Intramolecular Rotation in a Porphyrin Oimer Controls Singlet Oxygen Production

摘要

Singlet oxygen, O_2(a~1△_g), the lowest excited state of molecular oxygen, reacts with a wide range of organic molecules, including biomolecules. These reactions can have many consequences, including irreversible cellular damage and cell death.rnWe recently reported that conjugated porphyrin dimers, such as 1, can efficiently produce O_2(a~1△_g) by photosensitization. In this process, either one- or two-photon activation of the porphyrin dimer is followed by intersystem crossing to produce a triplet state which, in turn, transfers its energy to ground state oxygen, O_2(X~3Σ_g~-). Here, we demonstrate that the wavelength of light used to excite 1 is reflected in the quantum yield of O_2(a~1△_g) production. To our knowledge, such a wavelength-dependent effect is unprecedented and offers an additional degree of control in the photosensitized production of O_2(a~1△_g).