New insight into metalloporphyrin excited state structures and axial ligand binding from X-ray transient absorption spectroscopic studies

- XTA (X-ray transient absorption) can characterize nuclear/electronic structural dynamics associated with photoinduced metalloporphyrin ligation.
- XTA results revealed a unified mechanism for the axial ligation in nickel porphyrin which involves vacancy in the 3dz2 orbital created due to the transient degeneracy of two 3d orbitals in both the ground state and the photoexcitation.
- The environmental effect of the iron porphyrin - CO dissociation has been directly observed in XTA results featured by both 3d orbital energy level and transient nuclear structural characterization.