The triplet state decay kinetics and deactivation funnel geometry of a series of nonplanar saddle-shaped porphyrins

The triplet state lifetimes of the series of nonplanar saddle-shaped porphyrins are found to be much shorter than those of their planar analogs (hundreds of ns vs. a few ms). DFT calculations suggest the existence of two types of conformations in the triplet excited state: “undistorted” (characterized by triplet-ground state energy gaps ∼0.8-1 eV) and “distorted” (characterized by drastically shortened gaps ∼0.2 eV).