Electron spin resonance study of certain metallised dyes absorbed into wool

Abstract

The X-band e.s.r. spectra of Merino wool dyed with copper(II) tetrasulphonated phthalocyanine [Cu^II tspc] by hot and cold dyeing processes have been studied. In the hot dyeing process, which results in deep penetration of the dye molecules into the wool, a distribution of the dye amongst its aggregated forms is found which is closely similar to that found in frozen aqueous solutions containing 20 % V/V of dimethylformamide (dmf). This distribution is similar in other wool types, and is not affected by the state of aggregation of the dye in the dyebath. The rate of dyeing is increased as a result of an increase in the proportion of monomeric dye molecules in the dyebath.

The distribution of the low spin cobalt(II) tspc in wool, as observed by e.s.r., is also close to the distribution found for frozen aqueous solutions of cobalt(II) tspc containing 20 % V/V of dmf. Similar results to those obtained from the phthalocyanine chelates have been obtained by means of a study of chelates of the water soluble porphyrins, viz, tetrasulphonated tetraphenyl porphyrin (tssp) and tetracarboxyltetraphenyl porphyrin (tccp). The distribution of polymeric, dimeric and monomeric forms of the copper(II) chelates of the water-soluble porphyrins is again similar to that found in frozen aqueous solutions of the chelates containing 20 % by volume of dmf. We conclude that the dye molecules are in the amorphous phase of the wool structure.