Chemistry Commons^™

Approaches To The Synthesis Of Highly Substituted Arenes, Kh Tanvir Ahmed

Graduate Theses, Dissertations, and Problem Reports (ETD)

While benzene rings and their derivatives are among the most frequently encountered ring systems in natural products, pharmaceuticals, agrochemicals, dyes, and functional materials, polysubstituted arenes are relatively scarce. The analysis of FDA-approved small molecules provides valuable insights into the characteristics of successful drugs while also highlighting gaps in the availability of synthetic methods capable of efficiently accessing diverse substitution patterns on aromatic rings. Highly substituted arenes are typically synthesized through sequential modification of a pre-existing benzene core; however, this stepwise approach becomes increasingly challenging with each additional substitution. An alternative strategy involves the direct construction of benzene rings via annulation …

Free Energy Approaches To Understanding The Mechanism Of Membrane-Active Peptides, Hannah R. Scott

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cancer is a leading cause of death in the world today. Current methods of treatment fail to distinguish the difference between cancer cells and cells of healthy tissue, leading to off-target effects, often with terminal outcomes. A potential solution to this challenge is to target the cancer cells’ microenvironment. One universal characteristic across all cancer cells is the acidic extracellular environment. The pH-Low Insertion Peptide (pHLIP) is a membrane-active peptide with acid-sensitive function, undergoing folding and insertion into a transmembrane alpha-helix. pHLIP is a promising candidate to be used to deliver anti-cancer agents exclusively to cancer cells. Although the mechanism …

Assessment Of Analytical Workflows Of Gunshot Residue Evidence And Strategies For Implementation Of Advanced Technology In Crime Laboratories., Leah D. Thomas

Graduate Theses, Dissertations, and Problem Reports (ETD)

The rise in gun violence in the United States has increased the demand on forensic agencies to process evidence promptly and accurately. The exchange of imperceptible traces among objects, suspects, and victims can provide critical insights into the interactions and sequence of events during a crime. Gunshot residue (GSR) is a type of trace evidence that holds significant investigative value in shooting reconstructions. GSR can help identify potential shooters, intermediate targets, and bullet trajectories; however, its analysis is often expensive and time-consuming. Consequently, there is an urgent need for more effective solutions.

Methods for on-site screening can significantly streamline forensic …

Investigation Of Protein-Ligand Binding Interactions Through The Computational Methods Of Molecular Dynamics And Graph Neural Networks, Alexander Benjamin Wroe

Graduate Theses, Dissertations, and Problem Reports (ETD)

Studies in protein ligand binding are a significant focus in the field of medicinal chemistry

and biochemistry, facilitating a greater understanding of the structure-function relationship

of the protein and controlling function via drug development. In this research, we identify

new binding sites for lipids on the microbial membrane protein, proteorhodopsin, and apply

machine learning approaches to accelerate the generation of binding affinity-like data for the

use in the identification of potential small molecule drugs. The platelet activating factor

receptor. Cardiolipin, a lipid in membranes, and proteorhodopsin, a microbial proton pump,

are both commonly found in microbial membranes, but little is …

Development And Applications Of Capillary Vibrating Sharp-Edge Spray Ionization Coupled With Atmospheric Pressure Chemical Ionization (Cvssi-Apci), Madison Elizabeth Pursell

Graduate Theses, Dissertations, and Problem Reports (ETD)

Mass spectrometry (MS) is a technique that is used in fields in which both complex and non-complex mixtures are analyzed. The state-of-the-art ion sources that are utilized for MS are being demonstrated to be functional for direct infusion of samples as well as for use with online separations. However, ion sources, such as electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) can encounter problems such as ion suppression and an inability to ionize based on size and/or polarity, respectively. Further these sources are bulky and require gas flow, heat sources, and additional high voltage power supplies for optimal performance. …

Rational Design Of Small Molecules Targeting Mitochondrial Redox Proteins, Matheus Barbosa Belchior

Graduate Theses, Dissertations, and Problem Reports (ETD)

Reactive oxygen species play a crucial role in many cellular processes. Despite being a natural byproduct of cellular metabolism, overexpression of these species causes damage to the cell, leading to cell dysfunction. Central to the regulation of these highly reactive molecule is the mitochondria. Impairment in its function has been associated with oxidative stress within the cell. Herein, a ligand-based and structure-based approach to design new small molecules to inhibit mitochondrial redox proteins associated with oxidative stress and reactive oxygen species. In the first project two molecules were synthesized and characterized as potential monoamine oxidase B inhibitors. Results showed two …

