Physical Chemistry Commons^™

The Effects Of Free Volume And Processing On The Development Of Gas Separation Membranes, Jacob Schekman

Dissertations

Structure, thermal, mechanical, gas transport, and free volume properties of thiol-ene based systems are investigated and discussed. In the pursuit of generating low energy-cost polymer membranes for gas separation, it became apparent that UV-curing of thiol-ene materials presented several routes toward achieving this goal. Network structure plays a vital role in determining the gas transport properties of membrane materials. UV photopolymerization techniques provide a means to rapidly vitrify network morphologies which can be tuned depending on choice of monomer. Thiol-ene monomers offer a broad range of precursor materials from which to choose for the design of functional membrane materials.

Chapter …

Development Of An Enhanced Sampling Workflow To Accelerate Molecular Docking With Sparse Biophysical Information, Zachary Stichter

Masters Theses & Specialist Projects

Rapid docking of flexible biological macromolecules remains a significant open challenge in protein structure determination. While rigid docking is relatively simple with toolkits such as TagDock, a key obstacle to rapid flexible docking is the complexity and roughness of the free energy surface associated with protein conformational motion (often termed the many-minima problem), meaning conventional molecular dynamics methods do not effectively sample protein conformations near the interaction complex in accessible timescales. Methods such as metadynamics and replica exchange molecular dynamics exist to ameliorate this obstacle, yet these methods use nonphysical biases or random swaps to enhance sampling. In contrast, high …

Development Of A High-Resolution Mid-Infrared Spectroscopy Apparatus For The Study Of Methane And Other Astrochemical Molecules., S M Shah Riyadh

Electronic Theses and Dissertations

This research documents steps towards building a novel spectroscopic technique, namely, cavity-enhanced double-resonance (CEDR) spectroscopy, for investigating methane (CH₄) and other molecules with significance in astrochemistry. These efforts focus on tackling the complexities of their ro-vibrational energy levels and the inefficiencies in analyzing vibrational spectra, particularly for molecules with high symmetry and strong intramolecular interactions. In the CEDR spectroscopy, the first photon, generated by a continuous-wave optical parametric oscillator (CW-OPO) locked to a Doppler-free saturation absorption line, excites the molecule from its ground level to a selected excited ro-vibrational (rotational-vibrational) level, e.g., that of the asymmetric CH-stretch mode. …

Magnetic Properties Of Zgnrs With Nitrogen And Fluorine Adsorbates, A Computational Study, Justin Petit

Electronic Theses and Dissertations

Imposing dimensional restrictions on graphene sheets and adding impurities can give rise to carbon nanostructures with magnetic properties. In this work, zigzag graphene nanoribbons, zGNRs, with nitrogen and fluorine adatoms are investigated for magnetic properties of interest for spin devices. Geometry optimizations were done determining which position along a zGNR electrode that N and F would favorably attach to. Edge positions were determined as the most stable attachment site. M-cell zGNR electrodes (M = 1-3) edge-functionalized by N and F adatoms were investigated with respect to their band structures and spin densities in antiferromagnetic and ferromagnetic, AFM and FM, configurations. …

Computational Study Of Fluorescent Molecular Probes For The Early Detection Of Alzheimer's Disease, Gabriela Elizabeth Molina Aguirre

Open Access Theses & Dissertations

Alzheimer's disease is a debilitating brain disorder that affects memory, thinking, and behavior. It is the most prevalent form of dementia and the seventh leading cause of death in the United States. As, researchers have identified biomarkers that can indicate the presence of the disease many years before the first symptoms appear, so there is an opportunity for early detection and treatment follow-ups, which could significantly improve the quality of life for those affected by this disease.This dissertation investigates the relationship between molecular structure and optical properties of donor-bridge-acceptor (DBA) fluorescent molecular probes designed for detecting Amyloid-β and p-Tau protein …

Computational Investigation Of Transition Metal Photoredox Catalysis: Redox Property Tuning Via Ligand Modification, Christian Fernando Sandoval Pauker

