Chemistry Commons^™

Localized Surface Plasmon Resonance Of Single Silver Nanoparticles Studied By Dark-Field Optical Microscopy And Spectroscopy, Wei Cao, Tao Huang, Xiao-Hong Nancy Xu, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

Localized surface plasmon resonance (LSPR) of Ag nanoparticles (NPs) with different shapes and disk-shaped Ag NP pairs with varying interparticle distance is studied using dark-field optical microscopy and spectroscopy (DFOMS). Disk-, square-, and triangular-shaped Ag NPs were fabricated on indium tin oxide-coated glass substrates by electron beam lithography. The LSPR spectra collected from single Ag NPs within 5×5 arrays using DFOMS exhibited pronounced redshifts as the NP shape changed from disk to square and to triangular. The shape-dependent experimental LSPR spectra are in good agreement with simulations using the discrete dipole approximation model, although there are small deviations in the …

New Photovoltaic Acceptors: Synthesis And Characterization Of Functionalized C-Fused Anthradithiophene Quinones, Kerri Shelton

University of Kentucky Master's Theses

Stable organic semiconductors are critical to produce inexpensive, efficient and flexible thin film organic solar cells. A current chemical focus is the synthesis of stable, electron-accepting materials to be utilized as an acceptor layer in photovoltaics.¹ The Anthony group has shown that the functionalization of pentacene with suitable electron withdrawing groups provides a catalog of suitable acceptors for this purpose.² These pentacenes can be further modified to pack in a unique 1-dimensional "sandwich herringbone" crystal packing, leading to improved device current.³ To improve the stability of acene acceptors, we have taken two hetero-atom themed approaches. First, we …

Development Of Novel Electrophilic Ruthenium(Ii) And Iridium(Iii) Complexes And Their Applications As Homogeneous Catalysts, Ryan R. Ketcham

University of Kentucky Master's Theses

Our aim was to develop the synthetic potential and reaction chemistry of Ir³⁺ and Ru²⁺ electrophiles by preparing well-characterized complexes whose properties are controllable by modification of the ancillary ligand environment Specifically, we prepared a series of ruthenium complexes to serve as selective hydrogenation and hydrogenolysis catalysts of furan derivatives. We also expanded the synthesis of electrophilic Ir³⁺ di-thiolate complexes. These types of compounds could eventually serve as catalysts precursors for the addition of weak nucleophiles to alkynes and nitriles.

Investigation Of Synthetic Methods For Preparation Of 2O-Amino Derivatives Of 5-Amino- 1, 10-Phenanthroline: Applications To Cu+2 Based Impedance Sensors, Satish B. Chunchu

Master's Theses and Doctoral Dissertations

The main purpose of this project is to synthesize 2^o - derivatives of 5-amino-1, 10- phenanthroline (5-aphen) for application as self-assembled monolayers on gold interdigitated electrode array chips in standard impedance and impedance resonance-based Cu²⁺ sensors. Potential applications include monitoring Cu²⁺ leaching from anti-fouling coatings on ship hulls. The importance of the planned secondary alkyl amino derivatives will be to test their binding properties to the gold surface through dithiocarbamate linkages by monitoring the IDE impedance signal. Practical sensor development requires good impedance response, maximum binding to the gold IDE chip, and maximum long term stability of …

Crystallization And Preliminary X-Ray Crystallographic Analysis Of Ligand-Free And Arginine-Bound Forms Of Thermotoga Maritima Arginine-Binding Protein, Alessia Ruggiero, Jonathan D. Dattelbaum, Anna Pennacchio, Luisa Iozzion, Maria Staiano, Matthew S. Luchansky, Bryan S. Der, Rita Berisio, Sabato D'Auria, Luigi Vitagliano

Chemistry Faculty Publications

The arginine-binding protein from Thermotoga maritima (TmArgBP) is an arginine-binding component of the ATP-binding cassette (ABC) transport system in this hyperthermophilic bacterium. This protein is endowed with an extraordinary stability towards thermal and chemical denaturation. Its structural characterization may provide useful insights for the clarification of structure– stability relationships and for the design of new biosensors. Crystallization trials were set up for both arginine-bound and ligand-free forms of TmArgBP and crystals suitable for crystallographic investigations were obtained for both forms. Ordered crystals of the arginine adduct of TmArgBP could only be obtained by using the detergent LDAO as an additive …

