Green synthesis of luminescent blue emitters based on bistriazines with naphthalene as a π-conjugated spacer

A new series of luminescent blue emissive bistriazines is described. Bistriazines with a naphthalene spacer were prepared using a green methodology that involved microwave irradiation, solvent free conditions and a reaction time of only 10 min. The synthesis was followed by a simple purification procedure. D-σ-A-σ-π-σ-A-σ-D systems were constructed using 1,5-naphthylidene as a planar π-bridge and different donor substituents were attached to the triazine ring. UV–vis and fluorescence spectroscopy showed that the increased conjugation in bistriazines with respect to monotriazines resulted in a 40-fold increase in the photoluminescence quantum yield (ΦF). The bistriazines were efficient blue emitters with ΦF values up to 0.87. The aggregation behavior and the optical and thermal properties of these systems have been studied. The bistriazines showed good thermal stability in conjunction with high ΦF values and they are therefore very promising materials for use in optoelectronic devices. [Display omitted] •A series of bistriazines with strong blue luminescence is described.•Some derivatives show high photoluminescence quantum yields (ΦF = 0.87).•Bistriazines show aggregation in solution and aggregation-caused quenching (ACQ).