Synthesis, structural characterization and optical nonlinear properties of two azo- β-diketones

Synthesis, structural characterization and Density Functional Theory (DFT) studies of two azo-β-diketones, (3-((4-bromophenyl)diazenyl)pentane-2,4‑dione and 2-((4-bromophenyl) diazenyl)-1-phenylbutane-1,3‑dione prepared by coupling reaction of dizonium salt of 4-bromoaniline with acetylacetone and benzoylacetone. The products are characterized by FTIR, Mass, ¹H NMR and ¹³CNMR spectra. Density Functional Theory with B3LYP method in the level of basis sets 6–311 G (d,p) is used to optimize the geometry of the synthesized azo-β-diketone dyes. The energy of the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and ∆E gap energies from the DFT/B3LYP - 6‐311G(d,p) basis set are calculated. The lower value for ∆E (HOMO-LUMO) gap energy is 0.14756 eV of the first compound. The Z-scan method is adopted to study the optical nonlinear properties of the two compounds using a continuous wave laser beam at 473 nm wavelength. The two compounds showed high nonlinear refractive indexes of the order of 10⁻⁸ cm²/W.