Physical Chemistry Commons^™

Group 14 Metallocene Catalysts For Carbonyl Hydroboration And Cyanosilylation, Haley J. Robertson, Mallory N. Fujiwara, Allegra L. Liberman-Martin

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

A series of six Group 14 metallocene compounds (M = Ge, Sn, Pb) were studied as catalysts for carbonyl hydroboration and cyanosilylation reactions at room temperature. Both bis(pentamethylcyclopentadienyl) and tetramethyldisiloxa[3]metallocenophane compounds were compared. The tin and lead metallocenophanes exhibited the highest reactivity in hydroboration and cyanosilylation reactions. Hammett analysis of aldehyde hydroboration provided a ρ value of 0.73, suggesting a buildup of negative charge during the turnover-limiting step, consistent with the transition state for hydride transfer to the carbonyl center. NMR studies of Lewis acidity indicate that the Ge, Sn, and Pb tetramethyldisiloxa[3]metallocenophane compounds are weak Lewis acids.

Attochemistry Regulation Of Charge Migration, Aderonke Folorunso

LSU Doctoral Dissertations

Charge migration (CM) is a coherent attosecond process that involves the movement of localized holes across a molecule. This phenomenon is potentially useful to understand the fundamental principles of photochemistry, such as light harvesting. The first part of this dissertation discusses the molecular modes of attosecond charge migration. In this work, we used first-principles calculations to investigate the modes of charge migration (CM) in halogenated hydrocarbon chains at attosecond timescales. We have simulated the creation of a localized hole on the halogen atom using constrained density functional theory (DFT) and then tracked its subsequent dynamics with time-dependent DFT (TDDFT). Our …

Research Trends And Impact Report On Aggregation-Induced Emission (Aie), 2001-2021, Elsevier Analytical Services

Public Reports

Since the concept of AIE was first proposed in China in 2001, it has gradually grown to a field of science that attracts dedicated researchers from around the world. Elsevier's data analytics team used AIE experts' interpretation of current theoretical, technological, and industrial development trends in the field for reference to collect AIE-related global scientific publications (from the Scopus database) to serve as a publication set in the field of AIE. This was undertaken to present, accurately and objectively, the development of AIE research over the past two decades and the latest scientific advancements in the field; to facilitate the …

Density Functional Studies Of Molecular Separation And Charge Transport, Timothy Quainoo

Wayne State University Dissertations

This thesis presents a series of studies which can be grouped majorly into two sections both focusing on the utilization of density functional theory techniques; Molecular electronics and Molecular separation. Molecular electronics has been anticipated to hold a great future as it seeks to apply molecular building blocks in the creation of electronic components. On the other hand, the utilization of mild conditions in chemical processes is geared toward the major goals of green chemistry as it produces less waste and is cost-effective. Thus, this dissertation tackles and answers some of the unanswered questions in literature by using theoretical methods …

Solution Combustion Synthesis And Characterization Of Fumarolic Mineral Dolerophanite, Copper (Ii) Oxide Sulfate, Eric J. Cyganowski

Chemistry & Biochemistry Theses - Archive

Dolerophanite Cu₂OSO₄ is a rare mineral found almost exclusively in the fumaroles of volcano systems and is sensitive to temperature and humidity conditions. It has a monoclinic C2/m crystal structure characterized by two-dimensional layers composed of sulfate anions dispersed amongst copper (II) oxide backbones. There has been recent interest in dolerophanite due to the magnetic properties of its Kagome-like lattice as well as its potential use as a photocatalyst or Li-ion battery electrode. Literature on the material however has been limited by the available synthesis strategies. As such, this thesis work presents a novel strategy …

Phenanthrene Jamboree, Alexander D. Roth

Honors Theses

Using cyclopropanated and cyclobutanated phenanthrene precursors, our hero embarks on a mission to find as many reactive intermediates as possible. Fraught with danger, romance, and mangosteens, Anderson calls this work 'monstrous' and 'alarming.'

Investigating The Ultrafast Dissociation Dynamics Of Energetic Materials Using Femtosecond Time-Resolved Mass Spectrometry, Jacob M. Shusterman

Theses and Dissertations

Shock initiation of energetic materials produces cations and anions that can contribute to initial endothermic chemical reactions which lead to detonation. Hence, knowledge of the initial dissociation pathways of ionized energetic molecules is important for advancing the understanding of initiation mechanisms and meeting longstanding goals of the Department of Defense. Despite their potential importance, these transient charged species are difficult to detect in detonation experiments and are often ignored in molecular dynamics modeling of shocked energetic materials. However, the technique of pump-probe femtosecond time-resolved mass spectrometry (FTRMS) paired with complementary theoretical calculations can be used to elucidate initial unimolecular dissociation …

Probing Microscopic Properties Of Next Generation Materials Using Coherent Vibrational And Electronic Spectroscopy, S Mudiyanselage Sachithra Tikiri Kumara Wanasinghe

