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.