Chemistry Commons^™

Synthesis And Characterization Of (Pyno−)2gacl: A Redox-Active Gallium Complex, Jacob M. Kirsh , '17, Audra J. Woodside , '19, B. C. Manor, P. J. Carroll, Paul R. Rablen, Christopher R. Graves

Chemistry & Biochemistry Faculty Works

We report the synthesis of a gallium complex incorporating redox-active pyridyl nitroxide ligands. The (pyNO−)2GaCl complex was prepared in 85% yield via a salt metathesis route and was characterized by 1H and 13C NMR spectroscopies, X-ray diffraction, and theory. UV–Vis absorption spectroscopy and electrochemistry were used to access the optical and electrochemical properties of the complex, respectively. Our discussion focuses primarily on a comparison of the gallium complex to the corresponding aluminum derivative and shows that although the complexes are very similar, small differences in the electronic structure of the complexes can be correlated to the identity of the metal.

Quadruplexes In ‘Dicty’: Crystal Structure Of A Four-Quartet G-Quadruplex Formed By G-Rich Motif Found In The Dictyostelium Discoideum Genome, A. Guédin, Linda Yingqi Lin , '20, S. Armane, L. Lacroix, J.-L. Mergny, S. Thore, Liliya A. Yatsunyk

Chemistry & Biochemistry Faculty Works

Guanine-rich DNA has the potential to fold into non-canonical G-quadruplex (G4) structures. Analysis of the genome of the social amoeba Dictyostelium discoideum indicates a low number of sequences with G4-forming potential (249–1055). Therefore, D. discoideum is a perfect model organism to investigate the relationship between the presence of G4s and their biological functions. As a first step in this investigation, we crystallized the dGGGGGAGGGGTACAGGGGTACAGGGG sequence from the putative promoter region of two divergent genes in D. discoideum. According to the crystal structure, this sequence folds into a four-quartet intramolecular antiparallel G4 with two lateral and one diagonal loops. The G-quadruplex …

Striking The Right Balance Of Intermolecular Coupling For High-Efficiency Singlet Fission, Ryan D. Pensack, Andrew J. Tilley, Christopher Grieco, Geoffrey E. Purdum, Evgeny E. Ostroumov, Devin B. Granger, Daniel G. Oblinsky, Jacob C. Dean, Grayson S. Doucette, John B. Asbury, Yueh-Lin Loo, Dwight S. Seferos, John E. Anthony, Gregory D. Scholes

Chemistry Faculty Publications

Singlet fission is a process that splits collective excitations, or excitons, into two with unity efficiency. This exciton splitting process, unique to molecular photophysics, has the potential to considerably improve the efficiency of optoelectronic devices through more efficient light harvesting. While the first step of singlet fission has been characterized in great detail, subsequent steps critical to achieving overall highly-efficient singlet-to-triplet conversion are only just beginning to become well understood. One of the most elementary suggestions, which has yet to be tested, is that an appropriately balanced coupling is necessary to ensure overall highly efficient singlet fission; that is, the …

Absolute Configuration Of 2,2',3,3',6-Pentachlorinatedbiphenyl (Pcb 84) Atropisomers, Xueshu Li, Sean R. Parkin, Hans-Joachim Lehmler

Chemistry Faculty Publications

Nineteen polychlorinated biphenyl (PCB) congeners, such as 2,2′,3,3′,6-pentachlorobiphenyl (PCB 84), display axial chirality because they form stable rotational isomers, or atropisomers, that are non-superimposable mirror images of each other. Although chiral PCBs undergo atropselective biotransformation and atropselectively alter biological processes, the absolute structure of only a few PCB atropisomers has been determined experimentally. To help close this knowledge gap, pure PCB 84 atropisomers were obtained by semi-preparative liquid chromatography with two serially connected Nucleodex β-PM columns. The absolute configuration of both atropisomers was determined by X-ray single-crystal diffraction. The PCB 84 atropisomer eluting first and second on the Nucleodex β-PM …

Facially Amphiphilic Polyionene Biocidal Polymers Derived From Lithocholic Acid, Mitra S. Ganewatta, Md Anisur Rahman, Louis Mercado, Tinom Shokfai, Alan W. Decho, Theresa M. Reineke, Chuanbing Tang

Faculty Publications

Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cationic polymers can form core-shell micelles. These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species. It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities. Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.