Development Of Fast And Comprehensive Approaches For Gunshot Residue Interpretation Using Ambient Ionization, Mass Spectrometry, And Microparticle Sampling Studies, Thomas Dimmey Ledergerber

Graduate Theses, Dissertations, and Problem Reports (ETD)

The information derived from the forensic examination of gunshot residue (GSR) can be critical during the investigative and trial stages in the criminal justice system. However, the complexity of the GSR deposition, transfer, and persistence mechanisms calls for meticulous handling and identification processes. Novel advances in evidence interpretation and analysis via instrumental methods are current areas of growing interest that must be pushed along the chain from research to practice in a timely manner. Therefore, this research focuses on developing both rapid and comprehensive methods for detecting gunshot residue evidence and effectively communicating its significance to the investigators or trier …

3d Printed Microfluidic Platforms For Elisa-Based Diagnostics: Advancing Toward Point Of Care, Brandi Marie Binkley

Graduate Theses, Dissertations, and Problem Reports (ETD)

Protein biomarker detection is a critical analytical method for quantifying proteins in biological samples. It is relevant not only in medical diagnostics and research but also numerous other fields such as environmental monitoring, pharmacology, food safety, and biotechnology. Sensitive detection at picogram-per-milliliter (pg/mL) levels is essential for diagnosing diseases, monitoring progression, and tailoring treatments, especially for low-abundance biomarkers like troponin, interleukin 6, carcinoembryonic antigen (CEA), activin A, and vascular endothelial growth factor (VEGF). Immunoassays, particularly enzyme-linked immunosorbent assays (ELISAs), are the gold standard for protein biomarker detection due to their high specificity and sensitivity. The development of point-of-care (POC) diagnostic …

Developing Consensus-Based Methods For The Examination And Interpretation Of Contemporary Vehicle, Architectural, And Portable Electronic Device Glasses By Micro-X-Ray Fluorescence Spectrometry, Zachary Bailey Andrews

Graduate Theses, Dissertations, and Problem Reports (ETD)

Glass is a trace material that is commonly encountered during investigations of violent crimes. When glass is recovered at crime scenes, it can be used to establish links between suspects, victims, and the scene itself. The most discriminatory form of analysis for glass evidence is elemental analysis, and micro-X-ray fluorescence spectrometry (µXRF) is becoming an increasingly common technique used for this purpose. Recent advances in µXRF technology, such as the introduction of silicon drift detectors (SDD) and improved polycapillary optics are promising in enhancing the capabilities for the examination of glass evidence in forensic investigations. However, along with these advances …

Functionalized Carbon Nanohoops: Synthesis, Structural Insights, And Pathways To Carbon Nanobelts, Liu Li

Graduate Theses, Dissertations, and Problem Reports (ETD)

The development of structurally defined carbon nanostructures has gained significant attention due to their unique electronic, optical, and mechanical properties. Cycloparaphenylenes (CPPs), also known as carbon nanohoops, and carbon nanobelts (CNBs) represent key molecular segments of carbon nanotubes (CNTs), offering a bottom-up approach to precise nanotube construction. This dissertation focuses on the synthesis, structural characterization, and functionalization of CPPs, as well as the development of novel synthetic pathways for CNBs. A series of functionalized CPPs, including [9]-, [12]-, [15]-, and [18]CPPs, were synthesized using a modular approach involving a Diels-Alder adduct formation followed by a Ni(cod)2/bpymediated macrocyclization reaction. The influence …

Individual And Collective Properties Of Tunable Photochemical Belousov-Zhabotinsky Micro-Reactors, Kudakwashe Benedict Shumba

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cell-like model chemical systems are powerful tools that can be used to explore the role of intercellular coupling on population level behaviors in communities of biological cells. Firstly, we present a new method for fabricating such micro-reactors using the photosensitive Belousov–Zhabotinsky (BZ) reaction system employed in silica microparticles. These BZ micro-reactors have a tunable response to photochemical coupling, varying from a fully excitatory response to a fully inhibitory response. Their response can be tuned through variations in either the reactive mixture or, on an individual micro-reactor level, by changes in the synthesis temperature used during the fabrication of the silica …

