ABSTRACT
Synthesis of porphycene, rst reported in 1986,1 opened up a new area of interdisciplinary research, devoted to constitutional isomers of porphyrin. Four pyrrole rings and four methine units can be reshued in many dierent ways. Seven “nitrogen in” structural isomers of porphyrin that preserve an N4 coordination site are possible.2 Of those, four have been obtained until now-all, except porphycene, in the form of alkylated derivatives.3-7 In addition, another isomer, labeled “inverted”8 or “confused”9 porphyrin, has also been synthesized. ‰e structures and names of these compounds are presented in Figure 33.1.
