Chemistry Commons^™

Chemical Mechanism Of Udp-Galactopyranose Mutase From Trypanosoma Cruzi: A Potential Drug Target Against Chagas' Disease, Michelle Oppenheimer, Ana Lisa Valenciano, Karina Kizjakina, Jun Qi, Pablo Sobrado

Chemistry Faculty Research & Creative Works

UDP-galactopyranose mutase (UGM) is a flavoenzyme that catalyzes the conversion of UDP-galactopyranose to UDP-galactofuranose, the precursor of galactofuranose (Galf). Galf is found in several pathogenic organisms, including the parasite Trypanosoma cruzi, the causative agent of Chagas' disease. Galf) is important for virulence and is not present in humans, making its biosynthetic pathway an attractive target for the development of new drugs against T. cruzi. Although UGMs catalyze a non-redox reaction, the flavin must be in the reduced state for activity and the exact role of the flavin in this reaction is controversial. The kinetic and chemical mechanism of TcUGM was …

Crystal Structures And Small-Angle X-Ray Scattering Analysis Of Udp-Galactopyranose Mutase From The Pathogenic Fungus Aspergillus Fumigatus, Richa Dhatwalia, Harkewal Singh, Michelle Oppenheimer, Dale B. Karr, Jay C. Nix, Pablo Sobrado, John J. Tanner

Chemistry Faculty Research & Creative Works

UDP-galactopyranose mutase (UGM) is a flavoenzyme that catalyzes the conversion of UDP-galactopyranose to UDP-galactofuranose, which is a central reaction in galactofuranose biosynthesis. Galactofuranose has never been found in humans but is an essential building block of the cell wall and extracellular matrix of many bacteria, fungi, and protozoa. The importance of UGM for the viability of many pathogens and its absence in humans make UGMa potential drug target. Here we report the first crystal structures and small-angle x-ray scattering data for UGM from the fungus Aspergillus fumigatus, the causative agent of aspergillosis. The structures reveal that Aspergillus UGM has several …

Basis Set Dependence Of Higher-Order Correlation Effects In Π-Type Interactions, Emily J. Carrell, Cara M. Thorne, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The basis set dependence of higher-order correlation effects on -type interaction energies was examined by scanning the potential energy surfaces of five dimer systems. The dimers of acetylene (H-CC-H), diacetylene (H-CC-CC-H), cyanogen (NC-CN), diphosphorous (PP), and 1,4-diphosphabutadiyne (PC-CP) were studied in three different configurations: cross, parallel-displaced, and t-shaped. More than 800 potential energy curves (PECs) were generated by computing the interaction energies for all 15 dimer configurations over a range of intermolecular distances with the MP2, coupled-cluster single double (CCSD), and coupled-cluster single double triple (CCSD(T)) methods in conjunction with 21 basis sets ranging from a small 6-31G*(0.25) split-valence basis …

Histological Evaluation Of The Biocompatibility Of Polyurea Crosslinked Silica Aerogel Implants In A Rat Model: A Pilot Study, Firouzeh Sabri, J. D. Boughter Jr., D. Gerth, O. Skalli, T. C. N. Phung, G. R. M. Tamula, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Background: Aerogels are a versatile group of nanostructured/nanoporous materials with physical and chemical properties that can be adjusted to suit the application of interest. In terms of biomedical applications, aerogels are particularly suitable for implants such as membranes, tissue growth scaffolds, and nerve regeneration and guidance inserts. The mesoporous nature of aerogels can also be used for diffusion based release of drugs that are loaded during the drying stage of the material. From the variety of aerogels polyurea crosslinked silica aerogels have the most potential for future biomedical applications and are explored here. Methodology: This study assessed the short and …

Therapeutic Effects Of N-Acetylcysteine Amide In The Treatment Of Eye Disorders, Joshua W. Carey

