C₃-Symmetric Propeller-like Phenanthridine Derivative with Multiple Write-In Modes for Programmable Anti-Counterfeiting

Multistimuli-responsive fluorescent molecules (PF-B and PF-N) with logically programmable states are synthesized, which utilize a phenyl ring and a nitrogen atom, respectively, as the center connected with three isolated electron-accepting phenanthridine units. Both PF-B and PF-N exhibit fluorescence color changes to trifluoroacetic acid, Al3+, Fe2+, rigidifying polymer matrix, and heat, resulting in five write-in modes. Meanwhile, PF-N presents a larger bathochromic shift than that of PF-B upon applying an identical stimulus, beneficial from its intramolecular charge transfer (CT) character. The multiple stimulus-responsive feature endows PF-B and PF-N with flexible and diverse applications, including rewritable and security printing, and multiple optical outputs for anti-counterfeiting. More importantly, the response of the fluorophores depends not only on the present stimulus but also on the sequence of past stimuli. Additionally, the build-in reversibility and irreversibility of their responses to different stimuli remarkably diversify the outputs, leading to a well-programmed anti-counterfeiting scheme based on “sequential + OR” logic gates for the first time. This work not only provides a feasible strategy to develop multiple stimuli-responsive luminescence materials at the molecular level but also offers a general design principle of logic schemes for advanced anti-counterfeiting and data protection.