Fluorescence sensing of Cu2+ within a pseudo 18-crown-6 cavity

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, 1, with formula Zn₃(L₁)₂(CH₃COO)₂(H₂O)₂, has been successfully synthesized by the initial exploration of multidentate ligand H₂L₁-((E)-2,4-di-tert-butyl-6-((2-hydroxy-3-methoxybenzy-lidene)amino)phenol) with various metal ions under self-assembly reactions. Complex 1 is highly fluorescent in solution and as a solid, in addition to acting as a fluorescence sensor toward Ag^I in ethanol media. Compound 1 displays distinctive sensing of Ag^I 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 1 which interact with Ag^I; the ligands undergo oxidation cyclization reaction, leading to the formation of 2 with the formula Zn₃(L₂)₄(CH₃COO)₂·2CH₃CH₂OH·H₂O, and Ag^I reduction to elemental Ag powder. Compound 1 presents specific selectivity and sensitivity for Ag^I in ethanolic solution with a detection limit of 0.1722 μM. The orange color of 1 changes to colorless during the mixing of a small amount of Ag^I, revealing its potential practical application in naked-eye detection of Ag^I. Furthermore, 2 exhibits obvious fluorescence emission at 448 nm (λ_ex = 380 nm) and selectively responds to Cu^II over 11 kinds of metal ions with the fluorescence "turn-off" owing to the formation of 3 in ethanolic solution; it also has a detection limit of 0.0226 μM.

Enhanced fluorescent effect of graphitic C3N4@ZIF-8 nanocomposite contribute to its improved sensing capabilities

A novel graphitic carbon nitride (g-C₃N₄)@ZIF-8 nanocomposite was synthesized by a facile approach and applied as a fluorescent sensor.

A new rhodamine-based colorimetric chemosensor for naked-eye detection of Cu(2+) in aqueous solution

A new colorimetric probe 1 based on rhodamine B lactam was developed for naked-eye detection of Cu(2+). The optical feature of 1 for Cu(2+) was investigated by UV-vis absorption spectroscopy. Upon the addition of Cu(2+), the 1 displayed a distinct color change from colorless to pink, which can be directly detected by the naked eye. The stoichiometry of 1 to Cu(2+) complex was found to be 1:1 and the naked-eye detection limit was determined as low as 2 μM. The results suggest that the probe 1 may provide a convenient method for visual detection of Cu(2+) with high sensitivity.

Optical sensor: a promising strategy for environmental and biomedical monitoring of ionic species

In this review, we cover the recent developments in fluorogenic and chromogenic sensors for Cu²⁺, Fe²⁺/Fe³⁺, Zn²⁺and Hg²⁺.

A highly stable indium phosphonocarboxylate framework as a multifunctional sensor for Cu2+ and methylviologen ions

An indium phosphonocarboxylate framework (InPCF-1) with a novel 3,4,5-connected topology was synthesized, which serves as a selective and sensitive sensor for Cu²⁺ and MV²⁺ ions.

A novel 5-mercapto triazole Schiff base as a selective chromogenic chemosensor for Cu2+

A novel colorimetric cation sensor bearing phenol, thiol and HCN groups was designed and synthesized. In a DMSO/H2O (9:1, v/v) solution, the sensor exhibited highly selective recognition of Cu2+ among a range of metal ions tested. In the presence of Cu2+, solutions of the sensor underwent a dramatic color change from colorless to yellow, while the presence of other metal cations such as Zn2+, Pb2+, Cd2+, Ni2+, Co2+, Fe3+, Hg2+, Ag+ and Ca2+ had no effect on the color. The detection limit of the sensor toward Cu2+ is 8.0×10(-7) M and an association constant Ka of 4.3×10(5) M(-1) was measured. The sensing of Cu2+ by this sensor was found to be reversible, with the Cu2+-induced color being lost upon addition of EDTA.