Synthesis and Characterization of Schiff Base Compounds Containing Mono and Disulfonic Groups

Aromatic mono- or diamine compounds containing sulfonic groups are extensively utilized in the production of textiles, dyes, and polymers. Schiff base compounds are synthesized through the condensation reactions of these types of compounds with aromatic aldehydes or ketones. Due to their multifunctional nature, these Schiff base compounds serve as precursors in the synthesis of poly(ester)s, poly(ether)s, poly(urethane)s, and poly(azomethine)s. The Schiff base compounds were 2,5-bis((E)-(2-hydroxybenzylidene)amino)benzene sulfonic acid (SCH1) and 4,4'-bis((E)-(2-hydroxybenzylidene)amino)-[1,1'-biphenyl]-2,2'-disulfonic acid (SCH2). The yields of SCH1 and SCH2 were calculated to be 85% and 80%, respectively. Structural confirmation was achieved using FT-IR, UV-Vis, 1H NMR and 13C NMR measurements. Further characterization through fluorescence spectroscopy (PL), thermogravimetric analysis (TGA) and cyclic voltammetry (CV) revealed high thermal stability of the compounds, attributed to the phenyl groups in their structures. TGA measurements indicated the initial decomposition temperatures for SCH1 and SCH2 at 298°C and 347 °C, respectively, with the residual masses of 34.64% and 41.24% at 1000 °C.