With the continuing rise in demand for energy, it is becoming increasingly necessary to invest more effort into the research and development of new materials that generate or harvest energy. One avenue of materials science is continued research into perovskites, a class of materials having a similar structure to its namesake mineral, which has seen use in piezoelectrics, photovoltaics, and sensors. An adaptation of perovskites; hybrid organic-inorganic materials/metalates, referred to here as HOIMs or just simply as halometalates, have been promising alternatives to traditional perovskites. Derived from the perovskite A2+B4+(X-2)3 formula, HOIMs following the A2+Bn+Xn+2 format where A represents the organic cation, B the metal cation, and X the halide anion are synthesized from a combination of organic and inorganic components which allows for deviations from the stricter crystal structure of the perovskites. These organic components allow for lower temperature requirements and solution processability, making them promising materials with a low barrier of entry. Because of this versatility in synthesis and structure, the corresponding tunability of their constituents provides an excellent avenue of approach for the development of novel, task-specific HOIMs the physical, optical and electronic properties of which could be carefully controlled for. While there has been and currently is research being done to elucidate the tuning of individual changes to the various cation and anion sites within halometalate materials there remains a need to combine these various approaches together into a cohesive manual for the design and fabrication of these materials for future use. The hypothesis upon which this work is structured lies in that tying together of the disparate structures which have been shown to exhibit tunability before. That is the ability to individually yet cotemporally alter specific structural characteristics of an HOIM in such a way as to select for a unique combination of performant traits, and in so doing show a verifiable, reproducible methodology. This work investigates several promising halometalate materials whose similar structures allow for simple, stepwise alterations with the intent of measuring the effect these changes have on their physical arrangement and nonlinear properties.

With the continuing rise in demand for energy, it is becoming increasingly necessary to invest more effort into the research and development of new materials that generate or harvest energy. One avenue of materials science is continued research into perovskites, a class of materials having a similar structure to its namesake mineral, which has seen use in piezoelectrics, photovoltaics, and sensors. An adaptation of perovskites; hybrid organic-inorganic materials/metalates, referred to here as HOIMs or just simply as halometalates, have been promising alternatives to traditional perovskites. Derived from the perovskite A2+B4+(X-2)3 formula, HOIMs following the A2+Bn+Xn+2 format where A represents the organic cation, B the metal cation, and X the halide anion are synthesized from a combination of organic and inorganic components which allows for deviations from the stricter crystal structure of the perovskites. These organic components allow for lower temperature requirements and solution processability, making them promising materials with a low barrier of entry. Because of this versatility in synthesis and structure, the corresponding tunability of their constituents provides an excellent avenue of approach for the development of novel, task-specific HOIMs the physical, optical and electronic properties of which could be carefully controlled for. While there has been and currently is research being done to elucidate the tuning of individual changes to the various cation and anion sites within halometalate materials there remains a need to combine these various approaches together into a cohesive manual for the design and fabrication of these materials for future use. The hypothesis upon which this work is structured lies in that tying together of the disparate structures which have been shown to exhibit tunability before. That is the ability to individually yet cotemporally alter specific structural characteristics of an HOIM in such a way as to select for a unique combination of performant traits, and in so doing show a verifiable, reproducible methodology. This work investigates several promising halometalate materials whose similar structures allow for simple, stepwise alterations with the intent of measuring the effect these changes have on their physical arrangement and nonlinear properties.

Graphene and other two-dimensional (2D) materials exhibit remarkable electronic, thermal, and optical properties that can be tailored by material selection, structural design, and the incorporation of transition metals. This study explores graphite intercalation compounds (GIC) via sonication techniques and extends the approach to alternative carbon allotropes. This work also highlights our advancements on hexagonal boron nitride (hBN), a wide band gap insulator structurally related to graphene, and advancement of intercalation via sonication at ambient temperature.

Additionally, the manipulation of ferromagnetic 2D materials, including chromium (III) iodide and chromium sulfur bromide, is demonstrated through electron beam patterning, highlighting advancements in artificial spin lattices and spin ices.

