Nonanuclear nanocluster of lanthanide as iron ion, nitrite ion and nitrobenzene sensor

In this study, we investigated both down-shifting and upconversion luminescence properties for a series of isostructural dual-lanthanide nanoclusters, [Tb_xYb_9-x(acac)₁₆(OH)₁₀](OH) (denoted as Tb_xYb_9-x and x = 1–8). Among them, Tb₈Yb₁ exhibits outstanding luminescent sensing performance, with high sensitivity and selectivity for detecting iron ions (Fe³⁺) in aqueous solution (K_sv = 1.41 × 10³ M⁻¹; LOD = 0.945 mM), nitrite ions (NO₂⁻) in aqueous solution (K_sv = 3.45 × 10⁶ M⁻¹; LOD = 0.382 µM), and nitrobenzene (NB) in methanol (K_sv = 1.15 × 10⁵ M⁻¹; LOD = 11.27 µM). We further prepared Tb₈Yb₁@PVA composite film by integrating Tb₈Yb₁ with polyvinyl alcohol (PVA). This composite was easily utilized for the detection of NB in methanol and proved to be recycled up to five times, demonstrating the practicality and efficiency of this sensing approach. The luminescence sensing mechanisms were demonstrated using powder X-ray diffraction (PXRD), ultraviolet–visible (UV–vis) spectroscopy, and density functional theory (DFT) calculations, providing valuable insights into the structure–property relationships. This work highlights the potential of lanthanide-based nanoclusters for sensitive and selective chemical sensing applications.