Doctoral Dissertations

"The loss of vision from age-related eye diseases now affects over 30 million people in the United States and is expected to reach twice that number within the next couple of decades. Among these disorders, age-related macular degeneration and cataract formation represent the largest percentage of these cases. Therapeutic options available for treating age-related macular degeneration are limited and there is no noninvasive form of treatment for cataracts current available. Several studies have indicated that oxidative stress plays an important role in the pathology of these age-related eye disorders. If oxidative stress is responsible for the initiation and progression of …

N-Acetyl-L-Cysteine Amide Protects Retinal Pigment Epithelium Against Methamphetamine-Induced Oxidative Stress, Nuran Ercal, Joshua W. Carey, Shakila Tobwala, Xinsheng Zhang, Atrayee Banerjee, Eylem Y. Pinarci, Humeyra Karacal

Chemistry Faculty Research & Creative Works

Methamphetamine (METH), a highly addictive drug used worldwide, induces oxidative stress in various animal organs. Recent animal studies indicate that methamphetamine also induces oxidative stress in the retina, which is an em- bryonic extension of the forebrain. The aim of this study, therefore, was to evaluate the pro- tecttive effects of N-acetylcysteine amide (NACA) against oxidative stress induced by METH in retinal pigment epithelium (RPE) cells. Our stud- ies showed that NACA protected against METH- induced oxidative stress in retinal pigment epithelial cells. Although METH significantly de- creased glutathione (GSH) levels and increased reactive oxygen species (ROS) and malondial- dehyde …

Neutron Repulsion, Oliver Manuel

Chemistry Faculty Research & Creative Works

Earth is connected gravitationally, magnetically and electrically to its heat source and the source of its chemical elements - a neutron star obscured from view by waste products in the photosphere. Neutron repulsion makes the solar core like the hot filament in an incandescent light bulb. Excited neutrons are emitted from the pulsar, decay to hydrogen, and partially fuse into the helium now trapped with it in the photosphere, like a frosted light bulb. Neutron repulsion is the overlooked source of energy, the keystone of an arch that locks together many earlier, puzzling observations: 1.) Excess ¹³⁶Xe accompanied primordial …

Separation And Liquid Chromatography Using A Single Carbon Nanotube, Riju Singhal, Vadym Mochalin, Maria R. Lukatskaya, Gary Friedman, Yury G. Gogotsi

Chemistry Faculty Research & Creative Works

Use of a single template-grown carbon nanotube as a separation column to separate attoliter volumes of binary mixtures of fluorescent dyes has been demonstrated. The cylindrical nanotube walls are used as stationary phase and the surface area is increased by growing smaller multi-walled carbon nanotubes within the larger nanotube column. Liquid-liquid extraction is performed to separate selectively soluble solutes in a solvent, and chromatographic separation is demonstrated using thin, long nanotubes coated inside with iron oxide nanoparticles. The setup is also used to determine the diffusion coefficient of a solute at the sub-micrometer scale. This study opens avenues for analytical …

Monitoring The Reductive And Oxidative Half-Reactions Of A Flavin-Dependent Monooxygenase Using Stopped-Flow Spectrophotometry., Elvira Romero, Reeder Robinson, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Aspergillus fumigatus siderophore A (SidA) is an FAD-containing monooxygenase that catalyzes the hydroxylation of ornithine in the biosynthesis of hydroxamate siderophores that are essential for virulence (e.g. ferricrocin or N", N'''-triacetylfusarinine C). The reaction catalyzed by SidA can be divided into reductive and oxidative half-reactions. In the reductive half-reaction, the oxidized FAD bound to Af SidA, is reduced by NADPH. In the oxidative half-reaction, the reduced cofactor reacts with molecular oxygen to form a C4a-hydroperoxyflavin intermediate, which transfers an oxygen atom to ornithine. Here, we describe a procedure to measure the rates and detect the different spectral forms of SidA …

Investigation Of Polyurea-Crosslinked Silica Aerogels As A Neuronal Scaffold: A Pilot Study, Firouzeh Sabri, Judith A. Cole, M. Cody Scarbrough, Nicholas Leventis

