Electrochemical and solvatochromic study of cyclopalladated complexes

The electrochemistry and the optical absorption properties of a series of cyclopalladated complexes are reported. Variation of the cyclometallated ligand has been performed (azobenzene, 2-phenylpyridine and benzo[h]quinoline) as well as variation of the ancillary ligand (acetylacetone and hexafluoroacetylacetone). Results have confirmed that the LUMO energy levels of these complexes is mainly distributed on the cyclometallated ligand. High electronegativity of the fluorinated groups has a weak influence on the electrochemical and absorption properties of the complexes, except for the benzo[h]quinoline for which its planar and comparatively more aromatic character lead to a partial delocalisation of the LUMO energy level.