β-Pyrrole Functionalized Push or Pull Porphyrins: Excited Charge Transfer Promoted Singlet Oxygen Generation.

Singlet oxygen (O) producing photosensitizers are highly sought for developing new photodynamic therapy agents and facilitating O-involved chemical reactions. Often singlet oxygen is produced by the reaction of triplet-excited photosensitizers with dioxygen via an energy transfer mechanism. In the present study, we demonstrate a charge transfer mechanism to produce singlet oxygen involving push or pull functionalized porphyrins.

Zinc Tetrapyrrole Coordinated to Imidazole Functionalized Tetracyanobutadiene or Cyclohexa-2,5-diene-1,4-diylidene-expanded-tetracyanobutadiene Conjugates: Dark vs. Light-Induced Electron Transfer.

Using the popular metal-ligand axial coordination self-assembly approach, donor-acceptor conjugates have been constructed using zinc tetrapyrroles (porphyrin (ZnP), phthalocyanine (ZnPc), and naphthalocyanine (ZnNc)) as electron donors and imidazole functionalized tetracyanobutadiene (Im-TCBD) and cyclohexa-2,5-diene-1,4-diylidene-expanded-tetracyanobutadiene (Im-DCNQ) as electron acceptors. The newly formed donor-acceptor conjugates were fully characterized by a suite of physicochemical methods, including absorption and emission, electrochemistry, and computational methods. The measured binding constants for the 1 : 1 complexes were in the order of 10 -10  M in o-dichlorobenzene.