Charge Saturation And Neutral Substitutions In Halomethanes And Their Group 14 Analogues, Bernard K. Wittmaack, Chad Crigger, Matthew Guarino, Kelling J. Donald

Chemistry Faculty Publications

A computational analysis of the charge distribution in halomethanes and their heavy analogues (MH_4-nX_n: M= C, Si, Ge, Sn, Pb; X = F, Cl, Br, I) as a function of _n uncovers a previously unidentified saturation limit for fluorides when M ≠ C. We examine the electron densities obtained at the CCSD, MP2(full), B3PW91, and HF levels of theory for 80 molecules for four different basis sets. A previously observed substituent independent charge at F in fluoromethanes is shown to be a move toward saturation that is restricted by the low polarizability of C. This limitation …

Stabilizing Carbon-Lithium Stars, Nancy Perez-Peralta, Maryel Contreras, William Tiznado, John Stewart, Kelling J. Donald, Gabriel Merino

Chemistry Faculty Publications

We have explored in silico the potential energy surfaces of the C₅Li_n^n-6 (n = 5, 6, and 7) clusters using the Gradient Embedded Genetic Algorithm (GEGA) and other computational strategies. The most stable forms of C₅Li_5-^- and C₅Li₆ are two carbon chains linked by two lithium atoms in a persistent seven membered ring capped by two Li atoms. The other Li atoms are arrayed on the edge of the seven membered ring. In contrast, the global minimum structure for C₅Li₇⁺ is a bicapped star …

Synthesis, Assembly, And Characterization Of Monolayer-Protected Gold Nanoparticle Films For Protein Monolayer Electrochemistry,, Tran T. Doan, Michael H. Freeman, Adrienne R. Schmidt, Natalie T. Nguyen, Michael C. Leopold

Chemistry Faculty Publications

Colloidal gold nanoparticles protected with alkanethiolate ligands called monolayer protected gold clusters (MPCs) are synthesized and subsequently incorporated into film assemblies that serve as adsorption platforms for protein monolayer electrochemistry (PME). PME is utilized as the model system for studying electrochemical properties of redox proteins by confining them to an adsorption platform at a modified electrode, which also serves as a redox partner for electron transfer (ET) reactions. Studies have shown that gold nanoparticle film assemblies of this nature provide for a more homogeneous protein adsorption environment and promote ET without distance dependence compared to the more traditional systems modified …

Microwave-Induced Indium-Catalyzed Synthesis Of Pyrrole Fused With Indoline In Water, Dina Abrego, Debasish Bandyopadhyay, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

An expeditious microwave-induced indium metal-catalyzed synthesis of pyrrole fused with indoline in water is developed by reacting isatin and 4-hydroxyproline.

Microwave-Induced Bismuth Nitrate-Catalyzed Expeditious Enamination Of Β-Dicarbonyl Compounds Under Solvent-Free Conditions, Debasish Bandyopadhyay, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Bismuth nitrate-catalyzed, automated microwave-assisted expeditious synthesis of β- enaminones and β-enaminoesters has been carried out in an efficient manner under solvent-free condition. The reaction is general for primary, secondary (cyclic, heterocyclic and acyclic), benzylic as well as aromatic amines.

Microwave-Induced Stereoselectivity Of Β-Lactam Formation: Effects Of Solvents, Debasish Bandyopadhyay, Marco Yanez, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Synthesis of 3, 4-disubstituted 2-azetidinones has been achieved following Staudinger reaction under microwave-induced conditions. The stereoselectivity of β-lactam formation depends on the nature of the solvents used in the reaction.

Antimicrobial Activity Of Eugenol Derivatives, George Eyambe, Luis Canales, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

The antibacterial properties of the clove plant are due to the presence of eugenol, an aromatic phenolic compound. Eugenol was isolated from clove by stem distillation. The alkene group in eugenol was epoxidized resulting in the synthesis of epoxide-eugenol. The heterocyclic ring in epoxide was cleaved to a bromoalcohol derivative. The compounds synthesized epoxideeugenol, bromo alcohol and euginol were tested for antimicrobial activity against Staphylococcus aureus (ATCC 25923). Epoxide-eugenol was found to be the most effective antimicrobial agent among the three compounds tested.

