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Full-Text Articles in Organic Chemistry

Methodologies For Metal Functionalization Of Phosphorus Based Photopolymer Networks, Vanessa Béland Oct 2019

Methodologies For Metal Functionalization Of Phosphorus Based Photopolymer Networks, Vanessa Béland

Electronic Thesis and Dissertation Repository

Photopolymer networks with phosphonium cation, alkyl phosphine and olefin functionality were designed, synthesized and functionalized with metals by metathesis, coordination and hydrometallation reactions, respectively. The materials were strategically designed so that the metal functionalization step could be monitored and quantified. In some cases, this involved characterization by IR, NMR, or X-ray spectroscopic techniques, or by comparison to molecular analogues. It was found that by using a bi-functional photopolymer network, the material could be bi-metallized by orthogonal mechanisms. All metallized polymer networks were tested for their suitability as precursors to metal-containing ceramics. The polymers were pyrolyzed, and on analysis it was ...


Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow Sep 2019

Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow

Igor I. Slowing

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe2)(3)}(3) (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI(3)THF(n) and 3 equiv of KC(SiHMe2)(3). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-3-symmetric molecules that contain two secondary Li <- HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe2)(3)}(3) and DFT calculations. The Ln <- HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in la (Delta H-double dagger = 8.2(4) kcal.mol(-1); Delta S-double dagger = -1(2) cal.mol(-1)K(-1)) and 1a-d(9) (Delta H-double dagger = 7.7(3) kcal.mol(-1); Delta S-double dagger = -4(2) cal.mol(-1)K(-1)). Comparisons of lineshapes, rate constants, (k(H)/k(D)), and slopes of ln (k/T) vs 1/T plots for la and 1a-d(9) reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five beta-Si-H -> Ln and one gamma-C-H -> Ln. The calculations also suggest the pathway for Ln <- HSi/SiH exchange involves rotation of a single C(SiHMe2)(3) ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 degrees C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe2)(3)}(3) and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox(Me2))(2)) give {MeC(Ox(Me2))(2)}Ln{C(SiHMe2)(3)}(2), and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).


Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow Sep 2019

Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow

Aaron D. Sadow

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe2)(3)}(3) (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI(3)THF(n) and 3 equiv of KC(SiHMe2)(3). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-3-symmetric molecules that contain two secondary Li <- HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe2)(3)}(3) and DFT calculations. The Ln <- HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in la (Delta H-double dagger = 8.2(4) kcal.mol(-1); Delta S-double dagger = -1(2) cal.mol(-1)K(-1)) and 1a-d(9) (Delta H-double dagger = 7.7(3) kcal.mol(-1); Delta S-double dagger = -4(2) cal.mol(-1)K(-1)). Comparisons of lineshapes, rate constants, (k(H)/k(D)), and slopes of ln (k/T) vs 1/T plots for la and 1a-d(9) reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five beta-Si-H -> Ln and one gamma-C-H -> Ln. The calculations also suggest the pathway for Ln <- HSi/SiH exchange involves rotation of a single C(SiHMe2)(3) ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 degrees C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe2)(3)}(3) and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox(Me2))(2)) give {MeC(Ox(Me2))(2)}Ln{C(SiHMe2)(3)}(2), and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).


Photoswitchable Self-Complementary Hydrogen Bond Arrays, Suendues Noori, James A. Wisner Jun 2019

Photoswitchable Self-Complementary Hydrogen Bond Arrays, Suendues Noori, James A. Wisner

Western Research Forum

Background: Photochromism is the reversible transformation of a chemical material to another form by the absorption of electromagnetic radiation (light), where the two metastable forms have distinct absorption spectra and other properties. Photochromism in materials allows for the switching of their function solely based on irradiation with light. Polymers are used frequently as the building blocks for materials as they are versatile, multifunctional, can carry charge and be processed by solution-based deposition methods. Supramolecular polymers share the same definition as polymers with the exception that they are held together by reversible and directional non-covalent interactions such as hydrogen bonds. Synthesizing ...


