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Doctor of Philosophy / Department of Chemistry / Stefan Kraft / In the present study, the rescorcin[4]arenes decorated with an alternating arrangement of pyridinium and sulfonate moieties were synthesized to establish a molecular quadrupole. These rescorcin[4]arenes are capable of undergoing conformational changes from a ‘collapsed’ to ‘open’ state. The stability of the two state are controlled by the polarity of the solvent environment. The electrostatic interactions between pyridinium and sulfonates enforced a ‘quadrupolar collapse’ in solvents such as chloroform. While these interactions are disrupted in dimethylsulfoxide. A major synthetic challenge was functionalizing the resorcin[4]arene in a positive/negative/positve/negative pattern was successfully addressed. Comparison to dipolar resorcin[4]arene were undertaken to establish a quantitative measurement of the quadrupolar forces and to address the question of cooperatively provided addition attraction beyond two dipoles. A,C-functionalized-bis sulfonate resorcin[4]arenes and A,C function bis-pyridinium resocin[4]arenes were synthesized independently. Combining these dicationic and dianionic moieties provided an interdigitating dimeric unit with overall quadrupolar charge distribution. Disruption of the quadrupolar salt bridges in CDCl[subscript]3 was accomplished through the addition of DMSO or through dilution. DeltaG[superscript]o, DeltaH[superscript]o, and DeltaS[superscript]o have been determined for the dimer formation. Addition of pyridinium salts led to a disruption of the dimeric capsule. Host-guest binding studies established attractive binding to CS[superscript]2. Larger guests such as toluene, diiodobenzene, dicynanobenzene could not be encapsulated.

Choy, Chun Wing = 皺摺界面和柱形微粒群的靜電共振 / 蔡振榮. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 53-56). / Text in English; abstracts in English and Chinese. / Choy, Chun Wing = Zhou zhe jie mian he zhu xing wei li qun de jing dian gong zhen / Cai Zhenrong. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Electric field near corrugated interfaces --- p.1 / Chapter 1.2 --- Electrostatic resonances of cylindrical clusters --- p.2 / Chapter 1.3 --- Objective of the thesis --- p.4 / Chapter 2 --- Review on Green Function Formalism --- p.5 / Chapter 2.1 --- Integral equation formalism --- p.5 / Chapter 2.2 --- Periodic corrugated interfaces --- p.8 / Chapter 2.3 --- Solution by mode expansion --- p.11 / Chapter 2.4 --- Numerical Results --- p.12 / Chapter 3 --- Electric Field at the Interface --- p.15 / Chapter 3.1 --- Formalism --- p.15 / Chapter 3.2 --- Numerical Results --- p.18 / Chapter 3.3 --- Effective medium approximation --- p.22 / Chapter 3.4 --- Discussion --- p.24 / Chapter 4 --- Application of GFF in cylindrical clusters --- p.26 / Chapter 4.1 --- Review of Bergman's spectral representation --- p.26 / Chapter 4.2 --- Extension of Bergman's spectral representation using Green Function Formalism --- p.29 / Chapter 4.3 --- Finding pole spectrum using Green Function Formalism --- p.31 / Chapter 4.4 --- Numerical Results --- p.34 / Chapter 4.4.1 --- Two approaching cylinders --- p.34 / Chapter 4.4.2 --- Three cylinders arranging in a horizontal array --- p.40 / Chapter 4.4.3 --- Three cylinders arranging in an equilateral triangle --- p.42 / Chapter 4.4.4 --- Three cylinders arranging in an isosceles triangle --- p.46 / Chapter 5 --- Summary --- p.51 / Bibliography --- p.53 / Chapter A --- Multiple image method to a pair of cylinders --- p.57 / Chapter A.1 --- Dipole factor of a pair of cylinders --- p.57 / Chapter A.2 --- Spectral representation --- p.58 / Chapter B --- Illustration of Bergman-Milton Spectral Representation --- p.60 / Chapter B.1 --- Series combination --- p.61 / Chapter B.2 --- Parallel combination --- p.62

Biomolecular structure and interactions in aqueous environment are determined by a complicated interplay between physical and chemical forces including solvation, electrostatics, van der Waals forces, the hydrophobic effect and covalent bonding. Among them, electrostatics has been of particular interest due to its long-range nature and the tradeoff between desolvation and interaction effects [1]. In addition, electrostatic interactions play a significant role within a biomolecule as well as between biomolecules, making the balance between the two vital to the understanding of macromolecular systems. As a result, much effort has been devoted to accurate modeling and simulation of biomolecule electrostatics. One important application of this work is to compute the structure of electrostatic interactions for a biomolecule in an electrolyte solution, as well as the potential that the molecule generates in space. There are two valuable uses for these simulations. First, it provides a full picture of the electrostatic energetics of a biomolecular system, improving our understanding of how electrostatics contributes to stability, specificity, function, and molecular interaction [2]. Second, these simulations serve as a tool for molecular design, since electrostatic complementarity is an important feature of interacting molecules. Through examination of the electrostatics and potential field generated by a protein molecule, for example, it may be possible to suggest improvements to other proteins or drug molecules that interact with it, or perhaps even design new interacting molecules de novo [3]. There are two approaches in simulating a protein macromolecule in an aqueous solution with nonzero ionic strength. Discrete/atomistic approaches based on Monte-Carlo or molecular dynamics simulations treat the macromolecule and solvent explicitly at the atomic level. Therefore, an enormous number of solvent molecules are required to provide reasonable accuracy, especially when electric fields far away from macroscopic surface are of interest, leading to computational infeasibility. In this work, we adopt instead an approach based on a continuum description of the macromolecule and solvent. Although the continuum model of biomolecule electrostatics is widely used, the numerical techniques used to evaluate the model do not exploit fast solver approaches developed for analyzing integrated circuit interconnect. I will describe the formulation used for analyzing biomolecule electrostatics, and then derive an integral formulation of the problem that can be rapidly solved with precorrected-FFT method [4]. / Singapore-MIT Alliance (SMA)

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). "May 2009." Includes bibliographical references (p. 10/1-10/9). Also available via the World Wide Web.

The kinetic dispersion relation for a magnetized dusty plasma comprising of ions, electrons and massive, charged dust particles is solved for low frequency electrostatic instabilities in the dust plasma frequency regime. The free energy is provided by the drifting ion beam. The effect of varying parameters such as ion drift speed, particle densities, ion temperature and magnetic field strength on the real frequency and growth rate is examined. Initially light and heavy dust species of different charge are separately considered. This procedure is then repeated for a four-component plasma in an attempt to study the effect of the presence of both the dust species on low frequency electrostatic phenomena. Using a different plasma model, instabilities generated by an equal E x B drift of both the magnetized ions and electrons relative to the unmagnetized dust grains of both the heavy and light dust species is also investigated. The latter instabilities are applicable to the planetary ring plasmas of Saturn. Throughout our studies, numerical solutions of the full dispersion relation for the real frequency and growth rate are compared with approximate analytical solutions. / Thesis (M.Sc.)-University of Durban-Westville, 1999.

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