Modulation of singlet and triplet excited states through σ spacers in ternary 1,3,5-triazines

A series of ternary asymmetric triazines with tunable singlet and triplet excited states were successfully synthesized on the basis of σ-spacer methodology and a facile synthetic route. The optoelectronic properties are dominated by the conjugated donor–acceptor (D–A) backbone of peripheral carbazoles (D) and triazine core (A), and can be further modulated via the partially interrupted conjugation between the core and the third substituents by the σ spacers of N–CH3, NH, O, S and OSO, which offers new opportunities to fine tune the electronic structures and properties of triazines.