Development Of Bioorthogonal Molecular Tools On Gold Nanoparticles, Wilson Luo Jun 2019

Development Of Bioorthogonal Molecular Tools On Gold Nanoparticles, Wilson Luo

Electronic Thesis and Dissertation Repository

This thesis describes the development of bioorthogonal chemical tools — originally designed to form bonds cleanly and selectively in living systems — on gold nanoparticles (AuNPs) as a model reactive nanomaterial template to showcase chemical modifications in a facile and robust manner. To achieve this goal, new methodologies to cleanly incorporate strained alkyne (SA) and cargo-bearing triarylphosphine derivatives onto AuNPs were developed. The protocols described herein provide well-defined reactive AuNP interfaces that undergo bioorthogonal bond-forming and breaking reactions cleanly, selectively, and rapidly to enable chemical tuning of their properties and function.

In order to circumvent the high reactivity of SAs, which hindered ...


Mild Synthesis Of Perylene Tetracarboxylic Monoanhydrides With Potential Applications In Organic Optoelectronics, Xizhe Zhao May 2019

Mild Synthesis Of Perylene Tetracarboxylic Monoanhydrides With Potential Applications In Organic Optoelectronics, Xizhe Zhao

All Dissertations, Theses, and Capstone Projects

Perylene tetracarboxylic derivatives are considered good n-type semi-conductors. In past decades, there has been extensive study on their synthesis and electronic properties. Because of the high electron affinity, the ability to form π-π stacks, they have been widely utilized in organic photovoltaic solar cells, field-effect transistors and light-emitting diodes. Many of those applications prefer unsymmetrically substituted perylene tetracarboxylic derivatives. Perylene monoanhydrides are the most versatile intermediates for the preparation of unsymmetrically substituted perylene tetracarboxylic derivatives. In this thesis, I focused on introducing new synthesis methods for perylene monoanhydrides with labile functional group and their potential applications in organic optoelectronics.

In ...


Bridging The Molecular/Material Divide: An Investigation Into The Properties Of Polyesters, Terra Marie M. Jouaneh May 2019

Bridging The Molecular/Material Divide: An Investigation Into The Properties Of Polyesters, Terra Marie M. Jouaneh

Senior Honors Projects

By definition, polymers consist of large molecules composed of small, repeating units called monomers. These monomers give characteristic material properties to polymers, whether they be the melting point, the folding character, or the inherent stability. Many of the objects we encounter on a daily basis are composed of polymers. These polymers may be synthetic, such as the plastic in disposable bags, or natural, like glycogen in the liver. Recent developments in biotechnology have used synthetic polymers in drug delivery, contact lenses, and even organ transplants. Polyesters, in particular, have been utilized pharmacologically due to their biodegradable properties. Understandably, not all ...


Development Of In Situ Forming Hydrogels For Intra-Articular Drug Delivery, Andy Prince Feb 2019

Development Of In Situ Forming Hydrogels For Intra-Articular Drug Delivery, Andy Prince

Electronic Thesis and Dissertation Repository

Hydrogels are 3-dimensional crosslinked polymer networks that can absorb significant amounts of water. The physical properties associated with hydrogels affords them resemblance to biological tissues making them good candidates for biomedical applications. Many pharmaceuticals, specifically non-steroidal anti-inflammatory drugs (NSAIDs), have poor aqueous solubility, which limits their bioavailability and efficacy. People suffering from chronic osteoarthritis (OA) are required to frequently take large doses to mitigate pain, which can lead to serious side effects. Hydrogels are good strategies to deliver NSAIDs via articular injection because they can form solid gels in situ. This thesis describes the synthesis, formulation, mechanical testing, in vitro ...


Modification Of 2d Materials Utilizing Functional Polymer Interfacial Layers, Ryan Selhorst Jan 2019

Modification Of 2d Materials Utilizing Functional Polymer Interfacial Layers, Ryan Selhorst

Doctoral Dissertations

This dissertation describes the modification of 2D transition metal dichalcogenides (TMDCs). These materials exhibit unique electronic properties, ranging from metallic to insulating, and can transport either electrons (n-type) or holes (p-type). Polymers containing electronically-active moieties offer a path to control the electronic properties of a 2D material without altering the inherent structure of the semiconductor. This dissertation focuses on the synthesis of polymers bearing chalcogen-rich or zwitterionic moieties to alter the electronic and solution properties of 2D materials.

Chapter 2 describes polymers containing sulfur-rich tetrathiafulvalene (TTF) and their effects as electroactive coatings on the TMDC molybdenum disulfide (MoS2). These ...


Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang Jan 2019

Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang

Theses and Dissertations--Chemistry

Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with ...


