Theses and Dissertations from UMD
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Item USING VIBRATIONAL SUM-FREQUENCY-GENERATION SPECTROSCOPY TO EXPLORE THE ROLE OF SOLVENT ORGANIZATION IN DETERMINING ION LOCATIONS NEAR SILICA SURFACES(2024) Singh, Siddharth; Fourkas, John; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Chemical processes occurring at liquid–solid interfaces are fundamental to applications in fields such as energy storage and nanofluidic transport. In this thesis I establish that the general framework used to describe and understand these systems, the electrical double-layer model, is insufficient in describing interfacial electrolyte solutions in polar, aprotic organic solvents. Using vibrational sum-frequency-generation (VSFG) spectroscopy, a nonlinear optical technique that is indispensable for exploring interfacial organization and dynamics, I study different polar aprotic solvents at silica interfaces. These studies highlight the importance of the organization of such solvents in dictating the interfacial distribution of ions. In the first part of this dissertation, I compare electrolyte experiments in acetonitrile (MeCN) and propionitrile (EtCN) to determine how an increase in alkyl chain length can influence solvent organization at a liquid–solid (LS) interface, and thereby influence the interactions of ions with the interface. In the second part of the dissertation, I focus on a solvent mixture of EtCN and deuterated MeCN at a silica interface. VSFG data for solutions with different molar ratios of the two solvents indicate that there is preferential partitioning of each liquid at this surface. In the third part of this dissertation, I examine the effects of solvent chirality on the organizational behavior at an LS interface, and consequently on the effects of this organization on ion partitioning. The key result of my research is that a polar, aprotic, organic solvent’s structure, chirality, and mixing with other solvents, can drive the partitioning of ions in interfacial electrolyte systems, in contradiction to the predictions of the EDL.Item TOWARDS FULLY AUTOMATED ENHANCED SAMPLING OF NUCLEATION WITH MACHINE-LEARNING METHODS(2024) Zou, Ziyue; Tiwary, Pratyush; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Molecular dynamics (MD) simulation has become a powerful tool to model complex molecular dynamics in physics, materials science, biology, and many other fields of study as it is advantageous in providing temporal and spatial resolutions. However, phenomena of common research interest are often considered rare events, such as nucleation, protein conformational changes, and ligand binding, which occur on timescales far beyond what brute-force all-atom MD simulations can achieve within practical computer time. This makes MD simulation difficult for studying the thermodynamics and kinetics of rare events. Therefore, it is a common practice to employ enhanced sampling techniques to accelerate the sampling of rare events. Many of these methods require performing dimensionality reduction from atomic coordinates to a low-dimensional representation that captures the key information needed to describe such transitions. To better understand the current challenges in studying crystal nucleation with computer simulations, the goal is to first apply developed dimensionality reduction methods to such systems. Here, I will present two studies on applying different machine learning (ML) methods to the study of crystal nucleation under different conditions, i.e., in vacuum and in solution. I investigated how such meaningful low-dimensional representations, termed reaction coordinates (RCs), were constructed as linear or non-linear combinations of features. Using these representations along with enhanced sampling methods, I achieved robust state-to-state back-and-forth transitions. In particular, I focused on the case of urea molecules, a small molecule composed of 8 atoms, which can be easily sampled and is commonly used in daily practice as fertilizer in agriculture and as a nitrogen source in organic synthesis. I then analyzed my samples and benchmarked them against other experimental and computational studies. Given the challenges in studying crystal nucleation using molecular dynamics simulations, I aim to introduce new methods to facilitate research in this field. In the second half of the dissertation, I focused on presenting novel methods to learn low-dimensional representations directly from atomic coordinates without the aid of a priori known features, utilizing advanced machine learning techniques. To test my methods, I applied them to several representative model systems, including Lennard Jones 7 clusters, alanine dipeptide, and alanine tetrapeptide. The first system is known for its well-documented dynamics in colloidal rearrangements relevant to materials science studies, while the latter two systems represent problems related to conformational changes in biophysical studies. Beyond model systems, I also applied my methods to more complex physical systems in the field of materials science, specifically iron atoms and glycine molecules. Notably, the enhanced sampling method integrated with my approaches successfully sampled robust state-to-state transitions between allotropes of iron and polymorphs of glycine.Item Matrix Isolation and Gas-Phase Kinetics of Astrochemically Relevant