Date(s) - 04/05/18
11:45 am - 1:00 pm
Dr. Elena Jakubikova, Chemistry Department, NCSU; host Dr. Feifei Li
Title: “Iron Chromophores with a Twist: Toward Controlling the Intersystem Crossing in Fe(II)-polypyridines”
Fe(II)-polypyridines have recently gained a lot of attention as potential chromophores in artificial assemblies for solar energy conversion, such as dye-sensitized solar cells. The photoactive metal-to-ligand charge transfer states in most of these complexes, however, undergo ultrafast intersystem crossing (ISC) into the manifold of non-photoactive metal-centered states. The ISC in these systems is difficult to control, thus limiting their utility. Previous studies characterize the structural changes that occur during the ISC in Fe(II)-polypyridines mainly in terms of the metal-ligand bond lengths, neglecting other degrees of freedom, such as the ligand twisting and rocking motions. We employ the density functional theory (DFT), time-dependent DFT, and sparse-grid interpolation techniques to characterize the polypyridine ligand motions in model iron chromophores at different spin-state surfaces. Our results suggest that tuning the energetics of the ligand twisting and rocking motions is a possible pathway toward controlling the ISC processes in Fe(II)-polypyridines.