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An Investigation Of The Requirements For Excimer Formation And Charge Stabilization In Model Pi-Stacked Assemblies, Brandon Uhler Oct 2016

An Investigation Of The Requirements For Excimer Formation And Charge Stabilization In Model Pi-Stacked Assemblies, Brandon Uhler

Dissertations (1934 -)

Formation of -stacked excimers plays an important role in many systems, ranging from biological phenomena and polymer formation and function to photovoltaic devices and organic molecular electronics. In these systems, the geometrical reorganization of the ground state upon photoexcitation is still a subject of debate. In this work, we compare the dynamics of excimer formation and hole (charge) stabilization in fluorene and fluorene-based model systems. We use a variety of gas-phase methods to examine the spectroscopy and dynamics of these systems, including Two-Color Resonant Two-Photon Ionization (2CR2PI), Hole-Burning (HB), Laser Induced Fluorescence (LIF), and Dispersed Fluorescence (DF). In order to …


Resonance Raman Studies Of Oxygenated Forms Of Myoglobin And Cyp2b4 And Their Mutants, Ying Wang Jul 2016

Resonance Raman Studies Of Oxygenated Forms Of Myoglobin And Cyp2b4 And Their Mutants, Ying Wang

Dissertations (1934 -)

Important oxidative heme enzymes use hydrogen peroxide or activate molecular oxygen to generate highly reactive peroxo-, hydroperoxo- and feryl intermediates resulting from heterolytic O-O bond cleavage. Members of the cytochrome P450 superfamily catalyze difficult chemical transformations, including hydroxylations and C-C bond cleavage reactions. In mammals, these enzymes function to reliably produce important steroids with the required high degree of structural precision. On the other hand, certain other mammalian P450s serve a different role, efficiently metabolizing xenobiotics, including pharmaceuticals and environmental pollutants. Though so important, the precise mechanisms involved in such transformations are incompletely understood, because of difficulties in structurally characterizing …


Probing The Effects Of Nano-Domains On The Redox Products In Molecular Solvents-Rtils Mixtures, Abderrahman Atifi Jul 2016

Probing The Effects Of Nano-Domains On The Redox Products In Molecular Solvents-Rtils Mixtures, Abderrahman Atifi

Dissertations (1934 -)

Room temperature ionic liquids (RTIL) have been very attractive as replacements for molecular solvents (MS) in many areas in chemistry. The use of the RTIL in mixture with MS as reaction media will reduce the cost and viscosity of RTILs. The formation of RTIL nano-domains (nano-structures) in the mixture may lead to partitioning of solutes between the MS and the RTIL phase, where the properties and reactivity would be more like those in pure ionic liquids. In the present work, analytical approaches have been employed to probe the presence and effects of RTIL nano-domains on redox processes in the mixture. …


Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C And C-O Bond Activation Reactions, Junghwa Kim Apr 2016

Synthetic And Mechanistic Studies Of Ruthenium Catalyzed C-C And C-O Bond Activation Reactions, Junghwa Kim

Dissertations (1934 -)

Etherification of alcohols is one of the most fundamental transformations in organic synthesis. Williamson ether synthesis is the most well-known synthetic method of unsymmetrical ether synthesis which is still being used in both industrial and academic laboratories. We have developed a novel catalytic etherification reaction using two different alcohols by using a well-defined cationic ruthenium catalyst. The reaction scope as well as the mechanistic study of the reaction are described.Hydroacylation is considered to be a powerful synthetic transformation for producing functionalized ketones from relatively simple olefin substrates. Despite remarkable progress in intra and intermolecular hydroacylations, the substrate scope of the …


Photochemical Electrocyclic Ring Closure And Elimination Reactions Of N-(Oxothioxanthenyl)Naphthothiophene Carboxamides, Himali Devika Jayasekara Apr 2016

Photochemical Electrocyclic Ring Closure And Elimination Reactions Of N-(Oxothioxanthenyl)Naphthothiophene Carboxamides, Himali Devika Jayasekara

Dissertations (1934 -)

Photochemical cleavage reactions have found a widespread used in biological applications that require the photorelease of biologically active molecules such as proteins, peptides, neurotransmitters, and nucleotide phosphates. This research focuses on the design of photoremovable protecting groups which can be utilized to release these biomolecules by photolysis. These biomolecules are attached to the photoremovable protecting group at the sites of functional groups that are present within these substrates. Such functional groups are carboxylates, phosphates, thiolates, or phenolates, which upon exposure to light, are released as anions of varying basicities. The photochemical reaction involved is an electrocyclic ring closure between aromatic …


Novel Numerical Models Of Electrostatic Interactions And Their Application To S-Nitrosothiol Simulations, Maxim Vadimovich Ivanov Apr 2016

Novel Numerical Models Of Electrostatic Interactions And Their Application To S-Nitrosothiol Simulations, Maxim Vadimovich Ivanov

Dissertations (1934 -)

Atom-centered point charge model of the molecular electrostatics remains a major workhorse in the atomistic biomolecular simulations. However, this approximation fails to reproduce anisotropic features of the molecular electrostatic potential (MEP), and the existing methods of the charge derivation are often associated with the numerical instabilities. This work provides an in-depth analysis of these limitations and offers a novel approach to describe electrostatic interactions that paves the way toward efficient next-generation force fields. By analyzing the charge fitting problem from first principles, as an example of the mathematical inverse problem, we show that the numerical instabilities of the charge-fitting problem …


Synthesis And Characterization Of Biologically Relevant Fe(Ii) Complexes Containing Redox-Active (Hydro)Quinone Ligands, Amanda Elizabeth Baum Apr 2016

Synthesis And Characterization Of Biologically Relevant Fe(Ii) Complexes Containing Redox-Active (Hydro)Quinone Ligands, Amanda Elizabeth Baum

Dissertations (1934 -)

Redox-active p-(hydro)quinones work in concert with transition-metal centers to facilitate electron transfers in numerous biological contexts. While p-(hydro)quinones are known to interact with both heme and nonheme iron cofactors, the nonheme systems are particularly relevant to photosynthetic and bioremediation processes. In photosynthesis, two p-quinones facilitate an electron transfer away from the photoexcited P680 cofactor via a non-heme Fe(II) center. Based on EPR results, this interaction results in formation of transient Fe(II)/p-semiquinone (pSQ) species. In addition, a superoxo-iron(II)-pSQ species has been proposed as an intermediate of the oxidative cleavage mechanism of hydroquinone dioxygenases (HQDOs), which play a central role in the …