Single-Phase Multicenter Luminescent Lanthanide-Organic Frameworks for Ratiometric Detection of Nitrofurantoin

The real-time and rapid detection of nitrofurantoin (NFT) levels is of significant value, as this antibiotic poses a threat to human health via food chain accumulation. Here, we show a multicenter luminescent lanthanide-organic framework ({[Tb₂(AIPA)(PIPA)(H₂O)_3.66(DMF)_0.34]·0.75DMF·4H₂O}_n, HBNU-22-Tb), which was prepared via solvothermal reaction using two coordinationally similar 5-aminoisophthalic acid (H₂AIPA) and 5-(pyridin-4-yl)isophthalic acid (H₂PIPA) as mixed ligands. HBNU-22-Tb crystallizes in the P1̅ space group with the pcu topology and displays a three-dimensional framework with a one-dimensional channel of 8.432 × 9.311 Ų, which is suitable for the entrance of NFT, demonstrating convenient ratiometric luminescent detection of NFT levels with an ultrahigh sensitivity of 1.42 × 10⁶ M^-1. In addition, isomorphic HBNU-22-Gd and HBNU-22-Tb_0.87Eu_0.13 were obtained to study the luminescence mechanism of the HBNU-22 family and the influence of introducing more luminescent sites on the detection sensitivity, respectively. The static sensing mechanism was attributed to highly effective photoinduced electron transfer and competitive absorption processes.