Design and Synthesis of Donor-σ-π-σ-Acceptor-Type Dispiro Molecules.

Two novel donor-σ-π-σ-acceptor-type dispiro molecules-10-phenyl-10H-dispiro-acridine-9,9'-anthracene-10',9''-fluorene-2'',7''-dicarbo-nitrile (DiSAAF) and dispiro-fluorene-9,9'-anthracene-10',9''-quinolino[3,2,1-kl]phenoxazine-2,7-dicarbonitrile (DiSFAQ)-with excellent thermal stability are designed and synthesized. Both materials exhibit blocked long-range intramolecular charge transfer but show intermolecular charge-transfer emission in the film state. Their photophysical and thermal properties then are fully investigated and a maximum external quantum efficiency of 21.7% of the red phosphorescent device is achieved by DiSAAF.