Expanding the Synthesis and Applications of Morpholine-based Pyrrole Modified Porphyrins

The thesis proposes to refine and extend the ‘porphyrin breaking and mending’ methodology, to modify known and novel pyrrole-modified porphyrins (PMPs), to evaluate their (photo)physical properties in theory and experiment, and to explore – alone and in collaboration with specialty groups – their applications. The investigations were carried out such that the steric (e.g., ring-size of the non-pyrrolic heterocycle; b-to-o–phenyl linkages) and electronic influences (e.g., degree of saturation of the macrocycle, nature of functional groups) of the modifications on the physical properties of the PMPs could be delineated. The reaction of b-octaalkylporphyrins (octaethylporphyrin and etioporphyrin I) with ozone to generate chlorin-like chromophores was studied. Such a reaction was described firstly over 80 years ago but was not understood at the time. The work expands on the knowledge of converting porphyrins to porphyrinoids containing non-pyrrolic heterocycles of potential utility (Chapter 2). We introduce novel methodologies toward the synthesis of porphyrinoids carrying b-to-o-phenyl fusions and expand on the scope and limits of the chemistry and interconversion of PMPs (Chapter 3). The macrocycle conformation of [meso-tetraarylporphyrinato] metal complexes is metaldependent. Furthermore, hydroporphyrins and some of their analogues are known to be more conformationally flexible than the parent porphyrins, but the extent to which this is reflected in their metal-dependent conformations was much less studied. Therefore, their conformations were determined using X-ray crystal structure diffractometry and compared against those of their free bases, as well as against the conformations of the corresponding metalloporphyrins to further define the conformational and electronic effects governing pyrrole-modified porphyrins (Chapter 4).