Certain water-soluble porphyrins have been reported as attractive alternatives to currently employed sensitizers in the photochemical reduction of water to hydrogen.'They have also been found to accumulate in tumors, 2 and their use as diagnostic3 and thereapeutic agents has been e~ amined.~ All of these porphyrins owe their water solubility to the presence of readily ionized substituents (carboxylate, 4 sulfonate: or quaternary ammonium6 salts). ...