Wayne State University Dissertations

The dissertation research focused on understanding the relationship between the chemical structure of organic molecules and their photophysical properties, particularly examining coherent electronic and vibrational coupling within and between molecules, with implications for next-generation energy technologies. In Chapter 2, we employed both steady-state and transient optical and magnetic spectroscopic techniques to understand the electronic delocalization in both singlet and triplet exciton delocalization in weakly bound porphyrin dimeric molecules. Our results highlight that the delocalization of singlet exciton delocalization does not guarantee the delocalization of triplet excitons between weakly bound porphyrin macromolecules. Our studies demonstrate how one can access the electronic …

Experimental And Chemical Modeling Of Applied Dc Electric Field Induced H2 – Air Axisymmetric Laminar Co-Flow Diffusion Flames With Low Carbon Impurities, Susith Dilshan Pathmasiri Gunamuni Halowitage

Graduate Theses, Dissertations, and Problem Reports (ETD)

The effect of externally applied DC electric fields on flame structure was investigated in a stationary atmospheric axisymmetric laminar H₂–Air flame with less than 100 ppm carbon equivalent impurities. Flame OH chemiluminescence signals were recorded using a UV-sensitive CCD array as a function of voltage (+10 to -10 kV) applied to a stainless-steel ring electrode placed around the burner nozzle. Changes in chemiluminescence signal are reported as a function of electrode height above the burner, airflow, and fuel composition. Significant changes in OH* distributions were observed for voltages below -5 kV. Under optimum conditions, the height of the …

Self-Quenching Of Carbon Monoxide In The Presence Of Noble Gases, Madeline V. Hinkle

Honors Theses

Precise rate coefficients for the vibrational relaxation pathways of CO(v)-CO in the presence of Ar and Kr have been determined through the work of this thesis. This work was motivated by the need to find a more cost-effective alternative to using xenon as a bath gas, which has increased significantly in price in the past few years. Similar experiments within this lab at Bucknell have been conducted in the past using argon, which can be used in the same manner as xenon but comes at a much lower price, but the experiments yielded inferior results compared to those using xenon. …

Transient Diode Laser Absorption Spectroscopy For Measuring Collisional Quenching Rates Of Co And Its Potential For Studying H2o, Jordan M. Polvere

Master’s Theses

Motivated by the necessity of non-LTE models that account for species that are not in Local Thermodynamic Equilibrium (LTE) in Titan’s and Earth’s atmospheres, collisional quenching rates of CO and H2O_(g) have been studied. Providing more accurate and precise values of collisional quenching rate coefficients is crucial in the development of more advanced atmospheric models, which are important to fields of science such as meteorology and astronomy. Rates of collisional quenching of CO(v=1,2) by CO and CO(v=2) by N₂ at approximately 301-321 K were measured by transient diode laser absorption spectroscopy. The rate coefficients of CO(v=1)-CO, CO(v=2)-CO, and …

Assessing Fixed-Node Diffusion Monte Carlo For Radical Polymerization Reaction Energetics, Timothy Brian Huber

Graduate Research Theses & Dissertations

The art of quantum chemistry is grounded to the discovery of a time efficient computational method that can capture the essential physics. Historically, the Hartree-Fock method, where an electron moves in the mean field of the other electrons, has provided the orbitals used to construct a single-reference Slater determinant and thus formed the basis for molecular orbital calculations. Kohn-Sham density functionals have become overwhelmingly popular among the chemistry community due to their low computational cost. However, their prediction of thermodynamic properties important in free radical polymerization has shown difficulty due to an artificial delocalization of electron density and spin contamination …

Photoluminescence Of Beryllium-Related Defects In Gallium Nitride, Mykhailo Vorobiov, Mykhailo Vorobiov

Theses and Dissertations

This study explores the potential of beryllium (Be) as an alternative dopant to magnesium (Mg) for achieving higher hole concentrations in gallium nitride (GaN). Despite Mg prominence as an acceptor in optoelectronic and high-power devices, its deep acceptor level at 0.22 eV above the valence band limits its effectiveness. By examining Be, this research aims to pave the way to overcoming these limitations and extend the findings to aluminum nitride and aluminum gallium nitride (AlGaN) alloy. Key contributions of this work include. i)Identification of three Be-related luminescence bands in GaN through photoluminescence spectroscopy, improving the understanding needed for further material …

Tracking The Reaction Networks Of Criegee Intermediates Formed In The Ozone-Assisted Oxidation Reactions Of C5 Acyclic And Endocyclic Alkenes, Arden M. Floyd

Honors Undergraduate Theses

Uni- and bi-molecular reactions involving Criegee intermediates (CIs), characteristic to alkene-ozone reactions, play an important role in synthetic organic, atmospheric, and combustion chemistry. However, difficulty in detecting key intermediates has prevented a thorough understanding of the details of the ozonolysis mechanism. To gain new insights into how alkene structure affects the CI network, the ozone assisted oxidation reactions of trans-2-pentene and cyclopentene are investigated between 320 K and 760 K in an atmospheric pressure jet stirred reactor (JSR). Molecular-beam mass spectrometry in conjunction with single photon tunable synchrotron VUV radiation is used to identify elusive intermediates by means of …

