NIR-emitting squaraine J-aggregate nanosheets.

Click chemistry and Yamamoto coupling afforded an S-shaped π-scaffold composed of two directly connected dicyanomethylene-substituted squaraine dyes. This bis(squaraine) self-assembles into nanosheets in a cooperative self-assembly process, affording an absorption maximum at 886 nm and a fluorescence peak at 904 nm due to strong J-type exciton coupling.