These works are characterized using PXRD, TEM, and STEM coupled with EDS analysis. This comprehensive research underscores the potential of 2D materials for innovative applications in nanoelectronics and material science.

Graphene and other two-dimensional (2D) materials exhibit remarkable electronic, thermal, and optical properties that can be tailored by material selection, structural design, and the incorporation of transition metals. This study explores graphite intercalation compounds (GIC) via sonication techniques and extends the approach to alternative carbon allotropes. This work also highlights our advancements on hexagonal boron nitride (hBN), a wide band gap insulator structurally related to graphene, and advancement of intercalation via sonication at ambient temperature.

Additionally, the manipulation of ferromagnetic 2D materials, including chromium (III) iodide and chromium sulfur bromide, is demonstrated through electron beam patterning, highlighting advancements in artificial spin lattices and spin ices.

These works are characterized using PXRD, TEM, and STEM coupled with EDS analysis. This comprehensive research underscores the potential of 2D materials for innovative applications in nanoelectronics and material science.

Bacterial vesicles hold immense potential in various biomedical fields, including vaccines, antimicrobial agents, drug delivery systems, and cancer immunotherapy. Among these, outer membrane vesicles (OMVs) produced by Gram-negative bacteria are among the most extensively studied. While the exact mechanism of OMV production remains unclear, numerous environmental factors have been shown to influence both the yield and composition of OMVs. In this study, we investigated the effect of three different antimicrobial families on OMV production by E. coli. Interestingly, antimicrobials within the same family did not provide the same effects on OMV yield, suggesting that OMV production may not directly correlate with the antimicrobial mechanism of action.

OMVs have demonstrated tumor-inhibitory activity in multiple mouse tumor models. However, their potential toxicity poses a significant challenge, as OMVs have been shown to cause mortality in mice. To address this limitation, we developed bacterial-engineered vesicles (BEVs) as a safer alternative to OMVs. Proteomic analysis revealed that BEVs contained fewer outer membrane proteins compared to OMVs. In vitro assays, BEVs effectively repolarized pro-tumor macrophages (M2) to the anti-tumor phenotype (M1) and promoted dendritic cell maturation. Additionally, BEVs were shown to serve as a versatile platform for antigen peptide display, with the displayed peptides not interfering with BEVs' inherent immunomodulatory activity.

We further evaluated the anti-tumor efficacy of BEVs in a B16F10 melanoma model. The intravenous administration of BEVs significantly inhibited tumor growth and elicited robust immune responses. Flow cytometry analysis of spleen and lymph node samples from BEV-treated mice revealed an elevated M1/M2 macrophage ratio and an increased population of CD8+ T cells. To explore combination therapies, we generated cancer cell-derived vesicles (PD-1 CEVs) using PD-1-transfected B16F10 cells. Interestingly, while BEVs alone inhibited tumor growth effectively, the co-administration of BEVs and PD-1 CEVs resulted in comparable tumor suppression but attenuated immune responses. However, a significant decrease in regulatory T cell percentages was monitored among all vesicle-treated groups compared to the PBS control group. This unexpected immune modulation warrants further investigation to understand the mechanisms underlying PD-1 CEV-mediated immune suppression.

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Bacterial vesicles hold immense potential in various biomedical fields, including vaccines, antimicrobial agents, drug delivery systems, and cancer immunotherapy. Among these, outer membrane vesicles (OMVs) produced by Gram-negative bacteria are among the most extensively studied. While the exact mechanism of OMV production remains unclear, numerous environmental factors have been shown to influence both the yield and composition of OMVs. In this study, we investigated the effect of three different antimicrobial families on OMV production by E. coli. Interestingly, antimicrobials within the same family did not provide the same effects on OMV yield, suggesting that OMV production may not directly correlate with the antimicrobial mechanism of action.

