The ground-state geometries of DMACPyBP, PXZPyBP, and DPACzPyBP were optimized using density functional theory (DFT) at the PBE0/6-31G (d,p) level of theory in the gas phase starting from a geometry generated in Chem3D. The excited-state properties were calculated using time-dependent DFT (TD-DFT) within the Tamm-Dancoff approximation (TDA-DFT) based on the optimized ground-state geometries. The calculated energy levels of the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) are presented in Error! Reference source not found.and the data are summarized in Table .