Chemistry Faculty Research & Creative Works

Background: Polymer crosslinked aerogels are an attractive class of materials for future implant applications particularly as a biomaterial for the support of nerve growth. The low density and nano-porous structure of this material combined with large surface area, high mechanical strength, and tunable surface properties, make aerogels materials with a high potential in aiding repair of injuries of the peripheral nervous system. However, the interaction of neurons with aerogels remains to be investigated. Methodology: In this work the attachment and growth of neurons on clear polyurea crosslinked silica aerogels (PCSA) coated with: poly-L-lysine, basement membrane extract (BME), and laminin1 was …

Noncanonical Reactions Of Flavoenzymes, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetone phosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base …

Quantitative Analysis Of Co-Enzyme A In A Plant Tissues And Cancer Biomarkers In Urine Samples By Using Capillary Electrophoresis And Liquid Chromatography-Mass Spectrometry, Yongqing Jiang

Doctoral Dissertations

"Despite continuous effort and progress in cancer detection and therapy, cancer remains one of our greatest health concerns because of its low survival rate and rapid incidence increase. One reason for this is the late detection and therefore pre-cancer diagnosis is crucial. In pre-cancer studies, cancer biomarkers become significant because of the useful information it contains such as possible cancer type and stage. Separation and detection technique plays an important role in cancer biomarker identification.

Coenzyme A (CoA) facilitates more than 100 chemical reactions in cells. Because of its low abundance accumulated in cells, it is critical to develop a …

Investigation Of Biomarkers For Noninvasive Early Diagnosis Of Cancer, Sanjeewa Bandara Gamagedara

Doctoral Dissertations

"Cancer is the second leading cause of death worldwide, and deaths from cancer worldwide are projected to continue rising, with an estimated 12 million deaths in 2030. Cancer occurs when cells in a part of the body begin to grow out of control. It develops very rapidly, and early diagnosis offers a greater chance of successful treatment and a higher survival rate. Biomarkers are good potential tools for early diagnosis. The main hypothesis of this study is that the levels of certain metabolites present in human urine can indicate the current or future behavior of cancer. Therefore, these studies focused …

Part I: Quantitative Determination Of Total Corrosive Sulfur In Mineral Insulating Oils And Technical Liquids; Part Ii: Development And Validation Of A Broad Spectrum Microbial Disinfectant, Kyle Rodney Anderson

Doctoral Dissertations

"Part one of this dissertation deals with the development and validation of a test method for determination of total corrosive sulfur in mineral insulating oils other technical oils. The method involved reaction of corrosive sulfur compounds in oils with finely divided copper at temperatures ≥ 110 °C. The reaction yielded cuprous sulfide (Cu₂S), Cu₂S was then oxidized to cupric sulfate (CuSO₄), which was determined as sulfate with ion chromatography. The method offers a quantitative assessment of corrosive sulfur compounds in oils and eliminates ambiguities associated with the international standard methods for corrosive sulfur in mineral insulating oils and other technical …

Electrodeposition And Electrochemical Reduction Of Epitaxial Metal Oxide Thin Films And Superlattices, Zhen He

Doctoral Dissertations

"The focus of this dissertation is the electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices. The electrochemical reduction of metal oxides to metals has been studied for decades as an alternative to pyrometallurgical processes for the metallurgy industry. However, the previous work was conducted on bulk polycrystalline metal oxides. Paper I in this dissertation shows that epitaxial face-centered cubic magnetite (Fe₃O₄) thin films can be electrochemically reduced to epitaxial body-centered cubic iron (Fe) thin films in aqueous solution on single-crystalline Au substrates at room temperature. This technique opens new possibilities to produce special epitaxial metal/metal oxide …

Organic And Composite Aerogels Through Ring Opening Metathesis Polymerization (Romp), Dhairyashil Mohite

Doctoral Dissertations

"Aerogels are open-cell nanoporous materials, unique in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. Those exceptional properties stem from their complex hierarchical solid framework (agglomerates of porous, fractal secondary nanoparticles), but they also come at a cost: low mechanical strength. This issue has been resolved by crosslinking silica aerogels with organic polymers. The crosslinking polymer has been assumed to form a conformal coating on the surface of the skeletal framework by covalent bridging elementary building blocks. However, "assuming" is not enough: for correlating nanostructure with bulk material properties, it is important to know …

