The tautomerism, solvatochromism and non-linear optical properties of fluorescent 3-hydroxyquinoxaline-2-carboxalidine-4-aminoantipyrine

The Schiff base, 3-hydroxyquinoxaline-2-carboxalidine-4-aminoantipyrine, was synthesized by the condensation of 3-hydroxyquinoxaline-2-carboxaldehyde with 4-aminoantipyrine. HPLC, FT-IR and NMR spectral data revealed that the compound exists predominantly in the amide tautomeric form and exhibits both absorption and fluorescence solvatochromism, large stokes shift, two electron quasi-reversible redox behaviour and good thermal stability, with a glass transition temperature of 104 °C. The third-order non-linear optical character was studied using open aperture Z-scan methodology employing 7 ns pulses at 532 nm. The third-order non-linear absorption coefficient, β, was 1.48 × 10−6 cm W−1 and the imaginary part of the third-order non-linear optical susceptibility, Im χ(3), was 3.36 × 10−10 esu. The optical limiting threshold for the compound was found to be 340 MW cm−2.