Biomechanics Of The Atherosclerotic Lipidome: (Un)Expected Statin Interactions And Membrane Remodelling, Ethan M. Fong

Pomona Senior Theses

Statins interact with lipid membranes in ways that shape their pharmacokinetics, off-target effects, and pleiotropic actions, yet these interactions' mechanical and biophysical consequences remain poorly understood. This thesis employs a combination of surface plasmon resonance (SPR), quartz crystal microbalance with dissipation monitoring (QCM-D), and rheological modelling to characterize how representative statins intercalate within biomimetic supported lipid bilayers (SLBs) of healthy and diseased composition. SPR reveals that lipophilic statins exhibit higher apparent affinities and slower dissociation kinetics, especially in cholesterol- and anionic lipid-rich membranes. QCM-D analyses demonstrate that statins alter membrane mass, dissipation, and interfacial stiffness in a statin- and membrane-dependent …

Modification Of Nanoparticles For Designed Interfaces, Tony Lee Neely, Jr.

Theses and Dissertations

The work contained herein, is focused on the design, synthesis, and characterization of polymer nanocomposite interfaces and the property enhancement afforded from said interface design. Through the use of reversible addition fragmentation chain transfer (RAFT) polymerization for the grafting of polymer chains to silica nanoparticles, the surface of silica nanoparticles can be manipulated to tune the properties of the nanocomposite as a whole.

In the first part of this work, heterogeneity is introduced onto the surface of silica nanoparticles via a sequential RAFT polymerization to afford a bimodal brush system. A densely grafted, short brush population is polymerized from the …

Oriented Surface Immobilization Of Antibodies Using Enzyme-Mediated Site-Specific Biotinylation For Enhanced Antigen-Binding Capacity, Emily Beitello, Kwame Osei, Trent Kobulnicky, Faith Breausche, Jon A. Friesen, Jeremy D. Driskell

Faculty Publications – Chemistry

The effectiveness of surface-immobilized antibodies is often diminished by improper antibody orientation and limited stability, impeding the analytical performance of biosensors. Here, we report a novel enzyme-mediated strategy to biotinylate the Fc region of an anti-horseradish peroxidase (anti-HRP) antibody with site-specificity that enables oriented immobilization on a streptavidin-functionalized surface. Microbial transglutaminase (mTG) catalyzes the covalent coupling between the amine functional group on a biotin analogue (NH₂-PEG₄-biotin) and the side chain of a privileged glutamine residue (Q295) located on the heavy chain Fc region of IgG antibodies. For comparison, an anti-HRP antibody was biotinylated using an amine-reactive …

Rhenium Chalcogenide Clusters Containing Para-Substituted Phenylacetylide Ligands: Synthesis, Characterization, And Investigation Of Substituent Effects On Spectroscopic And Electrochemical Properties, Katherine L. Helmink, Cory A. Hicks, B. Sage Lauper-Cook, Steven J. Peters, Christopher J. A. Daley, Yann Molard, Lisa F. Szczepura

Faculty Publications – Chemistry

Four new organometallic [Re₆Se₈]²⁺-based cluster complexes containing para-substituted phenylacetylide ligands, [Re₆Se₈(PEt₃)₅(C≡C–C₆H₄–X)](SbF₆) where X = NO₂, CO₂Me, CH₃, and OMe, have been synthesized and fully characterized using ¹H, ¹³C{¹H} and ³¹P{¹H} NMR, IR, and UV–vis spectroscopy, HRMS, and elemental analysis. Three of these cluster complexes, [Re₆Se₈(PEt₃)₅(C≡C–C₆H₄–NO₂)]⁺, [Re₆Se₈(PEt …

Automatic Identification And Visualization Of Reaction Mechanisms Contained Within Direct Dynamics Simulations, Trent Kobulnicky, Emmanuel Boafo, George L. Barnes

Faculty Publications – Chemistry

Direct dynamics simulations are employed in many areas of chemistry and biochemistry. When paired with an appropriate underlying ab initio, semiempirical, or DFT-based potential energy surface and proper sampling of initial conditions, direct dynamics simulations provide an atomic-level view of the reaction dynamics within the system of interest, yielding considerable fundamental insights. Moreover, when a sufficient number of simulations are conducted, they provide a wealth of information regarding the overall trends in reactivity. However, they also generate large data sets that often require significant manual interpretation through inspection or developing case-specific analysis techniques. Here, we present an analysis method …

