ABSTRACT
In recent years, due to the abuse of antibiotics, nitro explosives and pesticides, which have caused great harm to the environment and human health, social concerns have prompted researchers to develop more sensitive detection platforms for these pollutants. In this paper, a novel two-dimensional Zn (II) coordination polymer, [Zn(L)0.5(1,2-bimb)]·DMF (1), [H4L=[1,1':4',1''-terphenyl]-2, 2'',4, 4'' -tetracarboxylic acid, 1,2-bimb = 1,2-bis(imidazol-1-ylmethyl)benzene] was synthesized using a hydro-solvothermal method. Among commonly used organic solvents, 1 exhibits significant stability. Fast and efficient fluorescence response can be achieved for tetracycline (TET), 4-nitrophenol (4-NP), fluazinam (FLU), and abamectin benzoate (AMB) with low detection limits. A binary intelligent logic gate device with FLU and AMB as chemical input signals is successfully constructed, which provides a new idea for biochemical detection. In addition, a portable visual test paper has been prepared, which has high sensitivity, good selectivity, and simple operation. It can be used for rapid detection of pollutants in daily life and has broad application prospects. Finally, a detailed discussion was conducted on the fluorescence sensing mechanism of 1 for detecting TET, 4-NP, AMB and FLU.
Subject(s)
Nitrophenols , Pesticides , Spectrometry, Fluorescence , Tetracycline , Nitrophenols/analysis , Nitrophenols/chemistry , Tetracycline/analysis , Pesticides/analysis , Spectrometry, Fluorescence/methods , Limit of Detection , Water Pollutants, Chemical/analysis , Zinc/analysisABSTRACT
A Cd-based metal-organic framework (Cd-MOF), named after {[Cd(ttc)(H2O)]·H2O}n (ttc = 1-imidazole-1-yl-2,4,6-benzene-tricarboxylic acid), was synthesized using the solvothermal reaction. The single-crystal structure was determined by single X-ray diffraction analysis, and crystalline characteristics and composition were confirmed by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TG), respectively. Structural analysis showed that the Cd2+ ion is in the seven-coordinated mode, in which ttc2- ion adopts the µ4-η1-η1-η2-η2 coordination mode. It is worth noting that the Cd2+ ion is connected to ttc2- to form a 2D network, and the adjacent 2D network is expanded into a 3D supramolecular network structure through weak hydrogen bonds. The fluorescence sensing experiments indicated that Cd-MOF could not only be used as a fluorescence sensor for Fe3+, fluazinam (FLU), and 2,4,6-trinitrophenolol (TNP) but also for sulfasalazine detection in aqueous solution. To verify the sensitivity of the fluorescent probe, we calculated its detection limit: 5.34 × 10-8 M (Fe3+), 7.8 × 10-8 M (FLU), 1.21 × 10-7 M (TNP), and 2.67 × 10-7 M (SECT). In addition, the quenching mechanism was thoroughly studied.
ABSTRACT
The construction of sensors with specific recognition functions can easily, sensitively and efficiently detect heavy metal ions, which is a demand in the field of electrochemical sensing and an important topic in the detection of environmental pollutants. An electrochemical sensor based on MOFs composites was developed for sensing of multiplex metal ions. The large surface area, adjustable porosities and channels in MOFs facilitate successful loading of sufficient quantities highly active units. The active units and pore structures of MOFs are regulated and synergetic with each other to enhance the electrochemical activity of MOFs composites. Thus, the selectivity, sensitivity and reproducibility of MOFs composites have been improved. Fortunately, after characterization, Fe@YAU-101/GCE sensor with strong signal was successfully constructed. In the presence of target metal ions in solution, the Fe@YAU-101/GCE can efficiently and synchronously identify Hg2+, Pb2+, and Cd2+. The detection limits (LOD) are 6.67 × 10-10 M(Cd2+), 3.33 × 10-10 M(Pb2+) and 1.33 × 10-8 M (Hg2+), and are superior to the permissible limits set by the National Environmental Protection Agency. The electrochemical sensor is simple without sophisticated instrumentation and testing processes, hence promising for practical applications.
