Synthesis, characterization and NLO properties of 1,4-phenylenediamine-based Schiff bases: a combined theoretical and experimental approach

Abstract

In the current study, three novel 1,4-phenylenediamine-based chromophores (3a–3c) were synthesized and characterized and then their nonlinear optical (NLO) characteristics were explored theoretically. The characterization was done by spectroscopic analysis, i.e. FT-IR, UV-Visible, and NMR spectroscopy, and elemental analysis. Notably, these chromophores exhibited UV-Visible absorption within the range of 378.635–384.757 nm in acetonitrile solvent. Additionally, the FMO findings for 3a–3c revealed the narrowest band gap (4.129 eV) for 3c. The GRPs for these chromophores were derived from HOMO–LUMO energy values, which showed correspondence with FMO results by depicting a minimum hardness (2.065 eV) for 3c. Among these compounds, 3c displayed the highest nonlinear behavior with maximum μ_tot, β_tot and γ_tot values of 4.79 D, 8.00 × 10⁻³⁰ and 8.13 × 10⁻³⁴ a.u., respectively. Our findings disclosed that the synthesized 1,4-phenylenediamine chromophores may be considered promising candidates for nonlinear optical materials, showing potential applications in the realm of optoelectronic devices.