Mapping The Reaction Networks Of Cis Formed In The Ozone-Assisted Oxidation Of C₆ Acyclic And Endocyclic Alkenes, Zachary Clarke

Honors Undergraduate Theses

Criegee intermediates (CIs) are highly reactive species generated during the ozonolysis of alkenes, exerting a critical influence on atmospheric oxidation, combustion chemistry, and synthetic processes. Their reactivity, encompassing unimolecular and bimolecular pathways, shapes oxidation mechanisms and product distributions in these environments. A key determinant of CI behavior is the structural nature of the parent alkene. Acyclic alkenes typically yield intermediates with minimal steric hindrance, facilitating rapid reactions, whereas endocyclic alkenes produce geometrically constrained CIs with enhanced internal stabilization, redirecting reaction pathways and reducing overall reactivity. Despite their importance, mechanistic understanding remains limited due to experimental challenges in detecting CIs and …

Assessing Interatomic Potentials For Molecular Dynamics Simulation Of Soybean Oil Pyrolysis, Tanner Garrett Rust

Graduate Theses/Dissertations

The world today relies on hydrocarbon combustion for many reasons, including its high energy density that provides ease of transportation. However, hydrocarbons sourced from fossil fuels are not expected to last forever. Biodiesel, a renewable alternative, has many attractive benefits but comes with other downsides. Biodiesel can gel in cold environments and may leave residue in an engine. Pyrolysis of biodiesel has shown promise in addressing these common detriments. Inducing pyrolysis on biodiesel feedstock (commonly soybean oil in the USA) would be an attractive option presuming it continues to produce fossil fuel analogs similar to biodiesel pyrolysis. Herein, Langevin molecular …

Effect Of Annealing On Photoluminescence From Defects In Gan, Oleksandr Andrieiev

Theses and Dissertations

Annealing is a critical process in modern GaN technology, essential for achieving p-type conductivity by activating the Mg_Ga acceptor, as first demonstrated by Shuji Nakamura in the early 1990s. Despite the omnipresence of hydrogen as an impurity in GaN crystals, the precise mechanisms governing hydrogen diffusion and acceptor passivation remain only partially understood. The presented research investigates the effects of annealing-induced activation and hydrogen passivation on C and Be acceptors in GaN grown by MOCVD, HVPE, and MBE methods. We explored these effects by using several annealing techniques, gas compositions, and thermal regimes. A transient behavior between the C …

Single-Atom Catalysts For Electrochemical Energy Conversion: Copper Single-Atom Catalyst For Oxygen Reduction Reaction And Quantification Of Site Density By Co Stripping Voltammetry, Dawatage Perera

Theses and Dissertations--Chemistry

Fuel cells are considered a promising technology for achieving cleaner and more sustainable energy production and utilization. However, one of the current major challenges is the economic viability associated with the extensive use of Pt group metal (PGM) catalysts, particularly on the cathode side. Therefore, non-PGM single-atom catalysts (SACs) have received considerable attention as alternatives for PGM catalysts in the oxygen reduction reaction (ORR), which occurs at the cathode of the fuel cell. Among various SAC structures, the non-PGM/nitrogen-doped carbon-based structure (M-N-C) stands out for its excellent ORR performance.

Chapter 2 illustrates the use of copper metal in place of …

Studies Towards Mechanistic Understanding Of The Suzuki-Miyaura Catalyst-Transfer Polymerization, Mitchell Tyler Howell

Graduate Research Theses & Dissertations

Semiconducting organic conjugated polymers show major promise for the manufacturing of organic electronic and optoelectronic devices. Their utility comes from inherent conductivity, elasticity, processability and low weight paving the way towards novel materials and applications. The molecular weight, polydispersity, and precise incorporation of structural elements into the conjugated backbone are among the important parameters that affect a conjugated polymer’s mechanical and electrical properties. Therefore, precise control over such parameters provides a path for electronic materials with tunable properties tailored for a specific application. Recent success in this endeavor has been achieved with Suzuki-Miyaura Catalyst-Transfer Polymerization (SCTP) which is a transition …

Fundamental Studies Of Optical Properties And Electrocatalytic Properties Of Low Dimensional Nanomaterials Carbon Nano Dots And 2d Transition Metal Dichalcogenides, Nadeesha Kothalawala

Theses and Dissertations--Chemistry

Low dimensional nanomaterials are widely used in a variety of applications such as opto-electronics, energy production and storage, and bio-medical applications due to their unique optical, catalytic, electronic, and mechanical properties. Most of the nanomaterials offer a plethora of modifications in their structure, composition, morphology, and dimensionality that can lead to the manipulation of their physiochemical properties. This dissertation presents insight into two types of compelling nanomaterials: carbon nanodots (CND) and transition metal dichalcogenides (TMD), investigating their optical and electrocatalytic properties respectively.

Carbon nanodots (CND) are a promising class of photoluminescent nanomaterials that hold a significant potential in many optoelectronic …