Abstract The present thesis deals with the nuclear magnetic resonance (NMR) spectroscopy of small solutes applied to the studies of liquid crystals and molecular sieves. In this method, changes induced by the investigated environment to the static spectral parameters (i.e. nuclear shielding, indirect and direct spin-spin coupling and quadrupole coupling) of the solute are measured. The nuclear shielding of dissolved noble gases is utilized for the studies of thermotropic liquid crystals. The relation between the symmetry properties of mesophases and the nuclear shielding is described. The different interaction mechanisms perturbing the observed noble gas nuclear shielding are discussed, particularly, the role of long-range attractive van der Waals interactions is brought out. The suitability of the noble gas NMR spectroscopy to the studies of lyotropic liquid crystals is investigated in terms of nuclear shielding and quadrupole coupling interactions. In molecular sieve systems, the effect of inter- and intracrystalline motions of solutes on their NMR spectra is discussed. A novel method for the measurement of the intracrystalline motions is developed. The distinctions in the 13C shielding of methane adsorbed in AlPO4-11 and SAPO-11, two structurally similar molecular sieves differing in composition, are indicated.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16874号 / 工博第3595号 / 新制||工||1543(附属図書館) / 29549 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 一義, 教授 佐藤 啓文, 教授 梶 弘典 / 学位規則第4条第1項該当

Model-based design is a powerful design technique for embedded system development. The technique enables virtual prototyping to develop and debug controllers before touching real hardware. There are many tools available covering the distinct steps of the design cycle including modeling, simulation, and implementation. Unfortunately, none of them covers all three steps. This thesis proposes a formalism coupling the model and the implementation of a controller for equation-based simulation tools. The resulting formalism translates defined controller models to platform specific code using a defined set of syntax. A case study of a line-following robot has been developed to illustrate the feasibility of the approach. The prototype has been tested and evaluated using a sequence of test scenarios of increasing difficulty. The final experiments suggest that the behaviors of both modeled and generated controllers are similar. The thesis concludes that the approach of model-implementation coupling of controllers in the simplest form is feasible for equation-based tools. This allows it to conduct the whole model-based design cycle within a single environment.

Master of Science / Department of Electrical and Computer Engineering / William B. Kuhn / Crosstalk and electromagnetic interference (EMI) are constant problems in the design of RF circuits. There have been several studies to analyze and improve isolation of transmission lines, but the focus has been mainly on digital circuits or the isolation goals have been on the order of 40-60 dB. When the isolation goals are much more stringent, such as 80-100 dB, much of a designer’s time is still spent ensuring that a circuit meets isolation and EMI constraints. This typically involves the use of extensive metal shielding over a circuit board. This thesis presents results from an isolation and EMI study to provide a simple reference that can be applied to typical substrates, provided proper scaling is used between substrates. The results in this thesis are reported from DC to 30 GHz using a low cost 4-layer FR4 process. The changes in isolation between various transmission lines types are investigated while varying line separation and length. It is shown that isolation between ground-backed coplanar waveguide (GBCPW) and stripline traces can reach 100dB through L-band and 60dB through Ku-band for 1.3in traces separated by 150mils. Due to the heavy usage of filters in RF design, the isolation between edge-coupled bandpass filters is also studied. It is seen that isolation levels of 100dB through L-band by enclosing the filters within stripline technology is possible, provided that signal launches and layer transitions are carefully designed. Within the passband of the 20 GHz filter tested, the isolation is less but is still significantly improved by use of enclosed stripline. Lastly, a preliminary assessment of EMI is presented which focuses on radiation levels as well as variables that can degrade isolation performance. The data illustrated in this thesis can provide guidance in the early stages of RF circuit design to determine appropriate structures to meet given design requirements. It also helps to assess the degree to which additional metal shielding can be avoided in PC board systems that use multi-layer technologies.

