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A terbium-based metal-organic framework (MOF) with exceptional water stability for highly selective detection of pesticide thiamethoxam (TMX) in aqueous solution is reported. To date, most reported lanthanide metal-organic frameworks (Ln-MOFs) still exhibit poor water stability, which may limit their practical applications in bio-sensing and detecting pollutants in environmental water samples. In this work, a Tb-MOF [Tb(BDC) 1.5 (DEF)·0.5H 2 O] n (1, BDC = 1,4-benzene dicarboxylate, DEF = N , N -diethylformamide) was prepared by hydrothermal reactions of 1,4-benzenedicarboxylic acid with the corresponding rare earth ions of Tb 3+ . Impressively, water stability surveys of compound 1 indicated that it maintained at least 90% of its emission intensity after storage in water for several months. This characteristic of long water stability is unusual as compared to other Ln-MOFs, making compound 1 an excellent candidate for sensing applications in the aqueous phase. In particular, the green emission of compound 1 could be quenched by the pesticide thiamethoxam (TMX), which was attributed to both the static and dynamic quenching processes based on an upward-curving Stern-Volmer plot. The quenching mechanism was speculatively attributed to the inner filter effect combined with the complex formation based on the electrostatic interaction of compound 1 and TMX, resulting in the promotion of the quenching efficiency. Finally, compound 1 was demonstrated to detect TMX in aqueous solution with rapid response and high selectivity., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Three supramolecular architectures, [Cu 2 (dpds) 2 (C 5 O 5 ) 2 (H 2 O) 4 ]·3H 2 O ( 1 ), [Cu(dpds)(C 5 O 5 )]·3H 2 O ( 2 ), and [Cu 2 (dpds) 2 (C 5 O 5 ) 2 ]·9H 2 O·C 2 H 5 OH ( 3 ) (dpds = 4,4'-dipyridyldisulfide and C 5 O 5 2- (croconate) = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), have been synthesized and structurally characterized. Compound 1 contains two crystallographically independent Cu(II) ions, which are both distorted octahedral geometry with elongation along the croconate- and H 2 O-bound axial positions and bonded with two N atoms of two dpds, two O atoms of one C 5 O 5 2- , and two H 2 O molecules. Two crystallographically independent dpds ligands, both adopting the bis-monodentate bridging mode, connect two Cu(II) ions to form a one-dimensional zigzag chain-like coordination polymer. In 2 and 3 , there are two and three crystallographically independent Cu(II) ions, respectively, which are all distorted octahedral geometries with elongation along the croconate-bound axial positions six-coordinated and bonded with two N atoms of two dpds ligands in cis- or/and trans-forms and four O atoms of two C 5 O 5 2- ligands. The dpds ligands in 2 and 3 all adopt the bis-monodentate bridging mode, and the C 5 O 5 2- ligands act as bridging ligands with bridging bis-bidentate through three C 5 O 5 2- oxygen atoms in 2 and bridging bis-bidentate through four adjacent C 5 O 5 2- oxygen atoms in 3 , respectively, linking the Cu(II) ions to generate a two-dimensional layered and a three-dimensional metal-organic framework, respectively. The structural diversity and dimensionality observed in 1 - 3 may be attributed to the cis- or/and trans-coordination sphere of Cu(II) centers with two dpds ligands and the coordination modes of croconate ligands. Thermal stability and in situ temperature-dependent structural variations of 1 - 3 have been verified by thermogravimetric analysis and powder X-ray diffraction measurements. Compounds 1 and 3 both exhibit water vapor capture behaviors with hysteresis isotherms., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)