Protein Detection And Structural Characterization By Mass Spectrometry Using Supramolecular Assemblies And Small Molecules, Bo Zhao Jan 2019

Protein Detection And Structural Characterization By Mass Spectrometry Using Supramolecular Assemblies And Small Molecules, Bo Zhao

Doctoral Dissertations

Mass spectrometry (MS) has played an increasingly prominent role in proteomics and structure biology because it shows superior capabilities in identification, quantification and structural characterization of proteins. To realize its full potential in protein analysis, significant progress has been made in developing innovative techniques and reagents that can couple to MS detection. This dissertation demonstrates the use of polymeric supramolecular assemblies for enhanced protein detection in complex biological mixtures by MS. An amphiphilic random co-polymer scaffold is developed to form functional supramolecular assemblies for protein/ peptide enrichment. The influences of charge density and functional group pKa on host-guest interactions ...


Photo-Isomerizable Complementary Hydrogen Bond Arrays, Jeffrey S. Pleizier Dec 2018

Photo-Isomerizable Complementary Hydrogen Bond Arrays, Jeffrey S. Pleizier

Electronic Thesis and Dissertation Repository

The use of light as an external stimulus provides a non-invasive technique to induce large changes in physical and chemical properties of a substrate. The incorporation of a photochromic subunit into supramolecular polymeric systems therefore adds a potential "smart" quality for polymer manipulation. The azo moiety (-N=N-) is one of the most popular photochromic units as the trans to cis isomerization results in a large degree of spatial rearrangement. This present thesis exploits the azo group by its incorporation into complementary hydrogen bonded complexes. Hydrogen bonding acceptor groups attached to the periphery of the central azo photoswitch provided strong ...


Copper Grafted Titanium Dioxide In Hydrogels For Photocatalysts, Salem Amsaaed Dec 2018

Copper Grafted Titanium Dioxide In Hydrogels For Photocatalysts, Salem Amsaaed

Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University

This study are based on the premise that the incorporation of metal ions into nano titania-PHEMA [poly (2-hydroxyethyl methacrylate)] hydrogels would enhance the desirable properties in the photodecomposition of pollutants. The investigation are centered in the use of Cu(II) as metal ion of interest. The development of TiO2-PHEMA-Cu hydrogels was conducted, and the characterization of the materials by FT-IR, XRD and fluorescence was performed. The absorption of copper(II) from the solution was monitored by UV-Vis. The FT-IR are found too, be the most effective tool too, analyze the interaction of Cu(II) with PHEMA in the ...


Synthesis And Characterization Of Alkynyl-Substituted Boron Formazanate Dyes, Alex Van Belois Sep 2018

Synthesis And Characterization Of Alkynyl-Substituted Boron Formazanate Dyes, Alex Van Belois

Electronic Thesis and Dissertation Repository

This thesis outlines the synthesis and characterization of the first alkynyl-substituted boron formazanate complexes and explores the electronic and structural changes that occur in these systems as a result of chemical modification at the boron centre. An alkynyl-substituted complex appended with a redox-active handle is also described, and the chemical reduction and oxidation of this system is explored. Finally, a model reaction is examined as a proof of concept toward the post-synthetic modification of these boron formazanate systems through copper(I)-assisted alkyne-azide cycloaddition chemistry. Exploiting chemistry at the boron centre opens up new possibilities toward incorporating function onto the ...


Examining The Effects Of Amino And Thiolate Ligands On The Reactivity And Selectivity Of Palladium On Carbon In Hydrogenation Reactions, Eric Liu, Christina Li Aug 2018

Examining The Effects Of Amino And Thiolate Ligands On The Reactivity And Selectivity Of Palladium On Carbon In Hydrogenation Reactions, Eric Liu, Christina Li

The Summer Undergraduate Research Fellowship (SURF) Symposium

Heterogeneous catalysts are used widely by chemical and energy industries because they show high reactivity but often suffer from lack of selectivity. On the other hand, ligands are commonly used in homogeneous catalysts to control the reactivity and selectivity; however, the effects of the ligands on the steric and electronic properties of heterogeneous catalysts are less understood. We examine the effects of four different ligands: 1-adamantanethiol, 1-adamantylamine, 1-dodecanethiol, and 1-dodecylamine, for the commercial hydrogenation catalyst palladium on carbon. Hydrogenation reactions are used as a screening tool to see the behavior that the different catalysts exhibit in the presence of unsaturated ...


