Here, a broad emission band is observed with a peak at ~470 nm in 4NICz, 5NICz, 6NICz, and 7NICz (Table ). The time-gated PL spectrum of 6,10NICz, meanwhile, shows significant delayed emission at the same energy as that observed in the steady-state PL spectrum and which largely masks the emission from any lower-energy PL process; however, a small shoulder can still be observed at ~486 nm. In 4-7NICz, the peak of the low-energy band varies little with structure, ranging from 467 nm (5NICz) to 479 (6NICz), and in 5NICz and 7NICz it is well resolved into a second peak at higher energy, at 438 and 442 nm, respectively. We assign this low-energy process to room temperature phosphorescence from T1, for the following reasons: 1) the band is at lower energy than the fluorescence (S1) band; 2) it is observed as delayed PL; and 3) the λPL is approximately invariant with structure, matching the trend in T1 energies predicted by computations. Further evidence for this assignment is provided in emission behaviour of the 1 wt% doped films in PMMA (vide infra). ).