Chemistry Commons^™

Systematic Optimization For Production Of The Anti-Mrsa Antibiotics Wap-8294a In An Engineered Strain Of Lysobacter Enzymogenes, Xusheng Chen, Shanren Li, Lingjun Yu, Amanda Miller, Liangcheng Du

Department of Chemistry: Faculty Publications

WAP-8294A is a group of cyclic lipodepsipeptides and considered as the first-in-class new chemical entity with potent activity against methicillin-resistant Staphylococcus aureus. One of the roadblocks in developing the WAP-8294A antibiotics is the very low yield in Lysobacter. Here, we carried out a systematic investigation of the nutritional and environmental conditions in an engineered L. enzymogenes strain for the optimal production of WAP-8294A. We developed an activity-based simple method for quick screening of various factors, which enabled us to optimize the culture conditions. With the method, we were able to improve the WAP-8294A yield by 10-fold in small-scale cultures and …

Β-Fluorofentanyls Are Ph-Sensitive Mu Opioid Receptor Agonists, Ricardo Rosas Jr., Xi-Ping Huang, Bryan L. Roth, Chris Dockendorff

Chemistry Faculty Research and Publications

The concept recently postulated by Stein and co-workers (Science2017, 355, 966) that mu opioid receptor (MOR) agonists possessing amines with attenuated basicity show pH-dependent activity and can selectively act at damaged, low pH tissues has been additionally supported by in vitro studies reported here. We synthesized and tested analogs of fentanyl possessing one or two fluorine atoms at the beta position of the phenethylamine side chain, with additional fluorines optionally added to the benzene ring of the side chain. These compounds were synthesized in 1 to 3 steps from commercial building blocks. The novel bis-fluorinated analog …

Status And Prospects Of Organic Redox Flow Batteries Toward Sustainable Energy Storage, Jian Luo, Bo Hu, Maowei Hu, Yu Zhao, T. Leo Liu

Chemistry and Biochemistry Faculty Publications

Redox flow batteries (RFBs) are regarded a promising technology for large-scale electricity energy storage to realize efficient utilization of intermittent renewable energy. Redox -active materials are the most important components in the RFB system because their physicochemical and electrochemical properties directly determine their battery performance and energy storage cost. Designable, tunable, and potentially low-cost redox-active organic compounds are promising alternatives to traditional redox-active inorganic compounds for RFB applications. Herein, the representative designs of redox-active molecules, recent development of organic RFBs (ORFBs), and advantages/disadvantages of different ORFB are reviewed. Especially the relationship between redox-active molecules’ physicochemical properties and their battery performance …

The Place Of Arbs In Heart Failure Therapy: Is Aldosterone Suppression The Key?, Uma Markan, Samhitha Pasupuleti, Celina M. Pollard, Arianna Perez Bhs Student, Beatrix Aukszi, Anastasios Lymperopoulos

Chemistry and Physics Faculty Articles

Since the launch of the first orally available angiotensin II (AngII) type 1 receptor (AT₁R) blocker (ARB) losartan (Cozaar) in the late 1990s, the class of ARBs (or ‘sartans’, short for Angiotensin-RecepTor-ANtagonistS) quickly expanded to include candesartan, eprosartan, irbesartan, valsartan, telmisartan, and olmesartan. All ARBs have high affinity for the AT₁ receptor, expressed in various tissues, including smooth muscle cells, heart, kidney, and brain. Since activation of AT₁R, the target of these drugs, leads, among other effects, to vascular smooth muscle cell growth, proliferation and contraction, activation of fibroblasts, cardiac hypertrophy, aldosterone secretion from the …

Using An Extended Broken Symmetry Approximation To Characterize Structure And Spectroscopic Properties Of 2fe-2s Clusters, Ashlyn M. Koval

Electronic Theses and Dissertations

Iron-sulfur proteins perform a wide variety of biological functions that assist in mediating protein function via electron transfer reactions. The Rieske and mitoNEET iron-sulfur clusters have been shown to undergo proton coupled electron transfer facilitated by a histidine ligand. The protonation state of the histidine residue is key to understanding the mechanism of proton coupled electron transfer. This work reports a study of the 2Fe-2S ferredoxin, Rieske, and mitoNEET clusters using the extended broken symmetry approximation. Calculations were performed on the ferredoxin cluster to establish appropriate methodologies. Calculations were then performed for Rieske and mitoNEET clusters to suggest experiments capable …

Triple Functionalization Of Titanium Aluminum Vanadium For Orthopedic Implant Applications, Ashley Blystone