Open Access Theses & Dissertations

In the last decade, photoredox catalysis has become a powerful tool in synthetic chemistry. It relies on the ability of catalytic systems that facilitate energy-demanding redox reactions thanks to photoinduced electron transfer processes. This dissertation focuses on the computational investigation of the redox properties of transition metal photoredox catalysts using density functional theory (DFT) calculations. The research systematically explores the effects of altering redox-active ligands on the thermodynamics of electron transfer events in the photoredox cycle. The electronic structure changes throughout oxidative and reductive quenching cycles are analyzed, with a particular focus on Cu(I) complexes. Through computational techniques, insights into …

Electrochemical Modulation Of Surface Plasmon Wave To Investigate Dna-Based Sensing Platforms And Detection Of Sars-Cov2., Anil Sharma

Electronic Theses and Dissertations

This study offers a thorough comparative analysis of optical and electrical signaling strategies for assessing the electrochemical properties of different redox-labeled DNA-based biosensing platforms. In addition, it illustrates the development of an optical interrogation technique with electrochemical modulation of surface plasmon waves (ECM-SPW) as a route for analyzing and implementing DNA-based hybridization sensors. For those quantitative analyses, we chose a model sensing platform composed of a methylene blue (MB)-modified single-stranded DNA (ssDNA) signaling probe and an unlabeled capture ssDNA probe that complements the signaling probe. Two types of signaling probes were employed in this work: one with MB attached to …

Electrocatalytic Cyclopropanation Of Active Methylene Compounds, Liang-Hua Jie, Hai-Chao Xu

Journal of Electrochemistry

The development of novel strategies to access cyclopropanes has become increasingly important due to the vital role of these three-membered ring structures in synthetic intermediates, natural products, and pharmaceuticals. Herein, we present an electrocatalytic method for the synthesis of cyclopropanes through intermolecular dehydrogenative annulation of active methylene compounds and arylalkenes. This electrochemical process requires no chemical oxidants, allowing for a speedy access to various functionalized cyclopropanes from inexpensive and readily available materials.

Electrochemical Syntheses Of Aryl-Substituted Benzothiophenes And Phenanthrenes Using Benzenediazonium Salts As The Aryl Radical Precursors, Li-Yuan Lan, Yang-Ye Jiang, Raymond Daniel Little, Cheng-Chu Zeng

Journal of Electrochemistry

Aryl-substituted benzothiophene and phenanthrene are important structural units in medicinal chemistry and materials science. Although extensive effort has been devoted to prepare these compounds and a variety of approaches have been developed to construct the 2-substituted benzothiophene core structure, environmental-friendly and efficient synthetic means are still desired. Based on our previous electrochemical Minisci-type arylation reaction with aryl diazonium salt as the aryl precursor, as well as the work from König’s group, herein, we described the use of paired electrolysis to achieve 2-aryl benzothiophenes and 9-aryl phenanthrenes employing benzenediazonium salts as the aryl radical precursors. Initially, 2-methylthiobenzendiazonium salt 1a and 4-methylbenzene …

Electrochemical Advanced Treatment Of Desulfurization Wastewater From Coal-Fired Power Plants, Ju-Cai Wei, Juan Yi, Xu Wu

Journal of Electrochemistry

Zero-emission of desulfurization wastewater is one of the main demands for coal-fired power plants. As typical high salinity wastewater, it is hard to purify the desulfurization wastewater from coal-fired power plants through traditional physicochemical treatment or biochemical treatment, e.g., COD and Cl^–. A high concentration of Cl^– ion in desulfurization wastewater restricts wastewater reuse and zero-emission. Electrochemical technology is an attractive method for high salinity wastewater zero-emission, which provides a versatile, efficient, cost-effective, easily automatable, and clean industrial process. For advanced treatment of effluent after triple box process treatment in power plants, this paper reports an electrochemical …

Investigation Of Surface Chemistry From Electron Irradiation Of Synthetic Schreibersite, Tyler Davis