Synthesis Of Alkyl Substituted Carbatripyrrins And Their Application To The Preparation Of Carbaporphyrins And Oxacarbaporphyrins, Ian A. Mclauchlan, Bethany K.X. Overbey, Tyler J. Smolczyk, John J. Woods, Timothy D. Lash

Faculty Publications – Chemistry

Unsubstituted carbatripyrrins have previously been shown to be useful intermediates in the synthesis of benzocarbaporphyrins and related core-modified analogues. However, the absence of substituents often resulted in the formation of poorly soluble products. In this study, four examples alkyl substituted carbatripyrrins were constructed by base-catalyzed condensation of dihydrofulvenes with pyrrole aldehydes. Further reaction with a pyrrole dialdehyde in the presence of trifluoroacetic acid afforded a series of carbaporphyrins, while reactions with 2,5-furandicarboxaldehyde generated oxacarbaporphyrins. These results demonstrate that alkyl substituted carbatripyrrins are promising precursors to new carbaporphyrinoid structures.

Synthesis Of Phenaliporphyrin, A Pah-Porphyrin Hybrid, From An Acenaphthene-Fused Cyclopropane Dialdehyde, Sunday Oladapo Jacob, Emily D. Harris, Melissa A. Mathius, Deyaa I. Abusalim, Gregory M. Ferrence, Timothy D. Lash

Faculty Publications – Chemistry

Phenaliporphyrin, a new aromatic benziporphyrin derivative, has been synthesized from an annulated cyclopropane dialdehyde intermediate. Corey-Chaykovsky cyclopropanation of dimethyl acenaphthylene-1,2-dicarboxylate gave a cyclopropane diester, and this was converted to the corresponding bis-Weinreb amide. Reduction with lithium aluminum hydride afforded an unstable dialdehyde and subsequent acid-catalyzed condensation with a tripyrrane dicarboxylic acid, followed by oxidation with aqueous ferric chloride, gave the targeted porphyrinoid system. This involves ring expansion of the acenaphthylene precursor to generate the phenalene unit. Phenaliporphyrin exhibits a porphyrin-like UV–vis spectrum with a Soret band at 443 nm and a relatively intense Q-band at 601 nm. The proton NMR …

Catalytic Innovation For Sustainable Styrene Production: Green Chemistry Strategies Utilizing Octahedral Ruthenium (Ii) Complexes Supported By A Single Bipyridine Ligand, Kennedy G. Musso, Brandon Quillian, Clifford Padgett, Jose Jimenez

College of Graduate Studies: Theses & Dissertations

This study investigates: 1) the synthesis and reactivity of the mono- substituted systems, [κ²-(t-bipy)Ru(NCMe)2(Ph)(PR3)][BArF'] supported by different ancillary ligands PR3 = (P(OCH3)3 and P(CH3)3) and a single bidentate ligand, 4,4′-di-tert-butyl-2,2′-bipyridine (t-bipy), and 2) UV/heat formation of di-PR3 and tri-PR3 systems supported by a single bidentate ligand to better understand the mechanism of styrene production. Utilizing [(η6-p-cymene)RuI(µ-I)]2 (1), the complexes (η6-p-cymene)RuI2(P(OCH3)3) (2) and (η6-p-cymene)RuI2(P(CH3)3) (3) were synthesized and phenylated to produce (η6-p-cymene)RuI(Ph)(PR3) (6; PR3 = P(OCH3)3 and 7; PR3 = P(CH3)3). Complex 4, (η6-p-cymene)RuCl2(P(CH3)3), was also synthesized and phenylated to produce (η6-p-cymene)RuClPh(P(CH3)3) (5) to understand the impact of chloride versus iodine …

Unraveling The Reactivity Of Nitrate Ester Explosives: Insights From Femtosecond Time-Resolved Mass Spectrometry And Computational Chemistry, Erica Britt