OMVs have demonstrated tumor-inhibitory activity in multiple mouse tumor models. However, their potential toxicity poses a significant challenge, as OMVs have been shown to cause mortality in mice. To address this limitation, we developed bacterial-engineered vesicles (BEVs) as a safer alternative to OMVs. Proteomic analysis revealed that BEVs contained fewer outer membrane proteins compared to OMVs. In vitro assays, BEVs effectively repolarized pro-tumor macrophages (M2) to the anti-tumor phenotype (M1) and promoted dendritic cell maturation. Additionally, BEVs were shown to serve as a versatile platform for antigen peptide display, with the displayed peptides not interfering with BEVs' inherent immunomodulatory activity.

We further evaluated the anti-tumor efficacy of BEVs in a B16F10 melanoma model. The intravenous administration of BEVs significantly inhibited tumor growth and elicited robust immune responses. Flow cytometry analysis of spleen and lymph node samples from BEV-treated mice revealed an elevated M1/M2 macrophage ratio and an increased population of CD8+ T cells. To explore combination therapies, we generated cancer cell-derived vesicles (PD-1 CEVs) using PD-1-transfected B16F10 cells. Interestingly, while BEVs alone inhibited tumor growth effectively, the co-administration of BEVs and PD-1 CEVs resulted in comparable tumor suppression but attenuated immune responses. However, a significant decrease in regulatory T cell percentages was monitored among all vesicle-treated groups compared to the PBS control group. This unexpected immune modulation warrants further investigation to understand the mechanisms underlying PD-1 CEV-mediated immune suppression.

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Small molecule metal complexes have diverse applications including usage as catalysts, single molecule magnets, photosensitizers and pharmaceuticals. Nature itself frequently takes advantage of such complexes for fundamental biological processes. For example, heme-based iron complexes provide O₂ for cellular respiration, while the active site of carbonic anhydrase catalyzes the hydration of CO₂. Now it is our turn to define and exploit the chemical characteristics of such metal complexes. This body of work is specific to the development and application of novel aminated ligands that, when coordinated to various metal centers, can be used for an assortment of applications. The first research project in this work reports a new benzimidazole-based ligand, which dimerizes upon coordination to afford a trinuclear Cu(I) complex. Due to the linear geometry of the Cu(I) metal centers, paired with the strong nitrogen coordinating groups, the resulting complex is resistant to oxidation in both air and water, even in the presence of strong oxidants. The complex is shown to be efficient in the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and used to tag anticancer drug candidates in vitro. The complex is fully characterized, and a catalytic cycle is proposed. The next project focuses on a series of amidine-based ligands featuring chiral functional groups proximal to the coordinating site. In doing so, the reaction of achiral substrates may be influenced to promote the formation of one enantiomeric product over the other. The ligands are shown to be active in catalyzing the hydroxymethylation of silyl enol ethers in the presence of bismuth chloride in aqueous solutions. The reaction is optimized and yields are reported. In the final research project, Ni(II) dimer complexes are investigated for their magnetic behavior. For octahedral Ni(II) dimers bridged by a common anion, it has previously been established that the ferromagnetic superexchange between the Ni(II) metal centers can be enhanced as the angle of the bridging anion approaches 90 degrees. Novel imidazole and pyridine-based ligands are synthesized to add to the catalogue of chlorine-bridged complexes in the literature. Further, their bromine-bridged analogues are synthesized in order to determine the effect the identity of the halide bridge has on the magnetic properties of the complex. These three projects, while functionally different with individual aims, fundamentally share the goal of probing the chemical space that influences intrinsic properties of unique metal complexes.

