Probing the Effect of Molecular Structure Saddling on Ultrafast Charge Migration via Time-Resolved X-ray Diffraction

Abstract: Metal-corroles are macrocycle organic molecules with numerous practical applications. In particular, copper corroles exhibit an interesting saddled geometry, which has attracted significant attention from theoreticians and experimentalists over the years. The present work is dedicated to understand the effect of structural saddling in a copper corrole on potential probe signals via imaging ultrafast coherent electron dynamics. A linearly polarized pulse is used to trigger the electron dynamics and time-resolved x-ray diffraction is employed to image the triggered dynamics. It is found that the symmetry reduction in the time-resolved diffraction signals and electronic flux densities is a signature of the saddling in a copper corrole during ultrafast charge migration. Moreover, analysis of the electronic flux density reveals that the diagonal nitrogen atoms mediate coherent charge migration between them via a central copper atom. Correlation of the flux densities and the diffraction signals indicates that the signature of the charge migration is encoded in time-resolved diffraction signals. A comparison of the static diffraction signals of nonsaddled planar copper porphyrin and saddled nonplanar copper corrole in their ground states is made.