Abstract:
Optical and redox properties of porphyrins, justly called “pigments of life”, place them among the most investigated compounds. After the synthesis of porphycene, the first known porphyrin isomer (1986), it became obvious that porphyrin characteristics can be advantageously modified by reshuffling the four pyrrole rings in the macrocycle. A theoretical paper predicted the electronic properties of all possible nitrogen-in isomers. Three of them were obtained later on, but other three still remain to be made.
Our research on porphycene and two other isomers - hemiporphycene and corrphycene – includes synthesis, tautomerism, optical properties, as well as practical applications, such as photodynamic inactivation of bacteria or viscosity sensing. I will present examples of these investigations, with a particular focus on comparing the chemistry and spectroscopy observed in three different experimental regimes: (a) ensemble studies; (b) isolation in supersonic jets and cryogenic matrices; (c) single molecule behavior observed by confocal fluorescence, Raman and scanning probe microscopies.