Electronic Theses and Dissertations

Orthopedic implant surgeries are on the rise in the United States, with well over a million surgeries performed annually. Common materials used for these applications include titanium and its alloy, titanium aluminum vanadium (Ti-6Al-4V). Ti-6Al-4V is chosen for this application due to its mechanical strength and corrosion resistance. However, Ti-6Al-4V does not support osseointegration and is susceptible to bacterial colonization. Therefore, these implants suffer from aseptic loosening and infection, necessitating removal and replacement. Revision surgery and treatment is financially burdensome and taxing on the patient. Current approaches focus on modifying the surface of Ti-6Al-4V through a variety of means to …

Testing The Robustness Of Solution Force Fields For Md Simulations On Gaseous Protein Ions., Justin H Lee, Katja Pollert, Lars Konermann

Chemistry Publications

It is believed that electrosprayed proteins and protein complexes can retain solution-like conformations in the gas phase. However, the lack of high-resolution structure determination methods for gaseous protein ions implies that their properties remain poorly understood. Many practitioners tackle this difficulty by complementing mass spectrometry-based experiments with molecular dynamics (MD) simulations. It is a potential problem that the standard MD force fields used for this purpose (such as OPLS-AA/L and CHARMM) were optimized for solution conditions. The question whether these force fields produce meaningful gas-phase data has received surprisingly little attention. Standard force fields are overpolarized to account for an …

Synthesis And Evaluations Of “1,4-Triazolyl Combretacoumarins” And Desmethoxy Analogs, Tashrique A. Khandaker, Jessica D. Hess, Renato Aguilera, Graciela Andrei, Robert Snoeck, Dominique Schols, Padmanava Pradhan, Mahesh K. Lakshman

Publications and Research

1,4-Triazolyl combretacoumarins have been prepared by linking the trimethoxyarene unit of combretastatin A4 with coumarins, via a 1,2,3-triazole. For this, 4-azidocoumarins were accessed by a sequential two-step, one-pot reaction of 4-hydroxycoumarins with (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), followed by reaction with NaN₃. In the reaction with BOP, a coumarin-derived phosphonium ion intermediate seems to form, leading to an O⁴-(benzotriazolyl)coumarin derivative. For the CuAAC reaction of azidocoumarins with 5-ethynyl-1,2,3-trimethoxybenzene, catalytic [(MeCN)₄Cu]PF₆ in CH₂Cl₂/MeOH with 2,6-lutidine, at 50 ^oC, was suitable. The 4-azidocoumarins were less reactive as compared to PhN₃ and …

What Is The Accuracy Limit Of Adiabatic Linear-Response Tddft Using Exact Exchange–Correlation Potentials And Approximate Kernels?, Jaspreet Kaur, Egor Ospadov, Viktor N. Staroverov

Chemistry Publications

Calculation of vertical excitation energies by the adiabatic linear-response time-dependent density-functional theory (TDDFT) requires static Kohn–Sham potentials and exchange–correlation kernels. When these quantities are derived from standard density-functional approximations (DFA), mean absolute errors (MAE) of the method are known to range from 0.2 eV to over 1 eV, depending on the functional and type of excitation. We investigate how the performance of TDDFT varies when increasingly accurate exchange–correlation potentials derived from Hartree–Fock (HF) and post-HF wavefunctions are combined with different approximate kernels. The lowest MAEs obtained in this manner for valence excitations are about 0.15–0.2 eV, which appears to be …

Vibronic Fingerprint Of Singlet Fission In Hexacene, Gang-Hua Deng, Qianshun Wei, Jian Han, Yuqin Qian, Jun Luo, Avetik R. Harutyunyan, Gugang Chen, Hongtao Bian, Hanning Chen, Yi Rao

Chemistry and Biochemistry Faculty Publications

Singlet fission has the great potential to overcome the Shockley–Queisser thermodynamic limit and thus promotes solar power conversion efficiency. However, the current limited understandings of detailed singlet fission mechanisms hinder a further improved design of versatile singlet fission materials. In the present study, we combined ultrafast transient infrared spectroscopy with ab initio calculations to elucidate the roles played by the vibrational normal modes in the process of singlet fission for hexacene. Our transient infrared experiments revealed three groups of vibrational modes that are prominent in vibronic coupling upon photoexcitation. Through our computational study, those normal modes with notable Franck-Condon shifts …

Erratum: "Imaging The Three‐Dimensional Orientation And Rotational Mobility Of Fluorescent Emitters Using The Tri‐Spot Point Spread Function", Oumeng Zhang, Jin Lu, Tianben Ding, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

In the original paper, a calibration error exists in the image-formation model used to analyze experimental images taken by our microscope, causing a bias in the orientation measurements in Figs. 2 and 3. The updated measurements are shown in Fig. E1. We have also updated the supplementary material for the original article to discuss the revised PSF model and estimation algorithms (supplementary material 2) and show the revised model and measurements (Figs. S1, S3, S7, S8, and S10–S13).

