Solvatochromic effects in the fluorescence of a few diamino aromatic compounds

Abstract

Solvatochromic effects of 14 solvents and various dioxane-water mixtures on the fluorescence spectra of three isomeric phenylenediamines, 2, 3-diaminonaphthalene (2,3-DAN) and 2,7-diaminofluorene (2, 7-DAF) have revealed the following: (i) the Bilot-Kawski expression of polarizability provides a better specific analysis of solvatochromic effects than the Lippert expression or the Dimroth parameter; (ii) no expression correlating the solvent polarity and Stokes shift expresses the effect of charge transfer interactions in exciplex formation; (iii) the two amino groups in 2,3-DAN are twisted with respect to the plane of the naphthalene ring.