π-Stacking modulates the luminescence of (dppz)Ni(Mes)Br (dppz = dipyrido[3,2-a:2′,3′-c]phenazine, Mes = 2,4,6-trimethylphenyl)

Article abstract of DOI:10.1002/zaac.200700082

The red colour of the novel organonickel complex [(dppz)Ni(Mes)Br] (dppz = dipyrido[3,2-a:2′,3′-c]phenazine, Mes = 2,4,6-trimethylphenyl) originates from long-wavelength MLCT/L′LCT charge transfer bands. However, luminescence in dilute solution comes presumably from the ³π- π* (phenazine) excited state. The red-shifted emission exhibited in concentrated solutions is assigned to dimers. In the solid state emission is quenched. The crystal structure reveals two different types of π-π stacking along the crystallographic a axis.