Solution And Solid-State Characterization Of Zn(Ii) Complexes Containing A New Tridentate N2S Ligand, Valerie Tran, Kate E. Allen, Martin Garcia Chavez, Christopher Aaron, Joseph J. Dumais, John T. York, Eric C. Brown

Chemistry and Biochemistry Faculty Publications and Presentations

A new N₂S ligand bis(pyridyl)(2-mercapto-1-methylimidazolyl)methane (2, Py₂MeImS) has been synthesized and characterized. Treatment of this ligand with bromide and triflate salts of Zn(II) results in the complexes (Py₂MeImS)ZnBr₂ (3) and [(Py₂MeImS)₂Zn](OTf)₂ (4), respectively. The solid-state structure of (Py₂MeImS)ZnBr₂ shows bidentate N,N-coordination of Py₂MeImS to the zinc ion, with the sulfur atom of the 2-mercaptoimidazole moiety uncoordinated. Two conformers of 3 rapidly interconvert in solution at room temperature, and variable temperature NMR studies and DFT calculations were used …

Synthesis And Characterization Of Fluorescent Nanojars, Vageesha Warnajith Liyana Gunawardana

Masters Theses

Self-assembly is a powerful tool utilized by synthetic chemists to create large, intricate structures for a variety of applications such as drug delivery, adaptable materials and electronics. In contrast to stepwise synthesis, this process allows the formation of intricate molecular architectures starting from synthetically rudimentary building blocks. Nanojars are class of self-assembling, cyclic copper(II) pyrazolate coordination compounds that encapsulate oxoanions with negative two or three charge. The strong anion binding characteristics of nanojars have potential towards developing novel tools for detecting biologically and environmentally relevant anions such as carbonate, sulfate and phosphate.

This work addresses the design and synthesis of …

Nanojars: Versatile Platform For Pyrazole Synthesis And Chemistry, And Selective Extraction Of Anions, Basil Mohammed Ahmed

Dissertations

This work is centered around nanojars, a family of nano-sized anion-incarcerating agents. It addresses various aspects of nanojar chemistry, such as synthesis strategies (including green methodologies) for pyrazole ligands needed for the preparation of nanojars, characterization and study of the mechanism of assembly of nanojars, and selective extraction of anions from water using nanojars.

Nanojars are neutral, supramolecular coordination complexes of the general formula [anion⊂ {Cu(μ-OH)(μ-pz)}_n], formed by the reaction of Cu²⁺, HO^‒ and pyrazolate ions (C₃H₂N₂‒, pz^‒) in the presence of oxoanions with large hydration energy …

Deconvoluting The Effects Of Surface Chemistry And Nanoscale Topography: Pseudomonas Aeruginosa Biofilm Nucleation On Si-Based Substrates, Jing Zhang, Jingling Huang, Carmen Say, Robert L. Dorit, Kate Queeney

Chemistry: Faculty Publications

Hypothesis

The nucleation of biofilms is known to be affected by both the chemistry and topography of the underlying substrate, particularly when topography includes nanoscale (nm) features. However, determining the role of topography vs. chemistry is complicated by concomitant variation in both as a result of typical surface modification techniques. Analyzing the behavior of biofilm-forming bacteria exposed to surfaces with systematic, independent variation of both topography and surface chemistry should allow differentiation of the two effects.

Experiments

Silicon surfaces with reproducible nanotopography were created by anisotropic etching in deoxygenated water. Surface chemistry was varied independently to create hydrophilic (OH- terminated) …

Scalable, Hydrophobic And Highly-Stretchable Poly(Isocyanurate-Urethane) Aerogels, Sadeq Malakooti, Saman Rostami, Habel Gitogo Churu, Huiyang Luo, Jenna Clark, Fabiola Casarez, Owen Rettenmaier, Soheil Daryadel, Majid Minary-Jolandan, Chariklia Sotiriou-Leventis, Nicholas Leventis, Hongbing Lu