Theses and Dissertations

This dissertation uncovers the ultrafast molecular mechanisms underlying the decomposition of nitrate ester explosives—nitroglycerin (NG), ethylene glycol dinitrate (EGDN), and amyl nitrate—through the integration of femtosecond time-resolved mass spectrometry and advanced computational chemistry. Although these compounds play fundamental roles in both military and civilian contexts, the precise molecular dynamics governing their pronounced reactivity and impact sensitivity have remained inadequately characterized. Our research establishes that low O–NO2 bond dissociation energies are the primary driver of ultrafast fragmentation and high reactivity in all three esters. The distinctive molecular architectures of these esters dictate their explosive properties: NG’s tri-nitrate configuration leads to exceptional …

Characterization And Optimization Of Sand And Tung Oil-Based Resins For Binder-Jet 3d Printing, Daniel I. Ajiola

College of Graduate Studies: Theses & Dissertations

Binder-jet 3D printing as a transformative technology in additive manufacturing, offers the ability to fabricate complex structures with diverse materials. This thesis investigates the use of a sustainable tung oil-based resin to create composites, exploring the potential for an eco-friendly alternative to synthetic binders.

The aim of this research is to develop and characterize a bio-based resin formulation, using tung oil as the primary binder, for application in binder-jet 3D printing with sand as the reinforcement. The resin formulation was prepared by combining tung oil, n-butyl methacrylate, divinylbenzene, and di-tert-butyl peroxide in precise proportions, ensuring a balanced mixture that supports …

Synthesis And Characterization Of A Biobased Polymer From Tung Oil And Pine Rosin & Characterization Of Polyhydroxybutyrate., Arijanet P. Osumah

College of Graduate Studies: Theses & Dissertations

This thesis presents two independents but thematically aligned research projects focused on the development and evaluation of sustainable polymers. The first involves the synthesis and characterization of a biobased polymer derived from tung oil and pine rosin. Tung oil, which is a triglyceride was chemically modified to produce tung oil diglyceride (TDG), which subsequently reacted with abietic acid-rich pine rosin to yield tung oil abietate (TOA), a biobased monomer. The TOA monomer was polymerized with butyl methacrylate (BMA) and divinylbenzene (DVB) using di-tert-butyl peroxide (DTBP) as a thermal initiator. The resulting polymer was thoroughly characterized using Fourier transform infrared spectroscopy …

Impact Of Y-Mixer Geometry And Flow Rate Modulation On Chemical Gradient Generators In Microfluidic Devices, Elizabeth Thurston Hutton

College of Graduate Studies: Theses & Dissertations

Various microfluidic structures are devised to generate tunable, stable spatiotemporal chemical gradients for single-cell studies. This work addresses the role of Y-mixer junctions in generating nonlinear gradients by increasing the width of one arm (bias), which is suspected to cause premature diffusion within the mixer. This study introduced a cinching feature to narrow the wider arm locally and redefine the junctions of these biased Y-mixers using four novel geometries defined by a 5-micrometer drawing rule. Furthermore, three flow rate factors allowed us to explore the impact on the generated gradient landscapes. The results showed that the four novel designs similarly …

Assessment And Health Benefit Of Vitamin C Using A549 Cell, Yetunde Adepoju

College of Graduate Studies: Theses & Dissertations

Vitamin C (ascorbic acid) is a vital micronutrient recognized for its antioxidant capacity and essential bodily functions, such as collagen formation, neurotransmitter activity, and regulation of the immune system. This study explores how vitamin C can protect and potentially heal cells under oxidative stress and inflammation, using A549 cells, a human lung epithelial cell line, as the model system. The cells were exposed to varying concentrations of vitamin C dissolved in water, DMSO, and 5% DMSO. To assess the outcome, cell viability was measured with an MTT assay. In addition, the expression of key genes related to oxidative stress and …

Facile Synthesis Of Gold, Copper, And Silicon Nanostructures By Laser Ablation In Liquid, Nicholas Simpson

Theses and Dissertations

Metal nanoparticle (NP) synthesis is a continually evolving area of research, owing to the widespread application of NPs in fields such as catalysis, drug delivery, and biosensing. Compared to bulk metal material, NPs contain a larger proportion of surface atoms and exhibit unique optical properties, thus making them ideal for applications where maximizing surface interactions is key. Moreover, their compositions can be altered in several different ways, as evidenced by metal alloy, core/shell, supported, and defective NPs. While conventional synthesis methods are capable of producing NPs in large quantities, they often require conditions of high temperature and pressure, strong reducing …

Development, Synthesis And Characterization Of Advanced Low- Cobalt And High-Nickel Cathode Materials For Lithium-Ion Batteries, Arjun Patel

Theses and Dissertations

This dissertation focuses on the improvement of structural and electrochemical stability of active materials for lithium-ion batteries. It explores the modification strategies to mitigate the issues related to Ni-rich cathode materials, along with the continuous production of cathode precursors using a slug flow reactor to improve the quality of the product.

