Tuning the Charge Transfer in λ-Phosphinines with Amino Substituents.

We report the substitution of λ-phosphinines (2,6-dicarbonitrile diphenyl-1-λ-phosphinine) with an amino group. The impact of these modifications on both the optical and redox properties is investigated using a joint experimental/theoretical approach. In particular, we show that the choice of the donor diphenylamino group dramatically impacts the nature of the charge transfer. The use of di(methoxyphenyl)amine redshifts the optical properties and allows thermally activated delayed fluorescence in the solid state. Finally, we demonstrated that λ-phosphinines with an amino group can be used as active emitters in an electroluminescent device.