With the ever-increasing interest in new photovoltaic materials, much attention is being given to the study of nanoparticles and their assembly. One of the primary goals in this field is the self-assembly of particles, such that they can be programmed to form a desired structure given only a template and a solution of particles. In my project, I investigate the effect of proteins (specially designed through de novo synthesis) on the aggregation of gold nanoparticles, with samples prepared in buffers of salt and Tris base. The particles used are nanospheres of sizes 100, 50 and 10 nm, as well as nanorods of different aspect ratios which can offer more information on the directionality of the assembly. To obtain the necessary data on these samples I use a number of spectroscopy techniques (ultraviolet-visible, dynamic light scattering and circular dichroism) and microscopy methods (hyperspectral and scanning electron). A stereospecific response is obtained from the protein-particle mixtures if the materials formed are chiral, that is, if they rotate plane polarized light. I have shown that the proteins stabilize the particles in a salt solution, which is an indication of protein-particle binding - similar results have been correlated in literature to the formation of a chiral organic-inorganic complex. Such complexes would potentially benefit from both the plasmonic properties of the nanomaterial by absorbing light at a particular wavelength in the visible range, as well as the stereospecificity imparted by the protein helix. Being able to achieve such a result is an important step towards understanding the optoelectronic properties of biotemplated nanostructures, which has a diverse array of applications, including materials for solar energy production, photodynamic cancer therapy in which tumor cells can be specifically targeted, and drug delivery systems. It would also be invaluable for the customizable design of catalysts, enzymes, probes, sensors and diagnostic tools.

Metal–organic frameworks (MOFs) are a class of crystalline, porous extended solids that are formed through coordination between metal cations and bridging organic ligands. These materials have been a topic of acute interest in the scientific community due to their intrinsic porosity, high surface area, and precise tunability. However, MOFs are typically insulating, which limits the scope of their applications. The recent development of electrically conductive MOFs has opened the door to exciting multifunctional applications in electrocatalysis, advanced electrochemical energy storage, chemical sensing, and much more. However, a molecular-level understanding of charge transport in MOFs remains lacking. My research aims to address this knowledge gap through the investigation of one-dimensional (1D) metal–organic chains. In this presentation, I will introduce the synthesis of a series of highly-tunable 1D metal–organic chains that exhibit delocalized π systems and high electrical conductivity along with studies of how structural parameters such as metal/ligand identity and chain geometry influence their overall electrical and magnetic properties. My preliminary results demonstrate trends in these structure-property relationships that may inform how these materials can be rationally designed with specific magnetic and conductive properties. Ultimately, this work will contribute towards a molecular-level understanding of charge transport and magnetism in metal–organic frameworks, enabling the design of new conductive porous materials that can use electricity to drive chemical processes.

Lead perovskites have attracted the interest of the industry for optoelectronic devices applications due to their strong and tunable absorptions. However, their stability and environmental toxicity impose a challenge in its use for commercial application. Bismuth perovskites are a promising alternative due to their similar ionic radius to lead with long-term stability and lower toxicity. To replace lead-based perovskites with bismuth-based ones, it is necessary to increase the photoluminescent quantum yields and extend the emission wavelength range. The crystalline structure of bismuth perovskites can be altered with a dopant to redshift the usually blue light emission. We doped bismuth-based perovskites with rare-earth metals via sonication. The produced materials were analyzed by ultraviolet-visible spectroscopy and photoluminescence spectroscopy. The collected measurements determine if a redshift was produced on the emission spectra. It is expected to see a redshift from the current 400 nm wavelength on the doped perovskites. However, the current results do not show a redshift, instead they show a change in intensity. The comprehension of how to efficiently produce redshifted bismuth perovskites can propel the industrial level use of this less toxic alternative.

Indium phosphide (InP) magic-size clusters (MSCs) are atomically-precise molecules that can be used as precursors to quantum dots (QDs). In a reaction to form InP MSCs, QDs are the thermodynamic product, whereas MSCs are a kinetic product, so there is a critical temperature below which a reaction will form MSCs but above which a reaction will form QDs. The goal of this project is to explore the effect of ligand identity on the formation and stabilization of InP MSCs and their subsequent conversion to QDs. For carboxylates, which bind weakly to InP surfaces, the critical temperature is about 120 ËšC. For phosphonic acids, which bind strongly to InP surfaces this temperature is so high that cannot be reached via a heating mantle – above about 400 ËšC. I am working to investigate the effects of native thiols/thiolate ligands on the synthesis of InP MSCs. Thiols are intermediate in their binding strength to and are commonly used with InP surfaces. I will probe the concentrations and temperatures at which thiolate-capped InP MSCs form. I hypothesize that the critical temperature for the synthesis of MSCs versus QDs reflects the ligand binding strength. If this is true, thiolate-capped InP MSCs should form readily at temperatures above 120 ËšC, but the temperature at which QDs are formed should be achievable via a heating mantle, opening up new parameter space for QD and cluster synthesis and study.

Diaryliodonium salts have recently been shown to facilitate metal-free mechanoredox free radical polymerizations. Prior literature reports focus on the role of diaryliodoniums as photoinitiators; these salts have well established fragmentation mechanisms and kinetic profiles. However, their use in mechanochemistry has not been extensively investigated. Mechanochemistry is an emerging field of chemistry that uses force as a stimulus for chemical reactions. Compared to traditional stimuli such as light, heat, and electricity, mechanical force avoids the use of transitional metal additives and often has a lesser environmental impact. This report looks to explore functionalized (e.g., electron-rich versus electron-deficient) diaryliodoniums and to determine the impact of reactivity in a mechanoredox polymerization setting. Herein we synthesized a library of salts of diverse electronic structures and tested them within an established mechanoredox ball mill system. We report data on their initiation based on radical trapping as well as changes in polymers molecular weight. The hypothesis is that salts with functionalities that withdraw electron density such as alkyl halogens or cyano groups will initiate faster than salts with electron donating functionalities due to their lower reduction potential as demonstrated in literature. Exploration of these functionalized salts will provide kinetic insight and open new avenues of synthesizing commodity polymers. This is particularly applicable in 3D printing, where having control over the rate of initiation could be used to tune downstream physical properties.

Enzymes offer a more sustainable means to perform highly selective and efficient chemical transformations that are otherwise difficult to attain using synthetic chemistry. However, our ability to harness the power of enzymes for the synthesis of diverse molecules is limited by a narrow substrate scope. Non-heme iron(II)/2-oxoglutarate oxygenases (Fe(II)/2OGs) are a superfamily of enzymes that offer a potential solution to this challenge as they can catalyze a wide array of reactions via C-H functionalization. The goal of my project is to expand the substrate scope of Fe(II)/2OGs to hydroxylate non-native amines, which are important precursors in pharmaceutical development. I have screened a panel of Fe(II)/2OG enzymes for stereoselective hydroxylation activity with non-native amine substrate analogues and am validating the hits via mutagenesis. Validated Fe(II)/2OG enzyme hits will be optimized by directed evolution with successive rounds of mutagenesis and screening. Finally, I will probe the scope of non-native amine substrates that can react with the evolved Fe(II)/2OGs. The proposed work will evolve the existing catalytic diversity of Fe(II)/2OG enzymes to include new selective chemical transformations that can be applied to a wide range of non-native biomedically relevant amine building blocks.