The First part of the dissertation examines the effect of substitution of cobalt with aluminum and iron on the electrochemical stability of Ni-rich lithium nickel cobalt manganese oxide (NCM) materials. This study investigates how Al and Fe doping work and how they impact the performance and stability of these …

Explorations Of Dna-Single-Walled Carbon Nanotube Interactions To Develop Multiplexed Molecularly Specific Biosensors For Inflammation, Amelia K. Ryan

Dissertations and Theses

Inflammatory cytokines such as interleukin-6 (IL-6) and interleukin-12 (IL-12) are central regulators of immune signaling and key biomarkers of disease, yet existing assays for their detection remain slow, invasive, and lack multiplexing ability. This dissertation advances the development of single-walled carbon nanotube (SWCNT) optical nanosensors capable of real-time, multiplexed, and molecularly specific cytokine detection through innovative use of single-stranded DNA (ssDNA) interfaces.

First, an IL-6-specific DNA aptamer was employed as both a dispersing agent and recognition probe for SWCNT fluorescence sensing. Sequence modifications, including anchor domains, truncations, and thermally induced refolding, were systematically tested to optimize sensitivity and selectivity. The …

Photoswitchable Inhibitors Of Eaat3, Karly Suhr

Electronic Theses & Dissertations (2024 - present)

Azobenzene is a photoswitchable molecule known for its high conversion yield and repeatability. The inclusion of an azobenzene moiety with a known inhibitor of your target of interest allows for greater study of function as well as potential therapies. Three derivatives were designed from azobenzene and known inhibitor of EAATs, TBOA, to synthesize photoswitchable inhibitors of EAATs. Further investigation into the function of EAATs and development of a specific inhibitor for EAAT3, an important glutamate transporter in the brain required for proper function, can then be conducted. Photoisomerization studies on the derivatives were conducted using UV/vis spectroscopy and NMR spectroscopy. …

Synthesis And Characterization Of Eco-Engineered Hollow Fe2o3/Carbon Nanocomposite Spheres: Evaluating Structural, Optical, Antibacterial, And Lead Adsorption Properties, Islam Gomaa

Nanotechnology Research Centre

This work presents a facile mechano-thermal route for the synthesis of carbon-decorated, hollow, mesoporous α-Fe2O3 microspheres. Comprehensive characterization (XRD, XPS, FT-IR, SEM/EDX, TGA, zeta-potential) confirmed the formation of phase-pure hematite with nanoscale crystallites (~19 nm), substantial residual surface carbon (~40 wt%) consistent with Fe–O–C linkages, and a positive surface charge (+15.9 mV). The hierarchical hollow/mesoporous architecture enables fast ion transport and provides extensive interior binding sites, resulting in rapid Pb(II) uptake that reaches 92% removal in ≈15 min at pH 5.0. The adsorption follows a Langmuir isotherm (qmax ≈ 70.6 mg/g) and pseudo-second-order kinetics, indicative of chemisorption coupled to efficient …

First-Principles Modeling Of Nitazoxanide Analogues As Prospective Pfor-Targeted Antibacterials, Islam Gomaa

Nanotechnology Research Centre

Pyruvate:ferredoxin oxidoreductase (PFOR) is a key Achilles’ heel in anaerobic pathogens. We integrate electronic-structure calculations (DFT), cheminformatic QSAR metrics, and residue-resolved docking to distill a concise “recognition code” and translate it into practical design rules. Using nitazoxanide (Nita; ΔG(bind) ≈ −10.0 kcal·mol−1) as a well-established reference, productive binding requires a conserved triad: a hydrogen-bond donor addressing Thr-997 and Cys-840, a π–π stack with Phe-869, and a recurrent π–σ contact to Thr-997 that orients the scaffold. Deacetylation to tizoxanide unmasks the phenolic donor and raises local electrophilicity, yet it also slightly loosens pocket packing (−9.6 kcal·mol−1). Strategic halogenation introduces a σ-hole …