In recent years much effort has been carried out to make integrated photonics a widespread technology to be exploited in current optical communication industry. It is hoped by substituting microelectronics by photonic chips and keeping the light carried by optical fibers in light domain for further processing, the cost and speed of communications will be vastly improved. Although this transition is challenging in various aspects, here in this thesis some of these issues are discussed and addressed. In this thesis firstly the limitations of current simulation tools for analysis of wide range of photonic devices is pointed out. Structures based on photonic crystals are taken into consideration at this point which because of finely detailed structures have shown to be challenging to be analyzed by conventional tools. In this regard three different common structures based on photonic crystals in both resonant and non-resonant regimes have been considered: lamellar gratings, metamaterials for Lüneburg lens and Bragg gratings in a LC-DFB laser. For each structure, an analytical method or homogenization approach is proposed which is claimed to be faster for analysis of such components than numerical methods. Comparisons of the results with conventional numerical methods prove accuracies of each approach. Furthermore, fiber-to-chip coupling and polarization management are discussed as other important issues in the field of integrated photonics. Concerning polarization management, stepped waveguide approach will be introduced as the most promising approach for SOI and III-V substrates and designs based on this structure reported in literature are reproduced and inaccuracies are pointed out and corrected accordingly. Also regarding fiber-to-chip coupling, a critical appraisal of the most recent proposed structures for edge coupling will be offered and the results will be reproduced by simulation tools. At the end, based on detailed comparisons, the most encouraging approach with low insertion loss and easy fabrication steps is introduced and novel platform for easy butt coupling single mode fibers to the coupler structure is proposed.

The development of new, efficient methods for the formation of carbon-carbon bonds using transition metal catalysis has broad applications in the field of organic chemistry and is the key to efficient chemical synthesis. Many efforts had been made to develop efficient ways to make these linkages particularly with the aid of metals such as Rh, Pd, Ni, Ru and Cu. Our group is primarily focused on exploring how these transition metals can activate typically inert functional groups, paving way to new synthetic routes to construct more complex molecules. Chapter 1 describes attempts that were conducted to achieve hydroacylation between an aldehyde and a non-conjugated alkene via a metal hydride intermediate. The use of RuHCl(CO)(PPh3)3 proved to be the most efficient catalyst for this transformation thus far. Mechanistic investigations were conducted to explore different possibilities to enable this transformation. This chapter also identifies a new self-aldol domino reaction, which consists of a self-aldol condensation of an aldehyde, followed by oxidation and decarbonylation giving rise to a ketone product. Finally, the use of a simple and direct method to access deuterated aldehydes using RuHCl(CO)(PPh3)3 as a catalyst and D2O as a deuterium source is outlined. Chapter 2 describes a novel Suzuki-Miyaura system that couples esters and boronic esters to form the corresponding ketone product. It was found that an NHC-based Pd catalyst is crucial in the transformation wherein it activates the C(acyl)-O bond of the ester. It is notable that this transformation takes place with the absence of decarbonylation. Reactivity under water in the presence of surfactants was also discovered. Results in aqueous media were demonstrated to be milder than in organic conditions, while achieving similar yields. This system was also applied to coupling of esters and anilines.

Transition metals are known to be the essential part in most of the catalysts, the heterogeneous and the homogenous catalysts; however, the ligands that attached to the metal centers can also alter the reactivity of the catalyst, and that is widely observed in nature. In our project, we are interested in the metal-ligand cooperation of a special type of ligand called the pincer ligand. Our focus is mainly on the tridentate Pincer Ligands with a pyridine backbone. Also, it contains a spacer that could be deprotonated and protonated during the aromatization and dearomatization process. Aromatization and dearomatization of the pincer ligand are responsible for the unique reactivity of the pincer complexes, especially in the hydrogenation and dehydrogenation reactions. Recently, huge developments have been made in the dehydrogenative coupling of aniline and benzyl alcohol via manganese pincer complexes. The most recent papers on that subject have been done by Beller in 2016[1], Kempe 2018 [2], and Hultzsch 2019 [3]. However, rhenium complexes have not been studied enough even though it is in the same seventh row of the transition metal. Therefore, the rhenium was studied as a possible alternative. Then, the synthesis of a well-defined PN3 rhenium complex was performed from the bipy-tBu ligand and the metal precursor Re(CO)5Cl. The ligand has a unique deformity as the phosphine sidearm is not attached to the metal center. Further investigation of the aniline and benzyl alcohol dehydrogenative coupling via PN3 rhenium pincer complex has been done. An optimal reaction condition was achieved, and the substrate scope was further examined with various alcohols and amines, and the result shows good to moderate conversion with decent selectivity towards the imine. Except for the secondary alcohols.

