Chemistry Commons^™

Synthesis Toward A Molecular Container Based On P-Tert-Butylcalix[4]Arene With Gate Features, Balasooriya Appuhamilage Dinesh Madushan Balasooriya

Masters Theses

Nowadays molecular and supramolecular chemistry have endless examples for the development of smart devices. Among those applications, nano-baskets of calixarenes play vital roles in host-guest chemistry. One of the main appealing concepts of this field is the development of host molecules with gate features. These hosts are designed and constructed for the delivery of chemical or biochemical species that are volatile, or reactive, or sensitive to normal solution environment and they are mainly functioned by predefined groups that are responsive toward stimuli such as concentration, temperature, pH and so on. In our previous study, we found that benzyl bromides can …

Computational Study Of The Nature Of Tetrel Bond, Yama Aman

Masters Theses

For more than a hundred years, the type of a chemical bond has been distinguished according to the relative electronegativities of chemical units at the ends of a bond. Whereas, the bond of unequally electronegative on both ends is called a polar covalent or even ionic bond or a non-polar covalent bond in case of both equal. Regardless the type of bonded elements, the whole idea for the bond was believed to be electron driven only. In the 20th century the development of the idea, that not just the electronic relation but specific elements are also able to characterize the …

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 …

Organocatalyzed Synthesis Of Epoxides From Chalcones Utilizing Amino Acids, Sabrina N. Kegeler

Masters Theses

The epoxide functional group is important throughout the chemical and pharmaceutical industries, as well as in nature. In the chemical industry, epoxides are present in resins and fragrances. In the pharmaceutical industry, epoxide-containing compounds are used as intermediates in the manufacturing of drugs. In nature, many natural products contain epoxide groups and are used for medicinal purposes, and for models to create synthetic molecules.

One approach to epoxide synthesis involves the use of an alkene precursor, a base, and an oxidizing agent. This is where my investigations began. The first step was to optimize the epoxidation reaction, examining substrate scope, …

Synthesis And Characterization Of Biomimetic Dinuclear And Tetranuclear Copper Complexes, Syed Rahmath Ullah Joy

Masters Theses

Seven new copper(II) complexes were prepared from the condensation reaction of 4-tert-butyl-2,6-diformylphenol with two equivalents of bis(pyrazolyl)ethanamine or 3,5-dimethyl-bis(pyrazolyl)ethanamine moieties in the presence of two equivalents of various copper(II) starting materials having different counter ions (i.e. acetate - AcO^-, perchlorate - CIO₄^-, tetrafluoroborate - BF₄^-, nitrate - NO₃^-, and chloride - Cl^-). The resulting copper(II) complexes were characterized in solid state by single crystal X-ray crystallography, and in solution by UV-Vis and ESI/MS spectroscopies.

X-ray crystallographic studies showed that in solid state two types of …

Pd-Based Photocatalysts For Sonogashira C-C Cross-Coupling Reactions, Komadhie Charuka Dissanayake

Masters Theses

Sonogashira C-C cross-coupling reaction has been heavily used for its simplicity, flexibility and value. Although the original Sonogashira C-C cross coupling reaction conditions entail the use of 0.5 mol% of Pd catalyst, 2 mol% of Cul as co-catalyst at room temperature, the experimental conditions used in laboratories to prepare some compounds vary substantially, especially with respect to the reaction time, temperature and loading amount of the catalysts. The most significant drawback of the conventional Sonogashira reaction is the use of Cul as it leads to the formation of homocoupling product when the reaction is exposed to air or oxidizing agents. …

Research And Development Of Optically Transparent Join With Low Processing Temperatures, Eric Kevin Muskovin

Masters Theses

The purpose of this study was to investigate durable solar cell cover glass joins produced by diffusion bonding with deep eutectic solvents (DES) and to develop a novel process of joining optically transparent materials at low temperatures. A joined PV cell-glass specimen was characterized using Raman, μ-FTIR, SEM-EDS, and thin-film XRD. DESs were created with malonic acid (MAL) and choline chloride (ChCl) of varying composition factors (CF; CF=MAL/ChCl). Joining borosilicate glass coupons was attempted using DESs with CF = 0.65 and 1 at temperatures between 100-150 °C for 20 hours. Joining the glass coupons failed at all temperatures and oxygen …

Apan Production Through Photooxidation Of Isoprene In The Presence Of NoX, Timothy Glidewell

Masters Theses

Peroxyacyl nitrates (PANs, RC(O)OONO₂) are of great importance in atmospheric chemistry. They act as transporters of reactive nitrogen, and radical delivery agents. There are no known natural emission sources of PANs; they are produced through reaction of volatile organic compounds (VOCs) and nitrogen oxides (NO_x) in the atmosphere.