Master's Theses

While phosphorus is one of the key elements for life on Earth, it has relatively low abundance in extraterrestrial environments, making it a target for astronomers and astrobiologists interested in the possibility of life beyond our planet. Schreibersite (Fe,Ni)₃P is one of the first P-containing minerals to condense during planetary cooling and one of the primary P-containing minerals in iron and stony-iron meteorites. Therefore, it is a likely P-bearing mineral in cometary cores and dust grains within the interstellar medium and circumstellar envelopes. Experiments in this project were performed with the aim of observing the formation of small …

Physical And Chemical Methods To Assess Performance Of Tpo-Modified Asphalt Binder, Rebecca M. Herndon, Jay Balasubramanian, Klaus Woelk, Magdy Abdelrahman

Chemistry Faculty Research & Creative Works

The Demand for Effective Asphalt Additives is Growing as Road Infrastructure Ages and More Sustainable Pavement Solutions Are Needed. Tire Pyrolysis Oil (TPO) is an Example Material that Has Been Gaining Attention as a Potential Asphalt Additive. While Physical Performance Grade (PG) Temperatures Are the Predominant Performance Requirements for Asphalt Binders, Chemical Properties Are Also Significant in the Evaluation of Asphalt Performance. There is a Need to Chemically Characterize the Aging of Asphalt Binders Modified with TPO and Link Chemical Changes in Binder Components to Binder Performance. This Study Compares 2%, 4%, and 8% TPO and Asphalt Binder Blends Via …

Elucidating The Effect Of Surface Modifications On Nanomaterial Function, Nicholas Langer

Dissertations (1934 -)

Nanoparticles (NPs) are an exciting class of materials with unique properties that inspire their use in sensing, catalysis, optoelectronic devices, and more. NPs are frequently coated in organic molecules, termed ligands, to increase their stability, but ligands also influence NP catalytic activity and their interactions with neighboring molecules. To fully realize the potential of nanomaterials as key components in novel complex systems, a more nuanced understanding of the relationships between NPs, ligands, and their surrounding microenvironment is critical. After a brief review of the NP field in Chapter 1, Chapter 2 begins the investigation of structure-function relationships with a cross-class …

Probing Charge Transport Mechanisms In 2d Semiconductive Metal Organic Framewoks, James Nyakuchena

Dissertations (1934 -)

Metal organic frameworks (MOFs) are a class of highly porous crystalline materials constructed from metal nodes connected by multitopic organic ligands. Due to their unique properties such as large surface area, tunable pore structure, and structural diversity, they have demonstrated potential in a wide array of applications including gas storage and separation, sensing, catalysis, and drug delivery. However, there are only a handful of MOFs reported that have electrical conductivity, which prevents their applications in photoelectronic and photocatalytic applications. This is because hard metals and redox inactive ligands with terminal hard linking bases such as carboxylates are often used in …

Recent Advances In Solar Photo(Electro)Catalytic Nitrogen Fixation, Jun-Bo Ma, Sheng Lin, Zhiqun Lin, Lan Sun, Chang-Jian Lin

Journal of Electrochemistry

Ammonia (NH₃) is an essential chemical in modern society. It is currently produced in industry by the Haber-Bosch process using H₂ and N₂ as reactants in the presence of iron-based catalysts at high-temperature (400–600 ^oC) and extremely highpressure (20–40 MPa) conditions. However, its efficiency is limited to 10% to 15%. At the same time, a large amount of energy is consumed, and CO₂ emission is inevitably. The development of a sustainable, clean, and environmentally friendly energy system represents a key strategy to address energy crisis and environmental pollution, ultimately aiming to achieve carbon neutrality. …

The Determination Of Pzc And Differential Capacitance Curve Of Platinum-Alkaline Polymer Electrolyte Interfaces, Chen-Xi Liu, Ze-Ping Zou, Mei-Xue Hu, Yu Ding, Yu Gu, Shuai Liu, Wen-Jing Nan, Yi-Chang Ma, Zhao-Bin Chen, Dong-Ping Zhan, Qiu-Gen Zhang, Lin Zhuang, Jia-Wei Yan, Bing-Wei Mao

