Chemistry Commons^™

Preparation And Capacitance Characteristics Of Nickel Oxide Electrode With Mesh-Like Structure, Hui Xu, Zhen-Jun Peng, Dong-Hong Guo, Jun-Ling Li

Journal of Electrochemistry

The mesh-like structure of NiO electrode was obtained by first preparing the precursors via hydrothermal process using nickel sulfate and carbamide as reactants, sodium hexametaphosphate as a surfactant, and followed by calcination of the precursors at 400 ℃. The structure, morphology and capacitance characteristics of NiO electrode were characterized by XRD, SEM and constant current charge-discharge testing techniques. The effects of hydrothermal temperatures on the electrochemical properties of NiO electrode were investigated. The results showed that the better property of nickel oxide was obtained when the mole ratio of nickel to urea was 1:4 and the hydrothermal temperature was 140℃. …

Electrochemical Behaviors Of Hydroquinone On Polypyrrole/Stab-Nammt/Gc Electrode, Rong Li, Jian Xiong, Wei-Qiong Zhu, Yuan-Yuan Han, Jin Xu, Xiao-Ying He

Journal of Electrochemistry

The PPy/STAB-MMT/GC electrode was made using montmorillonite modified by STAB and polypyrrole (PPy). The electrochemical behaviors of hydroquinone on the PPy/STAB-MMT/GC electrode were researched by cyclic voltammetry and square wave stripping voltammetry (SWSV). The results showed that the electrode reaction occurred on the hydroquinone electrode was controlled by diffusion in PBS (pH=6.0). The number of electron transfer was equal to the number of protons (n=m=1) with the effective area of PPy/STAB-MMT/GC electrode Aeff=0.031 cm². Under the optimized conditions, the linear response of peak current in SWSV with the concentration of hydroquinone in a range of 8.0×10^-6~8.0×10 …

Brief Introduction Of Organic Electrochemistry, Huan Wang, Jia-Xing Lu

Journal of Electrochemistry

Organic electrochemistry is a very useful tool for organic synthesis, not only because of the selective introduction or removal of electrons from organic molecules, but also for its green process. In this paper, electroorganic synthesis has been introduced from the systems, research methods and technologies to the characterization. Most of organic compounds could be electrochemically oxidized or reduced. Here, taking C=C compounds as an example, several kinds of electrochemical organic synthesis reactions are discussed, such as electrochemical addition, electrocatalytic dimrization, electropolymerization, etc. Electroorganic synthesis has been industrialized since 1960s. In this paper, electrosynthesis of adiponitrile was used as an example …

Electrochemical Properties Of Tungstogermanate And Electrocatalysis Of H2O2 On Gew11Co/P-Opd/Gc Electrode, Li-Li Zhu, Jian-Ying Qu, Jue Wang, Hao-Yue Feng

Journal of Electrochemistry

The electrochemical properties of Co-substituted trimeric tungstogermanate containing Keggin fragments were studied. Cyclic voltammograms revealed two couples of reversible redox peaks on glassy carbon (GC) electrode in acid solutions. They corresponded to two-electron reductions accompanying by the additions of four protons and three protons, respectively, both were controlled by adsorption. The differences in the peak potentials of 2-electron-4-proton and 2-electron-3-proton reactions were 31 mV and 35 mV, respectively..Furthermore, the tungstogermanate (GeW11Co) modified GC electrode with functionalization by poly(o-phenylenediamine) (P-oPD) was prepared readily by electropolymerization. The GeW11Co/P-oPD/GC electrode could electrocatalyze the reduction of hydrogen peroxide, which showed good stability and quick …

Preparation And Application Of Nano-Nio As Anode In Lithium-Ion Batteries, Cheng-Dong Bai, Jia-Jia Chen, Qi Zhang, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

In this work, the nano-NiO material was prepared by hydrothermal method. The surface morphologies and electrochemical properties of nano-NiO material were investigated. The special nano-NiO material with porous surface assembling honeycombs(100-200nm) was obtained by using surface active agents. The discharge capacity of nano-NiO electrode up to 2385.7 mAh/g was achieved at current density of 0.1A/g in the first circle,while 1100mAh/g could be maintained after 100 circles. At current density of 2.0A/g, the discharge capacity of 600 mAh/g was obtained. And when the current density was reduced to 0.1A/g, the discharge capacity was restored to 1050 mAh/g. The nano-NiO electrode exhibited …

A Brief Review Of Research Progress In The Development Of Engineering Models For Lithium Ion Batteries, Da-Wei Wang, Dong-Jiang Li, Jun Li, Yong Yang

