Synthesis and Photophysical Properties of Benzothiadiazole-Based Luminescence Materials with Tunable Emission Properties

Inspired by the advantages of long-wavelength emission of organic luminescence materials, this article presents two D-A-D type benzothiadiazole-based molecules with color-tunable emission from yellow to red via a suitable choice of the donor groups (phenyl/thiophenyl units). The optimized molecular structures indicated that the benzothiadiazole units are almost lying in a co-planer configuration with the donor groups, which would trend to strengthen the intermolecular interaction, resulting in a reasonable red-shifted emission with slightly fluorescence quenching. Thus, although the typical aggregation-induced emission (AIE) unit tetraphenylethene was introduced into those molecular skeletons, both compounds still display ACQ characteristic, due to the molecular aggregation via the strengthen intramolecular interaction (such as π-π stacking) could overwhelm the AIE effect. Thus, the large π-conjugated with planar molecular skeletons is not beneficial for constructing highly efficient AIE molecules.