Chemistry Faculty Research & Creative Works

Scalable, low-density and flexible aerogels offer a unique combination of excellent mechanical properties and scalable manufacturability. Herein, we report the fabrication of a family of low-density, ambient-dried and hydrophobic poly(isocyanurate-urethane) aerogels derived from a triisocyanate precursor. The bulk densities ranged from 0.28 to 0.37 g cm^-3 with porosities above 70% v/v. The aerogels exhibit a highly stretchable behavior with a rapid increase in the Young's modulus with bulk density (slope of log-log plot > 6.0). In addition, the aerogels are very compressible (more than 80% compressive strain) with high shape recovery rate (more than 80% recovery in 30 s). Under …

Preparation Of Supramolecular Amphiphilic Cyclodextrin Bilayer Vesicles For Pharmaceutical Applications, Kate E. Frischkorn

Master's Theses

Recent pharmaceutical developments have investigated using supramolecular nanoparticles in order to increase the bioavailability and solubility of drugs delivered in various methods. Modification of the carbohydrate cyclodextrin increases the ability to encapsulate hydrophobic pharmaceutical molecules by forming a carrier with a hydrophobic core and hydrophilic exterior. Guest molecules are commonly added to these inclusion complexes in order to add stability and further increase targeting abilities of the carriers. One such guest molecule is adamantine combined with a poly(ethylene glycol) chain. Vesicles are formed by hydrating a thin film of amphiphilic cyclodextrin and guest molecules in buffer solution that mimics physiological …

An Improved Method For The Analysis Of Fiber Evidence Using Polarized Light Microscopy, Samuel F. Kaplan

Student Theses

Using the basic fundamentals of polarized light microscopy, a new and improved method for identifying synthetic fibers is presented in this thesis. Using the equation of an ellipse in spherical coordinates, an EXCEL™ (Microsoft Inc., Seattle, WA) spreadsheet was developed that generated tables of data that provide a foundation for a new and more efficient method in fiber analysis. Intermediate refractive index values for each subclass of textile fibers were calculated based on the fiber's principal refractive index values. The angles of refractive index matching to known refractive index fluids vary from 0 to 90 degrees upon rotation of the …

Application Of The Entropy Concept To Thermodynamics And Life Sciences: Evolution Parallels Thermodynamics, Cellulose Hydrolysis Thermodynamics, And Ordered And Disordered Vacancies Thermodynamics, Marko Popovic

Theses and Dissertations

Entropy, first introduced in thermodynamics, is used in a wide range of fields. Chapter 1 discusses some important theoretical and practical aspects of entropy: what is entropy, is it subjective or objective, and how to properly apply it to living organisms. Chapter 2 presents applications of entropy to evolution. Chapter 3 shows how cellulosic biofuel production can be improved. Chapter 4 shows how lattice vacancies influence the thermodynamic properties of materials. To determine the nature of thermodynamic entropy, Chapters 1 and 2 describe the roots, the conceptual history of entropy, as well as its path of development and application. From …

The Effect Of Distance And Angle On Electronic Couplings Between F8bt-Based Oligomers, Jacob H. Wat

DePaul Discoveries

Organic semiconductors are often used as light-absorbers in photovoltaic devices and studying the energy flow through these materials is an important field of research. The energy flow is controlled by electronic coupling between the organic semiconductor molecules, which is affected by the distance between the molecules and their relative orientation. Here we calculated the couplings as a function of distance and relative orientation based on semi-empirical calculations of the low-lying excited states of pairs of organic semiconductor molecules. We showed that as distance increased, electronic couplings approach zero. Electronic couplings calculated as a function of rotation were maximized as the …

Synthesis Of A Bipyridine Ligand For Metal-Triggered Supramolecular Polymers, Andrew D. Gould

DePaul Discoveries

Intermolecular forces, such as H-bonding, ionic interactions and metal chelation between small molecules, can lead to the assembly of higher-order supramolecular nanostructures. A metal chelator, 2-(Pyridin-2-yl) pyridine-5-carboxylic Acid (a bipyridine derivative), is expected to aid in the formation of supramolecular structures as part of amphiphilic molecules that self-assemble in solution in the presence of metal ions. The bipyridine ligand currently under synthesis can be prepared through a five-step synthesis scheme. The second reaction of this synthesis (the coupling of two pyridine rings) resulted in a combination of the desired 1,2,5-isomer, as well as an unforeseen 1,2,3-isomer. Future research will therefore …

