Physical Chemistry Commons^™

Recent Advances In Non-Enzymatic Electrochemical Sensors For Theophylline Detection, Gustria Ernis, Yulia M T A Putri, Muhammad Iqbal Syauqi, Prastika Krisma Jiwanti, Yeni Wahyuni Hartati, Takeshi Kondo, Qonita Kurnia Anjani, Jarnuzi Gunlazuardi

Journal of Electrochemistry

Detection of target analytes at low concentrations is significant in various fields, including pharmaceuticals, healthcare, and environmental protection. Theophylline (TP), a natural alkaloid used as a bronchodilator to treat respiratory disorders such as asthma, bronchitis, and emphysema, has a narrow therapeutic window with a safe plasma concentration ranging from 55.5–111.0 μmol·L^–1 in adults. Accurate monitoring of TP levels is essential because too low or too high can cause serious side effects. In this regard, non-enzymatic electrochemical sensors offer a practical solution with rapidity, portability, and high sensitivity. This article aims to provide a comprehensive review of the recent developments …

In-Situ Electrodeposition Of Feco-Mof On Au Ultramicroelectrode For Highly Sensitive Detection Of Epinephrine, Yan Chen, Shang Jian, Si-Yu Wan, Xiao-Tong Cui, Zhong-Gang Liu, Zheng Guo

Journal of Electrochemistry

Metal-organic framework (MOF) nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors. The rational design of bimetallic MOF-functionalized microelectrode is of importance for improving the electrochemical performance but still in great challenge. In this work, the bimetallic FeCo-MOF nanostructures were assembled onto a gold disk ultramicroelectrode (Au UME, 5.2 μm in diameter) via an in-situ electrodeposition method, which enhanced the sensitive detection of epinephrine (EP). The in-situ electrodeposited FeCo-MOF exhibited a characteristic nanoflower-like morphology and was uniformly dispersed on the Au UME. The FeCo-MOF/Au UME demonstrated excellent electrochemical performance on the detection of EP …

Facile Synthesis Of Tetraaryl Phosphonium Ionic Liquids, Stephanie C. Jones, Devin J. Schwaibold, Grant Meadows, Brennan Shuler, Richard E. Sykora, Frank Rolf Fronczék, James H. Davis, Benjamin Wicker

EKU Faculty and Staff Scholarship

The syntheses of triphenyl-2-pyridylphosphonium salts, [Mopyphos]A, where A-= BF4-, B(C6H5)4-, (CF3SO2)2N-, Sac-, and Ace-. (Sac-= saccharinate, Ace-= acesulfamate) are described. These salts can be synthesized on a multi-gram scale with good yields and have been characterized by NMR, single crystal XRD, and HRMS. Thermal analyses indicate that the bistriflimide (Tf2N-= (CF3SO2)2N-) salts are especially amenable towards high-temperature ionic liquid (IL) applications with decomposition temperatures above 450 degrees C. The synthetic methods described herein can be utilized to generate several phosphonium bistriflimide ILs of the general formula [(C6H5)3P-Ar]Tf2N, where Ar = N-heteroaryl).

Effect Of Pre-Adsorbed Species On High-Pressure Adsorption Of Methane In Zeolite 5a Using Grand Canonical Monte Carlo (Gcmc) Simulations, Kanhamardi Lao, Brooks D. Rabideau

Shelby Hall Graduate Research Forum Posters

Natural gas upgrading, which removes impurities from methane (CH4), is essential for industrial applications, including liquefied natural gas (LNG) production and power generation, as well as for residential use. Removing non-hydrocarbon impurities such as carbon dioxide (CO2), nitrogen (N2), and water vapor (H2O), among others, along with separating heavier hydrocarbon gases from raw natural gas, is required to achieve high- purity methane and prevent pipeline corrosion. Zeolite 5A is a microporous aluminosilicate material with a pore size of approximately 5 Å, containing sodium and calcium cations that balance the framework’s negative charge. Its structure offers high thermal stability and a …

Metal Nitrides As Cathode Hosts For Lithium-Sulfur Batteries, Hai-Ji Xiong, Cheng-Wei Zhu, Ding-Rong Deng, Qi-Hui Wu

