Tunning Second-Order NLO Properties through Symmetry on Pyrazine Derivatives

Dr. Verònica Postils Ribó is a post-doctoral researcher at the Institut des Sciences Moléculaires at the University of Bordeaux.

Λ and X-shaped chromophores have been proved as a good alternative to 1D chromophores to obtain large response properties adequate for electro-optic devices. In this project linear and nonlinear properties of two new series of X-shaped pyrazine-derivative chromophores with (or almost) C_2v symmetry are investigated by means of density functional theory (DFT). The two series are differentiated by the orientation of the symmetry elements (C₂ axis and σ_v plane) of the point group, forming 2,3- and 2,6-isomers according to Figure 1. They comprise cyano groups as acceptor units, methoxy groups as donor units, and 2,5-thiophene groups as π-conjugated linkers that systematically enlarge the X shape of the chromophore. Focusing on the different orientation of the C_2v symmetry elements and how these structural changes affect the electronic structure and the characterization of the electronic excited states of the chromophores, a rationalization of the second-order nonlinear responses (mainly Hyper-Rayleigh Scattering (HRS) hyperpolarizabilities and depolarization ratios (DR)) will be done from a fundamental point of view.  

 

Contact : Benoît Champagne - benoit.champagne@unamur.be
Télecharger : vCal