Star-shaped D-π-A compounds with a 1,3,5-triazine core and N-aryl chromophore substituted fluorene arms: Synthesis, aggregation induced emission and two-photon absorption

Three star-shaped D-π-A compounds with a 1,3,5-triazine core and N-aryl chromophore (3,6-di-tert-butylcarbazole, phenoxazine and phenothiazine) substituted fluorene arms were designed and synthesized. Their photophysical properties were investigated systematically via spectroscopic and theoretical methods. All compounds exhibit strong 1π-π* transitions in the UV region and intense 1π-π*/intramolecular charge transfer (1ICT) absorption bands in the UV-vis region. Bathochromic shifts of the 1ICT bands were caused by the electron-donating N-aryl chromophores. All compounds exhibit aggregation induced emission properties in a solvent, and relatively high quantum efficiency in solid-states (Φ = 10%-20%). Moreover, these compounds show two-photon absorption (TPA) properties due to their good planarity and large π-conjugation. The largest TPA cross section value reaches up to 5000 GM at 800 nm. The multifunctional properties make these compounds potential candidates for application in organic light-emitting materials and two-photon bioimaging.