Species(2024) Hockey, Emily K.; Dodson, Leah G.; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Following the first detection of an interstellar molecule in 1937, there have been over 300 detected chemical species as of the writing of this dissertation. Interstellar molecules typically exist in a range of conditions including very low-temperature environments, making their existence unexpected and their chemistry exotic. The formation and evolution of such molecules can be strikingly different than here on Earth. This dissertation work reproduced the reaction conditions of astrophysical environments for laboratory experiments. Two classes of chemicals were studied to gain a more complete understanding of the potential energy surfaces of astrophysically relevant molecules. First, the formation of transient species was studied using a custom-built matrix-isolation spectrometer (detailed in Chapter 2). Second, the destruction of astrochemically relevant molecules via ultraviolet (UV) radiation was studied using multiplexed photoionization mass spectrometry. In the first portion of this dissertation, spanning Chapters 3−5, we study (a) the noncovalent interactions that lead to the formation of weakly bound complexes, (b) the structure of transient intermediates, and (c) fundamental effects of different matrix environments. In Chapter 3, we demonstrate the utility of this instrument by isolating and characterizing the weakly bound complexes between hydrogen cyanide (HCN) and methyl chloride (CH3Cl) using FTIR spectroscopy and quantum chemistry calculations. The study ultimately led to a hypothesis that the formation of weakly bound complexes with CH3Cl could catalyze formation of the isomers of prebiotic molecules. Isomerism became the focus of subsequent studies using this instrumentation, as an emphasis was placed on the importance of considering how host/guest interactions may perturb gas-phase isomer ratios during matrix deposition. Chapter 4 demonstrates the change in conformer abundance of methyl nitrite (CH3ONO) in relation to the gas-phase ratio as a result of depositing with different low-temperature matrices, an important finding in the continued development of matrix-isolation techniques. Chapter 5 continues this investigation, expanding to investigate how different matrices influence the photodynamics of CH3ONO upon UV irradiation. These chapters reiterate the need for a deeper understanding of not only the chemical systems, but the methods used to study them as well. The second portion—Chapters 6 and 7—investigates the fate of a molecule important both on Earth and in space: methanol (CH3OH). The products formed upon UV excitation of CH3OH have not been well-constrained previously. In a collaborative project with Sandia National Laboratories (SNL) and Lawrence Berkeley National Laboratory (LBNL), we carried out UV photodissociation studies on CH3OH at the Advanced Light Source (ALS) synchrotron, identifying and quantifying the photodissociation products via Multiplexed Photoionization Mass Spectrometry. Chapter 6 provides direct observation of the formation mechanism and subsequent reactivity under gas-phase reaction conditions of hydroxymethylene (HCOH)—an elusive singlet carbene—which was previously unattainable due to the transient nature of the molecule. Additionally, the results in Chapter 7 inform scientists of the destruction processes possible for this important astrochemical in regions of space with high ultraviolet radiation fields, as well as quantitatively assign branching ratios for all of the major photodissociation channels of CH3OH for the first time. Finally, Chapter 8 details future work that will utilize both instruments to completely characterize the potential energy surface of possible formation routes to polycyclic aromatic hydrocarbon and other unique transient species.Item BLANKET AND PATTERNED REPROGRAMMING OF AZOPOLYMER NANORIDGES AND APPLICATIONS TO CELLULAR BIOPHYSICS(2024) Abostate, Mona Hamdy Abdelrahman; Fourkas, John J; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The objective of this project is to tailor nanotopographies previously fabricated on large areas through photomodification. The original master patterns consist of nanoridges created using conventional lithography. Using an azopolymer as a photoresponsive material, replicas of the original master were prepared using soft lithography. The entire surface of the azopolymer nanoridges underwent photomodification using a 532 nm laser with varying polarizations and durations, in a process referred to as blanket reprogramming. This process resulted in controllable widening, buckling, or removal of the nanoridges due to photoisomerization and subsequent mass migration of the azopolymer. To replicate the reprogrammed surfaces, a molding procedure was employed using an acrylatic resin. The blanket reprogramming process was monitored in situ during exposure through diffraction of another reading laser beam. Cellular behaviors can be modulated in various biological contexts through interactions with their surroundings. The relationship between nanotopography and cell behavior is crucial, and has a wide range of biological consequences and medical applications. For example, nanotopography is employed to design antibacterial surfaces, preventing the adhesion of bacteria and biofilm formation, thereby reducing the risk of infections