Journal of Electrochemistry

Lithium ion battery has become an important and popular electrochemical device for energy storage.Suitable evaluation and understanding of electrochemical performance and state of charge play a key role in the applications of lithium ion batteries.Construction and utilization of engineering modeling for lithium ion batteries is an effective way to fulfill this target.In this paper,engineering models of lithium ion batteries based on electrochemical reaction,ionic diffusion and migration are introduced.The emphasis is placed on the development of engineering models by the introduction of side reaction,phase transition,stress and energy.The applications of engineering models in such simulations as charge-discharge,concentration distribution,current distribution,state of charge,stress and …

Superhydrophilic/Superhydrophobic Surface Constructions On Titanium And Their Effects On Anti-Bacterial Properties, Guo-Wei Wang, Qiao-Ling Huang, Ren Hu, Chang-Jian Lin, Hao Wang, Li-Hai Zhang, Pei-Fu Tang

Journal of Electrochemistry

The microbial infection of biomaterials often causes clinic problems and sometimes even leads to the prosthesis failure. It is, therefore, important to prevent the biomaterials from bacterial contamination. This can be done by using anti-bacteria drugs. However, this method causes physiological burdens to the patients and does not always work. To stop the contamination from the just beginning is believed to be a better choice. The first step for infection is the attachment of bacteria on the material. In this work, the thin TiO₂ nanotubes array films were constructed with totally different wettabilities showing either superhydrophobic or superhydrophilic. The …

Indirect Electrochemical Reduction And Cotton Dyeing Process In Fe(Ⅲ)-Oxalate-Calcium Gluconate System, Qing-Zhi Wang, Wei Wang

Journal of Electrochemistry

The electrochemical behavior and possible reaction mechanism in Fe(Ⅲ)-oxalate-calcium gluconate system were studied by cyclic voltammetry. The results showed that Fe(Ⅱ)-gluconate was the final reductant. The reduction time, the working voltage and the cathode area influenced the current efficiency. The high current efficiency of 89% for the indirect electrochemical reduction of Vat Scarlet R could be achieved with reduction time of 10 min, working voltage of 4 V and cathode area of 40 cm² in Fe(Ⅲ)-oxalate-calcium gluconate system.

The Effect Of Oxidation And Support On Tio2(110)-Supported Pdn (N=1-7) Clusters, S. Vincent Ong

Theses and Dissertations

First principles theoretical studies based on a gradient-corrected density functional approach have been carried out on the atomic and electronic properties and oxidation of Pdn (n=1-7) clusters supported on the TiO2(110) surface. The studies are aimed to address some of the fundamental issues related to the properties of supported Pdn clusters used as catalysts in oxidation reactions. Of those issues are the following: What are the atomic structures of Pdn clusters on the TiO2 surface? Upon oxidation, do O atoms from a dissociated O2 molecule spill over onto the underlying TiO2 sup- port? How strongly does spillover oxygen bind? What …

Preparation, Properties, And Reactivity Of Carbonylrhodium(I) Complexes Of Di(2-Pyrazolylaryl)Amido-Pincer Ligands, Sarath Wanniarachchi, Brendan J. Liddle, Sergey V. Lindeman, James R. Gardinier

Chemistry Faculty Research and Publications

A series of six carbonylrhodium(I) complexes of three new and three previously reported di(2-3R-pyrazolyl)-p-Z/X-aryl)amido pincer ligands, (^RZX)Rh(CO), (R is the substituent at the 3-pyrazolyl position proximal to the metal; Z and X are the aryl substituents para- to the arylamido nitrogen) were prepared. The metal complexes were studied to assess how their properties and reactivities can be tuned by varying the groups along the ligand periphery and how they compared to other known carbonylrhodium(I) pincer derivatives. This study was facilitated by the discovery of a new CuI-catalyzed coupling reaction between 2-(pyrazolyl)-4-X-anilines (X = Me or …

Sweep, Step, Pulse, And Frequency-Based Techniques Applied To Protein Monolayer Electrochemistry At Nanoparticle Interfaces, Debbie S. Campbell-Rance, Tran T. Doan, Michael C. Leopold

Chemistry Faculty Publications

Protein monolayer electrochemistry (PME), a strategy using synthetic platforms to study the electron transfer (ET) properties of adsorbed proteins, has been successfully applied to proteins adsorbed at monolayer-protected gold cluster (MPCs) assembled films, an adsorption interface shown to be an effective alternative, compared to traditional self-assembled monolayer (SAM) films, for the immobilization and study of ET proteins. Within PME studies, cyclic voltammetry (CV) remains the most commonly applied electrochemical technique in spite of several limitations that occur when the sweep technique is used at either platform. In particular, CV for PME at MPC films results in analysis complications stemming from …

Synthesis Of Oligopeptide Fragments For An Skp1 Mimetic, Jarret Curtis

Honors Capstones

No abstract provided.

Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, Suwit Suthirakun, Salai Cheettu Ammal, Guoliang Xiao, Fanglin Chen, Andreas Heyden, Hans-Conrad Zur Loye

Faculty Publications

The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO₃ have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO₃ at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO …

Field-Induced Xy And Ising Ground States In A Quasi-Two-Dimensional S=1/2 Heisenberg Antiferromagnet, Yoshimitsu Kohama, Marcelo Jaime, Oscar E. Ayala-Valenzuela, Ross D. Mcdonald, Eun Deok Mun, Jordan F. Corbey, Jamie L. Manson

Chemistry and Biochemistry Faculty Publications

High field specific heat up to 35 T, C-p, and magnetic susceptibility, chi, measurements were performed on the quasi-two-dimensional (2D) Heisenberg antiferromagnet [Cu(pyz)(2)(pyO)(2)](PF6)(2). While no C-p anomaly is observed down to 0.5 K in zero magnetic field, the application of field parallel to the crystallographic ab-plane induces a lambda-like anomaly in C-p, suggesting Ising-type magnetic order. On the other hand when the field is parallel to the c-axis, C-p and chi show evidence of XY-type antiferromagnetism. This dependence upon the field orientation occurs because the extreme two-dimensionality allows the intrinsic (zero field) spin anisotropy to dominate the interlayer coupling, which …

Organometallic Acene Complexes For Electronics Applications, Ilya Vinogradov

Kaleidoscope

No abstract provided.

Heavy Metal Analysis Of Sabine River And Toledo Bend Reservoir Bed Sediments, Michael A. Janusa

Faculty Posters

Core samples were collected from the Sabine River and Toledo Bend Reservoir beds, digested, and analyzed using atomic absorption spectroscopy for several heavy metals. The magnitude of heavy metal concentrations in the bed sediments and the pattern of deposition can help determine which heavy metals are present, the source of heavy metals found in the fish (bed sediment or water), and the source of the heavy metal pollution, if any: industrial, geologic, or atmospheric.

Valine Sulfonamidecinnamic Acid Asymmetric Crystal Reactions, Kraig A. Wheeler, Steven H. Malehorn, Annie E. Egan

Faculty Research and Creative Activity

Racemic and homochiral valine sulfonamidecinnamic acidscrystallize with components aligned by use of thecomplementary features of hydrogen bonds and moleculartopology to give supramolecular dimers. These discretemotifs effectively organize adjacent olefins for UV initiated10 single-crystal-to-single-crystal [2+2] photodimerizationreactions. The racemic crystals produce inversion relatedcyclobutane products, while the desymmetrized crystallinearchitectures of the homochiral phase promote asymmetricphotodimerization with 90% conversion.

Chemical Activity In Yba2cu3o7 − Δ Across The Normal To Superconducting Phase Transition, Juana Vivó Acrivos

Faculty Publications, Chemistry

The Gibbs free enthalpy, chemical activity across the transition temperature to superconductivity, Tc in YBa2Cu3O7 − δ is obtained from reciprocally enhanced X-Ray absorbance, XAS and diffraction, XRD data near the Ba L3,2 edges' energy Ea, and orientations in the X-ray beam for preferred Miller indexed [HKL] planes' scattering, that are enhanced near Tc. The standard enthalpy and entropy for the formation of mixed normal metal/superconducting domains above Tc, determined individually across the two Ba L3,2 edges, to better than a percent accuracy: ΔH≠≥ = − 220 meV, and ΔS≠≥ = − 2 meV/K when 121 ≥ T ≥ 92 …

Measurement Of Magnetic Susceptibility In Pulsed Magnetic Fields Using A Proximity Detector Oscillator, S Ghannadzadeh, M Coak, I Franke, P A. Goddard, J Singleton, Jamie L. Manson

Chemistry and Biochemistry Faculty Publications

We present a novel susceptometer with a particularly small spatial footprint and no moving parts. The susceptometer is suitable for use in systems with limited space where magnetic measurements may not have been previously possible, such as in pressure cells and rotators, as well as in extremely high pulsed fields. The susceptometer is based on the proximity detector oscillator, which has a broad dynamic resonant frequency range and has so far been used predominantly for transport measurements. We show that for insulating samples, the resonance frequency behavior as a function of field consists of a magnetoresistive and an inductive component, …