Biologically Active Alkaloids From Kopsia., Yap Wai Sum

Student Works (2010-2019)

Two Malaysian plants viz., Kopsia pauciflora and Kopsia grandifolia were investigated for their alkaloidal constituents. A total of 40 alkaloids were isolated and characterized from K. pauciflora, of which 12 are new alkaloids. The new alkaloids isolated include seven aspidofractinine alkaloids (1, 2, 3, 4, 5, 6, 7), and five eburnane alkaloids (8, 9, 10, 11, 12). K. grandifolia yielded a total of eight alkaloids. Of these, three are new. The new alkaloids are grandilodine A (41), grandilodine B (42), and grandilodine C (43). Grandilodine A (41), grandilodine C (43), and lapidilectine B (47) were found to reverse multidrug resistance …

Development Of A Versatile Man-Portable Obscurant Aerosol Generator: Characterization Of Aerosols In Laboratory And Field Environments, Robert William Schaub

Doctoral Dissertations

"The objective of research presented in this dissertation was to develop a readily deployable and environmentally benign obscurant system operating with a single liquid for the visible and near infrared regions. To achieve this objective, research efforts were directed in two areas: i. Evaluating suitable biogenic oils to replace the United States Army's "Fog Oil" as the obscurant fluid. ii. Design, fabrication and validation of a prototype man-portable / vehicle mountable modular obscurant aerosol generator. Petroleum middle distillate - "Fog Oil" has been the material of choice for wide area obscuration for several decades. Large quantities (thousands gallons) of the …

Synthesis And Binding Studies Of Peptide Mimetics, Anion Receptors, And Kinase Inhibitors, Nanditha G. Nair

Doctoral Dissertations

"A series of novel purine-based fluoroaryl triazoles were synthesized and assayed for their neuroprotective effects of hippocampal slice culture exposed to amyloid beta (Aß) oligomers. A monofluorinated triazole has been identified which has comparable neuroprotective effect as that of flavopiridol and roscovitine against the Aß induced neurotoxicity. Carnosine and histidine are biologically interesting antioxidants. In order to probe whether they exert their antioxidant effect through metal ion chelation, the Cu(ll) ion chelating abilities of these compounds were measured by UV-vis spectroscopy. Amyloid beta, the major component of senile plaques in Alzheimer's disease, is known to complex transition metal ions through …

Interfacial Effects On Dielectric Properties Of Polymer-Particle Nanocomposites, Sasidhar Siddabattuni

Doctoral Dissertations

"Dielectric materials that are capable of efficiently storing large amounts of electrical energy are desirable for many electronic and power devices. Since the electrical energy density in a dielectric material is limited to εV_b²/2, where ε is the dielectric permittivity of the material and V_b is the breakdown strength, increased permittivity and breakdown strength are required for large energy storage density. Interfacial effects can influence the dielectric properties, especially dielectric breakdown resistance in polymer-particle nanocomposites. Several functional organophosphates were used to modify the surface of titania and barium titanate nanofiller particles in order to achieve covalent interface …

Epitaxial Electrodeposition Of Metal Oxide Films And Superlattices Which Exhibit Resistance Switching, Rakesh V. Gudavarthy

Doctoral Dissertations

"This dissertation presents an investigation of the electrodeposition of metal oxide films and superlattices on conducting polycrystalline and single crystal substrates. In the first part of the study, electrodeposition of magnetite (Fe₃O₄) films and superlattices in the magnetite/zinc ferrite system which exhibit resistance switching is studied. Paper I reports the electrodeposition of superlattices in the magnetite/zinc ferrite system and shows that only superlattices exhibit multistate resistance switching. In paper II, simple polycrystalline magnetite films electrodeposited on stainless steel crystals exhibit multistate resistance switching which can be tuned by controlling the composition of the films. Paper II describes the epitaxial electrodeposition …

Decolorization Of Dyes And Distillery Waste Effluent: Comparison Of The Effectiveness Of Several Biological And Physico-Chemical Processes, Mylène Godin

