A robust Eu-MOF as a multi-functional fluorescence sensor for detection of benzaldehyde, Hg2+, and Cr2O72-/CrO42-

In this work, a novel Eu-MOF, {[Eu2(L)(phen)2(ox)2(H2O)2]·10H2O·phen}n (H2L = 2,6-bis(4-carboxyphenyl)pyrazine, phen = 1,10-phenanthroline), was assembled under hydrothermal conditions with good water stability and pH stability. The Eu-MOF could be used as a luminescent sensor for detecting gas/liquid benzaldehyde, Hg2+ and Cr2O72-/CrO42- with high sensitivity and selectivity based on luminescence quenching effects. The sensing mechanisms were systematically studied by ICP-AES, PXRD analysis and UV–vis spectroscopy. In addition, the Eu-MOF shows high adsorption of Hg2+ and can be successfully used to quantitatively detect Hg2+ in real samples such as tap water, green tea, and river water. The sensor exhibited a recovery rate in the range of 99.84 %∼102.34 % for detecting Hg2+. The portable fluorescent paper strips based on the Eu-MOF were also successfully fabricated, which can detect benzaldehyde both in gas and liquid phases. The fluorescence sensing system based on Eu-MOF provides a reference for the construction of portable environmental pollutant monitoring sensors.