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This thesis presents the synthesis, characterization and study of a range of heterometallated porphyrin nanorings. These studies revealed some fascinating electronic and supramolecular properties. Chapter 1 summarizes some of the work done in the Anderson group on porphyrin nanostructures and reviews the literature regarding template-directed synthesis. Chapter 2 describes the discovery of the novel technique “shadow mask templates”. We show that oligopyridine ligands can be used to dictate the sites of demetallation when a magnesium porphyrin nanoring is treated with acid. Magnesium centers that are coordinated to the template are protected whereas uncoordinated magnesium centers are removed. After site‐selective demetallation, the template can be removed, and other cations, such as zinc(II), copper(II), and silver(II) can be inserted into the free‐base porphyrin centers. This strategy provides a simple route to a wide range of heterometallated porphyrin arrays. Chapter 3 describes the investigation of quantum interference phenomena in bis copper and bis-silver six-porphyrin nanorings by EPR spectroscopy via measurement of the exchange coupling between the paramagnetic centers. Using orientationally selective DEER and RIDME, we investigate how various factors affect the exchange coupling between two spin centers in a porphyrin nanoring. Chapter 4 describes the thermodynamic and kinetic investigation of complexes where two oligopyridine templates stack on top of each other inside porphyrin nanorings. Using UV/vis/NIR titrations and kinetic ¹H NMR experiments, it was found that in a 12-porphyrin nanoring where there is space for the templates to bend, there is high positive allosteric cooperativity. In a 6-porphyrin nanoring where the templates are more constrained, there is negative cooperativity. In the case of the negatively cooperative systems, there is a high kinetic barrier for exchange of templates and reaching equilibrium can take up to several weeks. Chapter 5 describes how stacked templates can be used in a novel type of Vernier template-directed synthesis because they fit a favorable conformation of the targeted complex and does not require the complex to twist. This turns out to be a significant advantage when synthesizing complexes with sterically bulky solubilizing groups, and is the most efficient method to prepare a 12-porphyrin nanoring with THS-solubilizing groups.