VOCs can enter the atmosphere through biogenic and anthropogenic pathways. It has been estimated that isoprene makes up 70% of the biogenic VOCs (BVOCs) emitted annually. Isoprene has been shown to impact ozone levels in both rural and urban areas by sequestering and transporting NO_x in the form …

Characterization Of Γ-Butyrolactone Rings: A Computational And Toxicological Study, Donald C. Kidd

Masters Theses

Given the declining state of the natural environment, identifying green methodologies in synthetic chemistry is becoming paramount. An under explored area of green chemistry, is the use of catalytic systems in green solvents. One interesting concept in green chemistry is the use of N-Heterocyclic Carbenes (NHCs) as organocatalysts.

Thiamine or vitamin B1 was one of the first NHCs recognized. Thiamine is required for carbohydrate metabolism and helps the cell produce adenosine triphosphate (ATP). Over the last 20 years NHCs have been found to be efficient catalysts in carbon-carbon bond forming reactions.

But to date, little research has been done exploring …

Novel Spectroscopic Tools To Differentiate Drug-Dna Binding Interactions, Fadwa Dhafer Hamad

Masters Theses

DNA-drug interactions play a major role in therapeutics, diagnostics, forensics and imaging. Drugs bind to DNA in several ways based on the mode of interaction and they alter protein-DNA interactions or breaks/cleaves DNA that can lead to the cure of the disease. The major goal of the research carried out in this thesis is to develop novel optical spectroscopic tools that can differentiate Drug-DNA binding interactions mode whether its intercalation or minor-groove binding. To achieve this goal, we developed two-photon absorption (2PA) cross-section based technique to differentiate between Drug-DNA binding modes. The investigations were carried out on two drug molecules, …

Red Emissive Bodipy Dyes As Sensitizers For Near-Infrared Emission Of Lanthanide Complexes & Structural & Spectroscopic Studies Of Quinoline-Functionalized Bodipy Dyes, Adedayo Ayodeji Kukoyi

Masters Theses

Bioimaging has become a significant tool for the visualization of biological events and the detection of numerous biomarkers. However, detection sensitivity is compromised by background signal from the biofluid which interferes with signals from the probes that usually emit in the visible region Alternative probes such as those that emit in the near-infrared (NIR) region are necessary to overcome these shortcomings. Lanthanide ions have demonstrated efficiency with sharp characteristic emission in the visible and (NIR) region. Emission however is mostly achieved by indirect sensitization process in which energy from the triplet state of a sensitizer is transferred to the excited …

In Situ Ph Determination Based On The Nmr Analysis Of ¹H-Nmr Signal Intensities And ¹⁹F-Nmr Chemical Shifts, Ming Huang

Masters Theses

"The pH of an NMR sample can be measured directly by NMR experiments of signal intensities, chemical shifts, or relaxation time constants that depend on the pH. The ¹H NMR peak intensities of the pH indicator phenolphthalein change as it changes from the OH-depleted form to the OH-rich form in the range of pH = 11.1 to 12.7. Because this range is rather small, another NMR technique was utilized based on ¹⁹F chemical shifts. The shift of F^- in an aqueous solution of NaF changes in the alkaline range between pH = 11.0 and 14.0 and even …

Behavior Of Different Sizes Of Strontium Titanate Substrates In Electrochemical Modifications, Shuxin Luo

Masters Theses

In our previous atomic force microscopy (AFM) studies of 5 mm x 5 mm single crystal SrTiO₃ (STO(100)) substrates, rutile TiO₂ crystals were found on the substrates surfaces after electrochemical modification. These crystals were found mainly in the area of contact between the substrate and the gold-coated alligator clip that was not supposed to be immersed into the electrolyte and that served as a connection between the STO working electrode and the potentiostat circuit. The size and density of the crystals were found to depend on electrochemical potential, its polarity, the length of modifying time, and the total …

Functionalized Bodipy Dyes For Near-Infrared Emission Of Lanthanide Complexes, Rukshani Wickrama Arachchi

Masters Theses

For many decades, fluorophores have been used to investigate natural systems, but autofluorescence and photobleaching diminish the detection capacity. Recently, BODIPY based lanthanide complexes have been synthesized and their photophysical properties have been investigated. These complexes exhibit higher emission efficiencies at NIR region with longer NIR lifetimes upon exciting at longer wavelength.