Journal of Electrochemistry

Lithium-sulfur batteries are considered as one of the potential solutions as integrating renewable energy systems for large-scale energy storage because of their high theoretical energy density (2600 Wh·kg^–1) and specific capacity (1675 mAh·g^–1). Currently, various strategies have been proposed to overcome the technical barriers, e.g., “shuttle effect”, capacity decay and volumetric change, which impede the successful commercialization of lithium-sulfur batteries. This paper reviews the applications of metal nitrides as the cathode hosts for high-performance lithium-sulfur batteries, summarizes the design strategies of different host materials, and discusses the relationship between the properties of metal nitrides and their …

Enhancing Cycle Life Of Graphite ‖ Lifepo4 Batteries Via Copper Substituted Li2Ni1-XCuXO2 Cathode Prelithiation Additive, Jian-Ming Zheng, Jing-Wen Zhang, Tian-Peng Jiao

Journal of Electrochemistry

Lithium nickel oxide (Li₂NiO₂), as a sacrificial cathode prelithiation additive, has been used to compensate for the lithium loss for improving the lifespan of lithium-ion batteries (LIBs). However, high-cost Li₂NiO₂ suffers from inferior delithiation kinetics during the first cycle. Herein, we investigate the effects of the cost-effective Cu substitution of Li₂Ni_1-xCu_xO₂ (x = 0, 0.2, 0.3, 0.5, 0.7) synthesized by high-temperature solid-phase method on the structure, morphology, electrochemical performance of graphite‖LiFePO₄ battery. The X-ray Diffraction (XRD) refinement result demonstrates that Cu substitution strategy is favorable …

Sno2 Particles Embedded Into Carbon Coated Mesoporous SioX Rod As High Volumetric Capacity Anode For Lithium-Ion Batteries, Jia-Lin Guo, Ni-Ni Li, Peng Zheng

Journal of Electrochemistry

Due to the high capacity and moderate volume expansion of silicon protoxide SiO_x (160%) compared with that of Si (300%), reducing silicon dioxide SiO₂ into SiO_x while maintaining its special nano-morphology makes it attractive as an anode of Li-ion batteries. Herein, through a one-pot facile high-temperature annealing route, using SBA15 as the silicon source, and embedding tin dioxide SnO₂ particles into carbon coated SiO_x, the mesoporous SiO_x-SnO₂@C rod composite was prepared and tested as the anode material. The results revealed that the SnO₂ particles were distributed uniformly in the …

Epr Imaging Workshop: From Theory And Practice To Applications, Arthur H. Heiss, Ralph T. Weber, Sandra S. Eaton, Gareth R. Eaton

TeachEPR Submissions

Methods of imaging and insights from imaging are described. Practical aspects of sample type and dimensions are described.

Workshop presented at the 27th International EPR Symposium, sponsored by Bruker BioSpin EPR Division and the University of Denver, in Denver, Colorado on August 1, 2004.

Workshop On The Epr Of Aqueous Samples, Gareth R. Eaton

TeachEPR Submissions

The problem with water and other materials that absorb microwave energy are described. Dielectric properties are described as a function of frequency.

Workshop presented at the 25th International EPR Symposium on July 28, 2002.

Special Purpose Epr Resonators, Gareth R. Eaton

TeachEPR Submissions

Many types of EPR resonators are described.

Special applications that use various resonators are mentioned.

Lab Practical: Cw Basics, Gareth R. Eaton

TeachEPR Submissions

1. How do you position the sample in the resonator?
2. How do you select the center field for a spectrum?
3. How do you select the modulation amplitude?
4. How do you select the microwave power?

Lab Practical: Transition Metals: Epr Of A Vanadyl Complex, Gareth R. Eaton

TeachEPR Submissions

1. What information can you obtain from a spectrum of one orientation of a single crystal that is wide enough to encompass all of the vanadium hyperfine lines?

2. How does the spectrum change when you rotate the crystal? Look at both the position of the center of the spectrum and the hyperfine splitting.

