4NICz, 5NICz, 6NICz, 7NICz, and 6,10NICz were synthesized according to the scheme reported by Kader et al., full synthetic details are provided in the supplementary information. The structures of all intermediates and target compounds were unambiguously verified using 1 H NMR and There are three distinct features in the UV-Vis absorption spectra of each emitter in dilute toluene solution (Figure ). These are: 1) a low energy band with a peak between 350 -400 nm with an additional high-energy resolved shoulder; 2) a band with a peak around 320 nm; and 3) a structured high-energy band with a peak below 300 nm. The high-energy shoulder of the low-energy band is blue-shifted by ~ 15 nm relative to the main peak and is less intense in all compounds except in 4NICz, where the shoulder and peak have almost identical intensity. The trend in the λabs of the lowenergy band matches the trend in the predicted S1 energies, but the energies are generally more stabilized (Table ). The magnitude of the molar attenuation coefficient of the low energy band (ε) is roughly comparable for 4NICz, 7NICz and 6,10NICz (ε = 8.0, 8.2, and 9.5 10 3 M -1 cm -1 , respectively), while it is approximately double and triple this value for 6NICz and 5NICz (ε = 14.0