Activatable Near‐Infrared Versatile Fluorescent and Chemiluminescent Dyes Based on the Dicyanomethylene‐4H‐pyran Scaffold: From Design to Imaging and Theranostics

Abstract Activatable fluorescent and chemiluminescent dyes with near‐infrared emission have indispensable roles in the fields of bioimaging, molecular prodrugs, and phototheranostic agents. As one of the most popular fluorophore scaffolds, the dicyanomethylene‐4 H ‐pyran scaffold has been applied to fabricate a large number of versatile activatable optical dyes for analytes detection and diseases diagnosis and treatment by virtue of its high photostability, large Stokes shift, considerable two‐photon absorption cross‐section, and structural modifiability. This review discusses the molecular design strategies, recognition mechanisms, and both in vitro and in vivo bio‐applications (especially for diagnosis and therapy of tumors) of activatable dicyanomethylene‐4 H ‐pyran dyes. The final section describes the current shortcomings and future development prospects of this topic.