Effects Of High Pressure On Photochemical Reactivity Of Organic Molecular Materials Probed By Vibrational Spectroscopy, Jiwen Guan Jul 2018

Effects Of High Pressure On Photochemical Reactivity Of Organic Molecular Materials Probed By Vibrational Spectroscopy, Jiwen Guan

Electronic Thesis and Dissertation Repository

Chemical transformations of molecular materials induced by high pressure and light radiation exhibit novel and intriguing aspects that have attracted much attention in recent years. Particularly, under the two stimuli, entire transformations of molecular species can be realized in condensed phases without employing additional chemical constraints, e.g., the need of solvents, catalysts or radical initiators. This new synthetic approach in chemistry therefore satisfies increasing need for production methods with reduced environmental impacts. Motivated by these promises, my Ph. D thesis focuses on this state-of-the-art branch of high-pressure photochemistry. Specifically, high pressure is employed to create the necessary reaction conditions ...


Glycopolymer Functionalization Of Polymersomes, Josh Jadischke May 2018

Glycopolymer Functionalization Of Polymersomes, Josh Jadischke

Electronic Thesis and Dissertation Repository

Carbohydrates are important to cellular communication, recognition, and pathogenesis, making them a useful synthetic target for application in therapeutics and diagnosis. Synthetic carbohydrate presenting scaffolds can replicate or interrupt the binding interactions that occur in nature. Due to the weak nature of the monosaccharide-protein bond, most carbohydrate presenting scaffolds display saccharides in a multivalent manner to improve binding. Recently there has been an effort to combine carbohydrate containing scaffolds with polymersomes (vesicles composed of polymers), due to the structural resemblance of polymersome membranes to biological membranes. This thesis describes the progress towards functionalizing polymersomes with linear glycopolymers as a potential ...


Polymeric Hairy Nanoparticles With Helical Hairs: Synthesis And Self-Assembly, Md Hanif Uddin May 2018

Polymeric Hairy Nanoparticles With Helical Hairs: Synthesis And Self-Assembly, Md Hanif Uddin

Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University

Nanoscale particles based on the nature of building blocks often self-assemble into superstructures with distinctive spatial arrangements which can be used as functional materials for different application. Micro-phase separated hairy nanoparticle with helical hair can self-assemble to form supramolecular material which may mimic the properties and functions of the natural polymers such as protein and cellulose. Beside this hairy/core-shell nanoparticles also may find many applications such as in asymmetric catalysis, nano-fillers in tire and rubbers, model systems for biology, lithography and as sensors. In this work, we have successfully synthesized two hairy nanoparticles both of which has cross-linked polystyrene ...


Tumor-Targeting Fluorinated Phthalocyanines For Theranostic Applications, Erik Nathaniel Carrión May 2018

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 ...


Surface Organometallic Chemistry Of Supported Iridium(Iii) As A Probe For Organotransition Metal–Support Interactions In C–H Activation, David M. Kaphan, Rachel C. Klet, Frederic A. Perras, Marek Pruski, Ce Yang, A. Jeremy Kropf, Massimiliano Delferro May 2018

Surface Organometallic Chemistry Of Supported Iridium(Iii) As A Probe For Organotransition Metal–Support Interactions In C–H Activation, David M. Kaphan, Rachel C. Klet, Frederic A. Perras, Marek Pruski, Ce Yang, A. Jeremy Kropf, Massimiliano Delferro

Ames Laboratory Accepted Manuscripts

Systematic study of the interactions between organometallic catalysts and metal oxide support materials is essential for the realization of rational design in heterogeneous catalysis. Herein we describe the stoichiometric and catalytic chemistry of a [Cp*(PMe3)Ir(III)] complex chemisorbed on a variety of acidic metal oxides as a multifaceted probe for stereoelectronic communication between the support and organometallic center. Electrophilic bond activation was explored in the context of stoichiometric hydrogenolysis as well as catalytic H/D exchange. Further information was obtained from the observation of processes related to dynamic exchange between grafted organometallic species and those in solution. The ...