associated with medical devices. Nanostructured surfaces can inhibit the migration of cancer cells, offering insights into potential therapeutic strategies. Nanotopography is also used in nerve-regeneration scaffolds to guide neurite outgrowth, aiding in the repair of damaged neural tissue. We investigated the response of MCF10A breast epithelial cells to buckled acrylic nanoridges replicated from a master of azopolymer ridges photomodified by laser. The nanoridges became buckled after exposure to 532 nm light polarized parallel to the ridges. The impact of buckling on the dynamics and location of actin polymerization was investigated, as well as the distribution of lengths of contiguous polymerized regions. Azopolymers, known for their biocompatibility, have been employed by various research groups to create nanotopographies on which cells are plated and imaged. We conducted experiments using a spinning-disk confocal fluorescence microscope, testing exposure wavelengths ranging from 405 nm to 640 nm. Our objective was to assess the feasibility of live-cell imaging on azopolymer nanotopographies without inducing surface alterations. Our findings revealed the capability of live-cell imaging at high frame rates across a wide range of wavelengths. This result stands in contrast to prior studies, in which the selection of fluorescent dyes compatible with these materials was limited to those excited in the red spectrum and emitting in the near-infrared. I demonstrate that different patterns can be created through patterned reprogramming of the azopolymer nanoridges. A periodic arrangement of light strips was projected perpendicular to the ridges, thereby projecting an amplitude grating onto the azopolymer nanoridges. The spacing of this pattern can be adjusted by altering the mask or adjusting the magnification of the optical system. Furthermore, varying the direction of light polarization expands the potential for creating a wider variety of designs. Different types of reprogramming motifs can be implemented by projecting patterns at angles that are not perpendicular to the substrate, by tilting the incoming laser beam away from the horizontal. Various intriguing patterns, such as repeating curves, were observed, dependent on both the angle of the incident light and the direction of light polarization relative to the direction of the ridges.Item ESOTAXIS: IDENTIFYING THE FACTORS THAT INFLUENCE NANOTOPOGRAPHIC GUIDANCE OF THE DYNAMICS AND ORGANIZATION OF THE ACTIN CYTOSKELETON AND OTHER MOLECULES INVOLVED IN DIRECTED CELL MIGRATION(2024) Hourwitz, Matt; Fourkas, John T.; Losert, Wolfgang; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Directed migration is a crucial capability of cells in developmental and immunological processes. Defects in cell migration can lead to negative health outcomes. Cell motion depends on the organization and dynamics of internal components, especially the actin cytoskeleton, and the extracellular environment. Microscale and nanoscale topographical cues, with at least one dimension that is much smaller than most cells, can bias cell motion over long distances, due to the guidance of the organization and dynamics of the cytoskeleton and other molecules and assemblies within the cell. In this work, I describe a technique to reproduce patterned nanotopographic substrates for use in the study of esotaxis, the guided organization and dynamics of the actin cytoskeleton and other cellular components in response to nanotopographic cues. The guidance of actin drives directed cell motion along a pattern with dimensions much smaller than the cell. The dimensions of the nanotopography determine the extent to which cellular components are guided. Differences in the physical properties of the plasma membrane and the actin cytoskeleton among cell lines will influence the extent of guidance by nanotopography. Asymmetric patterns can accentuate the distinctions in esotactic responses among cell lines and drive contact guidance in different directions. The cytoskeletal response to nanotopography is a local phenomenon. A cell in contact with multiple nanotopographic cues simultaneously will show distinct organization of actin in the different regions of the cell. The importance of local actin dynamics requires an analysis method, optical flow, that can identify and track the distinct cytoskeletal motions in different parts of the cell. The formation of adhesions attached to the extracellular matrix is a characteristic of the migratory behavior of many types of cells and these adhesions are credited with allowing the cell to sense and interact with the underlying substrate. Actin can sense nanotopographic cues without the widespread availability of adhesive ligands. Although adhesion to the substrate strongly increases the extent of cell spreading and migration on nanoridges, epithelial cells can align with and migrate along nanotopography even with a dearth of adhesive cues. Therefore, actin is a supreme sensor of nanotopography that can drive directed cell migration.Item Design and Assembly of Block Copolymer-Modified Nanoparticles into Supracolloidal, Molecular Mimics(2023) Webb, Kyle; Fourkas, John T; Nie, Zhihong; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Large strides have been achieved in nanoparticle self-assembly, using various strategies to achieve ordered, supracolloidal structures, ranging