Guanidinium Sulfation Crystallization: Strategy for Enantiomeric Identification and Diastereomeric Resolution

The main portion of this thesis describes two distinct applications of guanidinium sulfation crystallization: use of a flat guanidinium chloride for enantiomeric identification and a chiral guanidinium bromide for diastereomeric resolution. Additionally, the following two chapters includes the modification of naturally occurring materials for pollution remediation and the synthesis of biodegradable polyesters for biomedical imaging.The importance of chirality can be found in a variety of fields including pharmaceuticals, fragrances, food additives, agrochemicals, and forensics. Most biologically active organic compounds such as amino acids and carbohydrates exhibit chirality, resulting in a high degree of stereoselectivity in processes that are mediated by biological systems. Since these metabolic and regulatory processes are sensitive to stereochemistry, often enantiomers of drugs will differ in terms of their behavior and activity in the body. This same problem arises in the aforementioned fields, where one of the enantiomers of the racemic mixture is active and the other enantiomer can either be inactive or even exhibit detrimental effects. Nonetheless, chiral products are often still marketed as racemic mixtures due to the difficulty in separation and production costs associated with accessing a single, active enantiomer. The first chapter of this thesis reviews the significance of chirality and provides several examples of the importance of a single enantiomer in various fields. The second chapter details the current field of absolute stereochemical determination and the development of our guanidinium sulfation crystallization methodology for enantiomeric identification. Extension of this methodology for the diastereomeric resolution of racemic mixtures is covered in the third chapter along with other complimentary techniques for the separation of enantiomers. Hazardous chemicals can escape to the environment through a number of natural and/or anthropogenic events. This environmental pollution is known to cause adverse health effects toward the public and non-targeted ecological species. The fourth chapter of this thesis details two common pollutants (volatile organic compounds and pesticides) and our efforts toward the remediation of each. The use of imaging agents and techniques are essential in the understanding of complex biological processes in situ and in real time. Polymeric materials have become increasingly popular for contrast imaging agents due to their inherent biodegradable and biocompatible profile. The fifth chapter of this thesis describes the synthesis, characterization, and X-ray evaluation of several iodoarene-containing polyesters. In the final chapter, a variety of acentric guanidinium sulfate salts are presented and discussed. These serendipitous structures all crystallized in the highly desired non- centrosymmetric space group while containing a strong network of hydrogen bonding