Halogen–Arene Interactions Assist in Self‐Assembly of Dyes

The “dye” is cast: An isodesmic self-assembly process of near-infared-absorbing, acceptor-substituted squaraine dyes, assisted by halogen–halogen and halogen–arene interactions, is observed in toluene. The aggregation process was monitored by UV/Vis/NIR absorption and NMR experiments, thus providing insight into the structural features (see figure; O red, I violet, N blue) as well as the binding strengths of the formed aggregates.