from dimers to chains and vesicles to 3-D lattices. However, these methods, while expanding the scope and accessibility of design, face inherent limitations in targeting complex structures with high yields, particularly when using isotropic building blocks (e.g. gold nanoparticles and polystyrene nanoparticles). Additionally, research studying the reversibility of nanoparticle assemblies is mostly limited to small-ligand-modified particles rather than polymer-modified nanoparticles. Polymers are particularly advantageous as they provide a higher degree of functionality to the nanoparticle surface and allow for increased control in directing particle interactions. This control is necessary to continue furthering the advancement of gold nanoparticles in plasmonics, sensors, and catalysts. Here, we introduce two strategies to assemble gold nanoparticles into supracolloidal nanostructures. Gold nanoparticles are modified with complementary, functionalized-block-copolymers that drive the assembly of the nanoparticles. The first strategy uses a diblock copolymer composed of a hydrophilic outer block and an acid or base-functionalized inner block. Upon mixing, particles are assembled due to the acid–base neutralization between the complementary block copolymers. The resultant supracolloids consist of nanoparticles precisely arranged in space, which mimic the geometries of small molecules. The particle interactions are fine tuned by varying the size and feeding ratio of the nanoparticles, along with the length and composition of the block copolymers. Careful tuning of these parameters yields nanostructures with different valences that were produced in high yield. Additionally, the implementation of a long outer, hydrophilic polymer block provided the assembled nanostructures stability when transferred from THF to water. Colloidal stability in an aqueous medium could allow for expanded use of these nanostructures in cellular uptake studies and biomedical applications. The second strategy uses a diblock copolymer composed of a hydrophilic outer block and an inner block containing either complementary host or guest moieties. Particularly, we take advantage of the well-established interactions between β-cyclodextrin and adamantane as the host and guest molecules. Upon the slow addition of water, particles assemble due to the host–guest interactions between the complementary block copolymers, as the hydrophobic adamantane moieties are driven within the β-cyclodextrin macrocycles. Fine tuning of the nanoparticle sizes and feeding ratios and the block copolymer lengths and compositions results in high yields of targeted supracolloids that also mimic the geometries of molecules. Interestingly, the size difference between the host and guest-modified particles led to different types of nanostructures. In addition, due to the reversibility of the host–guest interactions, we demonstrate the ability of our system to reorder in response to competitive host moieties. Upon addition of free β-cyclodextrin, the host–guest interactions are disrupted, resulting in disassembly of the nanostructures, which we could reassemble upon removal of the free cyclodextrin. Finally, due to the strength of the nanoparticle interactions, we also tested the selectivity of the nanoparticle interactions by assembling the host building block with different guest building blocks. We showed that when assembled with competing guest building blocks, the β-cyclodextrin building blocks preferentially interact the adamantane building blocks due to the stronger particle interactions. This reversibility and selectivity make our system a potential candidate for use in biosensors.Item Analyzing Dynamical Processes with Local Molecular Field Theory(2023) Zhao, Renjie; Weeks, John D; Chemical Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Local molecular field (LMF) theory provides a framework for describing the collective response of a system to long-range interactions in nonuniform liquids. Based on this theory, different roles played by the short and long-range components of the intermolecular interactions can be disentangled in determining relevant structural and thermodynamic properties in equilibrium. Furthermore, in dynamical processes, nonlocal long-range interactions are often associated with long relaxation times, and can contribute significantly to the stability of the system in different phases. In this thesis, LMF theory is utilized to quantify and analyze the dynamical effects arising from long-range Coulomb interactions in aqueous solutions, while elucidating how they are connected to strong local forces and fluctuations. The first half of the work concerns ionic and dipolar solvation dynamics, which plays an essential role in many solution phase chemical reactions. The physical models of Gaussian-smoothed charge and dipole distributions are conceptualized from LMF theory to investigate the molecular origins of linear and nonlinear effects in solvation dynamics. The long-range component of the solute-solvent electrostatic interaction is shown to underlie the linear response behavior of the system, while the short-range interactions introduce additional nonlinear effects. The LMF-based solvation models further demonstrate their functionality in probing the intrinsic dielectric dispersion of solvent water. The second half of the work is focused on the nucleation