An imidazole functionalized copper(II)‐organic framework for highly selective sensing of picric acid and metal ions in water

Abstract

An imidazole functionalized metal–organic framework (MOF), [Cu(HL)(H2O)]·(H2O)·(DMA) (HBU‐166, H3L = 4,4′,4″‐(1H‐imidazole‐2,4,5‐triyl)tribenzoic acid, DMA = N,N‐dimethylacetamide) was synthesized and characterized by single‐crystal X‐ray diffraction. HBU‐166 was observed as a two‐dimensional MOF and showed good stability in water, an acidic solution (pH = 4), and an alkaline solution (pH = 9). HBU‐166 exhibited ligand‐based luminescence with a blue shift, which could be attributed to the coordination effect. Moreover, HBU‐166 could be applied to detect nitroaromatic compounds (NACs) and metal ions in water with preferable selectivity and sensitivity. In particular, HBU‐166 could be used as a promising luminescent sensor for picric acid (PA) with enhancement of emission intensity. The mechanism for PA detection likely involved electron transfer and weak interaction between ligand and electron‐deficient of NACs at the beginning to increase the emission intensity. Additionally, HBU‐166 exhibited excellent selectivity in the sensing of 4‐nitrophenol and Fe3+ through fluorescence quenching.

Fusing rigid planar units to engineer twisting molecules as dual-state emitters

“…45 Previous studies have shown that the introduction of imidazole as a functional group in molecules could achieve specific recognition of picric acid (PA) over various nitroaromatic compounds (NACs) by exhibiting a characteristic change in spectroscopy and/or luminescent color owing to the protonbinding nature of imidazole. [46][47][48] Since PA is considered a hazard that is widely used in powerful explosives, plasticizers, and pharmaceuticals, 49,50 the development of PA sensors in recent years has attracted considerable attention. A fluorescence titration assay was carried out to assess the sensing performance.…”

Synthesis, Crystal Structure and Catalytic Performance of a novel Five‐Coordinated Energetic Copper(II) Compound

“…Some of these materials are kinds of 1D, 2D and 3D crystal materials formed by selfassembly of organic ligands (mainly aromatic compounds and azole compounds) with metal ions. [1][2][3][4] Imidazole, a kind of pentacyclic heterocyclic compound with one potential coordination nitrogen atom and three carbon atoms, [5][6][7][8][9] a kind of high nitrogen coordination compound, could be easy to coordinate with metal ions in a variety of coordination ways with a small volume. It also can reduce the steric hindrance and it is pentacyclic heterocyclic compound containing two potential coordination nitrogen atoms and three carbon atoms with relatively small volume, which may reduce steric hindrance and improve spatial bonding structure.…”

Imidazole-Based Metal–Organic Framework for the “On1–Off–On2” Fluorescence-Based Detection of Picric Acid and the Adsorption of Congo Red

“…The 1D chain SBUs are further linked by the backbone of the H 3 L ligands to form a 3D framework structure with {3 5 9.4 8 2.5 12 } {3 6 4.4 8 3.5 6 } topology (Figure d). The porosity of HBU-168 is 0.3466 according to the calculation results …”

“…Nitroaromatic compounds (NACs), metal ions, and dyes are frequently used in the processing of raw materials and synthesis of fine chemicals, pharmaceuticals, dyestuffs, spices, explosives, and pesticides; as a result, they are frequently released as waste, making them targets for sensing and adsorption. − For example, p -nitrophenol is used to prepare the over-the-counter drugs paracetamol and phenacetin. The aromatic rings, such as phenyl rings, in NACs have characteristic electronic effects that can result in changes in the properties of MOFs upon interaction. , For example, aromatic compounds having electron-withdrawing nitro groups can result in the formation of an electron-deficient environment in the MOFs.…”

“…The porosity of HBU-168 is 0.3466 according to the calculation results. 16 The powder X-ray diffraction (PXRD) pattern of HBU-168 is shown in Figure S2, which is almost identical to the simulated pattern obtained from the single-crystal X-ray structure, indicating phase purity. The thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) data are shown in Figure S3.…”