Templated Synthesis Of Glycoluril Hexamer And Monofunctionalized Cucurbit[6]Uril Derivatives, Derick Lucas, Tsuyoshi Minami, Greg Iannuzzi, Liping Cao, James B. Wittenberg, Pavel Anzenbacher Jr., Lyle Isaacs

Chemistry Faculty Publications

We report that the p-xylylenediammonium ion (11) acts as a template in the cucurbit[n]uril forming reaction that biases the reaction toward the production of methylene bridged glycoluril hexamer (6C) and bis-nor-seco-CB [10]. Hexamer 6C is readily available on the gram scale by a one step synthetic procedure that avoids chromatography. Hexamer 6C undergoes macrocylization. with (substituted) phthalaldehydes 12,14,.15, and 18-in 9 M H2SO4 or concd HCl at room temperature to deliver monofunctionalized CB[6] derivatives 13,16,17, and 19 that are poised for further functionalization reactions: The kinetics of the macrocyclization reaction between hexamer and formaldehyde or phthalaldehyde depends on the presence …

Synthesis And Antiproliferative Activity Of Some Steroidal Lactams, Yanmin Huang, Jianguo Cui, Sijing Chen, Chunfang Gan, Aimin Zhou

Chemistry Faculty Publications

Using cholesterol as starting material, a series of 6-substituted-3-aza-A-homo-3-oxycholestanes and 6-substituted-4-aza-A-homo-3-oxycholestanes were synthesized by the oxidation, reduction, oximation, Beckman rearrangement and condensation reaction. These synthesized compounds displayed a distinct cytotoxicity against MGC 7901, HeLa and SMMC 7404 cancer cells. Our results revealed that the structures of functional groups at position-6 on the steroidal ring are crucial for the IC50 value of antiproliferative activities of these compounds and the cytotoxic activity against MGC 7901 and SMMC 7404 cells was not significantly different between 4-N-lactams and 3-N-lactams when its 6-substituted group was a carbonyl or a hydroximino, but all 3-N-lactams showed a …

Statistical Thermodynamics Of Material Transport In Non-Isothermal Mixtures, Semen Semenov, Martin Schimpf

Chemistry and Biochemistry Faculty Publications and Presentations

This chapter outlines a theoretical framework for the microscopic approach to material transport in liquid mixtures, and applies that framework to binary one-phase systems. The material transport in this approach includes no hydrodynamic processes related to the macroscopic transfer of momenta. In analyzing the current state of thermodynamic theory, we indicate critically important refinements necessary to use non-equilibrium thermodynamics and statistical mechanics in the application to material transport in nonisothermal mixtures.

Optical Properties Of Antiferroelectric Cs2nb4o11: Absorption Spectra And First-Principles Calculations, H. L. Liu, C. R. Huang, G. F. Luo, Wai-Ning Mei

Chemistry Faculty Publications

We report a joint experimental and theoretical investigation of the optical properties of Cs2Nb4O11. In room temperature optical absorption spectra, we found a direct gap about 3.5560.05 eV and charge transfer excitations at about 4.96 and 6.08 eV, which are in good agreement with the first-principles calculations. Upon passing through the 165 C antiferroelectric to paraelectric phase transition, the peak energies of two charge transfer bands display almost no temperature dependence, yet they become even broader and exhibit enhanced oscillator strength. We infer this intriguing behavior as the manifestation of Nb cation distortions due to the charge-lattice interaction.

The Evolution Of Function In Strictosidine Synthase-Like Proteins, Michael A. Hicks, Alan E. Barber, Lesley Ann Giddings, Jenna Caldwell, Sarah E. O'Connor, Patricia C. Babbitt

Chemistry: Faculty Publications

The exponential growth of sequence data provides abundant information for the discovery of new enzyme reactions. Correctly annotating the functions of highly diverse proteins can be difficult, however, hindering use of this information. Global analysis of large superfamilies of related proteins is a powerful strategy for understanding the evolution of reactions by identifying catalytic commonalities and differences in reaction and substrate specificity, even when only a few members have been biochemically or structurally characterized. A comparison of >2500 sequences sharing the six-bladed β-propeller fold establishes sequence, structural, and functional links among the three subgroups of the functionally diverse N6P superfamily: …

Removal Of 2,4-Dichlorophenoxyacetic Acid By Calcined Zn–Al–Zr Layered Double Hydroxide, Allen Chaparadza, Jeanne Hossenlopp