Organic-Inorganic Hybrid Composites: Superhydrophobic Polymer Coatings With Photoreactive Perfluorinated Phthalocyanines, Abdul Azeez

Seton Hall University Dissertations and Theses (ETDs)

ABSTRACT

We report partly fluorinated and silicon-based polymers that incorporate inorganic/organic materials capable of generating reactive oxygen species (ROS) using only visible light and air. Polyvinylidene fluoride (PVDF), which incorporated a known perfluorinated phthalocyanine photosensitizer, F₆₄PcZn, supported on silicon and titanium oxides was further modified via chemical surface roughening to exhibit enhanced hydrophobicity when used as a coating. Water contact angles as high as ~159° have been observed, vs. ~ 92° for the unmodified polymer. The polymer matrix, however, does not resist the ROS it produces as evidenced by spectroscopic and SEM data. A polysiloxane matrix was similarly …

The Roundtable Of Scientific Communication: From Classroom To Course Creation, Back To Classroom And Beyond, Sean P. Hickey

LSU New Orleans Theses and Dissertations

This research encompasses many aspects of chemical education research including curriculum and pedagogical changes to the freshman and sophomore courses. Curriculum changes included the addition of recitations to the general chemistry and organic chemistry lectures and the creation of four new classes, CHEM 1001, 1002, 3091, and 3092. The addition of recitations was not limited to but was focused on improving DFW rates for these courses.

CHEM 3091 and 3092 are chemistry internship and undergraduate teaching assistant classes. These courses were necessary to offer outside internship opportunities and training for undergraduate teaching assistants, respectively. CHEM 1001 and 1002 are chemistry …

Microstructure And Materials Characterization Of Sol-Gel Synthesized Zro2 Systems, Sungsoo Park, Godlisten Shao

Tanzania Journal of Science

The roles of pH and thermal treatment on the microstructures of sol-gel synthesized mesoporous ZrO2 systems have been investigated. In order to control the crystal structures and particle sizes of the final products, the pH values of the reaction mixtures were controlled between 5 and 12 followed by calcination at temperatures ranging from 450 to 1000 °C. The microstructures of the zirconia systems were then examined by XRD, TEM, TGA, UV-visible DRS and nitrogen physisorption study analyses. It was found that pH values and calcination temperatures have significant influence on the crystallization temperature, phase transformation and particle size of the …

Development And Evaluation Of A Hybrid Adi/Swh Model Pre-Laboratory Curriculum, Tabitha Alitz, Dawn Del Carlo

Summer Undergraduate Research Program (SURP) Symposium

Previous Research:
• Students value each part of the pre-lab differently, struggle to connect all of the components, and therefore fail to see the big picture
• Students find the pre-lab moderately helpful in understanding both the concepts and mechanics of the lab, but find it less helpful at the end of the semester compared to beginning
• The cognitive load demands of the SWH pre-lab hinders students’ ability to participate in authentic scientific inquiry

Effects Of Halogen, Chalcogen, Pnicogen, And Tetrel Bonds On Ir And Nmr Spectra, Jia Lu, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Complexes were formed pairing FX, FHY, FH₂Z, and FH₃T (X = Cl, Br, I; Y = S, Se, Te; Z = P, As, Sb; T = Si, Ge, Sn) with NH₃ in order to form an A⋯N noncovalent bond, where A refers to the central atom. Geometries, energetics, atomic charges, and spectroscopic characteristics of these complexes were evaluated via DFT calculations. In all cases, the A–F bond, which is located opposite the base and is responsible for the σ-hole on the A atom, elongates and its stretching frequency undergoes a shift to the red. This …

Spontaneous Selective Deposition Of Iron Oxide Nanoparticles On Graphite As Model Catalysts, Chathura De Alwis, Timothy Leftwich, Pinaki Mukherjee, Alex Denofre, Kathryn Perrine

Michigan Tech Publications, Part 1

Iron oxide nanomaterials participate in redox processes that give them ideal properties for their use as earth-abundant catalysts. Fabricating nanocatalysts for such applications requires detailed knowledge of the deposition and growth. We report the spontaneous deposition of iron oxide nanoparticles on HOPG in defect areas and on step edges from a metal precursor solution. To study the nucleation and growth of iron oxide nanoparticles, tailored defects were created on the surface of HOPG using various ion sources that serve as the target sites for iron oxide nucleation. After solution deposition and annealing, the iron oxide nanoparticles were found to nucleate …

