Carbazole-naphthalene based colorant with rub induced and alkali sensitive fluorescence for security printing and latent fingerprint development

New functional materials that exhibit fascinating optical features are highly valued due to their diverse applications in anticounterfeiting and forensic science. A novel carbazole-naphthalene Schiff base derivative, CNS is developed as a smart mechanofluorochromic pH-sensitive pigment for solvent based anti-counterfeiting ink. The screen prints on UV dull paper exhibit good substrate adherence and rub resistance. The inked region is weakly fluorescent under 370 nm UV light, but display intensified orange fluorescence upon rubbing, allowing easy print authentication. Different emission colors observed under various excitation wavelengths before and after rubbing, enhance the security elements. Further, the prints showcase NaOH triggered change in the fluorescence color. These covert features ensure document and product authenticity, offering robust data security and anti-counterfeiting measures. Further, the applicability of the ground CNS in forensic science is established to distinctly observe levels 1 to 3 details of latent fingerprints on non-porous and semi-porous surfaces.