“…This resurgence of interest in the inversion of S 1 and T 1 excited-state energies was primarily initiated by the computational chemistry community. In recent years, researchers have explored design strategies for the engineering of IST molecules with theoretical and computational methods, 16–20 and the theoretical predictions were confirmed by spectroscopic measurements. 1,3,21,22 Molecular structures discovered by these explorations were predominantly nitrogen-doped phenalenes, such as cyclazine or heptazine derivatives, 1,2 along with related triangular 17,23 or hexagonal polycyclic aromatic hydrocarbons 24 with boron–nitride cores.…”