Reusable polymeric films for fluorometric Al3+ detection in anti-counterfeiting and security applications

Abstract

The development of three types of hydrazide-derived polymeric probes for the selective fluorescent detection of Al3+ in aqueous media and their anti-counterfeiting and security applications are described herein. The detection of Al3+ among several metallic cations via formation of Al3+-ligand coordination complexes is successfully demonstrated. Upon addition of Al3+ ions to an aqueous solution of these polymers, complexes P1-Al3+, P2-Al3+, and P3-Al3+ are formed. They exhibit strong turn-on blue (lambda(em) approximate to 451 nm; Stokes shift =74 nm), green (lambda(em) approximate to 505 nm; Stokes shift =110 nm), and red (lambda(em) approximate to 597 nm; Stokes shift =137 nm) fluorescence emissions, respectively, via a metal chelation-enhanced fluorescence mechanism. Additionally, polymeric films obtained from the combination of P1, P2, and P3 mixtures in various proportions allow the observation of a full-color range of turn-on fluorescence in response to Al3+ ions. These polymeric films also display recyclability as processing with F- caused their complexes with Al3+ to dissociate. Finally, the polymeric films are applied to the printing of anti-counterfeiting quick response (QR) codes on paper. These printed QR codes are expected to be used as concealed and recyclable anti-counterfeiting security tools.