Development Of A Screening Method For Drugs Of Abuse By Direct Analysis Of Dried Urine Spots Coupled To Mass Spectrometry, Melanie Goldstein

Student Theses

Fast and easy screening procedures are essential in any forensic toxicology laboratory to differentiate negative samples from presumptive positive cases. Immunoassay techniques, such as enzyme multiplied immunoassay technique (EMIT), are routinely employed as screening procedures. However, these techniques lack specificity (only differentiate group of drugs and not individual compounds) and it is difficult to add new compounds to the panel. Direct analysis of dried urine spots (DUS) by mass spectrometry (MS) offers a novel strategy to overcome these issues. DUS offer an improved storage alternative for biological samples, reducing costs and space requirements. In this work, an original method to …

Palladium(Ii) Complexes Of A Bridging Amine Bis(Phenolate) Ligand Featuring Κ² And Κ³ Coordination Modes, Brendan J. Graziano, Bradley M. Wile, Matthias Zeller

Chemistry and Biochemistry Faculty Scholarship

Bidentate and tridentate coordination of a 2,4-di-tert-butyl-substituted bridging amine bis­(phenolate) ligand to a palladium(II) center are observed within the same crystal structure, namely di­chlorido­({6,6′-[(ethane-1,2-diylbis(methyl­aza­nedi­yl)]bis­(methyl­ene)}bis­(2,4-di-tert-butyl­phenol))palladium(II) chlorido­(2,4-di-tert-butyl-6-{[(2-{[(3,5-di-tert-butyl-2-hy­droxy­phen­yl)meth­yl](meth­yl)amino}­eth­yl)(meth­yl)amino]­meth­yl}phenolato)palladium(II) methanol 1.685-solvate 0.315-hydrate, [PdCl₂(C₃₄H₅₆N₂O₂)][PdCl(C₃₄H₅₅N₂O₂)]·1.685CH₃OH·0.315H₂O. Both complexes exhibit a square-planar geometry, with unbound phenol moieties participating in inter­molecular hydrogen bonding with co-crystallized water and methanol. The presence of both κ² and κ³ coordination modes arising from the same solution suggest a dynamic process …

Selective Solvent Capture By Molecular Assemblies Of Diosmium Sawhorses, Gregory Powell, Cynthia Powell

Chemistry and Biochemistry

No abstract provided.

Elements Of An Effectiveresearch Presentation, Rachel Willand Charnley

Chemistry and Biochemistry Faculty Presentations and Other Materials

No abstract provided.

New Ideas From An Old Concept: The Hydrogen Bond, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Ongoing studies of the hydrogen bond (HB), in which a hydrogen (H) atom acts as a bridge between a pair of chemical groups, continues to offer new ideas about this interaction that have applications to biochemical processes. The ability of a proton to transfer within a HB can be controlled by conformational changes that cause small alterations to the HB geometry. The CH group, widely prevalent in biological systems, participates in HBs and contributes to the structure and stability of commonly occurring protein secondary structures such as the β-sheet. The concept of the HB has been extended to systems where …

Probing Mid-Infrared Plasmon Resonances In Extended Radial Fractal Structures., Gregory Q Wallace, Danielle M Mcrae, François Lagugné-Labarthet

Chemistry Publications

Infrared (IR) antennas made of metallic nanostructures are widely tunable from the near- to the far-IR range. They can be utilized for a variety of applications such as light harvesting and photonic filters, and their structural linear or circular anisotropy can be exploited to further enhance the sensitivity of spectroscopic measurements. Here gold dendritic fractal structures that were optimized to exhibit multiple resonances in the mid-IR range were characterized using a scattering-type scanning near-field optical IR microscope. The spatially resolved IR maps associated with the individual modes serve as a basis to understand the mode evolution between each fractal generation.

Organically Modified Inorganic Nanoparticles For Halochromic Ionophores And Nucleic Acids, William Johnston

Doctoral Dissertations

In this dissertation, four nanoparticle reaction schemes were developed as substrates for halochromic dyes or nucleic acids. The reaction schemes include the use of two substrates: silica nanoparticles and halloysite nanotubes. The protocols can incorporate silica (SiO2) nanoparticles and halloysite aluminosilicate (AlO2SiO2) nanotubes due to the presence of silane groups on the surface of either substrate. The reaction schemes are presented along with detailed protocols which were written to facilitate both reproducibility and to serve as an aid to further study and for easy modification of the protocol to suit a researcher's needs. The data is discussed in the materials …

