Ratiometric fluorescent and visual detection of arginine with a dual-ligand MOF-based sensing platform

Developing an efficient sensing material to detect amino acids through different fluorescent changes is of great significance. Herein, a dual-emission luminescent material Eu(BTA)@Zr-MOF was fabricated via a simple dualligand strategy. BTA (benzoyl trifluoroacetone) was further incorporated into the framework to balance the emission of Eu3+ ions and ligand. Intriguingly, Eu(BTA)@Zr-MOF exhibits a unique luminescent color transition between acidic and basic solutions. Taking advantage of this phenomenon, a pH modulated luminescent system was constructed for the detection of arginine (Arg). The designed Eu(BTA)@Zr-MOF exhibited outstanding sensitivity, high selectivity and excellent anti-interference ability for Arg detection with variable colors. Moreover, the blue fluorescent at 465 nm was significantly enhanced, while the red emission of Eu3+ ions remained stable upon addition of Arg, thus establishing a ratiometric fluorescent platform with excellent performance for Arg detection. In addition, a portable smartphone-combined hydrogel was successfully constructed, realizing the on-site, visual and quantitative analysis of Arg.