Media effects on the optical properties of proton donor group containing azobenzene derivatives

A series of hydroxy and carboxy group containing azobenzene compounds were synthesized and investigated by UV-vis and fluorescence spectroscopy. It could be shown that the ambient medium exerted a strong influence on the absorption behavior and the trans-cis isomerization behavior of the azo compounds. Especially in the case of hydroxy group functionalized azobenzenes, deprotonation with NaOH or a polymeric base changed the spectral behavior of the compounds remarkably. A strong bathochromic shift of the dyes' longest wavelength absorption band was observed. Furthermore, the influence of different solvents and different polymeric matrices on the trans-cis isomerization behavior of the azobenzenes was investigated. The results are discussed in terms of utilization of the azo dyes as probe molecules for interactions in polymer blends. (C) 2009 Elsevier B.V. All rights reserved.