Porphodimethenes/porphyrins: redox-switchable tetrapyrrolic macrocycles

Utilizing a general two-step procedure, a new class of porphodimethene macrocycles has been prepared, which can be easily converted to porphyrins bearing two 8-functionalized naphthalene spacers. Through straightforward modifications in the precursor molecules, macrocycles with a wide range of steric and electronic attributes can be isolated. With these simple ligands, metal-porphyrin complexes exhibiting interesting properties can be produced. For example, when two reactive groups are poised above the porphyrin, a reversible ring closure can take place under mild conditions, allowing for potential recognition sites close to a metal center to be electrochemically and chemically activated and deactivated. This intramolecular porphodimethene-porphyrin interconversion offers many exciting possibilities for the development of catalysis adept at specific transformations and for the design of novel sensors or photosensitizers.