Anion Sensing and Molecular Recognition Using Macrocycles

Abstract

This thesis describes the versatility of elaborated porphyrins and porphyrin-like macrocycles as selective sensors for anions. The development of anion sensors based on coordination complexes is briefly reviewed in the first chapter. Chapter Two describes the synthesis of free-base and metallo-picket fence type porphyrins. These elaborated porphyrins have been designed specifically for use as anion sensors. The picket groups include ferrocene and cobaltocenium. Chapter Three is comprised of two parts. The first half describes the theory of ion-selective electrodes and the second half details the detection and selectivity of anions by free-base and metallo-picket porphyrins incorporated in ion-selective electrodes. The results of these studies have established that manganese(III) porphyrin complexes are the most suitable as anion sensors. The synthesis of l,1'-bis-amidoferrocene complexes is reported in Chapter Four. A method for preparing unsymmetrical 1,1'-bis-amidoferrocene complexes is described here for the first time. X-ray crystal structures of both symmetrical and unsymmetrical 1,1'-bis-amidoferrocene complexes have established there are interesting differences in crystal packing between examples. Group 14 complexes of octamethyltetraazaanulene (OMTAA) are potential anion sensors and these systems are described in Chapter Five. The X-ray crystal structure of [Sn(OMTAA)CI(THF)]+ established an interesting cationic species is formed when more than a stoichiometric amount of stannic chloride is used. This complex is assumed to be the active element in anion sensors based on Sn(IV) porphyrins. The final chapter describes the use of free-base and metallo-porphyrins in molecular recognition of fullerenes (C60 and C70). Crystal structures of six porphyrin/fullerene cocrystallates are reported. These crystal structures provide important information regarding the consistently short porphyrin-fullerene distances attributable to van der Waals interactions.