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Azo dye location in textiles: a novel UV–vis approach
Author(s) -
Oakes John,
Batchelor Stephen N,
Dixon Sarah
Publication year - 2005
Publication title -
coloration technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.297
H-Index - 49
eISSN - 1478-4408
pISSN - 1472-3581
DOI - 10.1111/j.1478-4408.2005.tb00279.x
Subject(s) - tautomer , hydrazone , chemistry , orange (colour) , moiety , photochemistry , methyl orange , aqueous solution , amorphous solid , absorption spectroscopy , ultraviolet , polymer chemistry , organic chemistry , materials science , catalysis , physics , food science , photocatalysis , optoelectronics , quantum mechanics
Ultraviolet–visible spectra of Orange II exhibit blue shifts in apolar solvents due to the formation of the azo tautomer. Upon absorption to cotton, Orange II remains as the hydrazone tautomer and, like other phenylazonaphthol dyes or Methyl Orange, exhibits small red spectral shifts. Two superimposed spectra – characteristic of the azo and hydrazone tautomeric forms – are detected when dye 1 ( X = p ‐MeO) absorbs onto cotton. Only the azo form is observed on nylon; all other dyes, except Orange II, give blue shifts. A model is developed in which the more apolar moiety of the dye binds to pockets formed in the non‐crystalline (amorphous) regions of cotton, with those parts containing the sulphonate group protruding into aqueous pores. In nylon, the binding sites are more apolar with the sulphonate groups bound electrostatically.