Other Chemistry Commons^™

Esipt-Enabled Alkyne Migration Provides Rapid Access To Benzoxazinones, Andrés G. Muñoz

Electronic Theses and Dissertations

Benozoxazinones have long been of interest to agrochemical scientists and medicinal chemists because of their widespread biological activity. These scaffolds are also of interest to synthetic chemists, who recognize the utility of benzoxazinones for accessing functionalized heterocycles. The use of efavirenz, a benzoxazinone-based reverse transcriptase inhibitor used in the treatment of HIV-1, has brought increased attention to this privileged pharmacophore. While there exist numerous strategies for synthesizing benzoxazinones, methods that do not require the use of acutely toxic and environmentally hazardous reagents are lacking. Consequently, there is a need to develop new methods for constructing this valuable scaffold. Herein, we …

Photoassisted Synthesis Of Complex Polyheterocycles Via Rational Design Of Tailored Photoprecursors, Tina Alanna Holt

Electronic Theses and Dissertations

Natural products remain the most common source for drug leads, although diversity-oriented synthesis of unnatural complex molecules is gaining momentum. Our lab has been developing experimentally simple and straightforward approaches to complex molecular architectures via photochemical reactions involving a minimal number of experimental steps. In order to achieve this, photoprecursors were assembled via high yielding reactions. Next, we deployed photoinduced cycloadditions to create complex 3-dimentional structures. Lastly, with this obtained primary photoproduct, post-photochemical transformations were used to further grow its scaffold complexity.

One method to increase scaffold complexity is the [4+2] intramolecular cycloadditions of azaxylylenes, which are developed through standard …

Iron Speciation In Pm2.5 From Urban, Agriculture, And Mixed Environments In Colorado, Usa, Joseph R. Salazar, David J. Pfotenhauer, Frank Leresche, Fernando L. Rosario-Ortiz, Michael P. Hannigan, Sirine C. Fakra, Brian Majestic

Chemistry and Biochemistry: Faculty Scholarship

Atmospheric iron solubility varies depending on whether the particles are collected in rural or urban areas, with urban areas showing increased iron solubility. In this study, we investigate if the iron species present in different environments affects its ultimate solubility. Field data are presented from the Platte River Air Pollution and Photochemistry Experiment (PRAPPE), aimed at understanding the interactions between organic carbon and trace elements in atmospheric particulate matter (PM). 24-hr PM2.5 samples were collected during the summer and winter (2016–2017), at three different sites on the Eastern Colorado plains: an urban, agricultural, and a mixed site. Downtown Denver had …

Analytic Gradients For State-Averaged Multiconfiguration Pair-Density Functional Theory, Thais R. Scott, Matthew R. Hermes, Andrew M. Sand, Meagan S. Oakley, Donald G. Truhlar, Laura Gagliardi

Scholarship and Professional Work - LAS

Analytic gradients are important for efficient calculations of stationary points on potential energy surfaces, for interpreting spectroscopic observations, and for efficient direct dynamics simulations. For excited electronic states, as are involved in UV–Vis spectroscopy and photochemistry, analytic gradients are readily available and often affordable for calculations using a state-averaged complete active space self-consistent-field (SA-CASSCF) wave function. However, in most cases, a post-SA-CASSCF step is necessary for quantitative accuracy, and such calculations are often too expensive if carried out by perturbation theory or configuration interaction. In this work, we present the analytic gradients for multiconfiguration pair-density functional theory based on SA-CASSCF …

Organic Photochemistry: Remote Delivery Of Reactive Oxygen Intermediates Via A Heterogeneous Approach, Niluksha Walalawela Abeykoon

Dissertations, Theses, and Capstone Projects

Photosensitized oxidation reactions produce a number of intermediates species, which are generated in varying amounts over time. This complexity presents major challenges in the study of oxidation processes. Mechanistic efforts to separate and deliver reactive oxygen intermediates enable their controlled use in processes such as bacterial inactivation. This thesis describes a heterogeneous reaction approach taken to control the generation and delivery of reactive oxygen intermediates. The mechanistic details of photosensitized reactions were elucidated via synthetic, materials, and physical organic techniques to optimize the delivery of reactive oxygen intermediates. This thesis contains six chapters as described below.

Chapter 1 gives a …

Significance Of Hno3 Acid Photolysis On Surfaces In Tropospheric Chemistry, Honglian Gao

Legacy Theses & Dissertations (2009 - 2024)

The reactive nitrogen trace gases (NO_y) including nitrogen oxides (NO_x) and their secondary products are known to cause ground-level ozone pollution, photochemical smog, acid deposition, and overall air quality degradation. NO_x was believed to be permanently removed from the atmospheric by HNO₃ formation and deposition. However, our laboratory experimental results show that HNO₃ can be remobilized back to photochemically labile HONO and NO_x (re-NOx-ification). We have verified and quantified HONO and NO_x production from the photolysis of HNO₃ on various surfaces, including Pyrex, leaves of plants, and other environmentally relevant …

Distributions And Sources Of Hono In The Rural Troposphere, Ning Zhang

Legacy Theses & Dissertations (2009 - 2024)

Nitrous acid (HONO) is an important precursor of hydroxyl radical and plays an important role in the terrestrial boundary layer photochemistry. However, there are still many unknowns regarding HONO chemistry such as formation mechanisms and distributions in the troposphere, especially in rural and remote environments. In this research, we presented the first vertical concentration profiles of HONO in the troposphere, measured on a small aircraft platform. The HONO mixing ratios ranged from 4 to 17 pptv in the free troposphere and from 8 to 74 pptv in the rural boundary layer. The HONO distribution patterns were strongly correlated to the …

Interactions Of Hydrogen Peroxide And Oxalic Acid On Ice Films, Hui Yan

Legacy Theses & Dissertations (2009 - 2024)

The heterogeneous halogen chemistry plays a critical role in the ozone depletion events in the polar boundary layers. Pathways involving the conversion from photochemically active halogens to photochemically inactive halogens are necessary to understand the nature of ozone depletion, but the processes are not fully understood. The study of the effects of hydrogen peroxide (H₂O₂) and oxalic acid (C₂H₂