Synthesis and Crystal Structure of a Tb(III)-MOF and Its Luminescent Sensing for Erythromycin, Tetracycline, and 3,5-Dinitrosalicylic Acid

A new MOF {[Tb2(L)3(H2O)2]·H2O·0.5CH3OH}n (1) was synthesized using rare earth metal Tb3+ and organic ligand 4,4′-dioxoacetic acid diphenylsulfone (H2L) via solvothermal reaction. Single-crystal X-ray diffraction experiments showed that 1 is three-dimensional. Additionally, the detailed fluorescence sensing properties of 1 were studied, where 1 effectively sensitizes the characteristic emission of Tb3+ through the antenna effect. Notably, 1 can recognize erythromycin (ERY), tetracycline (TC), and 3,5-dinitrosalicylic acid (DNSA) in water, exhibiting significant quenching effects, with detection limits of 1.92 × 10–8 M, 2.73 × 10–7 M, and 2.21 × 10–7 M, demonstrating high selectivity and sensitivity. Based on these findings, a fluorescent test strip was developed for real water sample detection of ERY, TC, and DNSA. 1 demonstrated stable luminescence over a wide pH range and excellent water stability, making it suitable for various environmental conditions. The possible fluorescence quenching mechanism was also discussed. Time-resolved luminescence decay and XPS characterizations reveal distinct quenching pathways that are not dominated merely by the inner filter effect: dynamic collision quenching for ERY, synergistic competitive absorption and photoinduced electron-transfer effects for TC, and ground-state intermolecular interactions coupled with selective quenching of short-lived defect sites for DNSA.