Nonlinear optical studies of phenothiazine Schiff bases for optical limiting application

•Synthesized organic Schiff bases with significant absorption in the visible range.•Ground state absorption spectra illustrate effective intramolecular charge transfer.•Nonlinear optical properties exhibit reverse saturable absorption ascribed to sequential two-photon absorption.•Phe-Ma possesses higher nonlinear absorption and a lower optical limiting threshold. Synthesized Schiff-based organic molecules consisting of phenothiazine backbone (Phe-DNP, Phe-Ma, Phe-3) to investigate its optical limiting applications. The structural confirmation of compounds is carried out by FTIR and NMR spectroscopy. The quantum mechanical calculations of compounds are measured using Density functional theory (DFT) to investigate the electronic orientation in molecular orbitals and the theoretical bandgap. All the molecules show a broad absorption in the visible domain and the conjugated molecule absorption shifts towards the higher wavelength region. The effective intramolecular charge transfer of molecules in the order Phe-DNP> Phe-Ma>Phe-3 is understood from the ground state absorption spectra results. All the organic moieties exhibited sequential two-photon absorption upon studying the open aperture Z-scan technique. Phe-Ma molecule shows the highest nonlinear absorption (1.212× 10−10 m/W) and lowest optical limiting threshold (3.19 × 1012 W/m2) compared to other molecules suggesting that Phe-Ma could be a potential nonlinear optical limiter. Synthesized organic Schiff bases exhibit reverse saturable absorption ascribed to sequential two-photon absorption, which possesses higher nonlinear absorption and a lower optical limiting threshold. [Display omitted]