Dissertations and Theses @ UNI

Dyes and pigments are used extensively in many important industries. They are also important environmental contaminants and must be removed in a cost-effective manner from wastewater. The present investigation focuses on the use of several inexpensive physico-chemical and biological systems. The goal is to assess and compare their ability to decolorize water containing a representative triphenylmethane dye ( crystal violet), a representative azo dye (Congo red), and a rum distillery waste effluent, also known as still bottoms. The selected processes were photodegradation, ozonation, adsorption and bioremediation. Photodegradation was studied with three light sources, namely a commercially available 42 Watt fluorescent …

Dynamic Light Scattering And Zeta Potential Of Colloidal Mixtures Of Amelogenin And Hydroxyapatite In Calcium And Phosphate Rich Ionic Milieus, Vuk Uskoković, Roselyn Odsinada, Sonia Djordjevic, Stefan Habelitz

Pharmacy Faculty Articles and Research

The concept of zeta-potential has been used for more than a century as a basic parameter in controlling the stability of colloidal suspensions, irrespective of the nature of their particulate ingredients – organic or inorganic. There are prospects that self-assembly of peptide species and the protein-mineral interactions related to biomineralization may be controlled using this fundamental physicochemical parameter. In this study, we have analyzed the particle size and zeta-potential of the full-length recombinant human amelogenin (rH174), the main protein of the developing enamel matrix, in the presence of calcium and phosphate ions and hydroxyapatite (HAP) particles. As calcium and phosphate …

Synthesis And Physicochemical Properties Of Cationic Microgels Based On Poly(N-Isopropylmethacrylamide), Xiaobo Hu, Zhen Tong, L. Andrew Lyon

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Surfactant-free, radical precipitation copolymerization of N-isopropylmethacrylamide and the cationic co-monomer N-(3-aminopropyl) methacrylamide hydrochloride (APMH) was carried out to prepare microgels functionalized with primary amines. The morphology and hydrodynamic diameter of the microgels were characterized by atomic force microscopy and photon correlation spectroscopy, with the effect of NaCl concentration and initiator type on the microgel size and yield being investigated. When a 2,2'-azobis (2-amidinopropane) dihydrochloride (V50)-initiated reaction was carried out in pure water, relatively small microgels (similar to 160 nm in diameter) were obtained in low yield (similar to 20%). However, both the yield and size increased if the reaction was …

An Upper Limit For Macromolecular Crowding Effects, Andrew C. Miklos, Congang Li, Courtney D. Sorell, L. Andrew Lyon, Gary J. Pielak

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Background: Solutions containing high macromolecule concentrations are predicted to affect a number of protein properties compared to those properties in dilute solution. In cells, these macromolecular crowders have a large range of sizes and can occupy 30% or more of the available volume. We chose to study the stability and ps-ns internal dynamics of a globular protein whose radius is similar to 2 nm when crowded by a synthetic microgel composed of poly(N-isopropylacrylamide-co-acrylic acid) with particle radii of similar to 300 nm.

Results: Our studies revealed no change in protein rotational or ps-ns backbone dynamics and only mild …

Bulk Modulus Of Poly(N-Isopropylacrylamide) Microgels Through The Swelling Transition, B. Sierra-Martin, Y. Laporte, A. B. South, L. Andrew Lyon, A. Fernandez-Nieves

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report measurements of the bulk modulus of individual poly(N-isopropylacrylamide) microgels along their swelling transition. The modulus is determined by measuring the volume deformation of the microgel as a function of osmotic pressure using dextran solutions. We find that the modulus softens through the transition, displaying a nonmonotonous behavior with temperature. This feature is correctly reproduced by the theory of Flory for polymer gels, once the concentration dependence of the solvency parameter is properly incorporated.

Preparation And Crystal Structures Of Chiral And Non-Chiral Mixed Ligand Copper Complexes Containing N-Methyl Imidazole And Various N-Phthaloylalanines, Hiral Patel

Theses, Dissertations and Culminating Projects

A quasiracemate is the cocrystallization of two similarly shaped but chemically distinct molecules of opposite handedness. There has been extensive work done in the field of organic quasiracemates by Dr. Kraig A. Wheeler. Limited work has been done in inorganic quasiracemates. The goal of this study was to prepare various metal based enantiomers, racemates, and quasiracemates using A-phthaloylalanines, and TV-methylimidazole as ligands bound to copper arranged in a centrosymmetric pattern. In this study, we developed a method to prepare A-phthaloylalanines and its copper complexes. Three complexes have yielded crystal structures: a racemate, bis(7V-methylimidazole) bis(D,L-3-chloro-7V-phthaloylalanato)copper(II); a quasiracemate, bis(A-methyhmidazole)(L-3-chloro-iV-phthaloylalanato)(D-3-methyl-7V-phthaloylalanato) copper(II); and an …

