Detection of heavy metal ion in real samples with fiber based paper based on new rare earth cluster

Chromium (Cr) is an important material, but also one of the most toxic heavy metal pollutants, showing great threat to human health and ecological environment, thus, accurate and rapid detection of Cr³⁺ has far-reaching significance. In this work, based on the ligand of 2,3,4,5,6-pentafluorobenzoic acid (HPFBA) that does not contains oscillation effect group such as "CH, OH, and NH bond", three rare earth dinuclear cluster of Ln₂(PFBA)₆(phen)₂(H₂O)₂ (Ln = Tb³⁺1-Tb, Eu³⁺1-Eu, Gd³⁺1-Gd, phen = 1,10-phenanthroline) were obtained. 1-Tb shows excellent stability and luminescence properties. In depth investigation reveals that 1-Tb shows quick detection towards Cr³⁺ in water through luminescence "turn-off", with extremely short response time of 1.0 min, very low limit of detection (LOD) of 5.2 ppb and no interference from other ions. The LOD value is much lower than the total content of chromium for water in China (15 ppm, GB9078-1996). In the actual environment such as tap water, lake water, human, and serum, 1-Tb shows excellent detection and recovery rate for Cr³⁺. More interestingly, a fiber based paper of test paper that based on 1-Tb and ordinary filter paper was fabricated, which can probe Cr³⁺ by visible color changes to the naked eye under UV light.