Abstract
Part I. Small organic molecules can play important medicinal roles as markers for antitumor agents, drug delivery, drug discovery, and proteins. However, many small organic molecules aggregate, which can significantly alter their functionality. Therefore, understanding the aggregation process in these molecules is important. In this work, nuclear magnetic resonance (NMR) was used to study the aggregation of Sunset Yellow FCF, an organic dye, and cromolyn sodium, an asthma drug, by measuring changes in chemical shift, longitudinal (T1) and transverse (T2) relaxation times, and self-diffusion coefficients as a function of concentration and solution ionic strength. The NMR studies were also complemented using UV-visible spectroscopy, dynamic light scattering, and viscosity, pH, conductivity measurements. Models for aggregation in these molecules were refined to best fit all of the experimental data. Part II. In this work, we have developed shaped pulses that are capable of selectively suppressing magnetization with particular values of T1 and T2 relaxation times. These pulses, referred to as relaxation selective pulses, were optimized using gradient ascent pulse engineering (GRAPE) algorithm to be optimal with respect to selectivity while being robust to magnetic field inhomogeneity. When combined with pulsed field gradients, these pulses could be used to selectively suppress the magnetization for molecules with particular self-diffusion coefficients. Applications of these pulses to spectral editing and solvent suppression were performed.