Chemistry Faculty Research and Publications

The adsorption equilibrium, kinetics, and thermodynamics of removal of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solutions by a calcined Zn–Al layered double hydroxide incorporated with Zr⁴⁺ were studied with respect to time, temperature, pH, and initial 2,4-D concentration. Zr⁴⁺ incorporation into the LDH was used to enhance 2,4-D uptake by creating higher positive charges and surface/layer modification of the adsorbent. The LDH was capable of removing up to 98% of 2,4-D from 5 to 400 ppm aqueous at adsorbent dosages of 500 and 5000 mg L⁻¹. The adsorption was described by a Langmuir-type isotherm. The percentage 2,4-D …

Analysis Of Binding Site Hot Spots On The Surface Of Ras Gtpase, Greg Buhrman, Casey O'Connor, Brandon Zerbe, Bradley M. Kearney, Raeanne Napoleon, Elizaveta A. Kovrigina, Sandor Vajda, Dima Kozakov, Evgenii L. Kovrigin, Carla Mattos

Chemistry Faculty Research and Publications

We have recently discovered an allosteric switch in Ras, bringing an additional level of complexity to this GTPase whose mutants are involved in nearly 30% of cancers. Upon activation of the allosteric switch, there is a shift in helix 3/loop 7 associated with a disorder to order transition in the active site. Here, we use a combination of multiple solvent crystal structures and computational solvent mapping (FTMap) to determine binding site hot spots in the “off” and “on” allosteric states of the GTP-bound form of H-Ras. Thirteen sites are revealed, expanding possible target sites for ligand binding well beyond the …

Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Synthetic Studies Directed Toward The Frondosins, Do W. Lee, Rajesh K. Pandey, Sergey V. Lindeman, William A. Donaldson

Chemistry Faculty Research and Publications

A short, 4-step route to the scaffold of frondosin A and B is reported. The [1-methoxycarbonyl-5-(2′,5′-dimethoxyphenyl)pentadienyl]Fe(CO)₃⁺ cation was prepared in two steps from (methyl 6-oxo-2,4-hexadienoate)Fe(CO)₃. Reaction of this cation with isopropenyl Grignard or cyclohexenyllithium reagents affords (2-alkenyl-5-aryl-1-methoxycarbonyl-3-pentene-1,5-diyl)Fe(CO)₃ along with other addition products. Oxidative decomplexation of these (pentenediyl)iron complexes, utilizing CuCl₂, affords 6-aryl-3-methoxycarbonyl-1,4-cycloheptadienes via the presumed intermediacy of a cis-divinylcyclopropane.

C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay

Chemistry Faculty Research & Creative Works

The C1(naphthyl)-H, C2(naphthyl)-H, C3(naphthyl)-H and C8(naphthyl)-H bonds of the naphthyl group present in a group of naphthylazo-2'-hydroxyarenes (H ₂L) have been activated by [Rh(PPh ₃) ₃Cl] in a toluene medium. Here the cyclometallation is accompanied by metal centered oxidation [Rh(i)?Rh(iii)]. All the resulting cyclometallates [Rh(PPh ₃) ₂(L)Cl] (2-5) have been isolated in a pure form. The characterization of the cyclometallates [Rh(PPh ₃) ₂(L)Cl] have been done on the basis of spectral (IR, UV-vis, and FAB mass) data. The structures of the representative cyclometallates 2a, 3a, 4a, 4b and 5b have been determined by …

A Mild One-Pot Conversion Of Alkenes Into Amines Through Tandem Ozonolysis And Reductive Amination, Shivakumar Kyasa, Thomas J. Fisher, Patrick Dussault

Patrick Dussault Publications

The selective reduction of hydroperoxyacetals to aldehydes by sodium triacetoxyborohydride provides the basis for a mild one-pot synthesis of amines from alkenes.

Includes Supplementary Materials.

Nanomolar Binding Of Peptides Containing Noncanonical Amino Acids By A Synthetic Receptor, Leigh A. Logsdon, Christopher L. Schardon, Vijayakumar Ramalingam, Sharon K. Kwee, Adam R. Urbach

Chemistry Faculty Research

This paper describes the molecular recognition of phenylalanine derivatives and their peptides by the synthetic receptor cucurbit[7]uril (Q7). The 4-tert-butyl and 4-aminomethyl derivatives of phenylalanine (tBuPhe and AMPhe) were identified from a screen to have 20–30-fold higher affinity than phenylalanine for Q7. Placement of these residues at the N-terminus of model tripeptides (X-Gly-Gly), resulted in no change in affinity for tBuPhe-Gly-Gly, but a remarkable 500-fold increase in affinity for AMPhe-Gly-Gly, which bound to Q7 with an equilibrium dissociation constant (K_d) value of 0.95 nM in neutral phosphate buffer. Structure–activity studies revealed that three functional groups …