Small molecule metal complexes have diverse applications including usage as catalysts, single molecule magnets, photosensitizers and pharmaceuticals. Nature itself frequently takes advantage of such complexes for fundamental biological processes. For example, heme-based iron complexes provide O₂ for cellular respiration, while the active site of carbonic anhydrase catalyzes the hydration of CO₂. Now it is our turn to define and exploit the chemical characteristics of such metal complexes. This body of work is specific to the development and application of novel aminated ligands that, when coordinated to various metal centers, can be used for an assortment of applications. The first research project in this work reports a new benzimidazole-based ligand, which dimerizes upon coordination to afford a trinuclear Cu(I) complex. Due to the linear geometry of the Cu(I) metal centers, paired with the strong nitrogen coordinating groups, the resulting complex is resistant to oxidation in both air and water, even in the presence of strong oxidants. The complex is shown to be efficient in the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and used to tag anticancer drug candidates in vitro. The complex is fully characterized, and a catalytic cycle is proposed. The next project focuses on a series of amidine-based ligands featuring chiral functional groups proximal to the coordinating site. In doing so, the reaction of achiral substrates may be influenced to promote the formation of one enantiomeric product over the other. The ligands are shown to be active in catalyzing the hydroxymethylation of silyl enol ethers in the presence of bismuth chloride in aqueous solutions. The reaction is optimized and yields are reported. In the final research project, Ni(II) dimer complexes are investigated for their magnetic behavior. For octahedral Ni(II) dimers bridged by a common anion, it has previously been established that the ferromagnetic superexchange between the Ni(II) metal centers can be enhanced as the angle of the bridging anion approaches 90 degrees. Novel imidazole and pyridine-based ligands are synthesized to add to the catalogue of chlorine-bridged complexes in the literature. Further, their bromine-bridged analogues are synthesized in order to determine the effect the identity of the halide bridge has on the magnetic properties of the complex. These three projects, while functionally different with individual aims, fundamentally share the goal of probing the chemical space that influences intrinsic properties of unique metal complexes.

Global CO₂ emissions from industrial, power generation and transportation sources has led to the call for increased implementation of carbon capture strategies. The most developed of these is point source carbon capture, which refers to the process of capturing CO₂ directly from large (point) source emitters, before the CO₂ is released into the atmosphere. The challenge becomes separating CO₂ from the other components of the emitted gas, mainly nitrogen. Therefore, these processes typically involve the use of aqueous solutions of amines to absorb (capture) CO₂ from the gas stream, where the CO₂ and the basic amine in water react to form a carbamate and/or bicarbonate, depending on the specific amine used. An advantage when using amine solutions is that this reaction is reversible, as the absorbed CO₂ is released when the solution is heated allowing the amine to be reused in multiple cycles of absorption and regeneration.

This type of amine-based carbon capture works well, but it is not without some drawbacks. The temperature swings needed for this desorption process not only requires significant energy input but can also lead to gradual degradation of the amine, commonly referred to as thermal degradation. This can lead to solvent losses, reduced performance, and higher operational costs. In addition, the solvent can degrade due to exposure to oxygen and other contaminants present in the gas (such as SO₂, NOx). This oxidative degradation can lead to the formation of unwanted byproducts, some of which are regulated volatile organic compounds. To avoid unintended environmental effects, the amine degradation pathways need to be carefully understood and managed. Amine degradation can produce a combination of different species generating a complex matrix that when coupled with the high pH environment, can make degradation remediation challenging. This dissertation focuses on the degradation by-products of amine solvents in carbon capture systems and how the chemical differences between the amine and water impacts the volatility and the removal of these degradation compounds. A better understanding of theses impacts allows for the development of mitigation strategies minimizing any environmental impacts.

Mitigation of the unwanted degradation byproducts is achieved by either removing the contaminants from the solvent or capturing and neutralizing them within the system. First, an assessment was performed to understand the effectiveness of activated carbon adsorption, with implications for treating high pH solutions. While there were some benefits to this methodology, activated carbon adsorption was not completely effective and presented several limitations such as metal leaching from the activated carbon material. Given this, it is necessary to expand into other areas of degradation mitigation. First understanding the potential for emissions of any degradation products, including compounds such as aldehydes, is crucial given their known environmental and human health hazards. These emissions may be impacted by the composition of the amine solvent used, therefore the Henry’s volatility coefficient of acetaldehyde in relevant amine solutions were determined as a surrogate for other classes of potential degradation compounds. The volatility was determined to be significantly higher from the amine solvent when compared to water, which is critical fundamental information in aiding the development of proper mitigation strategies that can be implemented within capture systems. 

