A Trinuclear Zinc Coordination Cluster Exhibiting Fluorescence, Colorimetric Sensitivity, and Recycling of Silver Ion and Detection of Cupric Ion.

The detection and reusage of transition-metal ions play a crucial role in human health and environmental protection. Recently, various analytical methods and substances have been successfully applied to probe or sense silver ions; however, rare representative examples have been presented regarding the simultaneous detection of silver and silver recycling with the elemental silver powder form. Herein, an unparalleled sensing mechanism for silver ions and recycling silver in its elemental form is exemplified by a fluorescent trinuclear zinc coordination cluster possessing the dual function of colorimetric sensing of silver and responding cupric ions. A Schiff-base-based trinuclear zinc coordination cluster, , with formula Zn(L)(CHCOO)(HO), has been successfully synthesized by the initial exploration of multidentate ligand HL-(()-2,4-di--butyl-6-((2-hydroxy-3-methoxybenzy-lidene)amino)phenol) with various metal ions under self-assembly reactions. Complex is highly fluorescent in solution and as a solid, in addition to acting as a fluorescence sensor toward Ag in ethanol media. Compound displays distinctive sensing of Ag through the fluorescence quenching effect at 576 nm and signal augment at 446 nm over 11 kinds of cations in the absence of interference. The proposed sensing mechanism is attributed to the ligands in which interact with Ag; the ligands undergo oxidation cyclization reaction, leading to the formation of with the formula Zn(L)(CHCOO)·2CHCHOH·HO, and Ag reduction to elemental Ag powder. Compound presents specific selectivity and sensitivity for Ag in ethanolic solution with a detection limit of 0.1722 μM. The orange color of changes to colorless during the mixing of a small amount of Ag, revealing its potential practical application in naked-eye detection of Ag. Furthermore, exhibits obvious fluorescence emission at 448 nm (λ = 380 nm) and selectively responds to Cu over 11 kinds of metal ions with the fluorescence "turn-off" owing to the formation of in ethanolic solution; it also has a detection limit of 0.0226 μM.