Recent Advances in Croconaine Dyes for Bioimaging and Theranostics.

Croconaine (CR) dyes, the donor-acceptor-donor (D-A-D) type zwitterionic compounds with extended π-conjugation, can be readily synthesized via a straightforward condensation reaction. They have received much attention in bioimaging and theranostics, owing to their tailored structures and fascinating near-infrared (NIR) photophysical properties. In this topical review, we summarize the recent advances in biomedical applications for CR dyes. First, we introduce the classification and optical performance of CR dyes. Next, we highlight the chemistry and applications of CR dyes in bioimaging and theranostics. Finally, the summary and prospects of CR dyes for bioimaging and theranostics are discussed.