Tailoring Porphyrin (Nano)Structures

Many possibilities exist to modify the structure of porphyrins. These include variation of the central metal, N-substitution or modulation of the macrocyclic π-system. Recent years have seen a surge in π-annulated systems while a more established approach is the synthesis of nonplanar porphyrins via peripheral macrocycle interactions. Any of these strategies results in porphyrin systems with altered structure, conformation and physicochemical properties. What is lacking is true ‘conformational design’ of porphyrins, i.e., the use of the recent advances in organometallic chemistry in conjunction with structural studies to yield functional systems with predesigned conformations. Such an approach would aid development of new optical materials and catalysts.

Similarly, an expanding body of studies on porphyrin nanomaterials on surfaces is beginning to reveal how surface/macrocycle interactions alter the chemical properties of porphyrins. Metallation and metal exchange reactions are possible and specific types of porphyrin nanostructures are now accessible via logical 2D synthesis on metal surfaces. Initial studies of porphyrin-graphene interactions indicate that a combination of tailor made porphyrins with specific macrocycle-surface interactions can yield functional nanomaterials.