Metal–organic framework-5 as a novel phosphorescent probe for the highly selective and sensitive detection of Pb(II) in mussels

Abstract

Lead ion (Pb(II)) has emerged as a major mussel pollutant in recent decades, thus the development of sensors capable of detecting Pb(II) is of considerable interest. In this work, a novel, rapid, and “turn-on” phosphorescent sensor was developed to monitor Pb(II) using metal-organic framework-5 (MOF-5, Zn4O(TPA)3, TPA: terephthalic acid) as a highly selective and sensitive luminescent probe. A mechanism describing the leaching of Zn(II) from Zn4O complexes and self-assembly of TPA after Pb(II) coordination is proposed for the MOF-5-Pb(II) system. Using enhanced phosphorescence, the sensor displays a wide linear detection range of 0.01−10 μmol/L and a low detection limit of 2 nmol/L for the determination of Pb(II). Moreover, it is noteworthy that when immobilized in a polyethylene glycol (PEG) film, the MOF-5 probe exhibited a visually distinct color change at 1.0 μmol/L Pb(II) under 365 nm UV light. From these results, a test strip was prepared for semi-quantitative analysis of Pb(II) content. Finally, the proposed phosphorescent sensor was successfully utilized to detect Pb(II) content in mussel. This study demonstrates the first MOF-based “turn-on” phosphorescent sensor for monitoring Pb(II), from which future high-performance phosphorescent sensors to determine food pollutants may be developed.