Synthesis of Two New Dinuclear Lanthanide Clusters and Visual Bifunctional Sensing Devices Based on the Eu Cluster

Abstract The development of visual and multifunctional sensors, and further the fabrication of portable sensing devices is of great importance. Herein, two dinuclear lanthanide clusters are designed, and their accurate molecules are determined to be [Ln ₂ (DFBA) ₆ (dmp) ₂ (H ₂ O) ₂ ] (Ln ³⁺ = Eu ³⁺ ( 1‐Eu ) or Tb ³⁺ ( 1‐Tb ), HDFBA = 3,4‐difluorobenzoic acid, dmp = 4,7‐dimethyl‐1,10‐phenanthroline), by single‐crystal X‐ray diffraction. Interestingly, 1‐Eu shows rapid detection of ferrous ions (Fe ²⁺ ) and acetylacetone (acac), with the limit of detection (LOD) as low as 5.6 and 1.0 ppb, respectively. LOD of 5.6 ppb for Fe ²⁺ is far lower than the standard of World Health Organization (0.3 ppm, SDWA) and Chinese rural water quality standards (0.5 ppm, GB25467‐2010) for drinking water. As far as it is known, 1‐Eu is the most sensitive chemosensor for the detection of acac; the sensing can be discriminated by the naked eyes under 365 nm UV light. Furthermore, portable sensing devices of agarose gel, test paper, and sprayed films on plastic tube, glass, coin, test paper, stone, leaf, carbon rod, and iron sheet surfaces, based on 1‐Eu solution, are fabricated by facile methods, with visual and quick detection of Fe ²⁺ in water under various conditions, and show excellent recyclable sensing performance for acac vapor.