Photodemetalation of silver(II) tetraphenylporphyrin

The photolysis of AgIITPP (TPP = tetraphenylporphyrin) under reducing conditions leads to the release of Ag+ and formation of the free-base porphyrin H2TPP. It is suggested that this demetalation is initiated by LMCT excitation. The demetalated porphyrin undergoes secondary photoprocesses. In the presence of oxygen, the well-known formation of singlet oxygen takes place. Silver(II) porphyrins are thus able to function as sensitizers in photodynamic therapy. The released Ag+ ions could supplement or enhance the therapeutic effect.