processes in the aqueous environment. Simulating crystal nucleation from solutions requires efficient treatments for intermolecular interactions to drive the transitions on time scales affordable to molecular dynamics simulations. For this purpose, a LMF-based molecular model is employed to capture the renormalized long-range interactions, and well-tempered metadynamics is adopted to enhance the fluctuations arising from short-range interactions. By comparing to a short-range reference model, the necessity of long-range interactions in explaining metastability is revealed. Temporal fluctuations and direct evidence for the two-step nucleation mechanism are observed through the analysis using a deep learning-based approach. The results about these two types of dynamical processes contribute to a deeper understanding of the roles of short and long-ranges interactions in the aqueous systems.Item ENERGY TRANSFER DYNAMICS OF HIGH ENERGY MOLECULES(2023) Lukowski, Christopher; Mullin, Amy S; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation investigates the energy transfer dynamics of high-energy molecules excited electronically, vibrationally, and rotationally. The molecules studied in this thesis were excited electronically and vibrationally with UV photon absorption and rotationally with an optical centrifuge. The excited molecules are relaxed either by collisions or a chemical process. The products of the relaxation process are measured using high-resolution transient IR absorption spectroscopy to determine the state-resolved products and the energy partitioning. In the first study the collisional relaxation of highly vibrationally excited collidine with bath CO2 is investigated. The collidine was excited to an E_vib=38,552 cm-1 after absorption of a λ=266 nm photon and the full state-resolved distribution of the scattered CO2 is reported. The results are compared to previous studies done on methylated pyridines. The translational energy and rotational energy gain of the scattered CO2 is similar for the methylated pyridines, however, the integrated appearance rate constant for collidine-CO2 collisions is higher then the other methylated pyridine molecules. The effect that the donor complexity has on collisional relaxation is explored. For the second study, SO2 is electronically excited to the predissociative metastable C̃ electronic state. The SO product quantum yields, rotational distributions, and product energy partitioning show that translational energy is preferred by a 4:1 ratio over rotational energy for the photoproducts. The preference for translational energy is evidence that a linear transition state could be involved in the dissociation process. Theoretical calculations of the SO2 potential energy surfaces for the ground state and the excited state show that for SO2 photodissociation to occur near the dissociation threshold the SO2 in the C̃ state becomes linear and that coupling to the repulsive triplet state lowers the height of the energy barrier so dissociation can proceed. The third study used a tunable optical centrifuge to rotationally excite N2O into extreme rotational states. The optical centrifuge was tuned to selectively populate rotational states between J=100-200. N2O IR transitions for the (0001-0000) band are known up to J=100 for the R-branch. Line center profiles were collected over each IR transition between J=100-200 to identify the IR transition frequencies. The newly identified N2O transitions and the tunable optical centrifuge were used to maximize the population in N2O J=140 and J=165, using two different optical traps, to determine the relaxation dynamics in this region. Doppler-broadened line profiles show that rotational states below the maximized population have higher translational temperatures than rotational states near the peak of the distribution. From the near nascent distributions, the relaxation rate of the N2O was measured to be 65 % of the gas kinetic collision rate for both optical traps. This result is compared with a previous study on CO relaxation dynamics.Item MODEL COMPOUNDS GUIDE AFFINITY MEASUREMENT OF BERYLLIUM AND CALCIUM INTERACTIONS WITH PHOSPHOLIPIDS(2023) Davoudi, Omid; Klauda, Jeffery B; Sukharev, Sergei; Chemical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Divalent cations bound to anionic lipids are necessary co-factors for many signaling mechanisms taking place at both the inner and outer surfaces of the cytoplasmic membrane. Coordination of divalent ions jointly by phospholipid headgroups and specific protein domains mediates recognition and triggers secondary messenger cascades or membrane fusion events. Phosphoryl oxygens of phospholipids are common contributors to divalent ion coordination. With the aims of elucidating the affinities of the calcium ion Ca(2+) and its toxic competitor beryllium Be(2+) to different types of phosphate groups taking place in many ‘building blocks’ of the cell, improving simulation force fields and better understanding the nature of beryllium toxicity, here we use isothermal titration calorimetry (ITC) to study the thermodynamic parameters and coordination of these ions by phosphates. Particularly, we focus on the differences between phosphates in the phosphodiester configuration that connect the glycerol backbone with a headgroup (as in phosphatidylglycerol, PG) and terminal monoester phosphates such as in