Studies in Supramolecular Chemistry: Self-Sorting Systems, Parallel Reactions, and Differential Sensing Using Cruciform/Half-Cruciform Fluorophores

This dissertation presents different studies in supramolecular chemistry—the first three chapters deal with self-sorting of dynamic covalent libraries and one-pot parallel reactions, while the final two chapters describe the use of cruciform fluorophores in the construction of differential sensing arrays and the synthesis and characterization of “half-cruciform” fluorophores. Chapter One. This chapter introduces the broad field of supramolecular chemistry with an emphasis on dynamic covalent chemistry (DCC). Notable applications of DCC and simplification of dynamic covalent libraries via self-sorting induced by chemical and physical stimuli is reviewed. Chapter Two. Kinetic self-sorting of dynamic imine libraries, constructed from aromatic aldehydes and substituted anilines, was achieved through selective precipitation. The selectivity of the process is caused by the solubility differences among possible imines in the ethanol-water solvent mixtures used in precipitation. Chapter Three. Parallel reactions are introduced and self-sorting event is extended to include several competing reversible reactions. Four simultaneous dehydration reactions: imine formation, acetal formation, ester formation, and tertiary alcohol dehydration, were shown to proceed simultaneously in one pot using para-toluenesulfonic acid as the catalyst. Chapter Four. This chapter describes a protocol for discriminating structurally-related analytes using a differential sensing array constructed from 1,4-distyryl-2,5-bis(arylethynyl)benzene cruciform, benzobisoxazole cruciform, and benzobisoxazole-boronic acid hybrid sensors. This method relies on the differences of the emission colors of the cruciform solutions before and after analyte addition. Ten carboxylic acids, nine organoboronic acids, and twelve organic amines, and ureas were differentiated from each other using this procedure. Chapter Five. Nine “half-cruciform” fluorophores containing benzimidazole core were synthesized in two steps: oxidative condensation of 3-bromo-o-phenylenediamine with three commercially-available aromatic aldehydes, which installs the horizontal axis, followed by Sonogashira coupling with aryl alkynes, which installs the vertical axis. Computational studies show that donor/acceptor substituted half-cruciform can localize their frontier molecular orbitals. These compounds were found to be viable fluorescent sensors, as they showed significant changes in their UV/Vis absorbance and fluorescence properties upon addition of bases, acids, and small anions.Chemistry, Department o