Fluorescent Probes And Functionalized Nanoparticles For Bioimaging: Synthesis, Photophysical Properties And Applications, Xinglei Liu

Dissertations

The development of new organic molecular probes with excellent photophysical properties and high fluorescence quantum yields is of considerable interest to many research areas including one- and two-photon fluorescence microscopy, fluorescence-based sensing methodologies, and cancer therapy. Series of organic linear-/non-linear optical molecules including squaraine derivatives, and fluorene derivatives as well as other bioconjugates are designed and synthesized during the doctoral study for the aim of ion detection (Chapter 5), photo dynamic therapy, and deep-tissue imaging (Chapter 4). These optical probes are capable of absorbing light in the near infrared (NIR) window and thus have deeper penetration and cause less photodamage …

Kinetic Study Of Free Radical-Radical Reactions Of Combustion Importance At Elevated Pressures, Chao Yan

Dissertations

Combustion mechanisms consist of hundreds elementary reactions of free radicals and stable molecules. Radical-radical elementary reactions play important roles due to the high concentration in which free radicals are accumulated in combustion systems. Radical-radical reactions are typically multi-channel. Some of the channels might be of chain propagation or even chain branching nature, while other channels might be of chain termination nature. The relative importance of different channels is pressure dependent. Compared to radical-molecule reactions, radical-radical reactions are much less studied. This is due to the difficulties of well characterized quantitative production of radical species as well as due to the …

Design And Assessment Of Small Molecules As Free Radical Scavengers And Potential Multi-Target Therapeutic Agents Against Alzheimer’S Disease, Diabetes And Cancer, William Horton

Graduate Doctoral Dissertations

Complex diseases such as Alzheimer’s disease (AD), diabetes and cancer are difficult to manage with single target treatment approaches and unfortunately, they are wide-spread. For example, over 16 million people are expected to have AD in the US by 2050, thus new therapeutic approaches have to be developed. Multi-functional drug candidates have gained increasing popularity in treating complex diseases. The impact of oxidative stress in almost every disease progression makes them essential components in therapies for complex diseases. Endogenous systems typically maintain redox homeostasis within the cell, but in the diseased state these systems fail to alleviate oxidative stress. Supplementation …

Investigation On The Dissociative Photoionization Mechanism Of Furfural, Investigation Of The Absolute Photoionization Cross Sections Of Three Potential Propargylic Fuels, And Ab Initio Analysis On Potential Superbases Of Several Hyperlithiated Species: Li3f2o And Li3f2(Oh)N (N = 1, 2, 3), Matthew Winfough

Master's Theses

This thesis presents the study photoionization cross sections of three different propargylic biofuels; dipropargyl ether, propargyl alcohol, and propargylamine, in chlorine radical-initiated combustion experiments at the Chemical Dynamics Beamline (9.0.2) at the Advanced Light Source of the Ernest Orlando Berkeley National Laboratory in Berkeley, California. Additionally, the unimolecular dissociative photoionization mechanism of furfural was studied using photoelectron photoionization coincidence (PEPICO) spectroscopy at the vacuum ultraviolet beamline at the Swiss Light Source of the Paul Scherrer Institut in Villigen, Switzerland. Dissociation products and mechanisms for furfural were identified over a photon energy range of 10.9 to 14.5 eV. Lastly, a study …

Hydrogen Bonding In The Mixed Hf/Hci Dimer: Is It Better To Give Or Receive?, Sarah N. Johnson, Gregory S. Tschumper

Chemistry Faculty Research & Creative Works

The ClH⋯FH and FH⋯ClH configurations of the mixed HF/HCl dimer (where the donor⋯acceptor notation indicates the directionality of the hydrogen bond) as well as the transition state connecting the two configurations have been optimized using MP2 and CCSD(T) with correlation consistent basis sets as large as aug-cc-pV(5 + d)Z. Harmonic vibrational frequencies confirmed that both configurations correspond to minima and that the transition state has exactly one imaginary frequency. In addition, anharmonic vibrational frequencies computed with second-order vibrational perturbation theory (VPT2) are within 6 cm⁻¹ of the available experimental values and deviate by no more than 4 cm^{−1 …}

