Extremely Photostable Electron‐Deficient Phthalocyanines that Generate High Levels of Singlet Oxygen

Abstract A robust lead‐mediated synthetic procedure for the generation of phthalocyanines substituted with electron‐withdrawing groups has been developed. The free‐base phthalocyanine and various metal complexes were prepared without discernible degradation of the peripheral electron‐withdrawing substituents. Upon irradiation with red light, some of the thus‐obtained metal complexes generated high levels of singlet oxygen. In particular, a palladium complex exhibited attractive photostability upon exposure to singlet oxygen as a bleaching agent. The photostability of such complexes that may manifest concomitantly to the generation of high levels of singlet oxygen was attributed to the presence of the electron‐withdrawing groups, which results in energetically low‐lying highest occupied molecular orbitals.