Long-Range Electrostatic Interactions In Gold Catalysis And Fluorinating Reagent Development., Zhichao Lu May 2018

Long-Range Electrostatic Interactions In Gold Catalysis And Fluorinating Reagent Development., Zhichao Lu

Electronic Theses and Dissertations

Our research focus is on applying two long range electrostatic interactions--coulombic interaction between ion pairs and hydrogen bonding—to two tasks: exploring counterion effects in gold catalysis and utilizing hydrogen bonding for fluorinating reagent development. Cationic gold catalysis is considered one of the most important breakthroughs in organic synthesis over the past two decades. A wealth of empirical information on counterion effects is now available regarding homogeneous gold catalysis. However, the rational understanding of the counterion effect on reactivity is still elusive. We proposed a widely applicable model to rationalize the kinetic effect in gold catalyzed reaction. We first solved ...


Higher Energy Gap Control Of Fluorescence In Conjugated Polymers, Chien-Hung Chiang Mar 2018

Higher Energy Gap Control Of Fluorescence In Conjugated Polymers, Chien-Hung Chiang

LSU Doctoral Dissertations

Chemo- and biosensors based on fluorescent conjugated polymer benefit from greater detection sensitivity due to amplification of the electronic perturbations produced by analyte binding. This amplification stems from the exciton-transporting properties of conjugated polymers. A conventional design paradigm relies on the analyte binding events which generate sites of lower energy relative to the polymer energy: either fluorescence quenching sites (turn-off sensors) or bathochromically shifted fluorophores (turn-on sensors). In both type sensors, the excitons migrate to the lower-energy site created by analyte binding.

This dissertation primarily focused the investigation of an alternative paradigm when analyte binding creates higher energy gap sites ...


Understanding The Functional Group-Dependent Self-Assembly And Cellular Entry Of Cationic Conjugated Polymer Nanoparticles, Prakash Manandhar Mar 2018

Understanding The Functional Group-Dependent Self-Assembly And Cellular Entry Of Cationic Conjugated Polymer Nanoparticles, Prakash Manandhar

FIU Electronic Theses and Dissertations

Highly fluorescent conjugated polymers (CPs) are an important class of biomaterials used for various biological applications including labelling, sensing, and delivery of biological substances. Synthetic versatility and tunable emission make CPs a superior class of biomaterials. Understanding the structure-function relationship of CPs plays a vital role in designing high performing biomaterials. The cationic CPs are self-assembled to conjugated polymer nanoparticles (CPNs) in an aqueous environment due to their amphiphilicity. The physical and biophysical properties of CPNs are highly dependent on the chemical functionality and backbone structure of CPs. Modulation of the surface property and backbone structure of CPNs play an ...


Systematic Size Control In The Synthesis Of Zero-Valent Iron Nanoparticles, Grant C. Bleier Feb 2018

Systematic Size Control In The Synthesis Of Zero-Valent Iron Nanoparticles, Grant C. Bleier

Chemistry ETDs

A novel synthetic method for the production of highly magnetic, low size-dispersity nanoparticles through reversible magnetic agglomeration is introduced and studied in detail. Initially, a weakly coordinating surfactant (3-octadecyl-2,4-pentanedione) is employed to produce a wide range of nanoparticle sizes ranging from 8 to 20 nm in diameter. The kinetics faced in these reactions by cheap and widely available iron complex precursors can be avoided in this method with the introduction of thermodynamic control, which occurs in the form of a magnetic precipitation event that essentially halts nanoparticle growth. Utilizing this synthetic method, the length of the alkyl chain on ...


Study Of The Effect Of Steric Bulk Of Side Chains On The Properties Of Conjugated Polymers, Bei Zhang Jan 2018

Study Of The Effect Of Steric Bulk Of Side Chains On The Properties Of Conjugated Polymers, Bei Zhang

Theses and Dissertations--Chemistry

Donor-acceptor conjugated polymers opened a new era for conjugated polymer research due to the abundant selection and combination of different conjugated units. This class of polymers function as semiconductor materials with potential application in plastic consumer electronics. The frontier molecular orbital energies of the polymers are generally determined by the selection of donor and acceptor units in the backbone structure, and their substituents. The side chains attached to the backbone not only affect the solubility of the materials, but also their self-assembly and morphological characteristics, which indirectly govern optoelectronic properties. It is important therefore to consider backbone architectures and the ...


