Clean and Efficient\nGreen Protocol of <i>N</i>,<i>N</i>′‑Bis(2-(arylazo)-2-(aroyl)vinyl)ethane-1,2-diamines\nin Aqueous Medium without Catalyst: Synthesis and Photophysical Characterization

An interesting platform for the construction of novel <i>N</i>,<i>N</i>′-bis(2-(arylazo)-2-(aroyl)vinyl)ethane-1,2-diamines\nis reported in this work. These bis-arylazo compounds were assembled\nbased on the reaction of ethylenediamine with various 2-arylhydrazono-3-oxopropanals\nin aqueous conditions under both conventional stirring and microwave\nconditions at ambient temperature. The factors affecting the optimization\nconditions were intensively practiced. The structures of the new products\nwere established from their spectroscopic analyses and X-ray single\ncrystals. The photophysical behavior of the bis-arylazo derivatives\nwas examined. The UV–vis spectra showed maximum absorption\nband in the range of 348–383 nm with molar extinction coefficients\nranging from 0.89 × 10<sup>4</sup> to 4.02 × 10<sup>4</sup> M<sup>–1</sup> cm<sup>–1</sup>. The highest molar\nabsorptivity coefficient (∼45 × 10<sup>3</sup> M<sup>–1</sup> cm<sup>–1</sup>) was observed in CHCl<sub>3</sub> solvent.\nThe fluorescence properties showed that some compounds were interesting\nfluorophore materials with high Stokes shifts. The photoluminescence\nstudy of some compounds was promising, with maximal emission peaks\nranging between 417–436 nm.