ortho -Terphenylene Viologens with Through-Space Conjugation for Enhanced Photocatalytic Oxidative Coupling and Hydrogen Evolution.

A series of novel ortho- terphenylene viologen derivatives ( o- TPV 2+ ) with through-space conjugation (TSC) via the combination of ortho- terphenylene skeletons with viologen structure is reported. Their optoelectronic properties can be adjusted by N -arylation or N -alkylation reactions. Compared with other viologen derivatives, o- TPV 2+ not only exhibits strong photoluminescence but also retards the charge recombination process and stabilizes the diradical state without forming a quinoid structure due to the special TSC effect. Based on their special redox characteristics, o- TPV 2+ was applied to the photocatalytic oxidative coupling of benzylamine with 96% yield. In addition, p TA- o- TPV 2+ (tethered with p -toluic acid)-modified g-C 3 N 4 was used for visible-light-driven hydrogen production for the first time, exceeding 15 times the rate over unmodified g-C 3 N 4 .