Light-Harvesting And Light-Responsive Materials For Optoelectronic And Biological Applications, Youngju Bae Jan 2018

Light-Harvesting And Light-Responsive Materials For Optoelectronic And Biological Applications, Youngju Bae

Doctoral Dissertations

In photodynamic therapy, several critical standards are required of photosensitizers including high singlet oxygen quantum yield, biocompatibility in dark, and long term photochemical stability. In addition, current PDT systems lack active targeting strategies to tumor cells, and instead mainly rely on the natural distribution of PS in the body following injection and application of near-infrared light treatment in the tumor region. This thesis describes a series of BODIPY-based molecules that were designed, synthesized and studied as photosensitizers with high singlet oxygen generation capacity through utilizing the heavy atom effect. Additionally, aqueous solubility and active targeting capability were introduced by photosensitizer ...


Lignin Depolymerization: Mechanistic Analysis, Optimization And Application, Eric Michael Nagel Jan 2018

Lignin Depolymerization: Mechanistic Analysis, Optimization And Application, Eric Michael Nagel

Electronic Theses and Dissertations

Lignin is the most abundant aromatic biopolymer and is a potential source for phenolic chemical feedstocks. Lignin is composed of phenolic units connected by more than eight different linkages, the most common being β-O-4 which constitutes 50-60%. The hydrothermal decomposition of a guaiacol based β-O-4 lignin dimer was studied under neutral and basic conditions to elucidate the mechanism of β-O-4 bond cleavage and the formation of downstream products. Phenol-carbonyl condensation and vinyl-ether formation were shown to be the primary causes for low monomer yields under the tested conditions. Three Ni catalyst systems, Ni/C + H2, Ni/C-Zn, and Ni ...


Design And Synthesis Of Stimuli-Responsive Polymeric Nanogels Towards Therapeutic Translation, Mallory R. Gordon Jan 2018

Design And Synthesis Of Stimuli-Responsive Polymeric Nanogels Towards Therapeutic Translation, Mallory R. Gordon

Doctoral Dissertations

In the application of delivery of therapeutics, nanostructures of various composition have been employed due to their capacity to act as a host for lipophilic payloads. Advances in the synthetic preparation, size, morphology, and chemical or physical characteristics of polymers have impacted their development and versatility. A detailed understanding of polymeric nanoparticle host-guest properties is crucial to their practical translation to specific delivery applications. Further, these features must be highly tailorable to overcome biological barriers, stably encapsulate their therapeutic contexts, and exhibit payload release selectively in the target environment. In this dissertation, we aim to rationally design polymeric nano-scale assemblies ...


Impact Of Chemical Doping On The Thermoelectric Charge Transport Of Organic Semiconductors, Connor J. Boyle Jan 2018

Impact Of Chemical Doping On The Thermoelectric Charge Transport Of Organic Semiconductors, Connor J. Boyle

Doctoral Dissertations

The thermoelectric properties of organic semiconductors allow them to directly convert heat into electricity without the use of moving parts and to directly convert electricity into heat without the use of working fluids. These properties offer opportunities for the generation of electricity from non-conventional or renewable sources of heat and for refrigeration without the risk of leaking harmful working fluids at any length scale down to the nanoscale. Since organic materials are lightweight, flexible, and made from abundant resources, these opportunities could one day become affordable for widespread use and could be expanded to include specialized and otherwise difficult to ...


Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow Oct 2017

Homoleptic Trivalent Tris(Alkyl) Rare Earth Compounds, Aradhana Pindwal, Kaking Yan, Smita Patnaik, Bradley M. Schmidt, Arkady Ellern, Igor I. Slowing, Cheolbeom Bae, Aaron D. Sadow

Chemistry Publications

Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe2)(3)}(3) (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnI(3)THF(n) and 3 equiv of KC(SiHMe2)(3). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-3-symmetric molecules that contain two secondary Li <- HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe2)(3)}(3) and DFT calculations. The Ln <- HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in la (Delta H-double dagger = 8.2(4) kcal.mol(-1); Delta S-double dagger = -1(2) cal.mol(-1)K(-1)) and 1a-d(9) (Delta H-double dagger = 7.7(3) kcal.mol(-1); Delta S-double dagger = -4(2) cal.mol(-1)K(-1)). Comparisons of lineshapes, rate constants, (k(H)/k(D)), and slopes of ln (k/T) vs 1/T plots for la and 1a-d(9) reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five beta-Si-H -> Ln and one gamma-C-H -> Ln. The calculations also suggest the pathway for Ln <- HSi/SiH exchange involves rotation of a single C(SiHMe2)(3) ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 degrees C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe2)(3)}(3) and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox(Me2))(2)) give {MeC(Ox(Me2))(2)}Ln{C(SiHMe2)(3)}(2), and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).