Relative stability and optical nonlinearity of multiple conformers of 1,1′-substituted ferrocenes

Abstract

The relative stability and the first and second hyperpolarizabilities of various conformers of four 1,1′-diarylethenylferrocenes have been evaluated at the MP2 computational level. Relative stability on the basis of the minimum polarizability principle is in complete agreement with the conclusion from the minimum energy criterion at the higher computational levels. Since the pi–pi interaction is an attractive force, the conformer with the intramolecular pi–pi interactions belongs to the lowest energy structure and is most likely to be populated. The calculated second hyperpolarizability is in excellent agreement with the experimental data available. There appear two low-energy absorption bands in electronic absorption spectra, where the lower-energy band shifts to the red and is enhanced by molecular distortion. This band is responsible for the largest linear polarizability and second hyperpolarizability of the conformer with inversion symmetry and the magnitude of the latter is dominated by one-photon transition.

Keywords:

• ferrocene
• hyperpolarizability
• ab initio calculation
• pi–pi interaction

Acknowledgements

We acknowledge the support from the Nature Science Fund of the Education Department of Yunnan Province (No. 07Z11621) and the Initial Fund for New Researchers in Dali University (No. KY421040).