Thiophene π-bridge based NIR-II AIEgens for biomedical applications.

In the past five years, AIE luminogens (AIEgens) with emission in the second near-infrared (NIR-II) optical window have aroused great interest in bioimaging and disease phototheranostics benefiting from the merits of deep penetration depth, reduced light-scatting, high spatial resolution and minimal photo-damage. To construct NIR-II AIEgens, thiophene derivatives are frequently adopted as π-bridge by virtue of its electron-rich feature and good modifiability. Herein, we summarize the recent progress of NIR-II AIEgens by employing thiophene derivatives as π-bridge mainly compassing unsubstituted thiophene, alkyl thiophene, 3,4-ethylenedioxythiophene and benzo[c]thiophene, with a discussion about their structure-property relationships and biomedical applications. Finally, a brief conclusion and perspective in this fascinating area is offered.