Revisiting Croconaine Dyes: a Glimpse into their Applications in Bioimaging, Therapy and Metal Detection

Abstract Croconaine dyes have been repeatedly mentioned in scientific literature for their applications in imaging and photothermal therapy. However, they have not been adequately researched and represented compared to their more well-known analog, squaraine dyes. Although croconaine dyes exhibit favorable properties such as absorption in the near infra-red region and thermal stability upon laser light irradiation, the full realization of these properties for potential applications has not gained considerable attention. While numerous reviews on squaraine dyes are available, the corresponding number for croconaine dyes remains relatively insignificant. The current study aims to revisit the long-known oxocarbon analog, citing literature concerning its applications in various fields, especially analyte detection, photothermal therapy, and biological theranostics, thereby re-establishing its significance.