Journal of Electrochemistry

Alkaline polymer electrolyte (APE) is the core component of modern alkaline hydrogen and oxygen fuel cells, and its single ion conductor nature makes the "electrode/APE" interfaces different from the conventional "electrode/solution" interfaces in terms of ion distribution, electrical double layer structure and polarization behavior. Due to the complexity of the APE and the associated solid-solid interfaces, fundamental investigations are challenging and deeper understanding of the structures and properties of such interfaces is in the infant stage. In this work, we aim to investigate the double layer structure from the aspects of differential capacitance curve and potential of zero charge (PZC) …

Micropatterning And Functionalization Of Single Layer Graphene: Tuning Its Electron Transport Properties, Miao-Miao Cui, Lian-Huan Han, Lan-Ping Zeng, Jia-Yao Guo, Wei-Ying Song, Chuan Liu, Yuan-Fei Wu, Shi-Yi Luo, Yun-Hua Liu, Dong-Ping Zhan

Journal of Electrochemistry

As a promising 2D material, graphene exhibits excellent physical properties including single-atom-scale thickness and remarkably high charge carrier mobility. However, its semi-metallic nature with a zero bandgap poses challenges for its application in high-performance field-effect transistors (FETs). In order to overcome these limitations, various approaches have been explored to modulate graphene's bandgap, including nanoscale confinement, external field induction, doping, and chemical micropatterning. Nevertheless, the stability and controllability still need to be improved. In this study, we propose a feasible method that combines electrochemical bromination and photolithography to precisely tune the electron transport properties of single layer graphene (SLG). Through this …

Size Limits And Fission Channels Of Doubly Charged Noble Gas Clusters, Ianessa Stromberg, Stefan Bergmeister, Lisa Ganner, Fabio Zappa, Paul Scheier, Olof Echt, Elisabeth Gruber

Faculty Publications

Small, highly charged liquid droplets are unstable with respect to spontaneous charge separation when their size drops below the Rayleigh limit or, in other words, their fissility parameter X exceeds the value 1. The absence of small doubly charged atomic cluster ions in mass spectra below an element-specific appearance size n_a has sometimes been attributed to the onset of barrierless fission at X = 1. However, more realistic models suggest that n_a marks the size below which the rate of fission surpasses that of competing dissociative channels, and the Rayleigh limit of doubly charged van der Waals clusters …

Mechanistic Investigation Of C—C Bond Activation Of Phosphaalkynes With Pt(0) Complexes, Roberto M. Escobar, Abdurrahman C. Ateşin, Christian Müller, William D. Jones, Tülay Ateşin

Research Symposium

Carbon–carbon (C–C) bond activation has gained increased attention as a direct method for the synthesis of pharmaceuticals. Due to the thermodynamic stability and kinetic inaccessibility of the C–C bonds, however, activation of C–C bonds by homogeneous transition-metal catalysts under mild homogeneous conditions is still a challenge. Most of the systems in which the activation occurs either have aromatization or relief of ring strain as the primary driving force. The activation of unstrained C–C bonds of phosphaalkynes does not have this advantage. This study employs Density Functional Theory (DFT) calculations to elucidate Pt(0)-mediated C–CP bond activation mechanisms in phosphaalkynes. Investigating the …

Doubly Charged Dimers And Trimers Of Heavy Noble Gases, Gabriel Schöpfer, Stefan Bergmeister, Milan Ončák, Ianessa Stromberg, Masoomeh Mahmoodi-Darian, Paul Scheier, Olof Echt, Elisabeth Gruber