phosphatidic acid (PA) and most phosphorylated proteins. The comparison of small model compounds, dimethyl phosphate (DMP, mimicking phosphate in phosphatidyl glycerol) with glycerol-3-phosphate (Gly3P, emulating phosphate in phosphatidic acid) shows that the affinity of Be(2+) for Gly3P is about one order of magnitude higher than for DMP and may exhibit at least two binding configurations. The Be(2+) -DMP thermograms in most cases are well fitted with a one-site model. Upon completing the survey of small (model) compounds, we performed experiments to compare the binding parameters of Be(2+) to POPA and to POPG-containing liposomes with the parameters obtained on respective model compounds. We also present several pilot binding experiments performed with POPS liposomes; however, the fit is poor.Item A Breath of Fresh Air: Study of Reactive Porous Metal Oxides for Chemical Warfare Agent and Simulant Defeat(2022) Leonard, Matthew; Rodriguez, Efrain E; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Organophosphorus molecules are a wide class of compounds that are used commerciallyas fire retardants, plasticizers, and pesticides. Organophosphorus pesticides were developed to replace environmentally persistent pesticides, such as dichlorodiphenyltrichloroethane, more commonly known as DDT. However, organophosphorus pesticides have been proven to be carcinogenic and to affect neurodevelopment negatively. A sub-class of organophosphorus molecules are highly toxic acetylcholinesterase (AChE) inhibitors, known as nerve agents. Although the Geneva convention banned the use of chemical warfare agents (CWA), the nerve agent sarin has been used as recently as 2013 on Syrian civilians. In 2018, a Novichok nerve agent was used in the attempted assassination of a former Russian spy and his daughter. Current CWA respiratory protection employs bituminous coal (BPL), carbon which is impregnated with a mixture known as ASZM-TEDA. BPL carbon impregnated with ASZM-TEDA has a wide range of reactivity, but has not changed significantly since its inception. The next-generation filtration material will need to have a large surface area to maximize reactive sites and be robust to withstand degradation. Mesoporous and nanoparticle metal oxides are highly active materials that show promise in nerve agent defeat. Within this dissertation, the goal is to develop and study reactive metal oxides to understand the factors that are important for the decomposition of CWAs and CWA simulants. In Chapter 1, I introduce the history of CWAs, the downfalls of current filtration technology, and the candidates for the next generation filter. In Chapter 2, the methods and characterization techniques used within this work are presented and discussed. In Chapter 3, to determine the effects of cation selection on methyl paraoxon decomposition, Ce4+ was isovalently doped into anatase type TiO2. Through UV/Vis spectroscopy, the degradation of methyl paraoxon was tracked and fit to pseudo-first-order kinetics, then normalized to the synthesized material’s surface area. The rate constant, normalized to the material’s surface area (kSA), reveals CeO2 is 3 to 4.6 times larger than that of TiO2 and the Ce-doped titanias. The Ce-doped titanias showed little to no change in methyl paraoxon decomposition compared to TiO2. The lack of change within the Ce-dopant titania revealed that crystal structure is a larger driving factor for methyl paraoxon decomposition than the cation identity (i.e. Ce4+ and Ti4+). Chapter 4 presents a study on the gas surface interaction between sarin and dry CuO nanoparticles (NP) through infrared (IR) spectroscopy. Sarin adsorbs to CuO through the P=O bond, and proceeds to decompose on the surface. Distinct red shifts in the delta(P-CH3) and rho(P-CH3) modes indicate the cleavage of the P-F bond, producing isopropyl methyl phosphonic acid (IMPA). Concurrently, a mode attributed to (O-P-O) begins to grow in, demonstrating that sarin forms a bridging species on the surface. Sarin continues to degrade on the dry CuO surface once the sarin feed is removed. Upon heating above 423 K, all modes associated with IMPA simultaneously decrease, indicating that IMPA desorbs from the surface. These observations were further corroborated through computational methods. Finally, in Chapter 5, I seek to enhance the reactivity of CuO by placing the cation Cu2+ within a Jahn-Teller active geometry. Mesoporous NiO and Cu-doped NiO were synthesized and exposed to diisopropyl fluorophosphate (DFP) in different environments and studied through diffuse reflectance IR Fourier transform spectroscopy (DRIFTS). Ordered mesoporous Cu-doped NiO was successfully synthesized through a hard templating method. Through X-ray diffraction (XRD), Cu2+ was incorporated into the NiO rock-salt lattice without phase separation for < 20%. The mesoporous metal oxides (MMO) maintained high surface areas (67.89-94.38 m2/g), with a main pore size of ~2.4 nm. Shifts in the Raman spectra indicate the dopant, Cu2+, reduces nickel vacancies resulting in a decrease in Ni3+ defect states. Upon DFP exposure, NiO was highly oxidative producing CO, CO2, carbonyls, and carbonates due to the active oxygen species formed by the Ni2+ vacancies. The mesoporous Cu-doped NiO samples were less reactive to DFP oxidation, due to the Cu2+ occupying the nickel vacancies, resulting in a reduction of active oxygen species.