In this study, two BODIPY based lanthanide complexes were synthesized and their photophysical properties were evaluated. BODIPY based ligands were synthesized with phenanthroline as the ligand binding group. These ligands exhibit strong absorption at 527 nm and 532 nm, fluorescence at 540 nm and 548 nm with 0.55 …

Bodipy-Based Red Sensitizers For Near-Infrared Emission Of Lanthanide Complexes, Priyangika Prasadini Senevirathne

Masters Theses

During the past 20 years there has been a remarkable growth in the use of the fluorescence technique in biological studies. Fluorescence and time-resolved fluorescence spectroscopy are considered primary research tools in the field of biochemistry. Currently, fluorescence spectroscopy is a dominant methodology and used widely in biotechnology and medical diagnosis process. One impediment in using fluorescent probes is the fluorescence of biological substrates and fluorescence of diagnostic probes are significantly overlapped, and it decreases the detection sensitivity. Also, commercially available probes require UV or near-UV light excitation, causing severe degradation of biological substrates. Near-infrared emitting lanthanide complexes can overcome …

Molecular Recognition Profiles Of Molecular Cocrystals, Ian C. Tinsley

Masters Theses

The manner in which molecules recognize each other holds critical importance to nearly every area of science. This significance stems from the key underpinning of molecular assembly to our most basic understanding of chemical processes. Whether these interactions relate to small-molecule catalytic transformations or complex physiological processes, the structural features responsible for molecular association play into the well-known adage that form follows function where material property arises from the collective structural features of the molecular components. Because the form of chemical systems is derived from a complex blend of covalent and non-bonded contacts, codifying each contributor has become essential for …

Synthesis And Characterization Of Cu(Ii)-Cu(I) Mixed Valence Complexes, Hansani T. Lekam Wasam Liyanage

Masters Theses

Our study was focused on synthesis and characterization of new family of metal complexes that mimic the active site of copper containing enzymes. Our approach focused on preparing a series of metalloligands which vary systematically in structure and use them in combination with additional metallic centers to synthesize our desired complexes.

We synthesized a main ligand, which is named as HL^Q 2Pz, which contain a quinoline body, one amide bond and two pyrazolyl rings. We synthesized a copper complex by deprotonating HL^Q 2Pz using KOH. The ligand coordinated to the copper(II) center through its quinoline nitrogen, two of …

Understanding College Students’ Exam Process In A General Chemistry Course, Angela Willson

Masters Theses

The main way most college chemistry courses assess what a student has learned is through a summative exam. After introductory science courses, such as general chemistry, many students cite poor teaching and disappointing grades in these courses as a reason for dropping out of STEM programs. There has been a lack of qualitative research on students’ experiences of the complete process of taking an exam from start to finish, or the exam process, which includes preparing for an exam, taking an exam, receiving feedback, and responding to feedback after the exam has been graded.

My goal in this exploratory study …

Application Of Electrospray Ionization Mass Spectrometry For Ionic Liquids And Their Biodegradation Products, Sepideh Rahbarirad

Masters Theses

Ionic liquids (ILs) are organic salts with unique physico-chemical properties and are used as green alternatives to volatile organic solvents. ESI-MS is a sensitive technique to detect these stable, permanent ions. My research focused on (1) Identification of biodegradation products of ionic liquids and (2) Multiplexed tandem MS by modulation of ionization efficiency.

Studies, have demonstrated that ILs are toxic to the environment, which makes their biodegradability an important consideration. In this work, metabolites generated during the biodegradation of 1-butyl-3-methylimidazolium chloride (BMIM), a degradation resistant and commonly used ionic liquid, are identified using high performance liquid chromatography-mass spectrometry (LC-MS).

