Disrupting J‐Aggregation in Triazatruxene Dimers to Develop Responsive Luminescent Inks for Anti‐Counterfeiting Applications

Abstract The fight against counterfeiting is a crucial concern for economies around the world, underscoring the urgent need for effective measures to ensure the legitimacy of products and documents. Luminescent security inks have emerged as effective tools in this battle. The third generation of these inks, incorporating stimuli‐responsive organic materials, enables unique efficiency. In this work, the stimuli‐responsive behavior of three trialkylated triazatruxene dimers ( TRI1 , TRI2 , and TRI3) , endowed with N ‐alkyl chains of different length is investigated. Among them, TRI3 , with three flexible dodecyl chains, shows remarkable stimuli‐responsive fluorescence that is attributed to thermally or shear‐induced phase transitions between a tetragonal columnar phase and a discotic‐nematic liquid crystal phase. Such transformation involves the breakdown of highly emissive J‐aggregates with a strong influence on the resulting emissive color. Interestingly, these stimuli‐triggered transformations are spontaneously reversed, which renders this compound very interesting in the search of third‐generation security inks.