Superplastic Boronizing On Duplex Stainless Steel (Dss) Using Compression Method., Yong Siu Fung

Student Works (2010-2019)

The formation and growth of boride phases on duplex stainless steel (DSS) during superplastic boronizing (SPB) were studied in comparison with conventional boronizing (CB) from previous research. SPB is a surface hardening technique that combines boronizing with superplastic deformation. It utilizes the ultra high plasticity phenomenon in metal while carrying out boronizing in which boron atoms are diffused into the metal substrate to form hard boronized layer. The SPB process was conducted under compression mode at a strain rate of 2 × 10-4 s-1, at three different temperature conditions (1223 K, 1273 K, 1373 K) and strains (0.2 to 0.6). …

Biomimetic Synthesis Of Oligostilbenoids And Its Mechanistic Implications., Saraswati S. Velu

Student Works (2010-2019)

Oligostilbenoids are a class of polyphenolic compounds known for their interesting biological activities and structural diversities. They are found in abundance in Malaysian timber trees. Oligostilbenoids syntheses were undertaken in the hope of mimicking what nature does. This study was initiated by preparing 15 different stilbene monomer analogues possessing resorcinol i.e. 3,5-dihydroxy or methoxy substitution, and 3-hydroxy or methoxy pattern (resveratrol analogues) via the commonly used Heck cross coupling. To obtain analogues of natural dimers from stilbene monomers, two different oxidation techniques were employed: anodic oxidations and chemical oxidation mainly by means of various one electron oxidants. Firstly, constant …

Quality Of Wastewater In The El Paso, Texas Region--Analysis Of Pharmaceuticals And Personal Care Products Using High Performance Liquid Chromatography Tandem Mass Spectrometry, Rodolfo Guerrero Jr.

Open Access Theses & Dissertations

Pharmaceuticals and Personal Care Products (PPCPs), such as household cleaning materials, prescription medication, and personal hygiene products, are pollutants of emerging concern that are found in 80% of our water system. Because of their applications, PPCPs are subsequently being released into wastewater; however, current wastewater treatment facilities are not regulated or designed to remove PPCPs. Therefore, these compounds are discharged into the environment on a continual basis. The effects of PPCPs on human health are not yet well known; however, recent research has found that exposure to these chemicals has some adverse developmental effects on aquatic species at low concentrations …

Supramolecular Organization Of Nanoparticles, Brenda M. Porta Linnell

Open Access Theses & Dissertations

The study of supramolecular structures with nano-architectures has become an active area of research in recent years. They have the potential to generate functional materials with applications in medicine and emerging technologies. In this dissertation, the supramolecular organization of gold nanoparticles (AuNP) and other nano-scale structures such as discrete styrene-based polymers was investigated. The synthesis and characterization of metal-mediated AuNPs systems using pendant ligands on the AuNP such as 11-diethylenetriamine-undecane-1-thiol, 11-Mercapto-undecanoic acid [2-(2-amino-ethylamino)-ethyl]-amide, Bis(11-oxo-nicotinic acid, undecine)disulfide, and 11-mercaptoundecanoic acid, and using Cu(II) to mediate the formation of supramolecular AuNP systems with sizes of 200 nm ¡V 3 fÃ?m, are …

Gemini Metallo-Surfactants: Chemical And Physical Properties, Erich Ivan Valenzuela

Open Access Theses & Dissertations

Gemini surfactants are amphiphilic molecules that consist of two surfactant molecules chemically joined together by a spacer group. These molecules tend to self‐assemble into vesicles at much lower concentrations than traditional surfactants and have found many applications in catalysis, adsorption applications, drug‐delivery, nanoscale technology, and biotechnology. In this thesis, the synthesis, characterization and physical properties of a new type of Gemini surfactant derived from dinuclear Cu(II) metal complexes is presented. We call these molecules Gemini Metal‐Organic Surfactants (GMOs).

Three newly developed new GMOs (compounds 1‐3) are composed of Cu(II) ions ligated to a lipid‐functionalized triamine group and the metals are …