Sapphyrins and Texaphyrins

In 1966, sapphyrins 350, the first known examples of the expanded porphyrins, were discovered by Woodward and his colleagues during the course of their earlier work on the synthesis of vitamin B12. Since then, the search for other expanded pyrrolic macrocycles has ensued. In recent years, numerous new expanded porphyrins and their heterologues have been discovered 350- 3. The increasing knowledge of expanded porphyrins provides a new direction in developing an ideal photosensitizer for PDT (see also Chapter 9 by Sessler). 

Photophysical properties of metallotexaphyrins are of particular interest in photodynamic therapy. Much of the impetus for this attention is due to the fact that the texaphyrins absorb strongly in the 720-780-nm spectral 

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