The exploration and application of nanomaterials have been attracting researchers’ attention in recent decades. Nanocatalysts, as one of the very important classes of nanomaterials, have been developed for several generations. Nanotechnology makes light be possibly utilized in catalysis rather than only heat and allows multifunctional parts to be assembled in one catalyst. The TiO2 (as the representative of hetero-photocatalyst) and iron-based magnetic catalysts (as multifunctional catalyst) will be discussed in detail in this thesis. The first chapter will introduce the background of catalysts and nanomaterials. TiO2, especially black TiO2, will be mainly discussed in the aspects of properties, synthesis, and applications. Another part of the chapter will talk about the separation-friendly catalyst – magnetic heterogenous catalysts’ synthesis and applications. Chapter 2 focuses on the synthetic route we used and the characterization of black TiO2 catalysts and magnetic catalysts. Both anatase and rutile black TiO2 catalysts were successfully prepared originally from Degussa P25 using the ethanol reduction method. The re-whitening treatment was also examined on both black TiO2 catalysts. All catalysts were characterized and compared by diffuse reflectance (DR), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscope (XPS). Tauc plot results show that black TiO2 has smaller band gap than white TiO2. XPS revealed the existence of surface -OH species and Ti3+ in black TiO2. Furthermore, these two characterization techniques and XRD all proved that the blackening and re-whitening treatment does not change the crystalline phase of the catalysts, and the blackening treatment is reversible. For magnetic catalysts, we synthesized magnetic Fe2O3, Fe2O3@TiO2, copper/iron oxide magnetic TiO2, and black magnetic catalysts. Other than diffuse reflectance spectroscopy, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray elemental mapping analysis were used for determining the light-absorption properties, composition, and morphology of all synthesized magnetic catalysts. In addition, the magnetic separation was also achieved by simply applying an external magnetic field. Chapter 3 will discuss and compare the decarboxylation reaction activities of pristine, black, and re-whited TiO2 catalysts. The reactions were carried under the UV, blue, red, green, and white light irradiation. Unfortunately, the reaction was found only working under UV-light irradiation. The best solvent was dioxane which may be due to the proton affinity of the oxygen atom in dioxane molecule, which facilitates the deprotonation of the carboxylic acid. The optimal catalyst amount was found as 10 mg per 5 mL reaction mixture, and the kinetic study shows that the reaction is a pseudo-first order reaction. It is a pity that the performance of black TiO2 catalysts is worse than the pristine and re-whitened TiO2. Chapter 4 will talk about the sol-gel synthesized magnetic catalysts. These catalysts were used for aldehyde-alkyne-amine (A3) coupling reaction. The reaction was tested by light irradiating or traditional heating, but only heating can make the reaction proceed. Results also show that the coupling reaction requires copper to finish. The best solvent was found as toluene and the optimal reaction time is 6 hours at 120 ̊C. Sadly, the reactivity of copper/iron oxide magnetic TiO2 decreases a lot after three reaction cycles because of the copper leaching problem.

Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read' and `write' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall effect on spin orbit torque in nanoribbons with a hexagonal lattice. We find a dramatic modification of the nature of the torque (field like and damping-like component) when crossing the topological phase transition. The relative agnitude of the two torque components can be significantly modifies by changing the magnetization direction. Finally, motivated by recent experimental results, we conclude by investigating the features of spin-orbit torque in magnetic transition metal dichalcogenides. We find the torque is associated with the valley polarization. By changing the magnetization direction, the torque can be changed from a finite value to zero when the valley polarization decreases from a finite value to zero.

Thesis advisor: James Morken / This dissertation details two different alkene difunctionalization strategies that are utilized in the synthesis of three types of organoboron species in racemic and enantioenriched fashion. Chapter one will introduce the carbohydrate and DBU co-catalyzed transition-metal-free enantioselective diboration reactions of unactivated alkenes. Mechanistic insights guided reaction condition design will be discussed. In chapter two, a nickel-catalyzed conjunctive cross-coupling of 9-BBN borane and carboxylic acid derivatives is presented. Its development and detailed mechanistic studies, along with the efforts in asymmetric induction will be covered. Finally, the first enantio- and diastereoselective synthesis of 1,2-anti-silylboronates enabled by palladium-catalyzed conjunctive cross-coupling will be described. The optimization of chemo-, enantio- and diastereoselectivity in the reactions and their following transformations (e.g. oxidation and amination) is demonstrated. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.