Turn-up Luminescent Sensing of Ultraviolet Radiation by Lanthanide Metal-Organic Frameworks

Smartphone-integrated paper-based sensing platform for the visualization and quantitative detection of pymetrozine

Pymetrozine (PYM) is an effective pyridine insecticide for controlling aphids, while its residues pose a serious threat to human health. Herein, a europium complex (Eu-DBPA, DBPA represents deprotonated 2,5-dibromoterephthalic acid ligand) probe was prepared for the detection of PYM via fluorescence quenching. The detection process has the advantages of short response time (2 min), wide linear range (0-4 and 4-45 mg/kg) and low detection limit (2.2 μg/kg). Furthermore, a portable detection platform was designed by integrating Eu-DBPA-based paper strip with smartphone and applied for the visual detection of PYM in real cucumber, tomato, cabbage and apple samples, obtaining satisfactory recovery (99.00 %-107.00 %) and low standard deviation (RSD < 3.4 %). In addition, a logic gate device was designed to simplify the detection process. The smartphone-integrated paper-based probe detection platform provides a new strategy for intelligent and online identification of hazards in environmental and biological samples.

AIE Ligand-Based Luminescent Ln-MOFs for Rapid and Selective Sensing of Tetracycline

The design of highly stable and dual-emission lanthanide metal-organic frameworks (Ln-MOFs) is promising for practical chemical sensor applications. Rational design and synthesis of photoresponsive organic ligands provide a feasible approach to achieving highly fluorescent dual-emission Ln-MOFs. In this study, a tetraphenylpyrazine-based AIE ligand, H4L, was synthesized and combined with lanthanide ions (including Sm3+, Eu3+, Gd3+, and Tb3+) to fabricate a series of Ln-MOFs named Ln-L. The single-crystal analysis revealed that all Ln-L belonged to the tetragonal space group P4212 and featured a 2-fold interpenetrated 3D structure. Leveraging rational design, Eu-L exhibited a sensitive response to tetracycline, making it a promising fluorescence sensor for tetracycline detection. The experiments demonstrated that Eu-L could rapidly and quantitatively detect tetracycline and its analogs within 30 s. The lowest detection limits for tetracycline, oxytetracycline, and chlortetracycline were 0.43, 0.92, and 0.81 μM, respectively. Additionally, the probe displayed excellent reusability and exceptional selectivity. A plausible sensing mechanism was proposed, supported by both experimental and theoretical analyses. Furthermore, the study discovered that on-site and real-time determination of TCs in aqueous solutions could be achieved by using luminescence test papers and composite films derived from Eu-L.

A ratiometric radio-photoluminescence dosimeter based on a radical excimer for X-ray detection

A novel radio-photoluminescence material featuring fluorochromic responses toward UV or X-ray irradiation has been obtained. Such a unique monomer- to excimer-based luminescence transition allows for dosimetry of ionizing radiation in a ratiometric manner. Rather than quenching the luminescence, the radiation-induced radical species of Th-105 boost the excimer emission, rendering it as a rare material possessing radical-excimers.

Cage Bismuth Metal-Organic Framework Materials Based on a Flexible Triazine-Polycarboxylic Acid: Subgram Synthesis, Application for Sensing, and White Light Tuning

Bismuth-based metal-organic frameworks (MOFs) have always attracted the attention of many researchers. Here, we first report a crystalline Bi-MOF (Bi-TDPAT) based on a flexible triazine-polycarboxylic linker 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine (H₆TDPAT) and bismuth nitrate; its crystallite quality is adequately good and the diffraction data can be collected directly by single crystal X-ray diffraction rather than 3D electron diffraction. The structure of Bi-TDPAT belongs to a novel topology type btt. Notably, the synthesis scale of Bi-TDPAT can be expanded, and sub-gram synthesis can be realized. At the same time, we synthesized a microcrystalline material Bi-TATAB utilizing 2,4,6-tris(4-carboxylphenylamino)-1,3,5-triazine (H₃TATAB). The structures of the two materials were characterized by several microanalysis tools. Considering that Bi-TDPAT is a blue light-emitting material with a broad emission peak, we prepared a white light emitting composite material Eu/Tb@Bi-TDPAT by encapsulating Eu(III)/Tb(III) in Bi-TDPAT. In addition, the fluorescence sensing functions of Bi-TDPAT and Bi-TATAB were explored. The results showed that they could detect and recognize various nitrophenols, and the optimal limit of detection is as low as 0.21 μM, which can be reused even after five cycles. Energy competitive absorption (CA) and photo-induced electron transfer are the main sensing mechanisms. By comparing and analyzing the properties of these two bismuth-based crystalline materials, we believe that this work also provides inspiration for the synthesis and development of bismuth-based MOF in the future.