The structural diversity of organic compounds is accompanied by a broad range of chemical and physical properties, making them the building blocks of life, as well as suitable for many technological applications, from synthetic materials to drug design. This is a consequence of carbon’s ability to bind with itself and nearly all elements in almost limitless variety. Among the many different classes of compounds, porphyrins - aromatic macrocycles composed of four nitrogen-containing, smaller rings connected by carbon bridges, are of great interest for modern chemists. Apart from their key role in biological functions (active sites in heme for oxygen transport by blood cells, in chlorophyll for photosynthesis performed by plants) they are studied as elements of novel, molecular-scale materials. They can be easily functionalized by different methods used in organic synthesis (changing the side groups, incorporating different metals in the center, connecting many porphyrins together) to fine tune their magnetic, electronic and optical properties in order to create nanoscale structures with precisely tailored characteristics. Porphyrin arrangement in larger, cyclic structures of different ring size and connectivity of the subunits is of special interest, as it enables studying charge and energy transport and unlocking new phenomena not seen in linear structures. Some of the properties can be compared to those observed in very long, and thus harder to study, organic polymers - materials of interest as "molecular wires". Cyclic arrays of porphyrins are also known to form in biological, photosynthetic systems, making such structures relevant in the search for novel light-harvesting materials for energy production. Many of such nanorings of different size and structure have been reported in recent years, in particular by the Anderson group in Oxford, opening a whole field for future investigations. The goal of this research project was to use existing synthetic methodologies - in particular the use of internal templates, acting as "moulds" to facilitate ring formation, in order to create and study new porphyrin architectures. Main focus was placed on making compounds with porphyrin subunits directly fused together, potentially improving electronic communication along the large rings. The project was based in Oxford to make use of the extensive hands-on experience in making and investigating of similar compounds in the group.
