To gain insight into the electron density, transition energy, and oscillator strength of 2 and 3, time-dependent density functional theory (TD-DFT) calculations were performed (Figure ). The calculations predict that the neutral and anionic forms of 2a show absorption bands assigned to HOMO-LUMO transitions at λcal = 455 and 454 nm with oscillator strengths (f) of 0.0904 and 0.1726, respectively. These results were consistent with the experimentally observed hyperchromic effects of 2a. These results were consistent with the experimentally observed hyperchromic effects of 2a. The TD-DFT calculations also predicted a bathochromic shift in 3a. While the neutral and anionic forms of 3a show broad absorption at 410-530 nm and 420-630 m, respectively, the HOMO-LUMO transitions are calculated to be λcal = 488 and 652 nm with f values of 0.1726 and 0.1803, respectively. Nucleus-independent chemical shifts (NICS) were calculated to estimate the local aromaticity of each ring in both the neutral and anionic forms of 2a and 3a (Figure ).