Lab Practical: Pulse Epr, Gareth R. Eaton

TeachEPR Submissions

1. How do you over-couple the resonator for a pulse experiment?
2. How do you find a 2-pulse echo?
3. How do you select the microwave attenuation?

How To Measure Q, Gareth R. Eaton

TeachEPR Submissions

•Frequency bandwidth
–Using spectrometer frequency sweep
–Using a network analyzer

•Ring down following a pulse

Lab Practical: Nitroxides, Gareth R. Eaton

TeachEPR Submissions

1. How do you fill a capillary tube with an aqueous solution? How are capillaries positioned in the resonator?
2. How does the spectrum of a nitroxide change when the viscosity of a solution is increased?
3. How do you determine the concentration of the radical in the solution?

How To Measure B1, Gareth R. Eaton

TeachEPR Submissions

• CW Methods
• Pulsed EPR Methods

Lab Practical: Rapid Scan Epr, Gareth R. Eaton

TeachEPR Submissions

• To develop an understanding of the rapid scan experiment relative to other EPR methods.
• To observe the effects of scan rate on samples with differing T₂ relaxation times.

Infrared Cooling In An Anharmonic Cascade Framework: 2-Cyanoindene, The Smallest Cyano-Pah Identified In Tmc-1, Mark H. Stockett, Vincent J. Esposito, Eleanor K. Ashworth, Ugo Jacovella, James N. Bull

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Infrared (IR) cooling of polycyclic aromatic hydrocarbon (PAH) molecules is a major radiative stabilization mechanism of PAHs present in space and is the origin of the aromatic infrared bands (AIBs). Here, we report an anharmonic cascade model in a master equation framework to model IR emission rates and emission spectra of energized PAHs as a function of internal energy. The underlying (simple harmonic cascade) framework for fundamental vibrations has been developed through the modeling of cooling rates of PAH cations and other carboneaous ions measured in electrostatic ion storage ring experiments performed under “molecular cloud in a box” conditions. The …

Motion Of Nitroxide Radicals, Gareth R. Eaton

TeachEPR Submissions

A brief outline is presented of how motion of a nitroxide radical can be estimated from the continuous wave (CW) EPR line shape.

Types Of Epr Resonators, Gareth R. Eaton

TeachEPR Submissions

Fundamental properties of resonators are described with photographs of a variety of actual EPR resonators.

Distances Between Spins, Gareth R. Eaton

TeachEPR Submissions

• Distance measurement by measuring T₁ and T_2.
• Relation to DEER and CW simulation and half-field intensity.
• Dipolar and exchange interactions.
• The dynamic NMR spectral collapse picture.

Epr Workshop: Lab Practicals Summary, Gareth R. Eaton

TeachEPR Submissions

• Basics – nitroxide and trityl
• Nitroxides
• Metals - vanadyl
• Pulse
• Rapid scan

Workshop On Quantitative Epr, Dave Barr, Sandra S. Eaton, Gareth R. Eaton, Ralph T. Weber, Patrick Carl, Peter Höfer, Richard W. Quine, George A. Rinard, Colin Mailer

TeachEPR Submissions

Presentations on quantitative EPR at the workshop that preceded the writing of our text, Quantitative EPR.

Presented at the 31^st Annual EPR Symposium in Breckenridge, Colorado on July 27, 2008.

Vanadium Line Shapes, Gareth R. Eaton

TeachEPR Submissions

VO²⁺ complexed with water, acetylacetonate, and/or other ligands yields a well-resolved 8-line spectrum (I = 7/2 for V) in solution. Powder spectra show that the hyperfine couplings are anisotropic.

