A series of terpyridine derivatives for aggregation-induced emission, two-photon absorption and mitochondrial targeting

Herein, a series of multifunctional oxethyl triphenylamine substitutional terpyridyl analogues (1, 2, 3, 4 and 5) with aggregation-induced emission (AIE), two-photon absorption (2PA) and specially targeted mitochondria were presented. Their photophysical properties were systematically explored by two-photon excited fluorescence measurements and theoretical calculations. Importantly, the AIE mechanism was explained relying on their crystal structural information. It indicated that the introducing of oxethyl and π bridge of phenyl caused the fluorescence quenching in organic solvent and AIE in mixed solvent of ethanol and water. The nonlinear optical test revealed that strong ICT with a large dipole moment and high asymmetry of the terpyridyl analogue molecules were benefited for 2PA. Finally, based on their photophysical properties, the biological imaging applications were carried out, which indicated that the terpyridyl analogues may be potential biological probe for targeting mitochondria.