Exploration of DFT-based static and dynamic nonlinear optical activity of an acridine-1,8-dione derivative

In this study, DFT-based analyses of nonlinear optical (NLO) properties of an acridine-1,8-dione derivative were performed, and its experimental UV–vis spectra were recorded in neutral and alkaline media. In the alkaline medium, n-π∗ transition shows a shift of about 100 nm with the appearance of yellow color, which can easily be detected through the naked eye. DFT-based various geometric parameters and global reactivity descriptors of NPB and its deprotonated form (${\text{NPB}}^{-}$) were computed. The TDDFT-generated UV–vis spectrum was found to be consistent with the experimental one. Bond-length alternation indicates that the dominating charge-separated resonating form in the ground state leads to higher β_total. NPB shows a higher static NLO response compared to urea molecule (160 times higher ${\beta }_{\text{total}}$ and 154 times higher ${\gamma }_0$ in DMSO) as well as some reported acridine-1,8-dione and 1,4-DHP-derivatives. Therefore, to check its potential as an NLO material, dynamic NLO parameters were also explored. At a lower frequency (532 nm) ${\beta }^{\text{SHG}}$, ${\beta }_{\text{HRS}}$, and ${\gamma }^{\text{EFISHG}}$ values are significantly higher. Furthermore, a higher non-linear refractive index at 532 nm confirms its application as a potential NLO material.