Red AIE‐Active Fluorescent Probes with Tunable Organelle‐Specific Targeting

Abstract Cell staining is a fascinating research area where monitoring and visualizing different cell organelles can be done using fluorescence techniques. However, the design and synthesis of organelle‐targeting fluorophores is still a challenge for several specific organelles. Herein, a platform for synthesizing efficient red‐emitting aggregation‐induced emission luminogens (AIEgens) with donor–acceptor characteristics is reported. The core molecule can be easily functionalized in order to modulate organelle targeting. The three synthesized AIEgens exhibit quantum yields of up to 39.3% and two‐photon absorption cross‐section values of up to 162 GM. The two zwitterionic AIEgens, CDPP‐3SO 3 and CDPP‐4SO 3, with the sulfonate function group, are successfully utilized for specific one‐photon and two‐photon imaging of the endoplasmic reticulum (ER) in live human cells. Substituting the zwitterionic nature with a singly positive charge group, one‐photon and two‐photon imaging of CDPP‐BzBr shows mitochondrial specificity, indicating the importance of the zwitterionic group for ER‐targeting. Owing to the good in vitro photostability, cell viability, and high efficiency, these red dyes serve as a good potential candidate for specific organelle targeting, as well as illustrate how such a platform can easily aid in the study of structure–property relationships for designing such probes.