Chelating Compounds As Potential Flash Rust Inhibitors And Melamine & Aziridine Cure Of Acrylic Colloidal Unimolecular Polymers (Cups), Jigar K. Mistry

Doctoral Dissertations

Waterborne coatings on ferrous substrates usually show flash rusting which decreases the adhesion of the coating and the corrosion products can form a stain. Chelating compounds were investigated as potential flash rust inhibitors. Compounds being evaluated include amine alcohols, diamines and sulfur containing amines. A new corrosion inhibitor 2,5-bis(thioaceticacid)-1,3,4-thiadiazole (H2ADTZ) was synthesized and its performance characteristics were evaluated. It was noted that the observed structure of 1,3,4-thiadiazolidine-2,5-dithione (also known as 2,5-dimercapto-1,3,4-thiadiazole (DMTD or DMcT)) has been previously reported in three different tautomeric forms including -dithiol and -dithione. The relative stability of each form as well as the synthesis and characterization …

X-Ray Crystallography For The Study Of Nickel And Iron Salicylaldimines, Carla Schmiesing Eribal

Doctoral Dissertations

"X-ray diffraction of single crystals has developed dramatically over the last century by combining fundamental theories of light, diffraction, and statistics to generate the complete, geometric structure of molecules. The quality of the resulting X -ray structure data are reported in R₁ < 5%, wR2 < 12% and a goodness of fit value of one. This technique was applied specifically to the evaluation of the spin crossover (SCO) compound [Fe(salpm)₂]BF₄ʺ0.5EtOH and how the molecule's geometry changed during a two-step thermal LS-HS conversion. The crystal structure was measured at 100,175,225, and 296 K to yield final R₁ values of 0.047, 0.054, 0.051, and 0.058, respectively. The coordination bond lengths show the spin transitions occur between 100-175K at one crystallographically unique Fe and between 175-225K at the other Fe site. No strong long range interactions are found, suggesting a gradual spin transition. Reaction ofNi(Nalkyl-sal)₂ complexes with Ni(N0₃)₂ form either nickel dimeric, [Ni₃(Rsal)(N0₃)(MeOH)]₂ or trinuclear complexes, Ni₃(Rsal)₄(N0₃)₂. The binuclear complexes, with orthogonal bridging ligands, show overall ferromagnetic interactions. The crystal structures for Ni₃(Rsal)₄(N0₃)₂ from methyl to benzyl were solved and indicate no steric restriction on formation for the series. The trinuclear compounds form an isosceles triangle of metal atoms with the isopropyl analog showing an overall antiferromagnetic interaction with J=+11.386 and J23=-13.891. Lastly, xanthene spirolactam derivatives were structurally analyzed to determine binding modes for their selective and sensitive (µM) detection of metals Cr³⁺, Fe³⁺, Ni²⁺, Co²⁺ and the nerve gas mimic, dichlorophosphate"--Abstract, page iii.

Nano-Particles Induced Oxidative Stress In Immortalized Human Brain Endothelial Cells, Xinsheng Zhang

Doctoral Dissertations

"Nanoparticles are engineered structure with at least one dimension of 100 nanometers or less. These materials are increasingly being used for commercial purposes such as catalyst, semiconductor, cosmetics, microelectronic, and drug carrier. However, the toxicological impact of these materials has not yet been studied in detail, thereby limiting their use. In our present study, we use human brain endothelial cell line as a blood-brain barrier (BBB) model to investigate if two kinds of nanoparticles [ 1). Diesel exhaust particles (DEPs) and 2). single wall carbon nanotube (CNT) ] induced oxidative stress in cell model. Our studies showed that DEPs or …

Interstaple Dithiol Cross-Linking In Au 25(Sr) 18 Nanomolecules: A Combined Mass Spectrometric And Computational Study, Vijay Reddy Jupally, Rajesh Kota, Eric Van Dornshuld, Daniell L. Mattern, Gregory S. Tschumper, De En Jiang, Amala Dass