Multiplexed …

Environmental Applications Of Chromatography-Mass Spectrometry, Wisam Abdulabbas Flayyih Al Isawi

Masters Theses

Gas chromatography-mass spectrometry (GC-MS) and liquid chromatographymass spectrometry (LC-MS) are powerful analytical techniques that combine the separation power in a stationary phase with the detection power of mass spectrometry. GCMS and LC-MS have gained dominant positions in identifying and quantifying different analyte species due to their high selectivity, high sensitivity, and high reproducibility.

My research utilizes the analytical power of LC-MS and GC-MS to address two environmental issues: 1) Identification of biodegradation products of the ionic liquid 1- butyl-3-methylimidazolium chloride (BMIMCl) by an activated sludge microbial community using LC-MS and 2) identification and quantification of polycyclic aromatic hydrocarbons (PAHs) in …

Structures And Nuclear Quadrupole Coupling Tensors Of 1,2-Dichloroethane, 1-Chloro-2-Fluoroethane And 2,3-Dichloropropene Studied Using Microwave Spectroscopy And Computational Chemistry, Asela Sampath Dikkumbura

Masters Theses

The Fourier-transform microwave (FTMW) spectra of 1,2-dichloroethane (12DCE), 1-chloro-2-fluoroethane (1C2FE) and 2,3-dichloropropene (23DCP) have been studied in the 6 to 18 GHz range to determine experimental rotational constants, nuclear quadrupole coupling constants (NQCC) and quartic centrifugal distortions constants. These three molecules have different spatial arrangements (anti and gauche) resulting from different relative orientations of chlorine and/or fluorine atoms about the C-C single bond. The lowest energy anti conformer of 12DCE is non-polar and it is not detectable by microwave spectroscopy, but rotational spectra of gauche-12DCE with three isotopologues, gauche-1C2FE with three isotopologues, and both anti- …

Theoretical Investigations Of Difluorobenzene Interacting With Ne And Infrared Analysis Of 1,1-Dichloroethylene From Synchrotron Data, Seri P. Kamari

Masters Theses

The intermolecular interactions between two molecules are of great importance in proteins, polypeptides, DNA binding, and drug binding interactions. Dimers of chemical rings such as difluorobenzene with hydrogen containing molecules such as acetylene (HCCH) and atoms such as neon are classic systems for investigating weak interactions; however, the microwave spectrum of 1,2-difluorobenzene...Ne does not behave as expected. Possible explanation of this phenomenon is that there is some large amplitude motion perturbing the spectrum.

A computational study was performed to analyze the potential energy surface (PES) of Ne or Ar with ortho, meta, and para difluorobenzene, and reveal the …

Synthesis And Characterization Of Dicopper(Ii) Complexes With Biological Relevance, Ashley E. Hall

Masters Theses

The research discussed in this study focused on the design, synthesis, and characterization of new model complexes that mimic the type-3 enzyme, catechol oxidase, which oxidizes catechols to their corresponding quinones. Our approach focused on the design and synthesis new model complexes that contain a dicopper(II) center that can be fine-tuned in a variety of ways, such as sterics and exogeneous bridging molecules. This method allows a multitude of complexes to be created and compared to determine how the overall structure affects the catecholase activity of the complexes.

Two ligands were synthesized; they contain a phenolate body, two amide groups, …

Tracking Silver, Gold, And Titanium Dioxide Nanoparticles Through Drinking Water Systems By Single Particle - Inductively Coupled Plasma - Mass Spectrometry, Ariel Renee Donovan

Masters Theses

"Single particle (SP)-ICP-MS methods were developed to characterize and quantify Ti-containing, titanium dioxide, silver, and gold NP concentration, size, size distribution and dissolved metal element concentration in surface water and treated drinking water. The effectiveness of conventional drinking water treatments (including lime softening, alum coagulation, filtration, and disinfection) to remove NPs from surface water was evaluated using six-gang stirrer jar test simulations. Six-gang stirrers were used to simulate drinking water treatments including lime softening, alum coagulation, powdered activated carbon sorption, filtration, and disinfection by free chlorine. Lime softening effectively removed most nanoparticles added. Source and drinking waters from three large …

Functionalized Bodipy Dyes For Dye-Sensitized Solar Cells, Mahmoud A. Elkhalifa

Masters Theses

It is predicted that more than 20 terawatts of carbon-free energy will be demanded by 2050 to maintain a sufficient energy supply for the increasing global population, and photovoltaics are predicted to contribute significantly to the global energy needs. Dye-sensitized solar cells (DSCs) are an emerging class of photovoltaics (PV) that has produced promising power conversion efficiencies at low costs. Currently, electron recombination, dye aggregation, weak adsorption, and inefficient absorbance are among of the largest contributors to low DSC efficiencies.

