Synthesis and Serviceability of New Symmetric Bis-pyrazolone Metal Complex Acid Dyes

Synthesis of new symmetric bis-pyrazolone acid dye and its 3d transition metal complexes is studied. Bis-pyrazolone is synthesized from (E)-6,6’-(ethene-1,2-diyl)bis(3-hydrazinylbenzenesulfonic acid) and ethyl ace-toacetate. The synthesized bis-pyrazolone is coupled with diazonium salt of 4-sulpho-2-aminophenol in alkaline medium targeting bis-pyrazolone ligand acid dye. Various metal complexes are obtained by treating a methanolic solution of metal salts with ligand acid dye in basic media. Structures of the synthesized ligand dye and its metal complexes are confirmed by UV-Vis, FTIR, and NMR spectra. The ligand acid dye and metal complex dyes demonstrate absorption in UV-Vis in the range of 400–600 nm. Ligand acid dye and its metal complexes demonstrate good to high value of light speed, washing fastness and rubbing fastness on leather.