Violation Of Electrostatic Rules: Shifting Balance Between Pnicogen Bond And Lone Pair−Π Interaction Tuned By Substituents, Zongqing Chi, Tong Yan, Qing-Zhong Li, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Complexes were formed pairing ZCl3 (Z=P, As, Sb) with C2R4 (R= H, F, CN). The first interaction present is a pnicogen bond between the Z atom and the C=C π-bond. This bond weakens as the H atoms of ethylene are replaced by electron-withdrawing F and CN and the potential above the alkene switches from negative to positive. In the latter two cases, another set of noncovalent bonds is formed between the Cl lone pairs of ZCl3 and the π*(C=C) antibonding orbital, as well as with the F or CN substituents. The growing strength of these interactions, coupled with a large …

Copper-Based Ternary Oxide Semiconductors For Solar Energy Conversion And Environmental Remediation, Mohammad Kabir Hossain

Chemistry & Biochemistry Dissertations - Archive

Photoelectrochemical (PEC) water splitting using inorganic semiconductors is a promising approach to convert sunlight into sustainable fuels. However, many scientific and engineering challenges need to be overcome before its commercialization. Oxide semiconductors offer many advantages such as stability in a variety of electrolytes, a diverse range of bandgaps and their Earth-abundance in nature. In this respect, many binary metal oxides have been investigated thoroughly; however, unfortunately, a suitable candidate for PEC water splitting has not been identified. While many efforts are ongoing to overcome the limitations of binary metal oxides, it is also essential to expand the search to more …

The Roles Of Long Noncoding Rnas In Inflammation And Immune Responses, Monira Obaid

Chemistry & Biochemistry Dissertations - Archive

Inflammation is an immune response that protects the human body from infection, illness, or injury. The inflammatory response causes the activation of immune cells, such as leukocyte subsets (i.e., monocytes, macrophages, dendritic cells, neutrophils, eosinophils and others), T cells, and B cells, and induces production of inflammatory mediators such as cytokines, chemokines, and antibodies to fight against injury or infection. Uncontrolled and continued inflammation drives the development of many human diseases, including metabolic diseases, obesity, diabetes, autoimmune disorders, neurological disorder and cancer. Indeed, the signaling process associated with inflammation and immune response is very complex. Our understanding of inflammation and …

Catalytic C-C Silylation Reactions, Thirupataiah Avullala

Chemistry & Biochemistry Dissertations - Archive

In my doctoral studies, the research is mainly focused on developing highly regio- and chemoselective C–C silylation of cyclopropanol derivatives with a hydrosilyl acetal directing group. This approach involves use of a relay of Ir-catalyzed hydrosilylation of inexpensive and readily prepared cyclopropanoacetates and Rh-catalyzed C–C silylation to achieve dioxasilolanes and dioxasilepines. In Chapter 1, we report a redox-neutral, catalytic C–C activation of cyclopropyl acetates to produce silicon-containing five-membered heterocycles in a highly regio- and chemoselective fashion. The umpolung selective silylation leading to dioxasilolanes is opposed to contemporary selective C–C functionalization protocols of cyclopropanols. Lewis base activation of dioxasilolanes as silyl …

Development Of Innovative Theranostic Platforms For Biomedical Applications, Min Kyung Khang

Chemistry & Biochemistry Dissertations - Archive

Modern technologies have been successfully identifying patient’s disease-related genetic information and developing effective drugs continuously. The discovery of molecular biomarkers paves new roads for potential individualized therapeutic applications; thus far, the call for a more development of advanced targeting/delivery platforms is highly required in the bioengineering field. Unfortunately, bioengineered targeting platforms for drug delivery at the right place, right dosage and right time have still remained in the developmental stages. To develop innovative nanosystems for various biomedical applications, polymer chemistry and click chemistry are needed to improve the function of the nanosystems. My dissertation research is based upon a unique …

Non-Heme Iron Oxygenases: An Investigation Of The Protein Ligand Effects On The Chemical Reactivity In Miae And Cysteamine Dioxygenases, Philip Palacios

Chemistry & Biochemistry Dissertations - Archive

Considerable research interest has focused on the non-heme oxygenase/oxidase enzyme family because of vast array of chemically diverse O2-depedent oxidations they participate in. For example, the bacterial multicomponent monooxygenases (sMMOH and ToMOH) are bacterial diiron enzymes that are involved in the oxidations of simple carbon sources (methane and toluene) for nutrition and other cellular cycles. Investigations of the BMM systems have significant implications for the research and development in greenhouse emissions. The hydroxylase component of the BMM superfamily is coordinated by 2-Histidine-4-carboxylate ligands (Asp or Glu) [2H4C]. The [2H4C] configuration is the typical moiety for the 2-electron oxidation in the …