Affiliations: Laboratory of Luminescence and Molecular Structure, Center of Environmental Chemistry and Department of Chemistry, Faculty of Sciences, University of Chile, Casilla 653, Santiago, Chile
Note: [] To whom the correspondence should be addressed.
Note: [] Permanent address: Department of Chemistry, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile.
Abstract: Charge transfer electronic transitions in a series of para‐substituted \beta‐nitro‐styrenes are analyzed in order to characterize the \pi‐conduction channel between the electron‐donor substituents and the NO_{2} electron‐acceptor group, particularly the bridge effect of the olefinic molecular structure. Absorption bands assignment of the \pi\rightarrow\pi* electronic transitions in the near ultraviolet spectral region is carried out from an experimental and theoretical point of view. The photo‐induced charge transfer spectral bands of these aromatic compounds follow the same pattern as nitrobenzene, benzaldehyde and acetophenone and the electronic transition takes place in the \pi\rightarrow\pi*(^{1}L_{a}) excited state. Our present study based on ZINDO/S‐CIS M.O. calculations permits us to analyse the role of the NO_{2} electron‐acceptor group, and the ethylenic group, where this last structure merges as a second electron‐acceptor group. The calculated olefinic bridge molecular resistivities (\rho_{o}) of these \beta‐nitrostyrenes range from 2.1 to 2.5 (Å/quantum).
