The ortho-/para-emitters 5NICz and 7NICz possess a largely symmetrical T1, with a nodal plane passing through C2, C12c and N8, while in the meta-like emitters 4NICz and 6NICz this symmetry is distorted, with additional contribution from C2 and N8. Finally, 6,10NICz uniquely adopts the same distribution in its T1 state as its S1 state because the T1 and T2 excited states are inverted (Figure ).