The Absorption Spectra of Dyes. X. Note on the Configuration of the Component Molecules in the Complex State

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Abstract
The configuration of the component molecules in the complex formed between Chryophenine G (G) and the direct dyes (P),such as Chlorazol Sky Blue FF, has been discussed qualitatively with respect to the relation between the steric structure of the individual P molecules and the enthalpy or the entropy changes in the complex formations. the electrons to be transferred from the partner (P) to the G molecule are the π electrons of the functional (hydroxy) groups and are those of the inner-side groups when the respective coupling components of the dye have more than one functional group. The large the charge density of such an effective functional group becomes, the more the enthalpy change (−ΔH) is increased. It may be said with certainty that there must exist a certain configuration of the component molecules peculiar to the complex formation. Such a configuration may be seen for the configuration of G and ND (NW-acid←dianisidine→NW-acid). For other combinations of which the partner of G is more deformed in free than ND state, the shifts of equilibrium to the configuration for the complex state are almost due to an entropy change (−ΔS) which increases in proportion to the magnitude of the deformation.