Analytical And Toxicological Evaluation Of Flavor Chemicals In Electronic Cigarette Refill Fluids, Rachel Z. Behar, Wentai Luo, Kevin J. Mcwhirter, James F. Pankow, Prue Talbot

Chemistry Faculty Publications and Presentations

Thousands of electronic cigarette refill fluids are commercially available. The concentrations of nicotine and the solvents, but not the flavor chemicals, are often disclosed on product labels. The purpose of this study was to identify and quantify flavor chemicals in 39 commercial refill fluids that were previously evaluated for toxicity. Twelve flavor chemicals were identified with concentrations ≥1 mg/ml: cinnamaldehyde, menthol, benzyl alcohol, vanillin, eugenol, p-anisaldehyde, ethyl cinnamate, maltol, ethyl maltol, triacetin, benzaldehyde, and menthone. Transfer of these flavor chemicals into aerosols made at 3V and 5V was efficient (mean transfer = 98%). We produced lab-made refill fluids containing …

Nearly Defect-Free Dynamical Models Of Disordered Solids: The Case Of Amorphous Silicon, Raymond Atta-Fynn, Parthapratim Biswas

Faculty Publications

It is widely accepted in the materials modeling community that defect-free realistic networks of amorphous silicon cannot be prepared by quenching from a molten state of silicon using classical or ab initio molecular-dynamics (MD) simulations. In this work, we address this long-standing problem by producing nearly defect-free ultra-large models of amorphous silicon, consisting of up to half a million atoms, using classical MD simulations. The structural, topological, electronic, and vibrational properties of the models are presented and compared with experimental data. A comparison of the models with those obtained from using the modified Wooten-Winer-Weaire bond-switching algorithm shows that the models …

The Spin-Forbidden A^4z-—X^2n(1/2) Transition Of Geh Detected In Absorption Using Intracavity Laser Spectroscopy, James O'Brien, L. O'Brien, L. Harms

Chemistry & Biochemistry Faculty Works

The a 4Σ--X 2Π1/2 transition of GeH has been recorded in absorption for the first time using Intracavity Laser Spectroscopy (ILS). The GeH molecules were produced in a 0.40-0.60 A DC plasma discharge inside an aluminum hollow cathode, using 500 mTorr of Ar, 100 mTorr of H2, and 200 mTorr of GeH4. This cathode is located within the resonator cavity of a Coherent Verdi™ V-10 pumped dye laser. Effective path lengths for this series of measurements using the ILS method ranged from 2 to 7 km. Spectra were calibrated using the absorption spectrum of I2 collected from an extracavity cell, …

A Π-Conjugated Inorganic Polymer Constructed From Boron Difluoride Formazanates And Platinum(Ii) Diynes, Jasveer S. Dhindsa, Ryan R. Maar, Stephanie M. Barbon, Maria Olivia Avilés, Zachary K. Powell, Francois Lagugné-Labarthet, Joe Gilroy

Chemistry Publications

The first example of a π-conjugated polymer incorporating boron difluoride (BF₂) formazanates is introduced. The film-forming properties, controllable reduction chemistry, and low optical band gap (ca. 1.4 eV) of the polymer make it an excellent candidate for use as a light-harvesting n-type semiconductor in organic electronics. Comparison of the polymer to model compounds confirmed that its unique optoelectronic properties can be directly attributed to the presence of the BF₂ formazanate repeat unit and that the [Pt(PBu₃)₂]²⁺ unit must also be present to achieve the narrow band gaps observed.

Multi-Reference Systems In Chemistry; Unconventional Bonding In Organic Chemistry; Covalent Bonding In Transition Metal Clusters, Alan Wilfred Humason

Chemistry Theses and Dissertations

The geometries, chemical properties, and reactivities of molecules are determined by their electronic structure. The field of ab initio computational chemistry works to calculate the kinetic and potential energies between the nuclei and electrons of a molecule. These calculations usually begin with the determination the electronic ground state.

