalysts into an overall...
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...
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...
Synthesis and characterization of mixed valent molecules which contain two or more metals in different oxidation states is a rich field of chemistry informing fundamental electronic structure and electron transfer theories. Traditionally these studies are concerned with the direct electronic interaction between metals, but recent work on redox non-innocent ligands...
The worldwide community of patients affected by Basal Cell Carcinoma of the skin (BCC) is larger than that of any other cancer. While BCC is rarely lethal, currently available treatment strategies often leave patients with disfiguring scars on their faces, heads, and necks. Moreover, the high recurrence rates of BCC...
Emergent phenomena are phenomena that only arise from the bulk collective, not from individual pieces of that collective. The design of materials which host emergent phenomena can be achieved by controlling the interactions between constituent atoms, ions, or electronic spins in a material, and include materials such as permanent magnets...
A unifying concept across many fields, ranging from chemistry to architecture, is the bottom-up construction of sophisticated structures from simple building blocks. Materials with long-range order allow for consistent, predictable performance throughout the resulting structure. My research focuses on building highly ordered porous materials from atomic level building blocks based...
Biomedical imaging is an essential part of medicine that enables the non-invasive observation of biological phenomena. This, in turn, allows for more accurate and earlier diagnoses, monitoring of therapies, and even fundamental research into biological processes. Molecular imaging, a fast-growing subdiscipline of biomedical imaging, seeks to image biochemical processes at...
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...
Nanoparticle synthesis is capable of producing particles with any combination of structure, chemistry, size, shape, and surface. All of the different combinations of these physical properties can produce nanoparticles with almost countless materials properties suited for many applications. Given this interest in using nanoparticles in so many different fields, including...
Chirality and polarity describe orthogonal mechanisms of inversion symmetry breaking, which is the origin of valuable properties in crystalline materials including nonlinear optical activity, ferroelectricity, and piezoelectricity. Noncentrosymmetric (NCS) materials have numerous applications yet opportunities remain for cooperative coupling between chiral and polar basic building units to realize high-performance materials....
Meiosis is a highly regulated process necessary for proper chromosome division. Zincfluxes regulate mammalian meiosis; between prophase I and metaphase II, total intracellular zinc
increases by 50%, while 20% of zinc is released in “zinc sparks” following fertilization. Although
zinc fluxes had been shown to be conserved in mammals, it...
Spin-orbit coupling (SOC) underlies myriad phenomena in chemistry and physics. Arbitrary manipulation of spin-orbit coupling would enable precise control over such parameters as magnetic anisotropy, the sensitivity of quantum sensors, and even the selectivity of certain catalytic processes. Herein, I describe my efforts directed towards utilizing SOC as a handle...
The era of quantum information science (QIS) can usher revolutionary new capabilities ranging from quantum computation to quantum sensing. At the core of these technologies is the fundamental unit of QIS, the quantum bit or qubit. The power of qubits over their classical counterparts lies in their ability to be...
As the pursuit for higher performance and lower cost photovoltaics, and for new applications of optoelectronic devices moves beyond crystalline silicon, there are many unique opportunities for materials research into hybrid organic-inorganic, and organic semiconductors. This dissertation focuses on both hybrid organic-inorganic materials and organic materials for optoelectronic applications. In...
Transition metal oxides (TMOs) like perovskites are known to be versatile for functional properties such as ferroelectricity, magnetism, optical properties, and high-temperature superconductivity, because of their sensitive coupling between atomic structure and properties. By studying and understanding the fundamental structure-property relationships present in TMOs, it is possible to strategically engineer...
Subchalcogenides are rare compounds that have both metal-metal and metal-chalcogenide (sulfur, selenium, tellurium) interactions. Unlike conventional semiconductors, the metals do not obey the so-called 8-N octet rule for oxidation states, often resulting in low or zero valent metal atoms. The presence of both metal-metal and metal-chalcogenide bonding can also lead...
Thermoelectric modules that convert heat into electrical energy are attractive for improving global energy management. This thesis reports the synthesis and characterization of two new families of lead and tin chalcogenide alloys and focuses on the impact of the grain boundaries, phase segregation, and atomic vacancies on the electronic and...
The continued existence and use of chemical warfare agents (CWAs) have necessitated the development of materials which can safely and efficiently decontaminate these toxic chemicals in an environmentally benign fashion. Among the most prevalent CWAs, nerve agents (sarin, VX) and blistering agents (sulfur mustard [HD]) are considered the most toxic...
Molecules and materials featuring unpaired electrons are fundamental elements of modern energy, device, and imaging technologies. The high sensitivity of electronic spins to their surroundings renders these compounds further attractive as environmental sensors. In order to successfully realize these applications, the electronic spins must be precisely controlled. One promising strategy...
The development of heavy metal semiconductors is a growing field of interest for their application in photovoltaics, light emission, and radiation detection. This is due to their robust ability to convert incident photons of visible wavelength and high energy into charge current while remaining stable, optimizable, and readily synthesizable. As...
The Controlled, Site-Isolated Synthesis of Polyelemental Nanostructures in Polymer Nanoreactors Pengcheng Chen Polyelemental nanoparticles are an attractive class of materials due to their potential applications, which span the fields of catalysis, plasmonics, electronics, magnetics, targeted drug delivery, and bio-imaging. However, conventional synthetic methods for such structures are limited, especially when...
In multiatomic systems, high applied pressures reduce interatomic contact distances. At pressures comparable to those inside planets, this relatively simple principle completely changes the guiding principles of chemistry and physics established at near-ambient conditions. High-pressure investigations of precisely how the laws of nature evolve in the gigapascal and megabar regime...
Bioresponsive imaging probes act as beacons to allow detection, tracking, and study of otherwise invisible actors in biological systems. Understanding how these underlying systems function in their native context is essential to identifying dysfunction and generating effective remedies. Magnetic Resonance techniques are particularly interesting for this application because of the...
While Li-ion batteries are currently the preferred energy storage technology, multivalent alternatives such as Mg should be considered. Magnesium metal has a high volumetric capacity and has been shown to cycle with no dendrite formation. However, the highly charged Mg2+ ion cannot easily diffuse into the oxide cathodes favored in...
The emerging paradigm of quantum information science (QIS) vows to transform a wide range of fields, such as computation, communication, and sensing. The fundamental unit at the core of any QIS system is a quantum bit, or qubit. Rather than be restricted to one of two classical states (0 or...
Magnetic resonance imaging is a powerful research tool for studying anatomical processes in intact large organisms, as it is capable of generating high resolution images with unlimited penetration depth and excellent soft-tissue contrast. However one of the challenges faced by those seeking to use the technique to answer biochemical questions,...
The halide perovskites AMX3 (A = large cation, B = Sn or Pb, and X = halide) have been the subject of intense investigation due to their outstanding optical and electronic properties, which have enabled high solar cell efficiencies thanks to a beneficial electronic structure and long charge carrier lifetimes....
Polyolefins are the most versatile and widely used polymers worldwide. Depending on the polymer microstructure, polyolefins can exhibit a wide range of useful and tailored properties and applications. Metal-catalyzed coordinative olefin polymerization plays a center role in advancing polyolefin synthesis. This dissertation explores two strategies to modulate the polymer microstructures...
Spin-orbit coupling (SOC) is a powerful phenomenon that dictates the functional properties of transition metal complexes essential for information processing, catalysis, and magnetism. Though it is relegated to lower energy scales within the orbital description of first-row transition metal complexes, SOC impacts crucial aspects of electronic structure such as promoting...