BODIPY dyes are one of the most promising classes of dyes emerging for DSC application. These low molecular weight fluorophores …

Synthesis Of New Platinum-Based Anti-Cancer Drugs, Saud O. Albaroodi Yasser

Masters Theses

Cancer is considered the second leading cause of death after heart attack. Different treatments have been applied to kill cancer cells such as chemotherapy, which is the use of chemicals or drugs in order to treat cancer cells. Platinum-based anti cancer drugs are the backbone of chemotherapy, they play a crucial role in treating various malignant tumor. However, the disadvantages of these drugs are very painful on patients, such as nephrotoxicity and ototoxicity. In the last four decades, thousands of platinum-based anticancer drugs have been synthesized for hope in find a new drug with higher efficacy and less side effects.In …

Cappack Devices For Enhanced Qnmr Measurements In 1H Nmr Spectroscopy, Lingyu Chi

Masters Theses

"Quantitative NMR analyses can be improved by adding well-defined external references for measuring sample properties on absolute scales. Special Capillary-tube Package (CapPack) devices were invented that provide in situ information (e.g., temperature, pH, pressure, integration, chemical shift, lock, etc.) about a sample with spectral imprimaturs. A new microscale glass-sealing technique produced CapPack devices that can survive high temperatures and pressures in harsh environments. Two CapPack devices are discussed: (1) Gradient CapPack-- a device for examining the irradiation bandwidth of solvent-suppression pulse sequences; (2) T₁ CapPack - a device for examining the T₁ robustness of solvent-suppression pulse sequences. A …

A Simpler Route To Building Photochromic Cinnamaldehyde Semicarbazones, Byron R. Ebbert

Masters Theses

Photochromic semicarbazones are an interesting group of compounds that show potential in a broad range of applications, including as a more environmentally friendly replacement for photochromic metal complex compounds. Previous work has shown the feasibility to synthesize photochromic cinnamaldehyde semicarbazones (CSCs) from a benzaldehyde and a protected acetaldehyde Wittig reagent. A new, quicker, and cheaper approach to constructing these CSCs from crotonaldehyde was explored in this research. A three reaction sequence would convert crotonaldehyde to a CSC; first, an allylic bromination of the semicarbazone with N-bromosuccinimide (NBS); second, an Arbuzov reaction to prepare the semicarbazone phosphonate; and finally a condensation …

Derivatization And Separation Of Natural Estrogens (Estrone, 17Β-Estradiol, And Estriol) Using Gas Chromatography With Flame Ionization Detection (Gc-Fid), Dena L. Guptill

Masters Theses

A major cause of concern for estrogens found in the environment is that even at very low concentrations (10-100 ng/L) they can have a negative effect on aquatic ecosystems by disrupting endocrine systems. Due to the increasing importance of monitoring the levels of estrogens in the environment, a detection method was developed to identify and quantify three natural estrogens (estrone, 17β-estradiol and estriol) using gas chromatography with flame ionization detection (GC-FID). In addition, the efficacy of two derivatizing agents, N,O-bis(trimethylsilyl) acetamide (BSTA) and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), was evaluated. The GC detector (FID) was most responsive with E3, followed by E1 and …

Investigation Of Β-Cyclodextrin's Ability In Differentiating Chiral Guest Molecules And Synthesis Of 1,6-Diphenyl-2,4-Hexadiene-1,6-Dione, Guang Yang

Masters Theses

This research work comprised two projects. The first one mainly focused on the synthesis of 12 alanine derivatives and analysis of their interactions with β-cyclodextrin through ¹H NMR titration. And the other project was an investigation of the conjugation effect of alkynones in its addition reactions with tributyltin hydride.

The synthesis of the alanine derivatives involved methyl esterification of alanine and then the substitution of an NH hydrogen with a benzoyl group. A total of 4 different substitution groups, labeled as the "A" groups, were introduced on the para-position of the benzoyl's phenyl group. Since alanine has one chiral …