Preferential solvation through selective functional group recognition in p-nitroaniline

The solvatochromism of the charge transfer band of p-nitroaniline (PNA) in different binary solvent mixtures has been investigated from the spectroscopic transition energy (TE). The solvation is proposed to be localized due to the donor and acceptor group and the preference of one solvent above other is due to hydrogen bonding. The preferential solvation has been characterized from the trilinearity of molefraction–TE curves of the binary mixtures. In alcohol–dioxane mixtures, dioxane prefers to solvate amino group while the alcohols preferentially solvate the nitro group through hydrogen bonding. The IR spectral characteristics of PNA in dioxane and butanol also support the preferential solvation model. The thermodynamic parameters have been determined for the solvation process.

In alcohol–dioxane binary mixture, the solvation of p-nitroaniline is due to functional group recognition where nitro group is preferentially solvated by alcohol while the amino group is preferentially solvated by dioxane.Figure optionsDownload as PowerPoint slide