Benzo[1,2‐c;4,5‐cʹ]bis[1,2,5]thiadiazole‐porphyrin‐based near‐infrared dyes

Abstract

Abstract Benzo[1,2‐c;4,5‐cʹ]bis[1,2,5]thiadiazole (BBT) has intrinsic diradical character and herein it is used to construct organic near‐infrared (NIR) dyes together with the aromatic porphyrin unit. Three BBT‐porphyrin hybrid dyes 1–3 with different linkage modes are synthesized by Pd‐catalyzed Sonogashira cross‐coupling between meso‐ethynylene porphyrin units and monobromo‐/dibromo‐ BBT, or through unexpected homocoupling between the BBT units. They all possess small open‐shell diradical character and display intense NIR absorption in the range of 800–1000 nm. They also exhibit amphoteric redox behavior. BBT‐based diradicaloids are thus good candidates for organic NIR dyes.

Keywords

• benzo[1,2‐c;4,5‐c']bis[1,2,5]thiadiazole
• diradical character
• near‐infrared dye
• porphyrin