Supra‐Cyanines: Ultrabright Cyanine‐Based Fluorescent Supramolecular Materials in Solution and in the Solid State

Abstract Fluorescent materials with high brightness play a crucial role in the advancement of various technologies such as bioimaging, photonics, and OLEDs. While significant efforts are dedicated to designing new organic dyes with improved performance, enhancing the brightness of existing dyes holds equal importance. In this study, we present a simple supramolecular strategy to develop ultrabright cyanine‐based fluorescent materials by addressing long‐standing challenges associated with cyanine dyes, including undesired cis‐trans photoisomerization and aggregation‐caused quenching. Supra‐cyanines are obtained by incorporating cyanine moieties in a cyclic peptide‐based supramolecular scaffold, and exhibit high fluorescence quantum yields (up to 50 %) in both solution and in the solid state. These findings offer a versatile approach for constructing highly emissive cyanine‐based supramolecular materials.