Current engineering controls within CO₂ capture plants involve the use of water wash systems to reduce amine emissions, however some degradation products are also captured by this system which allows for their targeted neutralization. The composition of the wash-water poses yet another unique challenge as the complex matrix and increased the pH make it difficult to treat via traditional water treatment methods. An electrochemical-mediated treatment method was developed and evaluated to facilitate the decomposition of N-nitrosamines and aldehydes. The experimental results showed that even in the presence of this complex matrix, highly efficient decomposition of these hazardous compounds can be achieved.

Global CO₂ emissions from industrial, power generation and transportation sources has led to the call for increased implementation of carbon capture strategies. The most developed of these is point source carbon capture, which refers to the process of capturing CO₂ directly from large (point) source emitters, before the CO₂ is released into the atmosphere. The challenge becomes separating CO₂ from the other components of the emitted gas, mainly nitrogen. Therefore, these processes typically involve the use of aqueous solutions of amines to absorb (capture) CO₂ from the gas stream, where the CO₂ and the basic amine in water react to form a carbamate and/or bicarbonate, depending on the specific amine used. An advantage when using amine solutions is that this reaction is reversible, as the absorbed CO₂ is released when the solution is heated allowing the amine to be reused in multiple cycles of absorption and regeneration.

This type of amine-based carbon capture works well, but it is not without some drawbacks. The temperature swings needed for this desorption process not only requires significant energy input but can also lead to gradual degradation of the amine, commonly referred to as thermal degradation. This can lead to solvent losses, reduced performance, and higher operational costs. In addition, the solvent can degrade due to exposure to oxygen and other contaminants present in the gas (such as SO₂, NOx). This oxidative degradation can lead to the formation of unwanted byproducts, some of which are regulated volatile organic compounds. To avoid unintended environmental effects, the amine degradation pathways need to be carefully understood and managed. Amine degradation can produce a combination of different species generating a complex matrix that when coupled with the high pH environment, can make degradation remediation challenging. This dissertation focuses on the degradation by-products of amine solvents in carbon capture systems and how the chemical differences between the amine and water impacts the volatility and the removal of these degradation compounds. A better understanding of theses impacts allows for the development of mitigation strategies minimizing any environmental impacts.

Mitigation of the unwanted degradation byproducts is achieved by either removing the contaminants from the solvent or capturing and neutralizing them within the system. First, an assessment was performed to understand the effectiveness of activated carbon adsorption, with implications for treating high pH solutions. While there were some benefits to this methodology, activated carbon adsorption was not completely effective and presented several limitations such as metal leaching from the activated carbon material. Given this, it is necessary to expand into other areas of degradation mitigation. First understanding the potential for emissions of any degradation products, including compounds such as aldehydes, is crucial given their known environmental and human health hazards. These emissions may be impacted by the composition of the amine solvent used, therefore the Henry’s volatility coefficient of acetaldehyde in relevant amine solutions were determined as a surrogate for other classes of potential degradation compounds. The volatility was determined to be significantly higher from the amine solvent when compared to water, which is critical fundamental information in aiding the development of proper mitigation strategies that can be implemented within capture systems. 

Current engineering controls within CO₂ capture plants involve the use of water wash systems to reduce amine emissions, however some degradation products are also captured by this system which allows for their targeted neutralization. The composition of the wash-water poses yet another unique challenge as the complex matrix and increased the pH make it difficult to treat via traditional water treatment methods. An electrochemical-mediated treatment method was developed and evaluated to facilitate the decomposition of N-nitrosamines and aldehydes. The experimental results showed that even in the presence of this complex matrix, highly efficient decomposition of these hazardous compounds can be achieved.