Faculty Publications

Many doubly charged heteronuclear dimers are metastable or even thermodynamically stable with respect to charge separation. Homonuclear dicationic dimers, however, are more difficult to form. He₂²⁺ was the first noble gas dimer predicted to be metastable and, decades later, observed. Ne₂²⁺ is the only other dicationic noble gas dimer that has been detected so far. Here, we present a novel approach to form fragile dicationic species, by post-ionization of singly charged ions that are embedded in helium nanodroplets (HNDs). Bare ions are then extracted by colliding the HNDs with helium gas. We detect homonuclear doubly charged …

The Infrared Absorption Spectrum Of Phenylacetylene And Its Deuterated Isotopologue In The Mid- To Far-Ir, Vincent J. Esposito, Pierro Ferrari, Wybren Jan Buma, Ryan C. Fortenberry, Christiaan Boersma, Alessandra Candian, Alexander G. G. M. Tielens

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Anharmonicity strongly influences the absorption and emission spectra of polycyclic aromatic hydrocarbon (PAH) molecules. Here, IR–UV ion-dip spectroscopy experiments together with detailed anharmonic computations reveal the presence of fundamental, overtone, as well as 2- and 3-quanta combination band transitions in the far- and mid-infrared absorption spectra of phenylacetylene and its singly deuterated isotopologue. Strong absorption features in the 400–900 cm⁻¹ range originate from CH(D) in-plane and out-of-plane wags and bends, as well as bending motions including the C≡C and CH bonds of the acetylene substituent and the aromatic ring. For phenylacetylene, every absorption feature is assigned either directly or …

Role Of Electronegativity In Environmentally Persistent Free Radicals (Epfrs) Formation On Zno, Syed Monjur Ahmed, Reuben Oumnov, Orhan Kizilkaya, Randall W. Hall, Philip T. Sprunger, Robert L. Cook

Natural Sciences and Mathematics | Faculty Scholarship

Environmentally persistent free radicals (EPFRs), a group of emerging pollutants, have significantly longer lifetimes than typical free radicals. EPFRs form by the adsorption of organic precursors on a transition metal oxide (TMO) surface involving electron charge transfer between the organic and TMO. In this paper, dihalogenated benzenes were incorporated to study the role of electronegativity in the electron transfer process to obtain a fundamental knowledge of EPFR formation mechanism on ZnO. Upon chemisorption on ZnO nanoparticles at 250 °C, electron paramagnetic resonance (EPR) confirms the formation of oxygen adjacent carbon-centered organic free radicals with concentrations between 1016 and 1017 spins/g. …

Water Potential From Adaptive Force Matching For Ice And Liquid With Revised Dispersion Predicts Supercooled Liquid Anomalies In Good Agreement With Two Independent Experimental Fits, Raymond Weldon, Feng Wang

Chemistry & Biochemistry Faculty Publications and Presentations

A revised version of the Water potential from Adaptive force matching for Ice and Liquid (WAIL) was developed by using the previous data set for fitting the WAIL model but with a dispersion term calculated using symmetry adapted perturbation theory (SAPT). The model has no adjustable parameters and relies solely on fitting first-principles information. The new model, named revised WAIL (rWAIL), shows improved predictions of most properties of water when compared to the previously published WAIL model. The rWAIL model also compares favorably to other first-principles-derived water models, such as MB-Pol, at only a fraction of the computational cost. The …

Joint Time-Frequency Analysis: Taking Charge Penetration Depth And Current Spatial Distribution In The Single Pore As An Example, Nan Wang, Qiu-An Huang, Wei-Heng Li, Yu-Xuan Bai, Jiu-Jun Zhang

Journal of Electrochemistry

In recent years, joint time-frequency analysis has once again become a research hotspot. Supercapacitors have high power density and long service life, however, in order to balance between power density and energy density, two key factors need to be considered: (i) the specific surface area of the porous matrix; (ii) the electrolyte accessibility to the intra-pore space of porous carbon matrix. Electrochemical impedance spectra are extensively used to investigate charge penetration ratio and charge storage mechanism in the porous electrode for capacitance energy storage. Furthermore, similar results could be obtained by different methods such as stable-state analysis in the frequency …