Molecules that cannot be adequately described with a single, ground state configuration are called \textit{multi-reference systems}, which require the calculation of a linear combination of all pertinent electronic configurations, with a corresponding increase in computational cost. This is not `black box' methodology, because solving these systems requires a good understanding of the …

Advances In Local Vibrational Mode Theory And Unified Reaction Valley Approach (Urva), Yunwen Tao

Chemistry Theses and Dissertations

Since the establishment of the Local Vibrational Mode Theory and the Unified Reaction Valley Approach (URVA), these two research pillars have been pushed forward in the CATCO group and played an important role in (i) characterizing the chemical bonds in molecules and (ii) molecular chemical reactions. This dissertation elaborates my contributions to the Local Vibrational Mode Theory and the Unified Reaction Valley Approach (URVA).

We have applied the Local Vibrational Mode Theory to hydrogen bonding in liquid water and proposed an explanation for the Mpemba effect. We explored and discovered new directions of applying local vibrational modes majorly in characterizing …

Assessment Of The Viability Of Microwell Plates As Sample Holders For Analytical Excitation-Emission Spectroscopy Of Polyaromatic Hydrocarbons In 75% Ethanol, Lauren M. Ridley-Hoffman

Seton Hall University Dissertations and Theses (ETDs)

Polyaromatic hydrocarbons (PAHs) in the environment are a significant concern as many compounds in this class are potential carcinogens. PAHs resulting from petroleum spills can contaminate natural waters and the products obtain from them (fish and fish products in particular). Previous studies by Pena, et. al. on ethanolic extracts of organs from menhaden captured in the vicinity of the Deepwater Horizon (Macondo oil well) spill have shown that fluorescence excitation spectroscopy is a useful technique for detecting the presence of PAH metabolites and fluorescent vitamins. The study has also concluded that previous methods for analyzing PAHs using fluorescence spectroscopy used …

Tumor-Targeting Fluorinated Phthalocyanines For Theranostic Applications, Erik Nathaniel Carrión

Seton Hall University Dissertations and Theses (ETDs)

Hydrocarbon-based therapeutics and imaging agents are prone to chemical oxidation and degradation resulting in loss of activity and limited functional utility. Thus, more material is required to achieve long-lasting therapeutic effects. Phthalocyanines (Pcs) and their metal complexes (PcMs) can be utilized as prodrugs requiring only renewable energy resources namely, air and light, for cancer therapy and diagnostic (theranostic) applications related to photodynamic therapy (PDT). Replacement of labile C-H bonds in the Pc scaffold with a combination of fluoro and perfluoroisopropyl groups has resulted in a stable yet reactive oxidation catalyst of biological significance and importance. For example, F₆₄PcZn, …

Ii-Vi Semiconductor Nanowire Array Sensors Based On Piezotronic, Piezo-Phototronic And Piezo-Photo-Magnetotronic Effects, Shuke Yan

LSU New Orleans Theses and Dissertations

With the rapid progress of nanotechnologies, there are two developing trends for the next generation of sensors: miniaturization and multi-functionality. Device miniaturization requires less power consumption, or even self-powered system. Multi-functional devices are usually based on multi-property coupling effects. Piezoelectric semiconductors have been considered to be potential candidates for self-powered/multi-functional devices due to their piezotronic coupling effect. In this dissertation, ZnO and CdSe nanowire arrays have been synthesized as the piezoelectric semiconductor materials to develop the following self-powered/multi-functional sensors: (1) self-powered gas sensors of ZnO/SnO₂, ZnO/In₂O₃, ZnO/WO₃ and CdSe nanowire arrays have been …

Using Quenching To Detect Corrosion On Sculptural Metalwork: A Real-World Application Of Fluorescence Spectroscopy, Cory Hensen, Tami Lasseter Clare, Jack Barbera

Chemistry Faculty Publications and Presentations

Fluorescence spectroscopy experiments are a frequently taught as part of upper-division teaching laboratories. To expose undergraduate students to an applied fluorescence technique, a corrosion detection method, using quenching, was adapted from authentic research for an instrumental analysis laboratory. In the experiment, students acquire fluorescence spectra of sensing molecules in the presence of mock sculpture samples and discuss the condition of the sculptures based on the levels of soluble iron detected. This real-world-based experiment allows students the chance to engage with ongoing research and further understand the challenges with early detection of corrosion. Most students successfully completed the experiment, wrote a …