Eu(III)-organic complex as recyclable dual-functional luminescent sensor for simultaneous and quantitative sensing of 2,4,6-trinitrophenol and CrO42- in aqueous solution

Advance Progress on Luminescent Sensing of Nitroaromatics by Crystalline Lanthanide-Organic Complexes

Water environment pollution is becoming an increasingly serious issue due to industrial pollutants with the rapid development of modern industry. Among many pollutants, the toxic and explosive nitroaromatics are used extensively in the chemical industry, resulting in environmental pollution of soil and groundwater. Therefore, the detection of nitroaromatics is of great significance to environmental monitoring, citizen life and homeland security. Lanthanide-organic complexes with controllable structural features and excellent optical performance have been rationally designed and successfully prepared and used as lanthanide-based sensors for the detection of nitroaromatics. This review will focus on crystalline luminescent lanthanide-organic sensing materials with different dimensional structures, including the 0D discrete structure, 1D and 2D coordination polymers and the 3D framework. Large numbers of studies have shown that several nitroaromatics could be detected by crystalline lanthanide-organic-complex-based sensors, for instance, nitrobenzene (NB), nitrophenol (4-NP or 2-NP), trinitrophenol (TNP) and so on. The various fluorescence detection mechanisms were summarized and sorted out in the review, which might help researchers or readers to comprehensively understand the mechanism of the fluorescence detection of nitroaromatics and provide a theoretical basis for the rational design of new crystalline lanthanide-organic complex-based sensors.

A Novel 3D-Morphology Pyrene-Derived Conjugated Fluorescence Polymer for Picric Acid Detection

Aggregation-induced quenching (ACQ) is a hard problem in fluorescence material, leading to a poor utilization rate of fluorophores. In this work, 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) was synthesized and used as a precursor to build two kinds of fluorescence polymer. The TFFPy molecule with D2h symmetry can easily form polymers with C3 symmetry amines through the Schiff base reaction, making the resulting polymer a 3D amorphous material. Thus, ACQ of fluorophore can be reduced to minimum, making the most usage of the fluorescence of pyrene core. Fluorescence titration and DFT calculation can clearly prove this conclusion. The resulting CPs showed a highly sensitivity to picric acid, down to 3.43 ppm in solution, implying its potential in explosive detection.

Luminescent binuclear Zinc(II) organic framework as bifunctional water-stable chemosensor for efficient detection of antibiotics and Cr(VI) anions in water

To achieve the ultrastable LMOFs with predominant luminescent sensing performances, the aromatic π-electron mixed ligands strategy was introduced, and the ternary LMOF of {[Zn₂(HDDB)(bib)_1.5]·3H₂O}_n (1), was fabricated based on 3,5-di(2',4'-dicarboxylphenyl)benozoic acid (H₅DDB) and the N-donor of meta-bis(imidazol-1-yl)benzene (bib) under mixed solvothermal condition. LMOF 1 features the first reported 3D 3,4,4-c {6².8³.10}{6².8}₂{6³.8².10}₂ framework with 21.2 % porosity as well as high thermal and chemical stability. Further luminescent sensing showed that LMOF 1 as a bifunctional chemosensor possessing predominant detectability for sensitive detect the hexavalent chromates and nitroimidazoles/nitrofurans antibiotics in water through strong luminescent quenching effects, with excellent reusability as well as trace detection limits. Moreover, luminescent quenching mechanisms were further investigated from electron transfer and energy transfer viewpoints.

One-dimensional Europium-coordination polymer as luminescent sensor for highly selective and sensitive detection of 2,4,6-trinitrophenol

Three isostructural lanthanide coordination polymers (LnCPs), [Ln(L)₆(DMF)]_n {HL = 2-(2-formylphenoxy) acetic acid, Ln = Sm (1); Eu (2); Tb (3)} have been synthesized by solvothermal reaction and characterized. Single crystal analyses revealed that the architectures of these LnCPs own one dimensional chain which can be further packed into two-dimensional architectures by hydrogen bonds. Moreover, these LnCPs can offer strategically placed uncoordinated formyl groups, which may act as hydrogen-bond acceptor in the sensing of nitro explosives. Luminescence measurements reveal that LnCPs 2 and 3 exhibit strong luminescence in solid states. LnCP 2 shows quick, highly selective and sensitive detection of 2,4,6-trinitrophenol (TNP) with the high quenching constant (2.6 × 10⁴ M^-1) and low detection limit (3.39 μM), which indicates that LnCP 2 is more efficient than most of Eu-based coordination polymers for the sensing of TNP. Furthermore, LnCP 2 represents the first example of one-dimensional Eu-based sensors with formyl group as hydrogen-bonding site in the detection of TNP.