Lanthanide conjugated colour-tunable luminescent hydrogels as direct printable inks for anticounterfeiting and forensic applications

Abstract

Counterfeiting is a global concern that jeopardizes individuals, businesses, and nations, costing trillions of USD annually. To combat this, researchers are continuously developing strong security features to formulate anti-counterfeiting inks. Herein, a novel approach has been adopted to prepare advanced luminescent hydrogel with ligand H3BTC for important applications in authentication of goods and fingerprint detection. In present investigations, Tb3+ and Eu3+ ions conjugated H3BTC hydrogels have been synthesized which emits strong green (542 nm) and red (614 nm) colours under UV lamp (254 nm). Additionally, the colour tunability for intermediate colours i.e. yellow and orange have also been achieved by varying the concentrations of Eu and Tb in H3BTC hydrogel. These hydrogels can be directly printed on any substrate using conventional screen-printing techniques. Moreover, these hydrogels can directly be used for thumb impressions with green and red emissions under 254 nm UV lamp, while appearing white in normal light and making them promising for new alternative solutions to design next-generation security ink for anticounterfeiting and forensic applications.