Chemistry Faculty Research & Creative Works

A systematic study of cross-linking chemistry of the Au 25(SR) 18 nanomolecule by dithiols of varying chain length, HS-(CH₂)_n-SH where n = 2, 3, 4, 5, and 6, is presented here. Monothiolated Au₂₅ has six [RSAuSRAuSR] staple motifs on its surface, and MALDI mass spectrometry data of the ligand exchanged clusters show that propane (C3) and butane (C4) dithiols have ideal chain lengths for interstaple cross-linking and that up to six C3 or C4 dithiols can be facilely exchanged onto the cluster surface. Propanedithiol predominately exchanges with two monothiols at a time, making cross-linking bridges, …

Structures, Energetics And Vibrational Frequency Shifts Of Hydrated Pyrimidine, J. Coleman Howard, Nathan I. Hammer, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

More than 70 unique micro-hydrated structures of pyrimidine, ranging in size from 1 to 7 water molecules, have been characterized with the B3LYP density functional and the 6-311++G(2df,2pd) triple-ζ split-valence basis set. Explicitly correlated MP2-F12 single-point computations were performed on each structure with a correlation consistent triple-ζ basis set to estimate the relative and dissociation energies at the MP2 complete basis set (CBS) limit. Many of these new structures have significantly lower energies than those previously reported (by as much as 12.66 kcal mol-1). For clusters with 1 and 2 water molecules, the MP2-F12 relative and dissociation energies are virtually …

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 …

Substrate Binding Modulates The Activity Of Mycobacterium Smegmatis G, A Flavin-Dependent Monooxygenase Involved In The Biosynthesis Of Hydroxamate-Containing Siderophores, Reeder Robinson, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Mycobacterium smegmatis G (MbsG) is a flavin-dependent monooxygenase that catalyzes the NAD(P)H- and oxygen-dependent hydroxylation of the terminal amino group on the side chain of l-lysine in the biosynthetic pathway of the siderophore mycobactin. Mycobactins are essential for mycobacterium growth under iron-limiting conditions encountered during infection in mammals. Thus, enzymes involved in the biosynthesis of mycobactin represent potential drug targets. MbsG was expressed in Escherichia coli and purified using metal affinity and ionic exchange chromatographies. Recombinant MbsG represents the first member of this class of enzymes isolated in the active form, with a tightly bound FAD cofactor. The k cat …

Cloudy And Starry Milia-Like Cysts: How Well Do They Distinguish Seborrheic Keratoses From Malignant Melanomas?, S. M. Stricklin, William V. Stoecker, M. C. Oliviero, H. S. Rabinovitz, S. K. Mahajan

Chemistry Faculty Research & Creative Works

Background Seborrheic keratoses are the most common skin lesions known to contain small white or yellow structures called milia-like cysts (MLCs). Varied appearances can sometimes make it difficult to differentiate benign lesions from malignant lesions such as melanoma, the deadliest form of skin cancer found in humans. Objective the purpose of this study was to determine the statistical occurrence of MLCs in benign vs. malignant lesions. Methods a medical student with 10 months experience in examining approximately 1000 dermoscopy images and a dermoscopy-naïve observer analyzed contact non-polarized dermoscopy images of 221 malignant melanomas and 175 seborrheic keratoses for presence of …

Efficient And Accurate Methods For The Geometry Optimization Of Water Clusters: Application Of Analytic Gradients For The Two-Body:Many-Body Qm:Qm Fragmentation Method To (H2o)N, N = 3-10, Desiree M. Bates, Joshua R. Smith, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The structures of more than 70 low-lying water clusters ranging in size from (H₂O)₃ to (H₂O)₁₀ have been fully optimized with several different quantum mechanical electronic structure methods, including second-order Møller-Plesset perturbation theory (MP2) in conjunction with correlation consistent triple-ζ basis sets (aug-cc-pVTZ for O and cc-pVTZ for H, abbreviated haTZ). Optimized structures obtained with less demanding computational procedures were compared to the MP2/haTZ ones using both MP2/haTZ single point energies and the root-mean-square (RMS) deviations of unweighted Cartesian coordinates. Based on these criteria, B3LYP/6-31+G(d,2p) substantially outperforms both HF/haTZ and MP2/6-31Gz.ast. B3LYP/6-31+G(d,2p) structures never …

