Etude de la distribution de charge dans un composé organique à propriétés optiques non linéaires le Di-Methyl Amino Cyano Biphenyl (DMACB)

Abstract

We explored in this study the charge distribution in the organic compound with non-linear optical properties, The 4, 4 dimethyl amino -cyanobiphenyl (DMACB) The intra molecular charge transfer of this molecule results mainly from the electronic transmission of the electro-acceptor (Cyano) and electro-donor (Di- Methyl-Amino) groups. An accurate electron density distribution around the molecule has been calculated from a high-resolution Xray diffraction study. The data were collected at 123 K using graphite-monochromated Mo-Kα radiation to sin (θ)/λ = 1.24 Å-1. The integrated intensities of 13796 reflections were measured and reduced to 6501 independent reflections with I ≥3 (I). The crystal structure was refined using the experimental model of Hansen and Coppens (1978). We present also the thermal motion and the structural analysis obtained from the least square refinement based on F² and the electron density distribution obtained from the multipolar model.By using program MOPRO,the charts of experimental and dynamic density of the studies compound are represented .They testify quality to the data of the recording.The analysis of the electronic density made it possible to determine the value and the orientation of the dipole moment in the molecule of the DMACB.