Automated Workflow For Redox Potentials And Acidity Constants Calculations From Machine Learning Molecular Dynamics, Feng Wang, Jun Cheng

Journal of Electrochemistry

Redox potentials and acidity constants are key properties for evaluating the performance of energy materials. To achieve computational design of new generation of energy materials with higher performances, computing redox potentials and acidity constants with computational chemistry have attracted lots of attention. However, many works are done by using implicit solvation models, which is difficult to be applied to complex solvation environments due to hard parameterization. Recently, ab initio molecular dynamics (AIMD) has been applied to investigate real electrolytes with complex solvation. Furthermore, AIMD based free energy calculation methods have been established to calculate these physical chemical properties accurately. However, …

Measurements Of Rate Constant For Electrode Reactions, Lian-Huan Han, Jia-Yao Guo, Miao-Miao Cui

Journal of Electrochemistry

Standard electron-transfer rate constant is one of the intrinsic properties for an electrochemical reaction, which is significant in the study of electrode kinetics. It is a key criterion for one to clarify the mechanism and pathway of a specific electrochemical reaction, and to screening and design the electrocatalysts and battery materials. Herein, we will introduce the measuring methods of rate constant for electrode reactions, including polarization curve, rotating disk electrode, ultramicroelectrode, scanning electrochemical microscopy, electrochemical impedance spectroscopy, current step, potential step and cyclic voltammetry, etc., to provide a guide to investigate electrode kinetics for graduate students and researchers in the …

Confirmation Of Anomalous-Heat Report, Steven B. Krivit, Melvin H. Miles

Journal of Electrochemistry

This study identifies, for the first time, critical calculation errors made by Nathan Lewis and his co-authors, in their study presented on May 1, 1989, at the American Physical Society meeting in Baltimore, Maryland. Lewis et al. analysed calorimetrically measured heat results in nine experiments reported by Martin Fleischmann and his co-authors. According to the Lewis et al. analysis, each of the experiments, where calculated for no recombination, showed anomalous power losses. When we used the same raw data, our corrected calculations indicate that each experiment showed anomalous power gains. As such, these data suggest the possibility of a new, …

Rational Design Of Peptide-Based Materials Informed By Multiscale Molecular Dynamics Simulations, Dhwanit Rahul Dave

Dissertations, Theses, and Capstone Projects

The challenge of establishing a sustainable and circular economy for materials in medicine and technology necessitates bioinspired design. Nature's intricate machinery, forged through evolution, relies on a finite set of biomolecular building blocks with through-bond and through-space interactions. Repurposing these molecular building blocks requires a seamless integration of computational modeling, design, and experimental validation. The tools and concepts developed in this thesis pioneer new directions in peptide-materials design, grounded in fundamental principles of physical chemistry. We present a synergistic approach that integrates experimental designs and computational methods, specifically molecular dynamics simulations, to gain in-depth molecular insights crucial for advancing the …

Thin-Film Nanocomposite Membranes With Alumina Nanoparticles For Textile Wastewater Treatment Applications, Amr Mohamed Tayel

Theses and Dissertations

Thin-film nanocomposite (TFN) membranes are gaining great interest in industrial wastewater treatment due to their superior performance, especially for higher water flux and pollutants’ rejection, as well as improved chemical, thermal and mechanical stabilities, compared to other types of membranes. The performance of TFN membranes can be enhanced using different types of nanofillers, among which ceramic nanomaterials, such as Al2O3, offer a promising potential for applications involving treatment of industrial wastewater such as textile effluents, and this is due to their stability, hydrophilicity, and relative low cost. The study of the TFN membrane properties and structure allows the optimization and …

On The Exact Helium Wave Function Expansion, Ii, An Exponential Modulated Form, Carl W. David

Chemistry Education Materials

A 1¹S wave function’s expansion for 2 electron atoms and ions is proposed employing an appropriate exponential factor and Fock’s logarithmic terms. The leading coefficient’s are presented.