Ladder-type pentaphenylenes and their polymers: efficient blue-light emitters and electron-accepting materials via a common intermediate.

A new route to ladder-type pentaphenylenes has been developed in which both good hole-accepting p-type and electron-accepting n-type materials can be prepared from a common intermediate. This key intermediate is a pentaphenylene diester 5 obtained in high yield by Suzuki coupling of 2 equiv of fluorene boronates with 2,5-dibromoterephthalate. Addition of aryllithium followed by ring closure with boron trifluoride produced a blue-emitting ladder-type pentaphenylene.