Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6238. Adviser: Archie R. Portis, Jr. Includes bibliographical references (leaves 138-154). Available on microfilm from Pro Quest Information and Learning.

abstract: The objective of the present investigations is to experimentally determine the fundamental molecular properties of the transient metal containing pieces. The transient molecules have been generated using laser ablation production technique and detected by using laser induced fluorescence technique. Ultra-high resolution spectra of the diatomic molecules, 87SrF, 135&137BaF, YbF, HfF, and IrSi were recorded at a resolution of approximately 30 Mhz. The fine and hyperfine structure of these molecules were determined for the ground and the excited state. The optical Stark splittings of 180HfF and IrSi were recorded and analyzed to determine the permanent electric dipole moments of the ground and the excited state. An effective Hamiltonian operator, including the rotational, centrifugal distortion, spin-orbit, spin-spin, spin-rotation, Λ-doubling, magnetic hyperfine and quadrupole interactions, and Stark effect, was employed to model and analyze the recorded spectra. The electronic spectra of the triatomic molecules, TiO2 and ZrO2, were recorded using pulsed dye laser, LIF, spectrometer at a resolution of 300MHz. These molecules have C2v symmetry. The harmonic frequencies, lifetime measurements were determined. These spectra of ZrO2 and TiO2 were modeled using a normal coordinate analysis and Franck-Condon factor predictions. High resolution field-free and Stark effect spectra of ZrO2 were recorded and for future investigation. / Dissertation/Thesis / Ph.D. Chemistry 2013

abstract: Organic optoelectronic devices have remained a research topic of great interest over the past two decades, particularly in the development of efficient organic photovoltaics (OPV) and organic light emitting diodes (OLED). In order to improve the efficiency, stability, and materials variety for organic optoelectronic devices a number of emitting materials, absorbing materials, and charge transport materials were developed and employed in a device setting. Optical, electrical, and photophysical studies of the organic materials and their corresponding devices were thoroughly carried out. Two major approaches were taken to enhance the efficiency of small molecule based OPVs: developing material with higher open circuit voltages or improved device structures which increased short circuit current. To explore the factors affecting the open circuit voltage (VOC) in OPVs, molecular structures were modified to bring VOC closer to the effective bandgap, ∆EDA, which allowed the achievement of 1V VOC for a heterojunction of a select Ir complex with estimated exciton energy of only 1.55eV. Furthermore, the development of anode interfacial layer for exciton blocking and molecular templating provide a general approach for enhancing the short circuit current. Ultimately, a 5.8% PCE was achieved in a single heterojunction of C60 and a ZnPc material prepared in a simple, one step, solvent free, synthesis. OLEDs employing newly developed deep blue emitters based on cyclometalated complexes were demonstrated. Ultimately, a peak EQE of 24.8% and nearly perfect blue emission of (0.148,0.079) was achieved from PtON7dtb, which approaches the maximum attainable performance from a blue OLED. Furthermore, utilizing the excimer formation properties of square-planar Pt complexes, highly efficient and stable white devices employing a single emissive material were demonstrated. A peak EQE of over 20% for pure white color (0.33,0.33) and 80 CRI was achieved with the tridentate Pt complex, Pt-16. Furthermore, the development of a series of tetradentate Pt complexes yielded highly efficient and stable single doped white devices due to their halogen free tetradentate design. In addition to these benchmark achievements, the systematic molecular modification of both emissive and absorbing materials provides valuable structure-property relationship information that should help guide further developments in the field. / Dissertation/Thesis / Ph.D. Materials Science and Engineering 2014

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This thesis reports on the synthesis of a series of Lewis acidic boranes used as detectors for the cyanide or fluoride ion, and for the activation of molecular oxygen. Chapter III focuses on the formation of monodentate boranes featuring a pendant ferrocenyl moiety. A systematic study of the fluoride and cyanide binding capabilities of isomeric ferrocenyl-functionalized phenyl boranes was conducted via spectroscopic, crystallographic and voltammetric techniques. The synthesis of receptors supported by an indenyl scaffold was also investigated and the binding properties of such systems studied in details. All receptors proved to be competent at binding both cyanide and fluoride in dry solvents; moreover one such indenyl receptor can selectively bind cyanide in aqueous media and signal the binding event by a green-to-red colour change. Chapter IV constitutes an extension of the previous chapter targeting bidentate receptors with an (indenyl)(cyclopentadienyl)iron(II) back bone. A principle objective was the development of systems offering the chelation of fluoride, and hence a measure of selectivity over the more strongly basic cyanide ion. While bis(dimesitylborane) receptors proved to be synthetically inaccessible, a series of phosphine- and phosphonium-borane species was prepared and their comparative F-/CN- binding abilities determined. Thus, while cationic phosphonium boranes favour fluoride binding by employing a bifunctional binding motif, the neutral phosphine boranes exclusively bind cyanide. Chapter V details the activation of molecular oxygen by pentafluorophenyl-boranes in presence of weak reductants featuring a ferrocene unit. The highly Lewis acidic ferrocenyl bis(pentafluorophenyl)borane was initially studied, and its reaction with dry dioxygen shown to generate a (fully characterized) ferrocenium peroxoborate. Similar reactivity was observed for simple metallocenes such as cobaltocene and ferrocene (or even organic reductants) in presence of a strong Lewis acid, with the trapping of the O₂²- ion by the borane thought to be a key thermodynamic driving force for the O₂ reduction.

As the genetic content is internally located within DNA duplexed form, it has long been hypothesized that DNA undergoes a series of thermally induced conformational changes that assist in protein recognition events. The biological mechanisms for protein-DNA interactions have long been sought after, as little is still known mechanistically about how these complexes form. To study the local contributions to these breathing modes several atomistic simulations of DNA oligonucleotides were generated and analyzed by statistical models to predict metastable conformational states, the system timescales, and the kinetic pathways between states. In order to sample time-series DNA constructs, microsecond molecular dynamics (MD) simulation were performed. MD simulations provide atomstic resolution of macromolecules in explicit solvent and with modern computational workflows can extend well into microsecond timescales. While MD is a powerful tool, it creates a tremendous amount of time-dependent data. In recent years, Markov State Models (MSM), which project the dynamics of MD simulations onto discrete coordinates that follow a Markov chain, have become an invaluable tool to model and describe the kinetics of these large datasets. These models can be coarse-grained for chemical insight, however there does not yet exist a method which consistently and ``crisply'' describe the metastable barriers. To address this, I developed a new method, called Gradient Adaptive Decomposition (GRAD), which optimizes the macrostate model by refining borders with respect to the gradient along the free energy surface. The proposed method requires only a small number of initial microstates because it corrects for errors produced by limited number of seeds. Whereas many methods rely on fuzzy, or overlapping, partitions for proper statstical analysis of timescales, GRAD retains accuracy and crisp decomposition. I present a workflow of GRAD refined MSM to analyze the long timescale MD simulations of DNA oligonucleotides to assess the stacking conformational dynamics of DNA. Evaluating the complex network of transitions accessible found evidence suggesting that chiral directed mechanisms are critical in how DNA bases unstack. I explore how these local effects may be significant to long timescale dynamics and the biological impact in relation to breathing fluctuations. This dissertation includes unpublished co-authored material.

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