ABSTRACT
Due to the indiscriminate abuse of pesticides and antibiotics has caused serious threats to the environment and human and animal bodies, the detection of antibiotics and pesticides has attracted widespread attention in recent years. Herein, a novel 2D Cd (II)-MOF, [Cd(L)0.5(1,2-bimb)] (Cd-L-1,2-bimb), [H4L = 1, 1'-ethylbiphenyl -3, 3', 5, 5'- tetracarboxylic acid, 1, 2-bimb = 1, 2-bis[(1H-imidazol-1-yl) methyl] benzene] is synthesized. Cd-L-1,2-bimb has excellent stability in different organic solvents and in the range of pH 1.1-12.5. Cd-L-1,2-bimb exhibits high selectivity, high sensitivity, and fast luminescent response to pesticides [pyrimethanil (PTH, LOD = 2.2 µM) and abamectin benzoate (AMB, LOD = 2.39 µM)] and antibiotic contaminants tetracycline (TET, LOD = 0.13 µM). Cd-L-1,2-bimb displays discriminative fluorescence when detecting AMB and PTH, and is an implication logic gate. Finally, the possible detection mechanism of Cd-L-1,2-bimb toward different pollutants is also further investigated. This MOF-based multifunctional sensor opens up new prospects for environmental monitors.
Subject(s)
Metal-Organic Frameworks , Pesticides , Humans , Cadmium , Water , Benzoates , Tetracycline , Anti-Bacterial Agents/analysisABSTRACT
A highly stable heterometallic MOF, {[(Me2NH2)2]·[Cd2K2(L)2(H2O)]}n (H4L = terphenyl-2, 2', 4, 4'-tetracarboxylic acid) (1), was synthesized. 1 featuring one-dimensional channels can efficiently detect Aspartic acid with a low limit of detection (LOD) value (2.5 µM). More interestingly, 1 can encapsulate Eu3+ and sensitize the visible-emitting characteristic fluorescence of Eu3+ in aqueous solution. Then, Eu3+@CdK-MOF is found to be an excellent fluorescence sensor for the detection of Ornidazole (ODZ) and the portable ODZ test paper is also successfully designed. Eu3+@CdK-MOF can also be used as fluorescent ink to write some words. The words can be hidden when treated with acid vapor and then the words can be restored when treated with alkaline vapor. More importantly, the hidden information can be read repeatedly. Therefore, this reversible light-emitting and reusable property have great potential for development in information encryption and decryption and information storage.
Subject(s)
Metal-Organic Frameworks , Ornidazole , Aspartic Acid , Cadmium , Limit of DetectionABSTRACT
A stable luminescent Cd-MOF, formulated as [Cd(L)0.5(4, 4'-bpy)0.5]·H2O (1), (H4L = 1, 1'-ethylbiphenyl -3, 3', 5, 5'- tetracarboxylic acid, 4, 4' -bpy = 4, 4'-bipyridine), is acquired under solvothermal conditions. 1 exhibits stability in the pH range from 1.5 to 12.2 and in different organic solvents. 1 can detect tetracycline and nitrobenzene by fluorescence quenching with high sensitivity and selectivity. The detection limits are 0.14 µM and 14 nM, respectively. Interestingly, 1 can encapsulate Tb3+ and sensitize its characteristic peaks. Moreover, the fluorescent ink is prepared by using the luminescent properties of the Tb3+@Cd-MOF. The light of the fluorescent ink disappears in an acid gas HCl atmosphere and then reappears in an alkaline gas ammonia atmosphere. This phenomenon can be repeated and the reason for this phenomenon is also explained in the article. Therefore, Tb3+@Cd-MOF has huge application potential in information encryption.