New acid dyes and their metal complexes based on substituted phenols for leather: Synthesis, characterization and optical studies

Abstract

The present investigation deals with synthesis of new acid dyes from 4-amino-1-(4-sulfophenyl)-3-methyl-5-pyrazolone and phenol derivatives and their metal complexes (Cu (II) and Fe (II)). The phenol derivatives include 4-chlorophenol, 4-nitrophenol, 4-hydroxybenzene sulfonic acid,
2-nitrophenol-4-sulfonic acid, resorcinol and bisphenol A and bisphenol S. The newly synthesized dyes were applied to crust leather to assess their dyeing properties. The fastness properties of unmetallized dyes were less as compared to metal complexes due to the strong interaction of metals with leather protein. The structures of these dyes were also confirmed by UV, FTIR and NMR studies.