Electrochemical study of nitrostilbene derivatives:: nitro group as a probe of the push-pull effect

This paper reports electrochemical (tast polarography, differential pulse polarography, cyclic voltammetry) and spectroscopic investigations covering a series of stilbene derivatives having either one or two electron-donating groups (alkoxy, hydroxy, phenolate at pH > 9) located at one end of the molecules. The groups interact, through a conjugated system of pi electrons, with an electron-withdrawing group (nitro group) at the opposite end of the molecule. The push-pull effect on the molecule is obtained by the presence of the extended unsaturated pi electron system combined with a polar substituent with opposite electrical effects suitably attached to the conjugated systems. This arrangement gives relevant electro-optics characteristics to the molecules. The polar substituents are electroactive and, by comparison of the potential peaks of the compounds, it is possible to estimate the intramolecular electronic interactions within the molecule. Specifically, in this case, change in the potential peak of the nitro group allows conclusions about the push-pull effect in the system to be reached. (C) 2000 Elsevier Science B.V. All rights reserved.