The response of electronic and energetic properties of conjugated vs aromatic molecules to an external uniform electric field

Abstract

The susceptibility of electric and energetic properties of two sets of molecules to perturbation in a uniform electric field was investigated. The molecules of one set were deca-1,3,5,7-pentaene terminated with two functional groups, R1 and R2; those of the second set were 4-R1-4′-R2-p-diphenylbenzenes, with R1 and R2 being the same as in the polyene set. The polyene and aromatic molecules had similar lengths of the system of conjugated bonds between the two most extreme carbon atoms. Dipole moments were used as determinants of the overall charge transfer within the molecules. The electric field was directed along the main (longest) axes of the molecules from the negative pole to the positive. Comparison of the effect of the charge relocation in both sets of conjugated molecules revealed that the charge transfer imposed by the electric field was more efficient in the polyenes than in the aromatic compounds; however, for the molecule pairs with the same R1 and R2, reversal of the dipole moment direction falls at the same field strength. Parabolic dependence of the molecules’ energy as a function of field strength can also be interpreted in terms of the response of electron density to an electric field.