Tetra-imidazole functionalized pyrene for constructing Co-MOF and its application for sensing of cyanide ion

Exploring the Mechanism of Anionic Chemosensing by Imidazoles: A Review

Chemosensing of ions has gained considerable attention by chemists. Insight into the mechanism involved between sensors and ions always fascinates researchers to develop economical, sensitive, selective, and robust sensors. This review comprehensively explores the mechanism of interaction between Imidazole sensors and anions. With most of the research concentrating only on fluoride and cyanide, this review has highlighted a large gap in various anions detection including SCN^-, Cr₂O₇^2-, CrO₄^2-, H₂PO₄^-, NO₂^-, and HSO₄^-.This study also includes a critical analysis of different mechanisms and their respective limits of detection, with a discussion of the reported results.

A new zinc-organic framework with 1D channel for constructing a ratiometric Al3+-selective sensor and four inputs INHIBIT logic gate

To develop Al³⁺ fluorescent sensor is significant because the abnormal levels of Al³⁺ in environment may pose great threat to human body. Herein, a novel metal-organic framework {Zn(Dpada)(Imdba)·H₂O}_n (Dpada = 3, 6-di(1H-imidazol-1-yl) pyridazine and Imdba = 2, 2'-iminodibenzoic acid), named Zn-MOF, has been architected with one-dimensional channel under hydrothermal conditions. Zn-MOF exhibits good thermal and solvent stability and can also keep structural integrity over the pH range of 5.0 - 9.0. Fluorescent experiments show that Zn-MOF has high selectivity and sensitivity towards Al³⁺ via ratiometric fluorescence signal changes (F_{470 nm}/F_{390 nm}) and the detection limit is evaluated to be 0.69 μM. In addition, Zn-MOF performs good recyclability in sensing of Al³⁺ with at least 5 cycles. Besides, an INHIBIT logic gate has been constructed with chemical ions (Al³⁺, Cr³⁺, Fe³⁺ and Hg²⁺) as input signals and emission ratio (F_{470 nm}/F_{390 nm}) as output signal. Significantly, Zn-MOF can be applied to tracing Al³⁺ using real water samples, presenting great potential in water quality monitoring application.

Design of "turn-off" luminescent Ln-MOFs for sensitive detection of cyanide anions

Two novel 2D lanthanide metal-organic frameworks (Ln-MOFs), namely {[Eu₂(DBTA)₃(DMF)₂]·DMF}_n (1) and {[Tb₂(DBTA)₃(DMF)₂]·DMF}_n (2) (H₂DBTA = 2,5-dibromoterephthalic acid), have been successfully synthesized by the solvothermal method. Single-crystal X-ray diffraction results proved that the complexes possess the same topological structure of a (4²·6)₂(4²·8⁴)(4⁷·6³)₂-connected net. The recognition of CN^- from interfering anions with a low detection limit by "turn-off" luminescence makes them promising candidates for the highly selective and sensitive detection of the cyanide ion. The Ln-MOFs 1 and 2 exhibit excellent chemical sensing properties for CN^- with efficiency, selectivity, and excellent performance in various mixed anions. The evaluation parameters, including the quenching constant and detection limit, have been investigated to obtain the detection performance for CN^-.

Pyrene-Based AIE Active Materials for Bioimaging and Theranostics Applications

Aggregation-induced emission (AIE) is a unique research topic and property that can lead to a wide range of applications, including cellular imaging, theranostics, analyte quantitation and the specific detection of biologically important species. Towards the development of the AIE-active materials, many aromatic moieties composed of tetraphenylethylene, anthracene, pyrene, etc., have been developed. Among these aromatic moieties, pyrene is an aromatic hydrocarbon with a polycyclic flat structure containing four fused benzene rings to provide an unusual electron delocalization feature that is important in the AIE property. Numerous pyrene-based AIE-active materials have been reported with the AIE property towards sensing, imaging and theranostics applications. Most importantly, these AIE-active pyrene moieties exist as small molecules, Schiff bases, polymers, supramolecules, metal-organic frameworks, etc. This comprehensive review outlines utilizations of AIE-active pyrene-based materials on the imaging and theranostics studies. Moreover, the design and synthesis of these pyrene-based molecules are delivered with discussions on their future scopes.

Gold as a coordinator of an imidazole conjugated dye of BODIPY derivatives for the identification of simple mercaptans

Rapid detection of mercaptans in materials and the environment is of great help to material analysis and pollutant monitoring. Gold (Au) shows a high affinity to mercaptans. The coordination and steric effect of mercaptans to Au may be used for the development of new fluorescent sensors. It is possible to distinguish simple mercaptans (such as, HS^-, thioglycolic acid) from glutathione (GSH) using Au as a coordinator of dye. Herein, a water-soluble fluorescent sensor of an imidazole conjugated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivative (BIM) was characterized by spectroscopic methods. BIM showed a large Stokes shift and high affinity to metals. Especially, Au-combined BIM produced a new complex BIMAu showing improved fluorescence emission, which can be quenched by thioglycolic acid and sodium hydrosulfide, but less affected by GSH. The detection limit of thioglycolic acid was 0.014 µM. Both NaSH and thioglycolic acid coordinated with BIMAu, while GSH took Au³⁺ away from BIMAu. These results indicate that the gold coordination competition between imidazole-substituted dyes and mercaptans is a good method for the development of new fluorescence chemosensors.