Tetranuclear Cluster-Based Eu(III)-Metal-Organic Framework: Ratiometric Platform Design and Ultrasensitive Phenylglyoxylic Acid Detection

Phenylglyoxalic acid (PGA) is a typical metabolite produced by the invasion of styrene into the human body. The detection of PGA can not only reflect the health status of the human body but also assess the level of styrene contamination in the environment. Herein, a novel Eu(III)-MOF (Eu-ttpd) with excellent fluorescence properties was designed by employing the tetrazole-based ligand of 5-((4 '-(tetrazol-5 '-yl)benzyl)oxy) isophthalic acid (H(2)ttpd), which successfully used a fluorescent sensor for PGA. The as-synthesized Eu-ttpd features the unique 10-connected tetranuclear cluster [Eu-4(mu(3)-O)(2)(COO)(8)](4+) and exhibits a novel (3,10)-connected topological. Benefiting from the perfectly matched excited-state energy levels of the employed H(2)ttpd ligand with PGA, rapid photoinduced electron transfer (PET) and Dexter-ET can occur, which entitle Eu-ttpd a fast fluorescence quenching response to PGA with a remarkable LOD of 0.269 mu M. More importantly, by integrating Eu-ttpd and Mg,N-CDs into the polyacrylamide hydrogel, we optimized Eu-ttpd into a hydrogel sensor which exhibited enhanced detection ability (LOD = 0.052 mu M) accompanied by a distinguished color transformation (red-to-blue) and realized ultrasensitive and visual detection of PGA. This work offers an indication for the development of smart sensing materials for human health and environmental safety.

Automated summary

In this study, a novel Eu(III)-MOF fluorescent sensor (Eu-ttpd) was designed for rapid detection of PGA, and by integrating it into a hydrogel, ultrasensitive and visual detection of PGA was achieved.