Consequences Of Oxidative Dna Damage: Base-Pair Dissociation, Singlet Oxygenation And Dna-Protein Crosslinking, May Myat Moe

Dissertations, Theses, and Capstone Projects

8-Oxo-2′-deoxyguanosine (OG) is a common DNA lesion resulting from oxidatively generated damage and pairs with complementary cytidine (C) in Watson Crick base-pairing within duplex DNA. The WC-OG·C lesion, if not recognized or repaired, not only leads to G⋅C→T⋅A transversion mutations (through Hoogsteen (HG) base pairing of OG⋅A), but also renders the base pair being more vlunerable to ionizing radiation and singlet oxygen (1O2) damage. Leveraging on our previous accomplishments on the study of gas-phase reactions of 1O2 with 2′-deoxyguanosine radical cations, my research thesis expanded to the investigation of reaction dynamics of 9-methyl-8-oxoguanine (9MOG) radical cations. The experiments of following …

Investigating Dna Damage Caused By Reactive Oxygen And Nitrogen Species Via Guided-Ion-Beam Scattering And Computational Techniques, Jonathan Benny

Dissertations, Theses, and Capstone Projects

Among DNA nucleobases, guanine (G) is the primary target for one-electron ionization and oxidation, generating G●+ through various processes, including photooxidation, electrocatalytic oxidation, DNA-binding transition metals, ionizing radiation, and photolysis. This is due to the low adiabatic ionization potential and oxidation potential of guanine. Electron holes from other nucleobases can move to guanine, proving that G●+ production traps oxidative DNA damage. G●+ formation can exacerbate DNA damages and cause secondary reactions from reactive oxygen species (ROS) and reactive nitrogen species (RNS) during pathological processes. The following three projects were conducted using a customized electrospray ionization (ESI) guided-ion-beam tandem mass spectrometer, …

Studies On The Synthesis, Function, And Properties Of Troponoids, John-Charles A. Baucom

Dissertations, Theses, and Capstone Projects

Troponoids are a unique class of non-benzenoid aromatic compounds with a wide range of demonstrated applications in pharmaceuticals and molecular sensing. The cycloheptatrienone scaffold possesses a noteworthy degree of tunability as a function of ring oxygenation. This manuscript describes our efforts toward a better understanding of the physical consequences of the scaffold to better utilize the motif. Chapter the first discusses our efforts at elucidating the mechanism of troponoid inhibition of the Hepatitis B virus reverse transcriptase RNAse H enzymatic domain. Using homology modeling in conjunction with traditional in vitro assays we were able to establish the likely mechanism of …

The Role Of Confined Hydration And Water Reorganization In Molecular Binding, Joe Z. Wu

Dissertations, Theses, and Capstone Projects

An important factor in guiding the development of drug discovery efforts is the comprehensive assessment of a ligand or drug’s ability to bind its receptor. The metric used to measure this interaction strength is by calculating the binding free energy (BFE). To achieve this accurately, we combine two concepts: (1) Grid Inhomogeneous Solvation Theory (GIST) returns the local water thermodynamic and structural contributions to free energy; and the (2) Alchemical Transfer Method (ATM) obtains the absolute (ABFE) and relative binding free energy (RBFE) estimates between ligand pairs. In this work, we employ Alchemical Water-Transfer to tether bridging water(s) during the …

Dft Study Of The Mechanism Of Selective Hydrogenation Of Acetylene By Rhodium Single-Atom Catalyst Supported On Hy Zeolite, Melisa Su Yordanlı, Roberto Escobar, Jessica Meza, Deniz Akgül, Yuxin Zhao, Alper Uzun, Fatma Ahu Akin, Viktorya Aviyente, Abdurrahman Cagri Atesin, Tülay A. Ateşin

School of Earth, Environmental, & Marine Sciences Faculty Publications

The selectivity of acetylene hydrogenation by the Rh single-atom catalyst (SAC) supported on HY zeolite was investigated using density functional theory (DFT) and a 5/83T quantum mechanics/molecular mechanics (QM/MM) embedded cluster model. The calculated activation barrier (ΔG‡) for the oxidative addition of dihydrogen to the Rh metal center (15.9 kcal/mol) is lower in energy than that for the σ-bond metathesis of dihydrogen to the Rh—C bond (22.7 kcal/mol) and the Rh—O bond (28.4 kcal/mol). The activation barriers of the oxidative addition of subsequent dihydrogen molecules are significantly higher than that of the oxidative addition of the first dihydrogen molecule. These …

Introduction To Epr, Gareth R. Eaton

TeachEPR Submissions

A very brief introduction to the scope of EPR at the beginning of a workshop in 2019.