Electrochemistry, Acid-base Properties and Spectroelectrochemistry of Porphyrins, Corroles, and Related Molecules

This dissertation presents the electrochemistry, spectroelectrochemistry and acid-base properties of porphyrins, corroles and related molecules in non-aqueous media. The acid-base properties monitored by electrochemical methods and spectroscopy were examined as to four types of free-base porphyrins (with meso-substituents, with β-substituents, with negatively charged substituents and with positively charged substituents). Both neutral and protonated porphyrins involve multiple redox reactions depending upon the selected solvent, supporting electrolyte and the specific porphyrin structure. Electrochemical and thin-layer spectroelectrochemical characterization of porphyrins, corroles and hemiporphycenes were then discussed in different solvents. Each macrocycle not only exhibits well-defined ring-centered oxidations and ring-centered reductions, some of which has a metal-centered electron transfer but also has the electroactive peripheral substituents (N-alkylpyridyl groups in the case of porphyrin, pyrazine groups in the case of hemiporphycene and ferrocene groups in the case of corrole) who are able to add or abstract electrons on themselves. These electroactive substituents show strong (sometimes little) interaction between the two redox centers, the magnitude of which is rely on the factors of the central metal ions, the nature of the macrocycle and the used solvent.