Accurate Interaction Energies For Problematic Dispersion-Bound Complexes: Homogeneous Dimers Of Nccn, P2, And Pccp, Edward G. Hohenstein, Heather M. Jaeger, Emily J. Carrell, Gregory S. Tschumper, C. David Sherrill

Chemistry Faculty Research & Creative Works

All intermolecular interactions involve London dispersion forces. The accurate treatment of dispersion is essential for the computation of realistic interaction potentials. In general, the most reliable method for computing intermolecular interactions is coupled-cluster singles and doubles with perturbative triples [CCSD(T)] in conjunction with a sufficiently flexible Gaussian atomic orbital basis set, a combination which is not routinely applicable due to its excessive computational demands (CPU time, memory, storage). Recently, many theoretical methods have been developed that attempt to account for dispersion in a more efficient manner. It is well-known that dispersion interactions are more difficult to compute in some systems …

Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann

Chemistry Faculty Research & Creative Works

Thin films of FeSb₃ were characterized by electronic transport, magnetometry, x-ray diffraction, 57Fe and 121Sb nuclear inelastic scattering, and 57Fe Mössbauer spectroscopy. Resistivity and magnetometry measurements reveal semiconducting behavior with a 16.3(4) meV band gap and an effective paramagnetic moment of 0.57(6) _B, respectively. A systematic comparison of the lattice dynamics with CoSb₃ and EuFe ₄Sb₁₂ reveals that the Fe₄Sb₁₂ framework is softer than the Co₄Sb₁₂ framework, and that the observed softening and the associated lowering of the lattice thermal conductivity in the RFe₄Sb₁₂ filled skutterudites …

A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak

Chemistry Faculty Research & Creative Works

Various quaternary CuIn_xGa_1-xS₂ (0≤x≤1) chalcopyrite nanoparticles have been prepared from molecular single-source precursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility. Depending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This method has been used to generate up to 5g of nanoparticles and up to 150g from multiple batch reactions with excellent reproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown high reproducibility in nanoparticle size, composition, and bandgap.

Development Of A 3-Body:Many-Body Integrated Fragmentation Method For Weakly Bound Clusters And Application To Water Clusters (H2o) N=3-10, 16, 17, Desiree M. Bates, Joshua R. Smith, Tomasz Janowski, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

A 3-body:many-body integrated quantum mechanical (QM) fragmentation method for non-covalent clusters is introduced within the ONIOM formalism. The technique captures all 1-, 2-, and 3-body interactions with a high-level electronic structure method, while a less demanding low-level method is employed to recover 4-body and higher-order interactions. When systematically applied to 40 low-lying (H₂O)_n isomers ranging in size from n = 3 to 10, the CCSD(T):MP2 3-body:many-body fragmentation scheme deviates from the full CCSD(T) interaction energy by no more than 0.07 kcal mol-1 (or < 0.01 kcal mol-1 per water). The errors for this QM:QM method increase only slightly for various low-lying isomers of (H₂O)₁₆ and (H₂O)₁₇ (always within 0.13 kcal mol^{-1 …}

Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier

Chemistry Faculty Research & Creative Works

The synthesis of the title salt, [Ag(C ₆H ₇N ₄) ₂](NO ₃) ₃, was carried out employing a 1:2 molar ratio of 2,2'-biimidazole and silver nitrate respectively. The cation has crystallographically-imposed C2 symmetry with the metal atom in an almost linear coordination environment [N - Ag - N = 177.01 (17)°]. The crystal structure displays N - H⋯O and C - H⋯O hydrogen-bonding interactions.